Whole apples, smoothie, or juice: Effects on blood glucose and insulin

The varying health effects of eating fruit, as compared to drinking juice or smoothies, are often discussed. Curiously though little actual scientific research is directly cited showing the metabolic effects of eating fruit or drinking juice. This strange absence of data inspired me to search for myself to see what experimental results I could find in the literature. Somewhat surprisingly, I had to go back quite a way to find any research study describing such a comparison published in the Lancet on October 1st 1977 titled:

Depletion and disruption of dietary fibre. Effects on satiety, plasma-glucose, and serum-insulin

These researchers from the Bristol Royal Infirmary and the Long Ashton Research Station were interested in testing the fibre hypothesis, proposed by Thomas L. Cleave and detailed in his 1974 book ‘The Saccharine Disease’. Cleaves’ proposition was that the consumption of refined, fibre-depleted, carbohydrates results in overnutrition and obesity and diabetes, due to reduced satiety and excessive insulin secretion.

To compared the presence or absence of fibre they compared whole apples, pureed apple, and apple juice with all the fibre removed. The apple purée, what would now be called a smoothie, represents a food in which the fibre is present but the physical structure of the food disrupted. Based in the south-west of England and having the expertise from the Long Ashton Research Station, a small government agricultural research institute specialising in apples, and other fruit production, the apple seems the natural choice of experimental fruit.

The researchers involved went to quite some length to make the study as well controlled as possible. All the apples used were Golden Delicious apples, harvested from a single plot of land. The apple juice was made by pressing fresh apples, removing any traces of fibre, and then pasteurised. Each meal contained 60 grams of carbohydrate, equal to 482 grams of whole apple, roughly three apples. The apple smoothie was blended just before consumption with 150 millilitres of water added. To make sure everything was equal the volunteers also drank 150 millilitres of water with the whole fruit and juice.

The apples, smoothie, and juice was fed to ten healthy volunteers (rather honestly reported as all being staff in the department) aged between 24 and 40, with a healthy body weight, and importantly with a good set of teeth. These volunteers fasted overnight and avoided any alcohol for 24 hours before each test meal.

Blood glucose responses

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After eating the apples blood sugar increased, peaking at 30 minutes, and then quickly fell back to the fasting levels by 60 minutes. Blood sugar rose to the same level after drinking the smoothie or juice. What was more interesting is what happened after the blood sugar levels fall back down.

Instead of returning to normal levels after drinking the smoothie or juice the volunteers blood sugar dropped below fasting levels and remained lower for at least a couple of hours.

To see if drinking fast or slow influenced this effect the volunteers first drank their smoothie or juice fast as they wanted, and then in a second test drank gradually over the same time they had taken to eat their whole apples. Curiously, drinking slowly or quickly didn’t make any difference to their blood sugar response.

Insulin responses

apple-insulin

Insulin also peaked around 30 minutes after eating the whole apples and then dropped back to normal levels. After drinking the apple juice slowly, the volunteers’ insulin peaked at almost double the level it reached after eating the apples whole. Curiously, insulin did not reach such a high level after drinking the apple juice quickly. The insulin response to drinking apple smoothie was somewhere in between, but still higher than eating the apples whole. As with the juice, when they drank the smoothie quickly their insulin did not increase as much.

 

Surprisingly, the fibre in whole apples did not slow down the rise in blood sugar after eating compared to juice, as if often claimed. More worryingly, the effect of juice or smoothie seemed to be to disrupt the normal mechanisms that keep blood sugar under control after the initial blood sugar rise after eating. The rebound fall in blood sugar in the second and third hours after drinking the smoothie or juice was in stark contrast to the steady levels seen after eating the apples.

The greater rises in insulin after drinking the apple juice or smoothie means that more insulin was needed to keep blood sugar the same. Although drinking quickly reduced the peak in insulin a bit it didn’t help prevent the rebound drop in blood sugar. This means that removing the fibre from the apple, or even just breaking up the physical structure of the fibre, contributes to disrupting the normal mechanisms that regulate blood sugar and insulin after drinking it, compared to eating the fruit whole.

If repeated regularly these inappropriately insulin responses and falls in blood sugar after drinking juice seem unlikely to be very good for you.  In real world situations apple juice or smoothies are likely to be drunk in greater amounts than would be eaten as whole apples, further exacerbating these effects.

Additional points of interest

One volunteer in the study had to be excluded from the analysis as “…soon after her apple meal, she passed several watery stools containing obvious particles of fruit.” Almost half a kilo of apple was obviously too much for this poor woman. Another volunteer, after drinking the apple juice, showed blood sugar levels below 2.0 mmol/l (36 mg/dl), a very low level! These unusual findings are rarely reported in research papers now but do go to show how individual people can be in their responses.

Reference

Lancet. 1977 Oct 1;2(8040):679-82.
Depletion and disruption of dietary fibre. Effects on satiety, plasma-glucose, and serum-insulin.
Haber GB, Heaton KW, Murphy D, Burroughs LF.

Abstract:

“Ten normal subjects ingested test meals based on apples, each containing 60 g available carbohydrate. Fibre-free juice could be consumed eleven times faster than intact apples and four times faster than fibre-disrupted purée. Satiety was assessed numerically. With the rate of ingestion equalised, juice was significantly less satisfying than purée, and purée than apples. Plasma-glucose rose to similar levels after all three meals. However, there was a striking rebound fall after juice, and to a lesser extent after purée, which was not seen after apples. Serum-insulin rose to higher levels after juice and purée than after apples. The removal of fibre from food, and also its physical disruption, can result in faster and easier ingestion, decreased satiety, and disturbed glucose homoeostasis which is probably due to inappropriate insulin release. These effects favour overnutrition and, if often repeated, might lead to diabetes mellitus.”

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One week of food: Part 2. Friday – Sunday.

<<<For the first post of this weeks food see here.

The weekend usually involves more cooking for me and it is when I do my main shopping. This includes a visit to the supermarket, which is some walk away, and also stopping into my local butchers and fishmongers to stock up on food for the week.

Friday

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Breakfast consisted of porridge made from pinhead oats (steel cut) cooked with water and with honey and clotted cream on top. This was accompanied by a black coffee.

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Lunch at work of two bowels of oxtail, barley, and vegetable stew along with a punnet of cherries and a black coffee.

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Dinner: Beer and more of the same stew.

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Dessert: Clotted cream and cherries with some honey on top.

Saturday

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Breakfast: Pinhead oatmeal porridge cooked in the pressure cooker topped with cherries and pecans with some honey on top.

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Lunch: Caprese salad with some fresh tomatoes and mozzarella bought that morning on my weekly shopping trip to the big supermarket.

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Evening snack: A mince and mealie pie (ground beef and oatmeal pie) bought from my local butchers in the morning.

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Dinner: Fresh herring coated in oatmeal and marsh samphire from my local fishmonger with beetroot, onions, mushrooms, dulse, potatoes, and kale.

Sunday

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Brunch: Grilled kipper (cold smoked whole herring), marsh samphire, a fried duck egg, and left-over onion, mushroom, and dulse from the night before. This was followed by a some Scottish raspberries.

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Afternoon snack: Half a packet of pecans and a punnet of cherries.

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Dinner: Beef liver and poached duck eggs from my local butcher, with onion, mushroom, and leek with some mashed potato and butter.

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Dessert was a white grapefruit.

 

So there we have a week of my food shaped by both my tastes, available time and seasonal food (a lot of cherries), and my personal choices regarding health and nutrition.

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One week of food: Part 1. Monday – Thursday.

Tell me what you eat, and I will tell you what you are.”

– Brillat-Savarin.

So said Jean Anthelme Brillat-Savarin, famed epicure and gastronome. What he would think of me from my food I do not know, perhaps lacking in the multiple courses and elegant French desserts of Brillat-Savarin’s own table. Being rather inept at remembering to keep a written diary I decided, out of interest, to keep a photographic record of everything I eat for one week. Whether this is of interest to anyone else I do not know. My diet is not set in stone, nor constant, and tends to evolve over time. Nor is it something I recommend for everyone or expect everyone to like as I eat the way I do for my own reasons. While it is difficult for the the observer not to alter what they are observing I shall attempt to eat as I usually do. So without further ado, on to breakfast.

This weeks food was to a large extent based on food cooked at the weekend, supplemented with some a few freshly cooked additions. As I am currently finishing up my PhD my time during the week is limited making cooking ahead more important. Particularly at busy and stressful times I find that eating nutritious and delicious food is important to maintain my health.

Monday

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Breakfast: 12 o’clock.

A late breakfast at work as I didn’t feel very hungry in the morning. Black coffee made in the cafetiere. The oxtail stew was made and the weekend and stockpiled in the fridge for the week. This consisted of a oxtail broth together with the meat of the bones, pot barley, parsnips, carrots, onion, kale, frozen peas, and dulse. While not always the most photogenic food, it is very satisfying, nutritious, and filling. The cherries are British grown and as they are currently in season, and delicious, I am making the most of them.

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Lunch: 4 pm

More of the same oxtail, pot barley, and vegetable stew.

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Dinner: 8 pm

Dinner consisted of a manx kipper (a whole smoked herring), a soft boiled local duck egg, with a mix of cooked kale, fresh broad beans, onion, and a tin of smoked oysters. The duck egg and vegetables had been cooked at the weekend and were reheated from the fridge. Plus a Hobgoblin Gold beer to finish.

Tuesday
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Breakfast: 8 am.

Duck eggs and whole grain rice, with kale, smoked mussels, fresh broad beans, and onion plus butter. All the food was cooked on sunday and reheated this morning. Plus a black coffee. As I had leftover food to use up this morning my breakfast was larger than it often is and I was feeling in need of something substantial. Even for breakfast plating food attractively is quite important to me even on a normal morning, I like my food to look nice.

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Lunch: 1 pm.

More oxtail, barley, and vegetable stew made at the weekend, cherries, and black coffee. I made the effort to actually go outside for lunch today as the weather was good for once, braving the seagulls that commonly patrol such areas of Aberdeen. Again premake food in the form of weekend stew makes for a substantial ready made lunch to take to work.

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Late afternoon snack: 5 pm. More oxtail stew.

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Dinner: 8pm.

Cold dinners are comparatively rare for me, as I live in a cold, damp northern climate hot dinners are rather more satisfying. But as it is summer and the weather is still closer to what would generally be called “warm” I am making the effort to with some good buffalo mozzarella and British grown tomatoes. Currently on my third can of a four-pack of Wychwood Hobgoblin Gold.

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Dessert: 9 pm.

The season for British cherries is to short not to be taken full advantage of. They also combine well with some Cornish clotted cream and heather honey.

Wednesday.

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Breakfast: 9 am

Steelcut oatmeal cooked in my pressure cooker with cherries, pecans, and honey.

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Dinner: 5 pm

An early dinner, as no lunch today, of oxtail, barley and vegetable stew and some beef cheek, butter bean and vegetable stew.

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Dessert: 9 pm

Strawberry cheesecake Häagen-Dazs and another beer.

Thursday

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Breakfast: 10 am

Beef cheek, butter bean, and vegetable stew.

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Afternoon snack: 2 pm

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Dinner: 9 pm

Oxtail, barley and vegetable stew and some beef cheek, butter bean and vegetable stew. Together with a scotch whisky.

 

For the rest of the week see the next post here>>>

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Bone Broth, Gelatine, Oxalate, and Kidney Stones

Bone broth, also known as stock, is recently back in fashion with many purported health benefits. I will admit my own bias in being rather a fan of some good bone broth and suspect it is a beneficial component of the diet, although good research is currently still rather lacking.

However, it is important not to idolise particular foods, as almost all foods have some potential downsides. Therefore, I was interested to find a potential downside to bone broth in the link between broth, gelatine, oxalate, and kidney stones. This may seem unlikely as bone broth does not contain any oxalate, but bear with me as this first requires a diversion into the formation of kidney stones and where oxalate comes from.

Kidney stones

Kidney stones are really quite common, affecting about 1 in 10 people at some point in their lives. Most (~90%) kidney stones are formed of crystals of calcium and oxalate. Crystals of calcium oxalate begin to form when the concentration of calcium and oxalate reaches a high enough concentration. This means that a higher concentration of oxalate in the kidneys is a risk factor for developing kidney stones. As oxalic acid is found in a variety of foods, patients with recurrent kidney stones are often advised to limit their intake of foods containing a lot of oxalate. However, the oxalate from food only makes up a proportion of the oxalic acid in excreted from by the kidney, with estimates of between 24% and 53% originating from the diet (Holmes 2001).

Hydroxyproline metabolism

The rest of the oxalate passing through the kidneys is produced by the body itself. Oxalate is the final step in the breakdown of a common amino acid called hydroxyproline. Collagen is the major structural protein in the body and also the most abundant protein making up from 25% to 35% of all the protein in the body. Mostly found in fibrous tissues such as tendons, ligaments, and skin. It is also abundant in corneas, cartilage, bones, blood vessels, the gut, spinal discs, and the dentin in the teeth. Normally, the collagen in our connective tissues turns over at a very slow and controlled rate and is always slowly being broken down and rebuilt. This constant renewal of collagen requires the body to remove excess amino acids released during the process.

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The metabolic pathways of hydroxyproline metabolism into oxalate. Source: (Knight 2006).

The daily turnover of collagen from your own body is a major source of hydroxyproline. Just turning over your own collagen accounts for 5-20% of the urinary oxalate daily (Knight 2006). Excess hydroxyproline goes through a complex metabolic pathway in the liver. The majority of the hydroxyproline in this pathway is actually converted into another amino acid, glycine, and used for other purposes. There remainder is finally converted to oxalic acid and glycolate, which are excreted by the kidneys.

Bone broth gelatine contains hydroxyproline

Amino_Acid_Composition_in_Gelatin_chart

“Amino Acid Composition in Gelatine chart” by Hugahoody

We now return to bone broth of which hydrolysed collagen, better known as gelatine, is the main protein. It is gelatine that makes a good broth gel when cooled and contains the particular composition of amino acids that are currently making broth a popular health food. You can see from the pie chart below that hydroxyproline (Hyp) makes up 12% of the amino acids in gelatine. After eating broth or gelatine the body suddenly has a lot of hydroxyproline to deal with and a proportion of this is converted into oxalate.

A ten gram dose of gelatine increases hydroxyproline in the blood

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Change in blood hydroxyproline (Hyp) (inset), glycolate (■), and oxalate (–▲–) after ingestion of 10 g of gelatine. Source: (Knight 2006).

When gelatine is consumed there is a rise in the amount of hydroxyproline in the blood for several hours. In a fascinating paper from 2007, John Knight and his colleagues fed ten subjects thirty grams of supplemental gelatine and then measured their blood and urine. From their graph below you can see that the hydroxyproline (Hyp) levels rapidly rose in the blood and remained up to four times higher for several hours. However, oxalate levels in the blood are more tightly controlled and did not rise.

A ten gram dose of gelatine increases oxalate in the urine

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Amount of glycolate (■) and oxalate (–▲–)  in the urine following ingestion of 10 grams of gelatine. Source: (Knight 2006).

In comparison, the amount of oxalate in the urine increased for at least eight hours after consuming the gelatine. Oxalate concentration in the urine reached nearly five times higher a few hours after ingesting gelatine. This is due to the kidneys clearing oxalate out of the body as fast as it is being produced. This ten gram dose of gelatine would contain about a gram of hydroxyproline.

Lower doses of gelatine also increase oxalate in the urine

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Increases in urinary oxalate (■) and glycolate (□) excretion over fasting levels in a 6 hour period following ingestion of various amounts of gelatine. Source: (Knight 2006).

This is all very well you may say, but ten grams of gelatine is rather more than most people consume in one go. Well, the authors quite rightly followed this up with a range of doses of gelatine more commonly found in the diet. You can see from the graph below that one and two gram doses had little impact on the amount of hydroxyproline. Between five and ten grams of gelatine, there was a significant increase in both hydroxyproline in the blood and oxalate in the urine. Interestingly, 12 grams is the serving of gelatine recommended by a popular geleatine supplement company, just to give perspective on the amounts involved.

Relevance

It would be appropriate now to ask how relevant this information is. There is certainly no study on people who consume bone broth or gelatine regularly and their risk of kidney stones. There is some epidemiological evidence that suggests it may be relevant. This comes from studies comparing meat intake and vegetarians. A recent study has found an association between meat intake and kidney stones, with a significantly reduced risk of stones occurring in vegetarians or people eating less meat (Turney 2014). The hydroxyproline content of meat products is suspected to play a role in this increased risk. Meat is the main source of gelatine in most peoples’ diets and a hundred grams of beef can contain a few grams of collagen. Of course, this cannot be treated as conclusive evidence as it is only an association. In an older study, meat intake – which contains collagen and hydroxyproline – was linked to increasing oxalate excretion, but only in a subgroup of men with unexplained recurrent kidney stones (Nguyen 2001).

Implications

The research presented here is not a intended to scare people away from bone broth, stock, gelatine, or meat. Most people never get kidney stones and even for those who do, there are a number of factors that influence stone development. However, it is a potential factor that may be important for some people to know. As is it not commonly discussed, some people may not make a connection between broth or gelatine intake and kidney stones. If you need to reduce your oxalate levels, caution may be needed when taking extra gelatine or bone broth.

References
Holmes RP, Goodman HO, Assimos DG. (2001) Contribution of dietary oxalate to urinary oxalate excretion. Kidney International. 59(1):270-6.
http://www.ncbi.nlm.nih.gov/pubmed/11135080
“BACKGROUND: The amount of oxalate excreted in urine has a significant impact on calcium oxalate supersaturation and stone formation. Dietary oxalate is believed to make only a minor (10 to 20%) contribution to the amount of oxalate excreted in urine, but the validity of the experimental observations that support this conclusion can be questioned. An understanding of the actual contribution of dietary oxalate to urinary oxalate excretion is important, as it is potentially modifiable.
METHODS: We varied the amount of dietary oxalate consumed by a group of adult individuals using formula diets and controlled, solid-food diets with a known oxalate content, determined by a recently developed analytical procedure. Controlled solid-food diets were consumed containing 10, 50, and 250 mg of oxalate/2500 kcal, as well as formula diets containing 0 and 180 mg oxalate/2500 kcal. Changes in the content of oxalate and other ions were assessed in 24-hour urine collections.
RESULTS: Urinary oxalate excretion increased as dietary oxalate intake increased. With oxalate-containing diets, the mean contribution of dietary oxalate to urinary oxalate excretion ranged from 24.4 +/- 15.5% on the 10 mg/2500 kcal/day diet to 41.5 +/- 9.1% on the 250 mg/2500 kcal/day diet, much higher than previously estimated. When the calcium content of a diet containing 250 mg of oxalate was reduced from 1002 mg to 391 mg, urinary oxalate excretion increased by a mean of 28.2 +/- 4.8%, and the mean dietary contribution increased to 52.6 +/- 8.6%.
CONCLUSIONS: These results suggest that dietary oxalate makes a much greater contribution to urinary oxalate excretion than previously recognized, that dietary calcium influences the bioavailability of ingested oxalate, and that the absorption of dietary oxalate may be an important factor in calcium oxalate stone formation.”
Knight J, Jiang J, Assimos DG, and Holmes RP. (2006) Hydroxyproline ingestion and urinary oxalate and glycolate excretion Kidney International. 70(11): 1929–1934.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2268952/
“Endogenous synthesis of oxalate is an important contributor to calcium oxalate stone formation and renal impairment associated with primary hyperoxaluria. Although the principal precursor of oxalate is believed to be glyoxylate, pathways in humans resulting in glyoxylate synthesis are not well defined. Hydroxyproline, a component amino acid of collagen, is a potential glyoxylate precursor. We have investigated the contribution of dietary hydroxyproline derived from gelatin to urinary oxalate and glycolate excretion. Responses to the ingestion of 30 g of gelatin or whey protein were compared on controlled oxalate diets. The time course of metabolism of a 10 g gelatin load was determined as well as the response to varying gelatin loads. Urinary glycolate excretion was 5.3-fold higher on the gelatin diet compared to the whey diet and urinary oxalate excretion was 43% higher. Significant changes in plasma hydroxyproline and urinary oxalate and glycolate were observed with 5 and 10 g gelatin loads, but not 1 and 2 g loads. Extrapolation of these results to daily anticipated collagen turnover and hydroxyproline intake suggests that hydroxyproline metabolism contributes 20−50% of glycolate excreted in urine and 5−20% of urinary oxalate derived from endogenous synthesis. Our results also revealed that the kidney absorbs significant quantities of hydroxyproline and glycolate, and their metabolism to oxalate in this tissue warrants further consideration.”
Turney BW, Appleby PN, Reynard JM, Noble JG, Key TJ, Allen NE.(2014) Diet and risk of kidney stones in the Oxford cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC).European Journal of Epidemiology. 29(5):363-9.
http://www.ncbi.nlm.nih.gov/pubmed/24752465
“The lifetime prevalence of kidney stones is around 10 % and incidence rates are increasing. Diet may be an important determinant of kidney stone development. Our objective was to investigate the association between diet and kidney stone risk in a population with a wide range of diets. This association was examined among 51,336 participants in the Oxford arm of the European Prospective Investigation into Cancer and Nutrition using data from Hospital Episode Statistics in England and Scottish Morbidity Records. In the cohort, 303 participants attended hospital with a new kidney stone episode. Cox proportional hazards regression was performed to calculate hazard ratios (HR) and their 95 % confidence intervals (95 % CI). Compared to those with high intake of meat (>100 g/day), the HR estimates for moderate meat-eaters (50-99 g/day), low meat-eaters (<50 g/day), fish-eaters and vegetarians were 0.80 (95 % CI 0.57-1.11), 0.52 (95 % CI 0.35-0.8), 0.73 (95 % CI 0.48-1.11) and 0.69 (95 % CI 0.48-0.98), respectively. High intakes of fresh fruit, fibre from wholegrain cereals and magnesium were also associated with a lower risk of kidney stone formation. A high intake of zinc was associated with a higher risk. In conclusion, vegetarians have a lower risk of developing kidney stones compared with those who eat a high meat diet. This information may be important to advise the public about prevention of kidney stone formation.”
Nguyen QV, Kälin A, Drouve U, Casez JP, Jaeger P. (2001) Sensitivity to meat protein intake and hyperoxaluria in idiopathic calcium stone formers. Kidney International. 59(6):2273-81.
http://www.ncbi.nlm.nih.gov/pubmed/11380831
“BACKGROUND: High protein intake is an accepted risk factor for renal stone disease. Whether meat protein intake affects oxaluria, however, remains controversial in healthy subjects and in stone formers. This study was designed (1) to test the oxaluric response to a meat protein load in male recurrent idiopathic calcium stone formers (ICSFs) with and without mild metabolic hyperoxaluria (MMH and non-MMH, respectively), as well as in healthy controls, and (2) to seek for possible disturbed vitamin B(6) metabolism in MMH, in analogy with primary hyperoxaluria.
METHODS: Twelve MMH, 8 non-MMH, and 13 healthy males were studied after five days on a high meat protein diet (HPD; 700 gmeat/fish daily) following a run-in phase of five days on a moderate protein diet (MPD; 160 g meat/fish daily). In both diets, oxalate-rich nutrients were avoided, as well as sweeteners and vitamin C-containing medicines. Twenty-four-hour urinary excretion of oxalate was measured on the last day of each period, along with 4-pyridoxic acid (U(4PA)) and markers of protein intake, that is, urea, phosphate, uric acid, and sulfate. Serum pyridoxal 5′ phosphate (S(P5P)) was measured after protein loading.
RESULTS: Switching from MPD (0.97 +/- 0.18 g protein/kg/day) to HPD (2.26 +/- 0.38 g protein/kg/day) led to the expected rise in the urinary excretion rates of all markers of protein intake in all subjects. Concurrently, the mean urinary excretion of oxalate increased in ICSFs taken as a whole (+73 +/- 134 micromol/24 h, P = 0.024) as well as in the MMH subgroup (+100 +/- 144 micromol/24 h, P = 0.034) but not in controls (-17 +/- 63 micromol/24 h). In seven ICSFs (4 MMH and 3 non-MMH) but in none of the healthy controls (P = 0.016, chi square), an increment in oxaluria was observed and considered as significant based on the intra-assay coefficient of variation at our laboratory (8.5%). There was no difference in S(P5P)nd U(4PA)etween the groups after protein loading.
CONCLUSION: Approximately one third of ICSFs with or without so-called MMH are sensitive to meat protein in terms of oxalate excretion, as opposed to healthy subjects. Mechanisms underlying this sensitivity to meat protein remain to be elucidated and do not seem to involve vitamin B(6) deficiency.”
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Victorian Flour Sourdough Bread

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Victorian flour sourdough bread – first attempt.

My previous experiments with sourdough bread sparked my interest in what other old varieties of wheat flour were available to try. Particularly those originating from, and grown in, the British Isles. It seems curious that while there has been a resurgence of interest in traditional varieties of many other food, wheat is still treated as an undefined commodity. The variety of wheat used to produce the flour is rarely mentioned, excepting the few ancient varieties of wheat like spelt of einkorn wheat that are still grown as specialty food crops.

Through searching online for heritage British wheat flour I found Bakery Bits, with an online store selling a variety of baking ingredients including a fascinating range of traditional flours from a guy called John Letts under the brand  Lammas Fayre.

“Lammas Fayre flour by John Letts at Heritage Harvest is a very special range of heritage and ancient English organic flours available online exclusively from BakeryBits.

The product of over a decade of sweat and academic rigour, John Letts has collected an extensive range of historically and botanically authentic cereals. All grown organically on farms in Buckinghamshire and Wiltshire, John grows them the traditional way, that is, in mixed populations (strains) that are well suited to local growing conditions.

Modern cereals are grown one strain at a time and for huge, uniform yields. These cereals need to be mollycoddled since they cannot cope with variable climates, pests or diseases. Growing mixed populations, the traditional way, ensures that there is always a reasonable crop – and the ancient cereals are adapted to seek the nutrients they need from unfertilised soil: the modern strains need to be pampered with lots of fertilisers.

The flour that John makes from these cereals are rare (no one else has them) and in many cases, once gone, they will be unavailable until the following harvest.

All the flours are excellent for artisan bread bakers and are perfect for those wanting to try something new (…or old).”

This resulted in my purchase of a range of the flours currently available.  The first one I tried baking with was the Victorian Blend White Flour.

“Lammas Fayre’s Victorian Blend white flour is milled from a mix of 19th century bread wheat (Triticum aestivum) varieties grown organically at Collings Hanger Farm in the village of Prestwood in Buckinghamshire, and at Sheepdrove Organic Farm in Wiltshire. Stoneground and roller milled flours are blended to create a delicious, light cream-coloured flour ideal for baking bread, cakes, scones and biscuits.”

This flour is smooth and very powdery to the touch due to the roller milling of some of the flour, a method that became common during the Victorian period. This time I decided to use some of the flour to make a sourdough starter of the same flour before baking, rather than using a rye starter, as I had previously done. My first attempt pictured above, produced an attractive but rather flat loaf, not helped by my forgetting about it and leaving it baking in the oven too long. The dough was rather runny, the same proportions as I used before seemed to contain too high a proportion of water. The second loaf I made with this flour reduced the amount of water added by 50 grams.

Recipe

For the sponge:

  • 150 grams of starter – made of equal weight of Victorian flour and water.
  • 250 grams of Victorian flour.
  • 225 grams of water.

For the dough:

  • 300 grams of Victorian flour.
  • 10 grams of fine sea salt.
  • 1 table spoon of olive oil.
  • 1 tablespoon of honey.

Otherwise the method of baking was the same as in my previous post. The addition of honey was on a whim, as I am generally rather a fan of honey, and it resulted in a very dark brown crust due to the added sugars.

The second loaf using this recipe produced a stiffer dough and a loaf that rose higher. It would have produced a better looking loaf it I’d scored the dough more deeply when putting it into the oven.

I’m looking forward to trying more of the heritage Lammas Fayre wheat flours.

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Victorian flour sourdough bread – second attempt.

 

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Evidence of decreasing mineral density in wheat grain over the last 160 years

The wheat that we eat today has changed a great deal over the past century. The “Green Revolution“, the breeding of semi-dwarf, higher-yielding cultivars of wheat, and other cereal crops, has led to greatly increased grain production and crop yields since the mid-1960s. This undoubtedly contributed to the alleviation of global food shortages, however, modern plant breeding over the past sixty years has aimed for higher crop yields with little attention paid to the nutritional quality of the resulting cereal grains (Morris and Sands 2006). Increased yields of grain may have caused a reduction in the amounts of minerals in the grain, although this is difficult to test as the mineral contents can vary due to a wide range of factors including the plant variety, soil conditions, climate, and fertilizer treatment.

The Broadbalk Wheat Experiment

bottomcollageA study in 2008 aimed to limit these variable factors with the use of historic stored wheat samples from the Broadbalk Wheat Experiment. Started in 1843 and continuing to the present day this fascinating experiment has occupied 5 hectares of rural Hertfordshire, divided in the parallel plots, and tested different fertilizers and manure treatments on the most popularly grown wheat varieties of the day. All the while recording rainfall, temperatures, and storing away wheat and soil samples each year. In some of these plots, acting as controls, have varied little in their fertilizer treatments since the beginnings of the experiment.

Making use of these stored samples of grain, in their study in the Journal of Trace Elements in Medicine and Biology, Ming-Sheng Fan and her colleagues analysed the amounts of zinc, copper, iron, magnesium and phytate over the many years of the experiment.

Declining mineral content

Wheat minerals 1

Figure 1. Trends in wheat grain yield (a), harvest index (b), Zn (zinc) (c), Fe (iron) (d), Cu (copper) (e), and Mg (magnesium) (f) concentrations in wheat grain from three plots of the Broadbalk Experiment since 1845.

Beginning in the 1960s there is a clear trend for reductions in zinc, iron, copper, and magnesium. Between 1840 and 1960 the levels of these minerals had remained constant. This coincided with the increased yields due to the switch to new semi-dwarf wheat varieties. Between 1968–2005 in semi-dwarf cultivars, grain zinc, copper and magnesium concentrations decreased significantly in all plots. To quote the authors of the study,

“Mean concentrations in 2000–2005 were lower than the means of the long-straw cultivars by 33–49% for Zn, 25–39% for Cu and 20–27% for Mg. Grain Fe concentration did not show a significant decreasing trend during 1968–2005, but the mean concentrations were 23–27% lower than those of the 1845–1967 period. The trends of grain P, Mn, S and Ca (data not shown) were broadly similar to those of Zn, Cu and Mg…”

This could be due to the dilution effect, meaning that the grain is growing larger with the same mineral content, however the yields in Figure 1 suggest this is not the case. This shows that even in unfertilised wheat, where wheat yield did not increase, there was still the same drop in mineral content since the 1960s.

Direct direct comparison between the old and new cultivars

Between 1988 and 1990 in the  Broadbalk Experiment, an old tall variety of wheat called Squarehead’s Master was grown side-by-side with a modern semi-dwarf variety of wheat called Brimstone. This confirmed the previous trends as the Brimstone wheat had 18–29% lower concentrations of zinc, copper, iron and magnesium than Squarehead’s Master wheat.

Soil mineral concentrations

A common notion when discussing the nutrient content of modern food is that conventional farming causes a depletion of mineral nutrients in the soil, resulting in lower mineral concentrations in grain. To test for this the study authors measured stored soil samples from the past 160 years. Perhaps surprisingly they found that the concentrations of the minerals studied either remained the same or actually increased over the last 160 years. For sake of completeness they also measured the bioavailability of the minerals to the plants and found that the concentrations of bioavailable zinc, copper, and magnesium had all increased substantially over the last 160 years.

Phytate content of the wheat

The trends in the amount of phytate in the wheat was also measured as this is one of the best known modulators of mineral bioavailability in cereal grains. The ratio of phytate to minerals in the wheat declined over time.  This means there was more phytate relative to the amount of minerals and suggests that those minerals may be less well absorbed.

Conclusions

The declining mineral content of wheat reported in this study suggest that the Green Revolution of the 1960s has had an unintentional side effect decreasing mineral density in the wheat grain. This was due to the changes in the varieties of wheat grown, rather than farming practices, or use of extra fertiliser. The authors speculate one potential reason for this,

“Dwarfing of wheat cultivars is achieved by the introduction of the gibberellin-insensitive Rht genes [24]; as a result, proportionally more photosynthates are distributed to the grain. It is unlikely that the dwarfing genes would have a pleiotropic effect on the uptake of several mineral nutrients from the soil. A more plausible explanation is that the re-distribution of minerals from the vegetative tissues to grain does not catch up with the much enhanced re-distribution of photosynthates in the short-straw cultivars.”

Translated into English:

The reduced height (Rht) genes cause the wheat grow to a shorter height by making the wheat unresponsive to gibberellin, the equivalent of a plant growth hormone. Photosynthates are the sugars produced in the plant through photosynthesis, using energy from the sun. Growing shorter means less energy is needed for growth and more of those sugars are transported into the grain where they are formed into starch.

The authors speculate that the faster rate of sugars being transported in the grain and the resulting faster starch accumulating in the grain is not matched by an increase in minerals transported through the plant. So the overall density of minerals is reduced.

A limitation to this study was that only whole grain samples were analysed, as many people consume only refined white flour with much of the bran removed, where much the minerals are found. It would be interesting to know how much these decreases in mineral content has affected the minerals found in the starchy endosperm of the wheat, the part used to make white flour.

Still, even if you eat whole grain wheat products, due to the use of modern high-yielding wheat cultivars, you are unlikely to be consuming the same amounts of minerals as you would have done eating wheat 100 years ago.

References:

Fan MS et al (2008) Evidence of decreasing mineral density in wheat grain over the last 160 years. Journal of Trace Elements in Medicine and Biology. 2008;22(4):315-24
“Wheat is an important source of minerals such as iron, zinc, copper and magnesium in the UK diet. The dietary intake of these nutrients has fallen in recent years because of a combination of reduced energy requirements associated with sedentary lifestyles and changes in dietary patterns associated with lower micronutrient density in the diet. Recent publications using data from food composition tables indicate a downward trend in the mineral content of foods and it has been suggested that intensive farming practices may result in soil depletion of minerals. The aim of our study was to evaluate changes in the mineral concentration of wheat using a robust approach to establish whether trends are due to plant factors (e.g. cultivar, yield) or changes in soil nutrient concentration. The mineral concentration of archived wheat grain and soil samples from the Broadbalk Wheat Experiment (established in 1843 at Rothamsted, UK) was determined and trends over time examined in relation to cultivar, yield, and harvest index. The concentrations of zinc, iron, copper and magnesium remained stable between 1845 and the mid 1960s, but since then have decreased significantly, which coincided with the introduction of semi-dwarf, high-yielding cultivars. In comparison, the concentrations in soil have either increased or remained stable. Similarly decreasing trends were observed in different treatments receiving no fertilizers, inorganic fertilizers or organic manure. Multiple regression analysis showed that both increasing yield and harvest index were highly significant factors that explained the downward trend in grain mineral concentration.”
Morris CE. and Sands DC. (2006) The breeder’s dilemma – yield or nutrition? Nature Biotechnology. 24(9):1078–1080
“Plant breeders, challenged to create more nutritious crops, face seemingly radical choices that constitute a ‘breeder’s dilemma’. In the search for higher yields and lower farming costs, have breeders inadvertently selected for crops with reduced nutritional quality? To create foods that keep pace with our growing understanding of what constitutes healthy diets, plant breeders may need to make a significant shift away from traditional selection criteria. Subsidizing crop nutritional value rather than yield could be an important and economical driver for this shift in perspective.”

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Minty Pea Purée on Sourdough Toast

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Pea purée on buttered wholemeal spelt sourdough bread.

Few foods can match the vivid green of puréed frozen peas. The fresh taste of the peas combines beautifully with the mint an lemon to produce a very green flavour.

Gena Hamshaw of Food52 and creator of this recipe notes: “This dish is pure springtime comfort. A flavorful, bright green purée of mint, shallots, garlic, and peas meets crispy, rustic slices of toast.

Slices of toasted wholemeal spelt sourdough bread, lathered with a generous helping of butter, served as a fitting vehicle for these peas. The result was delicious and an excellent, sophisticated looking way of serving what is quite a simple meal of peas.

Ingredients (with slightly varying ingredients from the original recipe):

  • olive oil
  • A small red onion (instead of a shallot, thinly sliced
  • A generous helping of garlic, minced
  • An eyeballed quantity of frozen green peas
  • Some lemon juice
  • Salt, to taste
  • Black pepper, to taste
  • A handful of mint leaves
  • An onion was sliced and sauteed in olive oil for a couple of minutes. A generous helping of garlic and frozen peas was added and sautéed for another few minutes until the peas are warmed through.
  • The peas, onion, and garlic was placed in a food processor and the peas, lemon juice, lemon zest, salt, pepper , and mint leaves added in. The mixture was pulse mixed continuously until it is puréed but with some texture.Finally some extra mint leaves were blended in to taste.
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Adventures in sourdough bread.

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Wholemeal spelt sourdough bread with oxtail stew.

I have never baked my own bread. This is despite having had a go at cooking many different things over the years and so recently I decided to rectify this omission. Given that I have an interest in fermenting foods and historic cooking techniques the obvious choice was to attempt some sourdough bread with a fermentation of wild yeasts and bacteria.

This required both a starter and a method, as I had little knowledge on this subject. After searching around for recipes and becoming rather confused by the apparently many and various complicated methods for producing sourdough I stumbled upon an excellent article by Hugh Fearnley-Whittingstall in the Guardian newspaper. As usual Hugh manages to simplify the sometimes complicated subject of preparing  real food and make it readily understandable.

The first step was to make an active starter culture. I used Organic Wholemeal Rye Flour from Doves Farm to make the starter mixing together 100 grams of water and 100 grams of the flour in an open topped jar. The next day the same amount of flour and water were mixed in. Then each subsequent day the starter was halved and a fresh 100 grams of water and 100 grams of rye flour mixed in. The starter took a little while to get going but after a couple of weeks the culture was fermenting well and occasionally attempting to escape its jar.

Once my starter was ready it was time to move onto the bread baking. My sourdough making is complicated by the rather cool temperatures of my old granite Scottish home. With room temperatures rather lower than is normal my bread would require longer fermentation times than many recipes suggest.

Given my interest in the history of food and cooking I have so far chosen to try out a range of old varieties of wheat that I could get my hands on.

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Active wholemeal rye flour sourdough starter.

The recipe

For the sponge

  • 150ml active rye flour starter
  • 250g wholemeal spelt flour

For the loaf

  • 300g wholemeal spelt flour
  • 15 olive oil
  • 10g fine sea salt

Method

  • To cope with the cool temperatures, and the limitations of my being at work all day, I mixed the sponge in the evening after getting home from work.
  • The sponge was fermented overnight for 12 hours, by which time it had risen well and was frothy with bubbles.
  • In the morning I added in the salt, olive oil, and flour and mixed it into a dough. This was kneaded for 10 minutes and then placed in a greased bowl and covered in clingfilm.
  • After about 10 hours proving, when home from work, I punched down the dough and placed in a bowl lined with a well floured tea towel.
  • After about three hours proving again I heated the oven to 200C, sadly about he maximum my oven seems to reached judging my my oven thermometer, placing my cast iron bakestone in the oven preheat with a backing tray on the oven shelf below it.
  • The dough was turned out onto the hot bakestone and boiling water poured into the backing tray. The bread was baked for 40 minutes, topping up the boiling water at 15 minutes to maintain the humid atmosphere.

wpid-img_20150622_213425.jpgFirst sourdough bread – Spelt flour

This first loaf worked out really well and the spelt flour produced an earthy rich flavour when combined with the sourdough fermentation.

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Sourdough number two – Spelt flour.

This second loaf was also made with Doves Farm Organic Wholemeal Spelt Flour. Again the method worked well with spelt and scoring the dough when placing it in the oven helped the bread rise a little more than before.

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Sourdough number three – Einkorn flour.

Einkorn flour is the ancestor of all modern wheat, grown for many thousands of years since the beginnings of agriculture. The flour for this bread is Doves Farm Organic Einkorn Wholemeal Flour purchased from Real Foods in Edinburgh. Due to this it has a lower level of gluten than modern bread wheats, and the different structure of the gluten means it will never rise like a modern bread loaf. However, this current method I’m using produced a good loaf, equal in structure and shape to the spelt flour loaves. The flavour of einkorn in this bread is very distinctive, imparting a mild, almost nutty taste to the bread. This einkorn flour is also produced quite a pale light coloured loaf despite being wholemeal and the bran it contains much be light in colour.

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Sourdough number four – Khorasan (Kamut) flour.

For this loaf I used another ancient flour known as Khorasan, or Kamut, flour named after in the Khorasan region of Iran. This Doves Farm Organic Khorasan Wholemeal Flour was again found at Real Foods store in Edinburgh. Using the same method this flour produced a great tasting loaf, pale in colour and with a rich flavour all of its own.

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Sourdough number five – white spelt flour.

A new recent find in Aberdeen was some Doves Farm White Spelt Flour at the Grampian Health Food Store. This white flour had a lighter flavour due to the reduced bran, with a slightly more open texture to the bread.

This foray into bread baking has definitely stimulated my interest in the process of baking bread and sourdough fermentation. This method from Hugh Fearnley-Whittingstall has so far worked really well around the times I have available during the week and the cool temperatures in my home that require long proving times.

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The origins of semi-dwarf wheat

Wheat

John Linnell, Wheat (1860)

The late summer landscape of 19th Century England, such as painted by John Linnell, was filled with fields of tall golden wheat ripening in the sun. Across the Atlantic the prairies of the midwest states inspired the words by Katharine Lee Bates to America the Beautiful,

O beautiful for halcyon skies,
For amber waves of grain,
For purple mountain majesties
Above the enameled plain!
America! America!
God shed His grace on thee,
Till souls wax fair as earth and air
And music-hearted sea!

In contrast today, on the prairies of the midwest or the fields of England, the wheat is unlikely to be so tall or waving in such a poetic manner. The wheat grown today is rather shorter and stockier, with stronger stems. This is a result of wheat breeding over the past hundred years to increase the yield of wheat by reducing plant height and make the plants resistant to lodging in conditions of intensive agriculture. Wheat breeders developed plants with shorter and stiffer straws, producing semi-dwarf, high-yielding varieties that were much better adapted to intensive agriculture. Before this time the traditional varieties of wheat grown were limited in the yield they could produce as adding more fertiliser resulted in the wheat stalks growing taller and weaker making them vulnerable to breaking.

The modern semi-dwarf varieties of wheat have recently come into public attention due to the publication of popular diet books blaming these new types of wheat for a plethora of modern health problems. However, rather than these alleged health issues, I was interested to know where these semi-dwarf wheats came from and the origin of the genes responsible. In an interesting article from 2005, Katarina and Ksenija Borojevic outline the history of the genes responsible for our modern dwarf wheat, with more of a focus on Europe, rather than the better known efforts in America that resulted in the Green Revolution.

The story starts further back than you might imagine, and to Korea, where naturally occurring short stemed wheat varieties were grown as far back as the third and fourth centuries A.D. The genes responsible were natural mutations rather than a production of any human intervention. These short varieties of wheat found there way to Japan as a result of the Korean-Japanese War during the sixteenth century. Semi-dwarf wheat varieties were widely grown in Japan by the 19th Century and served to provide the dwarfing genes for all our modern wheat varieties now grown around the world.

The variety Akakomugi, a 19th Century Japanese landrace of semi-dwarf wheat, provided the dwarfing genes first transferred to Europe in the early 20th Century. The Italian wheat breeder Nazareno Strampelli was to use this Japanese wheat, crossing Akakomugi with an Italian wheat by 1913 to produce a new shorter, lodging resistant Italians wheat. By 1918 a number of new semi-dwarf wheat varieties had been developed from this initial hybridisation which soon became very well known and were grown in Italy and South America, particularly in Argentina. By 1931 Nazareno Strampelli, using further hybridisations, had produced another improved variety called San Pastore that proved to be an extraordinary success and was widely grown in Italy and many other countries for more than 35 years.

These wheat breeding initiatives were supported and encouraged by the Italian government as they coincided with a drive for Italy to be self sufficient in food. This was known, as occurred during Mussolini’s time, as the Battle for Grain. These new semi-dwarf wheat hybrids enabled Italy to double its cereal production from 1922 to 1939 and and to become more or less self-sufficient in cereal production, where previously they had been heavily reliant on foreign imports.

After World War II, the Yugoslav government was also keen to encourage national self sufficiency and imported dwarf Italian wheat varieties during the 1950’s. These were widely grown, and through hybridisation with local wheats, enabled the development of new high-yielding winter wheat that were grown on a large-scale. Average yields increased from 1.36 tons of wheat per hectare up to 5.21 tones per hectare. Neighbouring countries including Hungary, Bulgaria, Romania, the former Czechoslovakia obtained similar results.

The gene responsible for reduced height originating in the Japanese Akakomugi wheat is known as Rht8 (abbreviated for reduced height 8). The function of this gene is still not clear but has been suggested to reduce sensitivity to brassinosteroids, a class of plant hormones that promote stem elongation and cell division. The identity of this Rht8 gene was only discovered at the end of the 20th Century and has been shown to have contributed its semi-dwarf characteristics of wheat across South Central Europe and the former USSR.

Semi-dwarf wheat reached the Americas via a completely separate route and through unrelated genes. Japanese wheat breeders, continuing their work on reduced height wheat, produced a new variety in 1932 that became known as Norin 10. This was produced by crossing an old Japanese dwarf landrace wheat called Daruma with American wheat varieties. Norin 10 grew to just two feet tall, instead of the usual four.

Norin 10 was never an important variety in Japan but found its way to the USA due to the occupying US army after the Second World War. S. D. Salmon, a scientist working on wheat research with the U.S. Department of Agriculture (USDA) was serving as an advisor of the occupation army when he made a  visit to the Marioka Agriculture Research Station on Honshu in Japan. He returned to the US, with wheat samples, given by Japanese scientists during his visit, Norin 10 was among these samples.  The genes making Norin 10 a short wheat  are the Rht1 and Rht2 genes that make the wheat plant insensitive to another type of plant growth hormones called gibberellins.

In 1952, an agronomist working at Washington State University called O. A.Vogel used this Norin 10 to cross with a popular wheat variety grown in Washington at the time. The resulting variety called Gaines became the predominant wheat variety in the Pacific Northwest in the late 1960s with farmers producing record wheat yields. It was from Washington State that Norin 10 was acquired by Norman Bourlag at the International Maize and Wheat Improvement Center (CIMMYT) in Mexico where new dwarf  wheat varieties were developed and later spread around the world, resulting in the Green Revolution and earning Norman Bourlag the 1970 Nobel Peace Prize. Adding the dwarfing genes in Norin 10 to their wheat breeding enabled the development of high yielding wheat varieties that could stand high levels of added fertiliser. These varieties developed at the CIMMYT dramatically increased wheat yields around the world, first enabling Mexico to become self sufficient in wheat and later countries like India and Pakistan.

It is clear the genes responsible for dwarfism in wheat plants have a long history and a complex route has taken them from ancient Korea into modern wheat plants in Europe and the rest of the world. While the work North America and the green revolution has attracted most of the attention, in Europe at least, genes introduced in the early 20th Century have also been important in the development of of modern wheat. It is also interesting that parts of Europe have been eating semi-dwarf hybrid wheat since the 1920s. Whatever the alleged health implications of these modern wheat varieties, the genes that make make them shorter have a long history and appeared spontaneously long before the work of modern genetics and crop manipulation.

 

Sources:

Borojevic K. and Borojevic K. (2005) The Transfer and History of “Reduced Height Genes” (Rht) in Wheat from Japan to Europe. Journal of Heredity96(4):455-459.

“Wheat is the main crop and often a strategic crop in many European countries. From a historical perspective, we describe the transfer of “reduced height genes” (Rht genes) from Japanese wheat varieties to wheat varieties in Europe and their influence on the increase of the total wheat production in the last century. Historic pathways of Rht genes were influenced directly or indirectly by wheat breeders exchanging seed samples and by some governments importing large quantities of wheat during historically critical periods for their countries.”

Borojevic K. and Borojevic K. (2005) Historic Role of the Wheat Variety Akakomugi in Southern and Central European Wheat Breeding Programs. Breeding Science. 55(3):253-256

“The old semidwarf, not very attractive, Japanese wheat variety Akakomugi was the source of the dwarfing gene Rht8 and photoperiodic insensitive gene PpD1 to many semidwarf wheat varieties in South and Central Europe in the 20th century. Integrating the Rht8 and PpD1genes in wheat varieties offered the best opportunities for reducing plant height, accelerating time of flowering, improving grain fill before the onset of dry summer conditions, enhancing spikelet fertility, and consequently increasing yields. Many breeders from South and Central Europe and from the former Soviet Union were creating winter short high yielding wheat varieties without knowing at the time that Akakomugi was the donor of such important genes. At the end of the 20th century, it was discovered that dwarfing gene Rht8 and photoperiodic insensitive gene PpD1 are located on the short arm of chromosome 2D in wheat. Microsatellite analyses proved that Akakomugi is the source for the Rht8 and PpD1 genes in many short wheat varieties in South and Central Europe.”

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Bourbon, Brandy and Armagnac: Phenolics and antioxidant capacity

In a recent post I looked into the science behind the phenolic compounds found in my favorite Scottish malt whiskies, and extracted into said water of life via the action of alcohol and water on the wood of the oak barrels they are aged within. I realise this was quite neglectful of the fact that a range of other distilled spirits undergo barrel aging to produce their unique characteristics. Thankfully science has not been so negligent on this topic and a study from 1999 in the Journal of Agricultural and Food Chemistry investigated this very subject.

spirits TAS

The graph shows the mean total antioxidant status (mmol/L) of distilled spirits analysed by Goldberg et al in their 1999 study.

This study analysed both the total antioxidant capacity and the amounts of a range of phenolic and furan compounds. This included both a single malt scotch whisky and a blended whisky, although unfortunately for comparison with my previous post they do not mention the age of this whisky. Judging from the amount of ellagic acid in the table below it could be suggested to be a 10-12 year old single malt. Of more interest here is that the study also included an American bourbon, French brandy and Armagnac. This study included a few different compounds found in barrel aged spirits. The structures of these are shown below, illustrating the complexity of compounds that develop during the aging process.

spirits TAS compounds

Structural formulas of the main compounds mentioned.

Looking at the graph above and table below a particularly interesting finding is that American bourbon exceeded the Scotch malt whisky in both its antioxidant capacity and levels of individual phenolic compounds. The authors suggest some reasons for this:

“Bourbon whiskey is made by rather different procedures. Two, in particular, are worthy of note. The distillation takes place at a quite low proof, not exceeding 160; this has the effect of allowing many congeners to pass over with the ethyl alcohol. The second is the use of charred oak barrels for aging, periods of up to 8 years not being uncommon. It appears that these two processes may account for the higher phenolic and furan contents and TAS of this whiskey compared with the previous three whiskies”

Perhaps also the use of freshly made oak barrels increases the transfer of phenolic compounds into bourbon, as compared to Scotch whisky which reuses previously used barrels. Vanillic Acid, Syringaldehyde were found in the highest amounts in bourbon. The lower levels identified in the Canadian rye whisky are mostly likely to a much shorter duration of barrel ageing.

spirits TAS table

The quantities of six polyphenols in the various spirits tested.

The striking feature of this study is the high amounts of all phenolic compounds in Armagnac, which had by far the highest concentrations of gallic acid, syringic acid, vanillin, and ellagic acid, as well as the second highest of vanillic acid, syringaldehyde, coniferaldehyde, and trimethoxyphenylacetic acid. This is possibly due to the exacting and protected methods used to produce Armagnac, of which wood aging of up to 10 years in Limousin oak for cognac and black Monlezun oak, a “black oak” from the Monlezun forest in Gascony, for armagnac, is a notable feature. Of interested, the ellagic acid found in both whiskies and Armagnac, is also proposed to be responsible for some of the health benefits of fruits such as blackberries, cranberries, pomegranates,raspberries, which are the main source of ellagic acid in the diet. However, the amounts in even Armagnac are rather low in comparison.

While the evidence from my previous post showed that long aged Scottish malt whisky, aged 25 years, had a much higher level of phenolic compounds than any in this study, the age of Scotch malt whisky at which most people drink it may not quite reach the levels of phenolics found in American bourbon, and is probably rather inferior to Armagnac. As the phenolic compounds extracted from oak wood during the aging of alcohol are common to all aged spirits, any health effects mentioned in my previous post would apply to all. However, it is worth remembering any possible health benefit is going to be redundant if consumed in large quantities.

*Any spelling mistakes in the post are due to the influence of good whisky.

References:

Goldberg DM, Hoffman B, Yang J, Soleas GJ. (1999) Phenolic constituents, furans, and total antioxidant status of distilled spirits. Journal of Agricultural and Food Chemistry. 47(10):3978-85

Abstract:

“The concentrations of 11 phenols and 5 furans were measured in 12 categories of distilled spirits by HPLC methodology, together with the total antioxidant status (TAS) of the same beverages. Ellagic acid was the phenol present in highest concentration in all beverages. Moderate amounts of syringaldehyde, syringic acid, and gallic acid, as well as lesser amounts of vanillin and vanillic acid, were measurable in most samples of whiskey, brandy, and rum but were largely undetectable in gin, vodka, liqueurs, and miscellaneous spirits. 5-(Hydroxymethyl)furfural was the predominant furan in the former three beverages, notably cognac, with 2-furaldehyde the next highest, but these were undetectable in most of the latter beverages. Highest TAS values were given by armagnac, cognac, and bourbon whiskey, all three of which tended toward the highest concentrations of phenols. Negative TAS values were exhibited by rum, vodka, gin, and miscellaneous spirits in line with the low or undetectable phenol concentrations in these beverages. Wood aging is the most likely source of phenols and furans in distilled spirits. Those beverages exposed to this treatment contain significant antioxidant activity, which is between the ranges for white and red wines, with the potential to augment the antiatherosclerotic functions attributable to the ethanol that they contain.

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