Structures of [A] Phylloquinone (vitamin K1) and [B] Dihydrophylloquinone (hydrogenated vitamin K1). Source (Davidson 1996).

Vitamin K is a fat soluble vitamin that occurs in foods in a series of molecular forms as can be seen from this recent post. However, as well as those various forms of vitamin K, both phylloquinone and the various menaquinones, normally found in our food there is another structural form that is only found in modern processed foods and does not occur in nature. This is the dihydrophylloquinone, which as we shall see may not be an ideal part of out diets.

Vitamin K1 (Phylloquinone) is generally the most common source of vitamin K in the diet in terms of quantity originating from plants where it plays a key role in plant photosynthesis. A common source of phylloquinone in modern diets is edible oils produced form the seeds of plants. According to the USDA database, soybean oil, rapeseed oil (canola oil) and olive oil contain 25, 10 and 8 mcg per tablespoon respectively while other oils do not contain meaningful amounts. The soybean oil and canola oil used in modern processed foods have often been partially or fully hydrogenated to increase the oil solidity and improve the shelf life of food products with well known negative consequences due to the resulting trans fats that occur as part of the process.

An unintended and generally unknown consequence of the hydrogenation process is conversion of phylloquinone (vitamin K1) to dihydrophylloquinone. This new form of vitamin K does not occur naturally but is found in fats like hydrogenated soybean oil and shortening though not in the original soybean oil (Davidson 1996).

The result of this is that food produced using hydrogenated oils now also contains dihydrophylloquinone. This has been investigated by Elder (2006) in some processed foods purchased in the USA. The vitamin K measured in whole foods from this study was listed in my previous post, no dihydrophylloquinone was detected in any of the whole foods.

It can be seen from this table that small amounts of dihydrophylloquinone are found in most fast foods, with the highest levels in chicken nuggets and tenders. These are likely to contain the most hydrogenated oil and probably mean any food fried in hydrogenated oils would contain high amounts. While the amounts are low in most products these are foods that can be eaten in large quantities, rather than the 100 gram amounts listed in the table, which could result in rather larger intakes than at first appears. This figures are in agreement with amounts found in processed foods in a previous study (Durmont 2003). In 1997 dihydrophylloquinone was detected in infant formula containing soybean oil (Indyk 1997). Another study from 1999 estimated that average mean daily intakes of dihydrophylloquinone of 19 and 15 mcg in men and women, although those in the top 5% of intakes were estimated to be eating 43 and 32 mcg for men and women (Booth 1999). Dihydrophylloquinone has been detected in human blood with a positive association with trans fat intake in the diet with bakery products like cookies and fast food such as French fries estimated to be the main sources (Erkkila 2005). This raises the question at to what the impact might be of this new form of vitamin K on the health of the people consuming it.

Evidence suggest that in rats, compared to vitamin K1, less of the dihydrophylloquinone is converted into menaquinone-4  (mk-4). Feeding the rats dihydrophylloquinone resulted in reduced mk-4  in kidney, heart, testes and brain (Booth 2008). The reduced conversion of dihydrophylloquinone to mk-4 in the brain of rats has also been shown to reduce sulfatide metabolism in the brain, a key component of the myelin that surrounds the nerve cells in the brain (Crivello 2010). The ability of rats to convert any dihydrophylloquinone into mk-4 was questioned by another study that found that though the dihydrophylloquinone was well adsorbed and could be found in the brain, pancreas, kidney, testis, abdominal aorta, liver and femur of the rats, none of this was converted into mk-4. While the dihydrophylloquinone could fulfill some of the basic blood clotting functions of phylloquinone none of it was converted into mk-4 in these tissues (Sato 2003). However, these studies on rats are not an exact equivalent of human vitamin K metabolism and so direct comparisons are difficult to make. It does though raise questions as to what influence this new form of vitamin K may have on long term health.

Epidemiological research has examined the  links between dietary  dihydrophylloquinone and human bone health. Greater dietary intakes of dihydrophylloquinone were associated with lower bone mineral density in men and women. This association remained significant after adjusting for other markers of diet quality (Troy 2007). While these results are interesting, as the research was of an epidemiological nature the dihydrophylloquinone could still just be a marker for other unhealthy aspects of diet and lifestyle. However one small study that directly tested the effect of dihydrophylloquinone on bone formation and resorption in young adults suggests this may not just be an association (Booth 2001).  When given to young adults the dihydrophylloquinone, in comparison to phylloquinone, was less well absorbed and had no measurable biological effect on measures of bone formation and resorption. This is unlikely to be a good thing when you consider that most people in the United States dihydrophylloquinone consume on a daily basis.

These findings suggest to me that dihydrophylloquinone would be best avoided in the diet, along with the trans fats it often accompanies. It may be hoped that it is decreasing in  the average diet now compared to the heyday of hydrogenated fats when they were seen as the ideal ingredient in all our foods. However, one method of decreasing trans fats in processed foods is via the use of fully hydrogenated fat mixed with non-hydrogenated fat and other additive to produce the desired properties. However, while the use of full hydrogenation will reduce the trans fat in products it will not decreasethe amount of dihydrophylloquinone. In the end the best policy is avoiding all processed foods and products that might contain this most modern form of a vitamin.

References

Booth SL and Suttie JW. (1998) Dietary intake and adequacy of vitamin K. The Journal of Nutrition. 128(5):785-8. (Pubmed).

The current daily recommended dietary allowance for vitamin K is 1 microg/kg. Reliable measurements of vitamin K content in foods are now available, and data from 11 studies of vitamin K intake indicate that the mean intake of young adults is approximately 80 microg phylloquinone/d and that older adults consume approximately 150 microg/d. The vitamin K concentration in most foods is very low (<10 microg/100 g), and the majority of the vitamin is obtained from a few leafy green vegetables and four vegetable oils (soybean, cottonseed, canola and olive) that contain high amounts. Limited data indicate that absorption of phylloquinone from a food matrix is poor. Hydrogenated oils also contain appreciable amounts of 2′, 3′-dihydrophylloquinoneof unknown physiological importance. Menaquinones absorbed from the diet or the gut appear to provide only a minor portion of the human daily requirement. Measures of the extent to which plasma prothrombin or serum osteocalcin lack essential gamma-carboxyglutamic acid residues formed by vitamin K action, or the urinary excretion of this amino acid, provide more sensitive measures of vitamin K status than measures of plasma phylloquinone or insensitive clotting assays.

Booth SL, Webb DR, Peters JC. (1999) Assessment of phylloquinone and dihydrophylloquinone dietary intakes among a nationally representative sample of US consumers using 14-day food diaries. Journal of the American Dietetic Association. 99(9):1072-6. (Pubmed).

“OBJECTIVE: To estimate dietary intakes of phylloquinone and dihydrophylloquinone in a representative sample of the American population using 14-day food diaries. DESIGN: Vitamin K food composition data were applied to 14-day food diaries completed by a nationally representative sample of approximately 2,000 households that participated in a Market Research Corporation of America menu census survey between July 1991 and June 1992. Dietary intakes were estimated for phylloquinone and dihydrophylloquinone. SUBJECTS: Subjects were 4,741 men, women and children with demographic characteristics similar to those of the US census population. STATISTICAL ANALYSIS PERFORMED: Descriptive statistics and 2-sample t tests. RESULTS: Mean reported intakes of phylloquinone among adults increased with age. Men and women in the 18- to 44-year-old groups reported mean phylloquinone intakes below the current Recommended Dietary Allowance for vitamin K. Of all study participants, 99.3% reported consumption of dihydrophylloquinone during the 14 days of diet recording; reported intakes peaked before the age of 6 years; after the age of 6 years intakes were constant. APPLICATIONS: The Market Research Corporation of America data provide a reference range for dietary intakes of 2 forms of vitamin K in the US diet: phylloquinone and dihydrophylloquinone. Given the putative role of vitamin K in bone mineralization, low intakes of phylloquinone reported among young adults highlight the need to educate the US population about the requirement for and sources of vitamin K. The abundance ofdihydrophylloquinone in the US diet suggests the need for study of its biological activity relative to phylloquinone.”

Booth SL, Lichtenstein AH, O’Brien-Morse M, McKeown NM, Wood RJ, Saltzman E, Gundberg CM. (2001) Effects of a hydrogenated form of vitamin K on bone formation and resorption. The American Journal of Clinical Nutrition. 74(6):783-90. (Journal).

BACKGROUND: Hydrogenation of vegetable oils affects blood lipid and lipoprotein concentrations. However, little is known about the effects of hydrogenation on other components, such as vitamin K. Low phylloquinone (vitamin K1) intake is a potential risk factor for bone fracture, although the mechanisms of this are unknown. OBJECTIVE: The objective was to compare the biological effects of phylloquinone and its hydrogenated form,dihydrophylloquinone, on vitamin K status and markers of bone formation and resorption.DESIGN: In a randomized crossover study in a metabolic unit, 15 young adults were fed a phylloquinone-restricted diet (10 microg/d) for 15 d followed by 10 d of repletion (200 microg/d) with either phylloquinone ordihydrophylloquinone. RESULTS: There was an increase and subsequent decrease in measures of bone formation (P = 0.002) and resorption (P = 0.08) after dietary phylloquinone restriction and repletion, respectively. In comparison with phylloquinone, dihydrophylloquinone was less absorbed and had no measurable biological effect on measures of bone formation and resorption. CONCLUSION: Hydrogenation of plant oils appears to decrease the absorption and biological effect of vitamin K in bone.

Booth SL, Peterson JW, Smith D, Shea MK, Chamberland J, Crivello N. (2008) Age and dietary form of vitamin K affect menaquinone-4 concentrations in male Fischer 344 rats. The Journal of Nutrition. 138(3):492-6. (Pubmed).

“Phylloquinone, the primary dietary form of vitamin K, is converted to menaquinone-4 (MK-4) in certain tissues. MK-4 may have tissue-specific roles independent of those traditionally identified with vitamin K. Fischer 344 male rats of different ages (2, 12, and 24 mo, n = 20 per age group) were used to compare the conversion of phylloquinone to MK-4 with an equivalent dose of another dietary form of vitamin K, 2′,3′-dihydrophylloquinone. Rats were age- and diet-group pair-fed phylloquinone (198 +/- 9.0 microg/kg diet) or dihydrophylloquinone (172 +/- 13.0 microg/kg diet) for 28 d. MK-4 was the primary form of vitamin K in serum, spleen, kidney, testes, bone marrow, and brain myelin fractions, regardless of age group. MK-4 concentrations were significantly lower in kidney, heart, testes, cortex (myelin), and striatum (myelin) in the dihydrophylloquinone diet group compared with the phylloquinone diet group (P < 0.05). The MK-4 concentrations in 2-mo-old rats were lower in liver, spleen, kidney, heart, and cortex (myelin) but higher in testes compared with 24-mo-old rats (P < 0.05). However, there were no age-specific differences in MK-4 concentrations among the rats fed the 2 diets. These data suggest that dihydrophylloquinone, which differs from phylloquinone in its side phytyl chain, is absorbed but its intake results in less MK-4 in certain tissues. Dihydrophylloquinone may be used in models for the study of tissue-specific vitamin K deficiency.”

Crivello NA, Casseus SL, Peterson JW, Smith DE, Booth SL. (2010) Age- and brain region-specific effects of dietary vitamin K on myelin sulfatides. The Journal of Nutritional Biochemistry. 21(11):1083-8. (Pubmed).

“Dysregulation of myelin sulfatides is a risk factor for cognitive decline with age. Vitamin K is present in high concentrations in the brain and has been implicated in the regulation of sulfatide metabolism. Our objective was to investigate the age-related interrelation between dietary vitamin K and sulfatides in myelin fractions isolated from the brain regions of Fischer 344 male rats fed one of two dietary forms of vitamin K: phylloquinone or its hydrogenated form, 2′,3′-dihydrophylloquinone (dK), for 28 days. Both dietary forms of vitamin K were converted to menaquinone-4 (MK-4) in the brain. The efficiency of dietary dK conversion to MK-4 compared to dietary phylloquinone was lower in the striatum and cortex, and was similar to that in the hippocampus. There were significant positive correlations between sulfatides and MK-4 in the hippocampus (phylloquinone-supplemented diet, 12 and 24 months; dK-supplemented diet, 12 months) and cortex (phylloquinone-supplemented diet, 12 and 24 months). No significant correlations were observed in the striatum. Furthermore, sulfatides in the hippocampus were significantly positively correlated with MK-4 in serum. This is the first attempt to establish and characterize a novel animal model that exploits the inability of dietary dK to convert to brain MK-4 to study the dietary effects of vitamin K on brain sulfatide in brain regions controlling motor and cognitive functions. Our findings suggest that this animal model may be useful for investigation of the effect of the dietary vitamin K on sulfatide metabolism, myelin structure and behavior functions.”

Dumont JF, Peterson J, Haytowitz D, Booth SL. (2003) Phylloquinone and dihydrophylloquinone contents of mixed dishes, processed meats, soups and cheeses. Journal of Food Composition and Analysis.16:595–603.(Science Direct).

“Assessment of dietary intakes of phylloquinone (VK-1) and dihydrophylloquinone (dK) has been limited by an overall deficit of food composition data, especially for mixed dishes and processed foods. Ninety-eight geographically representative food samples, obtained as part of the National Food and Nutrient Analysis Program (NFNAP), were analyzed for VK-1 and dK using reversed phase HPLC with fluorescent detection. The VK-1 concentrations of the mixed dishes, processed meats, soups, and cheeses ranged from zero (nondetectable, ND) to 11.1 mg/100 g; the dK concentrations ranged from zero (ND) to 22.4 mg/100 g. No dK was detected in the cheese samples. Minimal variation in VK-1 content was observed between the cooked and uncooked samples. Mixed dishes, processed meats, soups, and cheeses contain relatively small amounts of phylloquinone and dK when compared with vegetables and certain plant oils. However, since these foods may frequently be consumed in large amounts, they may be important dietary contributors of vitamin K.”

Indyk HE and Woollard DC. (1997) Vitamin K in milk and infant formulas: determination and distribution of phylloquinone and menaquinone-4. The Analyst. 122(5):465-9. (Pubmed).

“A method is described for the determination of phylloquinone and menaquinones following enzymatic digestion, extraction and a single-stage HPLC technique utilizing post-column reduction with zinc and fluorescence detection. The technique is applicable to both routine compliance control of phylloquinone supplemented infant formula powders (30-150 micrograms per 100 g) and fundamental studies of the K vitamins at endogenous levels in fluid milks (0-5.0 micrograms per 100 g). Analytical figures of merit include a detection limit of 30 micrograms on-column, recoveries greater than 98% for both K1 and MK4, an RSDR of 2.35% (K1) and 2.32% (MK4) and a regression correlation of 0.9932 for a wide range of infant formulas when compared against an alternative HPLC-UV technique. MK4 and 2′,3′-dihydrophylloquinone, both with undefined bioactivity, were detected at measurable levels in a range of infant formulas. Although the higher menaquinones were found to be essentially absent in the milk of several species, the significant presence of MK4 relative to K1 has been confirmed in all milks examined, with both dominant forms correlated during early lactation in the cow. These observations suggest an as yet unrecognized physiological function for MK4 in infant nutrition.”

Elder SJ, Haytowitz DB, Howe J, Peterson JW, Booth SL. (2006) Vitamin k contents of meat, dairy, and fast food in the U.S. Diet. Journal of Agriculture and Food Chemistry. 54(2):463-7. (Pubmed).

“The purpose of this study was to determine the contents of three forms of vitamin K [phylloquinone,dihydrophylloquinone, and menaquinone-4 (MK-4)] in representative samples (including different samples within the same food category) of meat (n = 128), dairy and eggs (n = 24), and fast foods (n = 169) common to the U.S. diet. The findings of our analysis indicate that no single food item in these categories is a rich dietary source of any one form of vitamin K. However, these foods are often consumed in large quantities; hence, they may be of importance in overall contribution to total vitamin K intake. The presence of MK-4 in meat, eggs, and dairy foods could be important as physiologic functions unique to MK-4 are identified.”

Erkkilä AT, Lichtenstein AH, Jacques PF, Hu FB, Wilson PW, Booth SL. (2005) Determinants of plasma dihydrophylloquinone in men and women. The British Journal of Nutrition. 93(5):701-8. (Pubmed).

Commercial hydrogenation results in the formation of trans fatty acids. An unintended consequence of the hydrogenation process is conversion of phylloquinone (vitamin K1) to dihydrophylloquinone. Plasmadihydrophylloquinone concentrations have yet to be characterized in population-based studies. Dietary determinants of plasma dihydrophylloquinone were estimated using a semi-quantitative food frequency questionnaire in 803 men and 913 women in the Framingham Offspring Study. Geometric meandihydrophylloquinone intake was 21.3 (95 % CI 20.4, 22.3) microg/d in men and 19.4 (95 % CI 18.5, 20.2) microg/d in women. Detectable (>0.05 nmol/l) plasma dihydrophylloquinone concentrations were measured in 41 % and 30 % of men and women, respectively. The multivariate odds ratio (OR) of detectable plasmadihydrophylloquinone from the lowest to the highest quartile category of dihydrophylloquinone intake were 1 (referent), 1.13 (95 % CI 0.83, 1.53), 1.66 (95 % CI 1.21, 2.26) and 1.84 (95 % CI 1.31, 2.58), P for trend <0.001, adjusted for sex, age, body mass index, triacylglycerols, season and energy intake. Higher trans fatty acid intake was associated with higher multivariate OR for detectable plasma dihydrophylloquinone (OR comparing extreme quartiles 2.41 (95 % CI 1.59, 3.64), P for trend <0.001). There were limitations in the use of plasma dihydrophylloquinone, evident in the high proportion of the population that had non-detectabledihydrophylloquinone concentrations. Despite this caveat, higher plasma dihydrophylloquinone was associated with higher dihydrophylloquinone intake and higher trans fatty acid intake.

Peterson JW, Muzzeya KL, Haytowitzb D, Exlerb J, Lemarb L and Bootha SL (2002) Phylloquinone (vitamin K1) and dihydrophylloquinone content of fats and oils. Journal of the American Oil Chemists’ Society. (Sringer).

“Assessment of vitamin K (VK) dietary intakes has been limited by the incompleteness of VK food composition data for the U.S. food supply, particularly for VK-rich oils. The phylloquinone (VK-1) and 2′,3′-dihydrophylloquinone (dK) concentrations of margarines and spreads (n=43), butter (n=4), shortening (n=4), vegetable oils (n=6), and salad dressings (n=24) were determined by RP-HPLC with fluorescence detection. Each sample represented a composite of units or packages obtained from 12 or 24 outlets, which were geographically representative of the U.S. food supply. Butter, which is derived from animal fat sources, had less VK-1 compared to vegetable oil sources. The VK-1 and dK of the margarines and spreads increased with fat content and the degree of hydrogenation, respectively. In some margarines or spreads and in all shortenings, the dK concentrations were higher than the corresponding VK-1 concentrations. As the fat content of salad dressings increased, the VK-1 concentrations also increased. Fat-free foods had <1 μg/100 g of either form of the vitamin. No dK was detected in the salad dressings or oils tested. Some margarines, spreads, and salad dressings may be significant sources of vitamin K in the U.S. food supply.”

Troy LM, Jacques PF, Hannan MT, Kiel DP, Lichtenstein AH, Kennedy ET, Booth SL. (2007) Dihydrophylloquinone intake is associated with low bone mineral density in men and women. The American Journal of Clinical Nutrition. 86(2):504-8. (Pubmed).

“BACKGROUND: Poor diet may affect bone status by displacing nutrients involved in bone health. Dihydrophylloquinone, a form of vitamin K present in foods made with partially hydrogenated fat, is a potential marker of a low-quality dietary pattern. OBJECTIVE: Our objective was to examine the cross-sectional associations between dihydrophylloquinone intake and bone mineral density (BMD) of the hip and spine in men and women. DESIGN: Dihydrophylloquinone intake was estimated with a food-frequency questionnaire, and BMD (in g/cm(2)) was measured by dual-energy X-ray absorptiometry in 2544 men and women (mean age: 58.5 y) who had participated in the Framingham Offspring Study. General linear models were used to examine the associations between dihydrophylloquinone intake (in tertiles: <15.5, 15.5-29.5, and >29.5 microg/d) and hip and spine BMD after adjustment for age, body mass index, energy intake, calcium intake, vitamin D intake, smoking status, physical activity score, and, for women, menopause status and estrogen use. RESULTS: Higher dihydrophylloquinone intakes were associated with lower mean BMD at the femoral neck [lowest-to-highest tertiles (95% CI): 0.934 (0.925, 0.942), 0.927 (0.919, 0.935), and 0.917 (0.908, 0.926), P for trend = 0.02], the trochanter [lowest-to-highest tertiles (95% CI): 0.811 (0.802, 0.820), 0.805 (0.797, 0.813), and 0.795 (0.786, 0.804), P for trend = 0.02], and the spine [lowest-to-highest tertiles (95% CI): 1.250 (1.236, 1.264), 1.243 (1.242, 1.229), and 1.227 (1.213, 1.242), P for trend = 0.03] in men and women after adjustment for the covariates. Further adjustment for markers of healthy and low-quality dietary patterns did not affect the observed associations. CONCLUSIONS: Higher dihydrophylloquinone intakes are associated with lower BMD in men and women. This association remains significant after adjustment for other markers of diet quality.”

Sato T, Ozaki R, Kamo S, Hara Y, Konishi S, Isobe Y, Saitoh S, Harada H. (2003) The biological activity and tissue distribution of 2′,3′-dihydrophylloquinone in rats. Biochemica et Biophysica Acta. 1622(3):145-50. (Pubmed).

“2′,3′-Dihydrophylloquinone (dihydro-K1) is a hydrogenated form of vitamin K1 (K1), which is produced during the hydrogenation of K1-rich plant oils. In this study, we found that dihydro-K1 counteracts the sodium warfarin-induced prolonged blood coagulation in rats. This indicates that dihydro-K1 functions as a cofactor in the posttranslational gamma-carboxylation of the vitamin K-dependent coagulation factors. It was also found that dihydro-K1 as well as K1 inhibits the decreasing effects of warfarin on the serum total osteocalcin level. In rats, dihydro-K1 is well absorbed and detected in the tissues of the brain, pancreas, kidney, testis, abdominal aorta, liver and femur. K1 is converted to menaquinone-4 (MK-4) in all the above-mentioned tissues, but dihydro-K1 is not. The unique characteristic of dihydro-K1 possessing vitamin K activity and not being converted to MK-4 would be useful in revealing the as yet undetermined physiological function of the conversion of K1 to MK-4.”