Dihydro-vitamin K1: primary food sources and estimated dietary intakes in the American diet

Dietary Vitamin K Intake and the Risk of Pancreatic Cancer: A Prospective Study of 101,695 American Adults

No epidemiologic studies have been conducted to assess the association of intake of dietary vitamin K with the risk of pancreatic cancer. We used prospective data from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial between 1993 and 2009 to fill this gap. A total of 101,695 subjects were identified. Dietary intakes of phylloquinone (vitamin K1), menaquinones (vitamin K2), and dihydrophylloquinone (dihydrovitamin K1) were assessed using a food frequency questionnaire. Cox regression was applied to calculate hazard ratios and 95% confidence intervals. During a mean follow-up of 8.86 years (900,744.57 person-years), 361 cases of pancreatic cancer were documented. In the fully adjusted model, dietary intakes of phylloquinone (for quartile 4 vs. quartile 1, hazard ratio (HR) = 0.57, 95% confidence interval (CI): 0.39, 0.83; P for trend = 0.002) and dihydrophylloquinone (for quartile 4 vs. quartile 1, HR = 0.59; 95% CI: 0.41, 0.85; P for trend = 0.006), but not menaquinones (for quartile 4 vs. quartile 1, HR = 0.93; 95% CI: 0.65, 1.33; P for trend = 0.816), were found to be inversely associated with the risk of pancreatic cancer in a nonlinear dose-response manner (all P values for nonlinearity < 0.05), and this was not modified by predefined stratification factors and remained in sensitivity analyses. In conclusion, dietary intakes of phylloquinone and dihydrophylloquinone, but not menaquinones, confer a lower risk of pancreatic cancer. Future studies should confirm our findings.

Vitamin K and cardiovascular complications in CKD patients

Vitamin K, well known for its role in coagulation, encompasses two major subgroups: Vitamin K1 is exclusively synthesized by plants, whereas vitamin K2 mostly originates from bacterial synthesis. Vitamin K serves as a cofactor for the enzyme γ-glutamyl carboxylase, which carboxylates and thereby activates various vitamin K dependent proteins. Several vitamin K-dependent proteins are synthesized in bone but the role of vitamin K for bone health in CKD patients, in particular the prevention of osteoporosis is still not firmly established. Here we focus on another prominent action of vitamin K, in particular vitamin K2, namely the activation of matrix Gla protein (MGP), the most potent inhibitor of cardiovascular calcifications. Multiple observational studies link relative vitamin K deficiency or low intake to cardiovascular calcification progress, morbidity and mortality. Patients with advanced chronic kidney disease (CKD) are particularly vitamin K deficient, in part because of dietary restrictions but possibly also due to impaired endogenous recycling of vitamin K. At the same time this population is characterized by markedly accelerated cardiovascular calcifications and mortality. High dose dietary supplementation with vitamin K2, in particular the most potent form menaquinone-7 (MK7), can potently reduce circulating levels of dephosphorylated uncarboxylated, i.e. inactive MGP in patients with end stage kidney disease. However, despite this compelling data basis, several randomized controlled trials with high dose MK7 supplements in patients with advanced CKD have failed to confirm cardiovascular benefits. Here we discuss potential reasons and solutions for this.

Dietary reference values for vitamin K

Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) derives dietary reference values (DRVs) for vitamin K. In this Opinion, the Panel considers vitamin K to comprise both phylloquinone and menaquinones. The Panel considers that none of the biomarkers of vitamin K intake or status is suitable by itself to derive DRVs for vitamin K. Several health outcomes possibly associated with vitamin K intake were also considered but data could not be used to establish DRVs. The Panel considers that average requirements and population reference intakes for vitamin K cannot be derived for adults, infants and children, and therefore sets adequate intakes (AIs). The Panel considers that available evidence on occurrence, absorption, function and content in the body or organs of menaquinones is insufficient, and, therefore, sets AIs for phylloquinone only. Having assessed additional evidence available since 1993 in particular related to biomarkers, intake data and the factorial approach, which all are associated with considerable uncertainties, the Panel maintains the reference value proposed by the Scientific Committee for Food (SCF) in 1993. An AI of 1 μg phylloquinone/kg body weight per day is set for all age and sex population groups. Considering the respective reference body weights, AIs for phylloquinone are set at 70 μg/day for all adults including pregnant and lactating women, at 10 μg/day for infants aged 7-11 months, and between 12 μg/day for children aged 1-3 years and 65 μg/day for children aged 15-17 years.

Bone Health and Osteoporosis: The Role of Vitamin K and Potential Antagonism by Anticoagulants

BACKGROUND

Vitamin K's effects extend beyond blood clotting to include a role in bone metabolism and potential protection against osteoporosis. Vitamin K is required for the gamma-carboxylation of osteocalcin. Likewise, this gamma-carboxylation also occurs in the liver for several coagulation proteins. This mechanism is interrupted by coumarin-based anticoagulants in both the liver and bone.

METHODS

A thorough review of the literature on vitamin K, osteocalcin and their role in bone metabolism and osteoporosis, as well as the potential bone effects of anticoagulant therapy was conducted.

CONCLUSIONS

Epidemiological studies and clinical trials consistently indicate that vitamin K has a positive effect on bone mineral density and decreases fracture risk. Typical dietary intakes of vitamin K are below the levels associated with better BMD and reduced fracture risk; thus issues of increasing dietary intakes, supplementation, and/or fortification arise. To effectively address these issues, large-scale, intervention trials of vitamin K are needed. The effects of coumarin-based anticoagulants on bone health are more ambiguous, with retrospective studies suggesting that long-term therapy adversely affects vertebral BMD and fracture risk. Anticoagulants that do not affect vitamin K metabolism are now available and make clinical trials feasible to answer the question of whether coumarins adversely affect bone. The research suggests that at a minimum, clinicians should carefully assess anticoagulated patients for osteoporosis risk, monitor BMD, and refer them to dietitians for dietary and supplement advice on bone health. Further research is needed to make more efficacious decisions about vitamin K intake, anticoagulant therapy, and bone health.

Comparative effects of plant oils on the cerebral hemorrhage in stroke-prone spontaneously hypertensive rats

OBJECTIVES

Since oils and fats can induce metabolic syndrome, leading to cardiovascular and cerebrovascular diseases, the present study was performed to find out whether the plant oils affect the cerebral hemorrhage in stroke-prone spontaneously hypertensive (SHR-SP) rats.

METHODS

From 47 days of age, male SHR-SP rats were given drinking water containing 1% NaCl to induce hypertension, and simultaneously fed semi-purified diets containing 10% perilla oil, canola oil, or shortening. The onset time of convulsion following cerebral hemorrhage was recorded, and the areas of hemorrhage and infarction were analyzed in the stroke brains.

RESULTS

In comparison with 58-day survival of SHR-SP rats during feeding NaCl alone, perilla oil extended the survival time to 68.5 days, whereas canola oil shortened it to 45.7 days. Feeding perilla oil greatly reduced the total volume of cerebral hemorrhage from 17.27% in the control group to 4.53%, while shortening increased the lesions to 21.23%. In a microscopic analysis, perilla oil also markedly decreased the hemorrhagic and infarction lesions to 1/10 of those in control rats, in contrast to an exacerbating effect of shortening. In blood analyses, perilla oil reduced blood total cholesterol and low-density lipoproteins which were increased in SHR-SP, but canola oil further increased them and markedly lowered platelet counts.

DISCUSSION

Perilla oil delayed and attenuated cerebral hemorrhage by improving hyperlipidemia in hypertensive stroke animals, in contrast to the aggravating potential of canola oil and shortening. It is suggested that perilla oil should be the first choice oil for improving metabolic syndrome in hypertensive persons at risk of hemorrhagic stroke.

Dihydrophylloquinone intake is associated with low bone mineral density in men and women

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.

Dietary lipids impacts on healthy ageing

Healthy ageing is gaining attention in the lipid nutrition field. As in vivo biomarkers of healthy ageing, we have evaluated the survival, learning/memory performance, and physical potencies in rodents fed a diet supplemented with high-linoleic acid (LNA, omega6) safflower oil or high-alpha-linolenic acid (ALA, omega3) perilla oil for long periods. The results suggested that perilla oil with a low omega6/omega3 ratio is beneficial for healthy ageing. In order to address this issue further, we determined the survival of stroke-prone SHR (SHRSP) rats fed a conventional rodent diet supplemented with 10% fat or oil. Survival was longer with omega3-rich oils compared with omega6-rich oils. However, some kinds of vegetable oils and hydrogenated oils shortened the survival of SHRSP rats to an unusual degree (ca. 40% compared with that of omega6-rich oil) that could not be accounted for by the fatty acid and phytosterol composition of the oils. The observed decrease in platelet counts was associated with pathological changes in the kidney and other organs. Dihydro-vitamin K1 is proposed as a likely candidate as a stroke-stimulating factor in hydrogenated oils. Thus, factors other than fatty acids (omega6/omega3 balance) and phytosterols must be taken into account when fats and oils are evaluated in relation to healthy ageing.

Determinants of plasma dihydrophylloquinone in men and women

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. Plasma dihydrophylloquinone 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 mean dihydrophylloquinone intake was 21·3 (95 % CI 20·4, 22·3) μg/d in men and 19·4 (95 % CI 18·5, 20·2) μg/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 plasma dihydrophylloquinone 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-detectable dihydrophylloquinone concentrations. Despite this caveat, higher plasma dihydrophylloquinone was associated with higher dihydrophylloquinone intake and higher trans fatty acid intake.

Vitamin K, bone turnover, and bone mass in girls

BACKGROUND

Vitamin K has been suggested to have a role in bone metabolism, and low vitamin K intake has been related to low bone density and increased risk of osteoporotic fracture.

OBJECTIVE

The objective of this study was to determine whether phylloquinone (vitamin K(1)) intake and biochemical indicators of vitamin K status are related to bone mineral content (BMC) and markers of bone formation and bone resorption in girls.

DESIGN

Vitamin K status [plasma phylloquinone concentration and percentage of undercarboxylated osteocalcin (%ucOC)] was measured at baseline in a study of 245 healthy girls aged 3-16 y. Cross-linked N-telopeptide of type 1 collagen (NTx) breakdown, osteocalcin, and bone-specific alkaline phosphatase were measured to reflect bone resorption and formation. BMC of the total body, lumbar spine, and hip and dietary phylloquinone intake were measured annually for 4 y.

RESULTS

Phylloquinone intake (median: 45 microg/d) was not consistently associated with bone turnover markers or BMC. Better vitamin K status (high plasma phylloquinone and low %ucOC) was associated with lower bone resorption and formation. Plasma phylloquinone was inversely associated with NTx and osteocalcin concentrations (P < 0.05), and %ucOC was positively associated with NTx and bone-specific alkaline phosphatase concentrations (P < 0.05). Indicators of vitamin K status were not consistently associated with current BMC or gain in BMC over the 4-y study period.

CONCLUSIONS

Better vitamin K status was associated with decreased bone turnover in healthy girls consuming a typical US diet. Randomized phylloquinone supplementation trials are needed to further understand the potential benefits of phylloquinone on bone acquisition in growing children.

The biological activity and tissue distribution of 2',3'-dihydrophylloquinone in rats

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.

Vitamina K: metabolismo e nutrição

O objetivo desta revisão foi discutir aspectos que envolvem a compreensão do metabolismo da vitamina K e os recentes avanços quanto ao papel da vitamina na nutrição humana. São abordadas questões sobre as fontes da vitamina, sua absorção, distribuição e metabolismo, recomendações dietéticas, avaliação do estado nutricional relacionado à vitamina K e ainda fatores que afetam sua concentração plasmática. Diante das novas evidências sobre a participação da vitamina K no metabolismo ósseo, pesquisas adicionais são necessárias a fim de identificar as possíveis conseqüências à saúde, a longo prazo, de deficiência subclínica desta vitamina. Pesquisadores e comitês futuros encontram um desafio no que se refere a investigar novos requerimentos nutricionais da vitamina.

Effects of a hydrogenated form of vitamin K on bone formation and resorption

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 or dihydrophylloquinone.

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.

Natural vitamins may be superior to synthetic ones

There appears to be a tendency to label those who profess that natural vitamins are better than synthetic ones as quacks. This broad brush label may be stifling legitimate nutrition research. This paper describes physiochemical differences between certain natural and synthetic vitamins, proven clinical advantages of natural vitamins, and some of the effects this labeling may lead to. It concludes that lessons of history as well as modern science support the view that natural vitamins are nutritionally superior to synthetic ones.

Assessment of phylloquinone and dihydrophylloquinone dietary intakes among a nationally representative sample of US consumers using 14-day food diaries

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 of dihydrophylloquinone in the US diet suggests the need for study of its biological activity relative to phylloquinone.

Demographic, dietary and lifestyle factors differentially explain variability in serum carotenoids and fat-soluble vitamins: baseline results from the sentinel site of the Olestra Post-Marketing Surveillance Study

Biochemical measures of nutrients or other dietary constituents can be an important component of nutritional assessment and monitoring. However, accurate interpretation of the nutrient concentration is dependent on knowledge of the determinants of the body pool measured. The purpose of this study was to identify the determinants of serum carotenoid and fat-soluble vitamin concentrations in a large, community-based sample (n = 1042). Multiple linear regression analysis was used to examine effects of demographic characteristics (age, sex, race/ethnicity, education), health-related behavior (exercise, sun exposure, smoking, alcohol consumption), and intake (diet, supplements) on serum retinol, 25-hydroxyvitamin D, alpha-tocopherol, phylloquinone, and carotenoid concentrations. Age, sex, race/ethnicity, vitamin A intake, and alcohol consumption were found to be determinants of serum retinol concentration. Race/ethnicity, vitamin D intake, body mass index, smoking status, and sun exposure were determinants of serum 25-hydroxyvitamin D concentration. Determinants of serum alpha-tocopherol were age, sex, race/ethnicity, alpha-tocopherol intake, serum cholesterol, percentage of energy from fat (inversely related), supplement use, and body mass index. Age, sex, phylloquinone intake, serum triglycerides, and supplement use were determinants of serum phylloquinone concentration. Primary determinants of serum carotenoids were age, sex, race/ethnicity, carotenoid intake, serum cholesterol, alcohol consumption, body mass index, and smoking status. Overall, the demographic, dietary, and other lifestyle factors explained little of the variability in serum concentrations of retinol (R2 = 0.20), 25-hydroxyvitamin D (R2 = 0.24), and the carotenoids (R2 = 0.15-0.26); only modest amounts of the variability in serum phylloquinone concentration (R2 = 0.40); and more substantial amounts of the variability in serum alpha-tocopherol concentration (R2 = 0.62).

Dietary intake and adequacy of vitamin K

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'-dihydrophylloquinone of 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.

Plasma concentrations of dihydro-vitamin K1 following dietary intake of a hydrogenated vitamin K1-rich vegetable oil

Dihydro-vitamin K1 is a dietary form of vitamin K1 (phylloquinone) produced during the hydrogenation of vegetable oils. To determine if dihydro-vitamin K1 is present in plasma following dietary intake of a hydrogenated fat, eight healthy adults consumed each of two diets containing 30% of calories from fat, of which 20% was either soybean oil or a partially hydrogenated soybean oil-based stick margarine. Of the fats and oils analyzed, dihydro-vitamin K1 was only found in the hydrogenated products. The soybean oil diet contained 180 +/- 12 micrograms (mean +/- SD) of vitamin K1/day and nondetectable levels of dihydro-vitamin K1, whereas the stick margarine diet contained 199 +/- 7 micrograms of vitamin K1/day and 23 +/- 2 micrograms of dihydro-vitamin K1/day. After consuming each diet for five weeks, plasma dihydro-vitamin K1 concentrations were higher (P = 0.002) in all eight subjects when consuming the stick margarine diet (0.56 +/- 0.33 nmol/L) compared to the soybean oil diet (0.12 +/- 0.11 nmol/L). There was no significant change in plasma vitamin K1 concentrations when the two diets were compared. In conclusion, dihydro-vitamin K1 is detectable in plasma following dietary intake of a hydrogenated vitamin K1-rich vegetable oil.