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

The Contribution of Lipids to the Interindividual Response of Vitamin K Biomarkers to Vitamin K Supplementation

SCOPE

A better understanding of factors contributing to interindividual variability in biomarkers of vitamin K can enhance the understanding of the equivocal role of vitamin K in cardiovascular disease. Based on the known biology of phylloquinone, the major form of vitamin K, it is hypothesized that plasma lipids contribute to the variable response of biomarkers of vitamin K metabolism to phylloquinone supplementation.

METHODS AND RESULTS

The association of plasma lipids and 27 lipid-related genetic variants with the response of biomarkers of vitamin K metabolism is examined in a secondary analysis of data from a 3-year phylloquinone supplementation trial in men (n = 66) and women (n = 85). Year 3 plasma triglycerides (TG), but not total cholesterol, LDL-cholesterol, or HDL-cholesterol, are associated with the plasma phylloquinone response (men: β = 1.01, p < 0.001, R2  = 0.34; women: β = 0.61, p = 0.008, R2  = 0.11; sex interaction p = 0.077). Four variants and the TG-weighted genetic risk score are associated with the plasma phylloquinone response in men only. Plasma lipids are not associated with changes in biomarkers of vitamin K function (undercarboxylated osteocalcin and matrix gla protein) in either sex.

CONCLUSION

Plasma TG are an important determinant of the interindividual response of plasma phylloquinone to phylloquinone supplementation, but changes in biomarkers of vitamin K carboxylation are not influenced by lipids.

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.

Vitamin K metabolism: current knowledge and future research

Vitamin K is an essential fat-soluble micronutrient that is required for the post-translational γ-carboxylation of specific glutamic acid residues in hepatic and extra-hepatic proteins involved in blood coagulation and preventing cartilage and vasculature calcification. In humans, sources of vitamin K are derived from plants as phylloquinone and bacteria as the menaquinones. Menadione is a synthetic product used as a pharmaceutical but also represents an intermediate in the tissue-specific conversion of vitamin K to menaquinone-4, which preferentially resides in tissues such as brain. Research into vitamin K metabolism is essential for the understanding of vitamin K biology in health and disease. Progress in this area, driven by knowledge of vitamin K and the availability of markers of vitamin K status, has already proved beneficial in many areas of medicine and further opportunities present themselves. Areas of interest discussed in this review include prophylactic administration of vitamin K1 in term and preterm neonates, interactions between vitamins K and E, the industrial conversion of vitamin K to dihydro-vitamin K in foods, tissue-specific conversion of vitamin K to menaquinone-4, the biological activity of the five and seven carbon metabolites of vitamin K and circadian variations.

Vitamin K, an example of triage theory: is micronutrient inadequacy linked to diseases of aging?

The triage theory posits that some functions of micronutrients (the approximately 40 essential vitamins, minerals, fatty acids, and amino acids) are restricted during shortage and that functions required for short-term survival take precedence over those that are less essential. Insidious changes accumulate as a consequence of restriction, which increases the risk of diseases of aging. For 16 known vitamin K-dependent (VKD) proteins, we evaluated the relative lethality of 11 known mouse knockout mutants to categorize essentiality. Results indicate that 5 VKD proteins that are required for coagulation had critical functions (knockouts were embryonic lethal), whereas the knockouts of 5 less critical VKD proteins [osteocalcin, matrix Gla protein (Mgp), growth arrest specific protein 6, transforming growth factor beta-inducible protein (Tgfbi or betaig-h3), and periostin] survived at least through weaning. The VKD gamma-carboxylation of the 5 essential VKD proteins in the liver and the 5 nonessential proteins in nonhepatic tissues sets up a dichotomy that takes advantage of the preferential distribution of dietary vitamin K1 to the liver to preserve coagulation function when vitamin K1 is limiting. Genetic loss of less critical VKD proteins, dietary vitamin K inadequacy, human polymorphisms or mutations, and vitamin K deficiency induced by chronic anticoagulant (warfarin/coumadin) therapy are all linked to age-associated conditions: bone fragility after estrogen loss (osteocalcin) and arterial calcification linked to cardiovascular disease (Mgp). There is increased spontaneous cancer in Tgfbi mouse knockouts, and knockdown of Tgfbi causes mitotic spindle abnormalities. A triage perspective reinforces recommendations of some experts that much of the population and warfarin/coumadin patients may not receive sufficient vitamin K for optimal function of VKD proteins that are important to maintain long-term health.

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.

Excretion of the urinary 5C- and 7C-aglycone metabolites of vitamin K by young adults responds to changes in dietary phylloquinone and dihydrophylloquinone intakes

The physiological function and putative health roles of vitamin K-dependent proteins now extend beyond their classical role in hemostasis and include bone mineralization, arterial calcification, apoptosis, phagocytosis, growth control, chemotaxis, and signal transduction. Current assessments of vitamin K status do not reflect the variety of molecular forms of vitamin K. We assessed whether urinary excretion of 2-methyl-3-(5'-carboxy-3'-methyl-2'-pentenyl)-1,4-naphthoquinone (7C-aglycone) and 2-methyl-3-(3'-3'-carboxymethylpropyl)-1,4-naphthoquinone (5C-aglycone), vitamin K metabolites common to both phylloquinone and the menaquinone series, reflect dietary vitamin K intake. In a randomized crossover study, 9 adults resided in a metabolic unit for two 30-d periods separated by a free-living period of > or = 4 wk. During each residency, subjects consumed 3 sequential diets: a control diet (93 microg phylloquinone/d) for 5 d, a phylloquinone-restricted diet (11 microg/d) for 15 d, followed by a randomly assigned repletion diet for 10 d with either phylloquinone (206 microg/d) or dihydrophylloquinone (240 microg/d). During the second residency, the alternative repletion diet was assigned. Urinary excretion of the 5C- and 7C-aglycones was measured in sequential 24-h collections. The 5C-aglycone accounted for approximately 75% of total excretion and declined in response to phylloquinone restriction (P = 0.001) to approximately 30% of that during the control diet period. Repletion with phylloquinone and dihydrophylloquinone doubled the excretion rate of the major 5C-aglycone by 24 h (P < 0.001), and tripled excretion by 4 d. There was a linear relationship between the logarithm of total urinary excretion and dietary vitamin K intake (r = 0.699, P < 0.001). We conclude that the urinary excretion of vitamin K metabolites reflects dietary phylloquinone intake and offers the first candidate marker of global vitamin K status.

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.

Comparative dietary intake and sources of phylloquinone (vitamin K1) among British adults in 1986-7 and 2000-1

Using data from 7 d weighed dietary records, dietary intake and sources of phylloquinone (vitamin K1) were examined by socio-demographic and lifestyle factors in 1916 participants aged 16-64 years from the 1986-7 Dietary and Nutritional Survey of British Adults, and 1423 participants aged 19-64 years from the 2000-1 National Diet and Nutrition Survey. Using UK-specific food content data, geometric mean phylloquinone intakes were estimated as 72 (95% CI 70, 74) and 67 (95% CI 65, 69) microg/d in 1986-7 and 2000-1 respectively (P<0.001). In 1986-7, 47% of participants had phylloquinone intakes below the UK guideline for adequacy (> or =1 microg/kg body weight per d), compared with 59% in 2000-1 (P<0.001). In both surveys, daily phylloquinone intake was higher among men than women and increased significantly with age. Participants of manual occupational social class, or who were smokers, had lower phylloquinone intake than their counterparts. Participants living in Scotland and northern England had lower phylloquinone intake than those living elsewhere in mainland Britain, particularly in 1986-7 when the contribution from vegetables was also lower than elsewhere. However, by 2000-1 this regional difference was no longer significant. Overall, vegetables contributed 63% of phylloquinone intake in 1986-7 and 60% in 2000-1, with cooked leafy green vegetables (LGV) providing 23 and 19% respectively. In both surveys, the contribution of vegetables (cooked LGV in particular) was directly associated with age. These data show a decrease in phylloquinone intake from 1986-7 to 2000-1, mainly owing to lower consumption of cooked LGV.

Effect of phylloquinone supplementation on biochemical markers of vitamin K status and bone turnover in postmenopausal women

While current intakes of phylloquinone (vitamin K1) in many populations are believed to be sufficient to maintain normal blood coagulation, these may be insufficient to cover the requirements for optimal bone metabolism. Therefore, the objective of the present study was to investigate the effect of increasing phylloquinone intakes above the usual dietary intake for 6 weeks on biochemical markers of vitamin K status and bone turnover in postmenopausal women. Thirty-one postmenopausal women completed this 3 × 6-week randomised cross-over study, in which volunteers were supplemented with 0 (placebo), 200, and 500 μg phylloquinone/d. In addition, the volunteers were given 10 μg vitamin D3/d throughout the study period. With increasing phylloquinone intake, the concentration of serum γ-carboxylated and under-γ-carboxylated osteocalcin was significantly increased and decreased, respectively, in a dose-dependent manner (P < 0·001). Mean serum phylloquinone concentration was significantly (P < 0·001) higher with daily supplementation with 500 μg phylloquinone/d compared with that during either of the placebo or 200 μg phylloquinone/d supplementation periods, which did not differ (P = 0·15). Serum total osteocalcin was significantly (P < 0·001) increased in response to daily supplementation with 500 (but not 200) μg phylloquinone compared with placebo. Serum bone-specific alkaline phosphatase as well as the urinary markers of bone resorption (N-telopeptide cross-links of collagen, pyridinoline and deoxypyridinoline) and urinary γ-carboxyglutamate were unaffected by phylloquinone supplementation. In conclusion, while daily supplementation with 200 and 500 μg phylloquinone/d for 6 weeks increased vitamin K status in postmenopausal women, it had no effect on bone turnover.

Dietary vitamin K intake and anticoagulation in elderly patients

PURPOSE OF REVIEW

Vitamin K is an essential co-factor for the synthesis of several coagulation factors. Oral anticoagulants competitively inhibit enzymes that participate in vitamin K metabolism. The purpose of this review is to evaluate the potential interaction of dietary vitamin K and coagulation stability, particularly in the elderly patient.

RECENT FINDINGS

Recent prospective evidences suggest that dietary vitamin K plays an essential role in anticoagulation stability. Vitamin K intake of more than 250 microg/day was shown to decrease warfarin sensitivity in anticoagulated patients consuming regular diets. In a randomized crossover study, brief periods of changes on vitamin K intake also had significant effects on coagulation parameters. Patients that were allocated to an 80% decrease of intake increased International Normalized Ratio (INR) by almost 30% 7 days after the intervention. Similarly, it was estimated by dietary records that for each increase in 100 microg of vitamin K intake, the INR would be reduced by 0.2. A recent study also demonstrated that over-the-counter multivitamin supplements contain enough vitamin K1 to significantly alter coagulation parameters.

SUMMARY

Contemporary data strengthen the concept that the interaction between dietary vitamin K and coumarin derivatives is clinically relevant and plays a major role in INR fluctuations in chronic anticoagulated patients.

Intake and sources of phylloquinone (vitamin K(1)) in 4-year-old British children: comparison between 1950 and the 1990s

OBJECTIVES

To compare dietary intake and sources of phylloquinone (vitamin K1) in 4-year-old British children between 1950 and the 1990s, and report their variation by sociodemographic factors.

DESIGN

Nationally representative samples of 4-year-olds from the longitudinal Medical Research Council National Survey of Health and Development (NSHD) (1950) and the cross-sectional National Diet and Nutrition Surveys (NDNS, 1992/93 and 1997).

SETTING

Great Britain.

SUBJECTS

Subjects were 4599 children born on 3-9 March 1946 (NSHD) and 307 children in the 1990s (NDNS).

RESULTS

Geometric mean dietary phylloquinone intake was significantly higher in 1950 (39 mug day(-1), 95% confidence interval (CI) 37, 40) compared with the 1990s (24 mug day(-1), 95% CI 22, 25) (P<0.001). This difference remained when intake was expressed per MJ energy intake and per kilogram body weight, and after accounting for sex, region and occupational social class of the family. In 1950, phylloquinone intake in Scotland was significantly lower than in the rest of Britain. By the 1990s these regional differences had disappeared. Food sources of phylloquinone intake changed significantly between 1950 and the 1990s, with fats and oils contributing more and vegetables less, although vegetables contributed most (60% and 48%, respectively) to phylloquinone intake in both surveys.

CONCLUSIONS

Phylloquinone intakes of children have decreased significantly since 1950. With the suggested need for adequate phylloquinone intake for optimal development and maintenance of bone and the cardiovascular system, the substantially lower phylloquinone intakes reported in children of the 1990s, compared with 1950, may have implications for the health of these two systems in later adulthood.

Phylloquinone (vitamin K1) intakes and food sources in 18-64-year-old Irish adults

Dietary vitamin K1 (phylloquinone) levels that are sufficient to maintain normal blood coagulation may be sub-optimal for bone, and habitual low dietary intakes of vitamin K may have an adverse effect on bone health. The objective of the present study was to measure the intake and adequacy of phylloquinone intake and the contribution of foods to phylloquinone intake in a nationally representative sample of Irish adults. The North/South Ireland Food Consumption Survey database was used, which contains data collected using a 7 d food diary in a randomly selected sample of Irish adults aged 18-64 years (n 1379; 662 men and 717 women). Phylloquinone intakes were estimated using recently compiled food composition data for phylloquinone. The mean daily intake of phylloquinone from food sources was 79 (SD 44) microg. Intakes were significantly higher (P<0.001) in men than in women at levels of 84 and 75 microg/d. The main contributors to phylloquinone intakes were vegetables (48 %), particularly green vegetables (26 %). Potatoes (including chipped and fried potatoes), dairy products and fat spreads contributed 10 % each and meat contributed 8 %. In men, social class and smoking status influenced phylloquinone intakes. Of the population, 52 % had phylloquinone intakes below 1 microg/kg body weight and only 17 % of men and 27 % of women met the US adequate intakes of 120 and 90 microg/d, respectively. The present study shows that habitual phylloquinone intakes in Irish adults are low, which may have implications for bone health.

Effect of vitamin E supplementation on vitamin K status in adults with normal coagulation status

BACKGROUND

Cases of enhanced anticoagulant effect in response to high-dose vitamin E supplementation have been reported among patients taking oral anticoagulants. Although a vitamin E-vitamin K interaction was proposed to underlie this effect, it has not been systematically investigated in adults with normal baseline coagulation status.

OBJECTIVE

The objective was to study the effect of 12 wk of supplementation with 1000 IU RRR-alpha-tocopherol/d on biochemical measures of vitamin K status in men and women not taking oral anticoagulants.

DESIGN

Vitamin K status, which was assessed with the use of plasma phylloquinone concentrations, the degree of under-gamma-carboxylation of prothrombin (proteins induced by vitamin K absence-factor II, PIVKA-II), and the percentage of undercarboxylated osteocalcin (ucOC), was determined in 38 men and women with rheumatoid arthritis (study A) and in 32 healthy men (study B) participating in 2 independent, 12-wk randomized clinical trials of vitamin E supplementation (1000 IU/d).

RESULTS

Mean (+/- SD) PIVKA-II increased from 1.7 +/- 1.7 to 11.9 +/- 16.1 ng/mL (P < 0.001) in study A and from 1.8 +/- 0.6 to 5.3 +/- 3.9 ng/mL (P < 0.001) in study B in response to 12 wk of vitamin E supplementation. An increase in PIVKA-II is indicative of poor vitamin K status. In contrast, the other measures of vitamin K status (ie, plasma phylloquinone concentration and percentage of ucOC) did not change significantly in response to the supplementation.

CONCLUSIONS

High-dose vitamin E supplementation increased PIVKA-II in adults not receiving oral anticoagulant therapy. The clinical significance of these changes warrants further investigation, but high doses of vitamin E may antagonize vitamin K. Whether such an interaction is potentially beneficial or harmful remains to be determined.

Role of dietary vitamin K intake in chronic oral anticoagulation: prospective evidence from observational and randomized protocols

PURPOSE

The potential association between vitamin K intake and coagulation instability has been explored primarily in case reports and small, retrospective, uncontrolled studies. We prospectively evaluated the effects of dietary vitamin K intake on anticoagulation parameters.

METHODS

In an observational protocol, clinical characteristics and vitamin K intake, assessed semiquantitatively, were evaluated in 39 outpatients who made 230 visits to our anticoagulation clinic. In a randomized crossover protocol, 12 patients with stable anticoagulation underwent 4-day in-hospital dietary interventions, 1 to 2 weeks apart, providing a 500% increase and an 80% decrease in vitamin K intake relative to the baseline level.

RESULTS

Univariate analysis of the observational data demonstrated a progressive, statistically significant inverse association between the vitamin K intake score and different levels of anticoagulation. Multivariate logistic regression analysis showed that vitamin K intake was independently associated with both overcoagulation and undercoagulation. In the randomized protocol, the international normalized ratio increased from 2.6 +/- 0.5 at baseline to 3.3 +/- 0.9 at day 7 (P = 0.005) in subjects on the vitamin K-depleted diet and decreased from 3.1 +/- 0.8 at baseline to 2.8 +/- 0.6 at day 4 (P = 0.04) in those on the vitamin K-enriched diet.

CONCLUSION

Our prospective data strengthen the concept that the interaction between vitamin K and coumarin is a clinically relevant, major independent factor that interferes with anticoagulation stability.

Factors affecting intestinal absorption of highly lipophilic food microconstituents (fat-soluble vitamins, carotenoids and phytosterols)

Highly lipophilic food microconstituents (HLFMs) with octanol-water partition coefficients log10 P(c) > 8 include the fat-soluble vitamins (A, E, D and K) and phytochemicals with potential health benefits, the carotenoids and phytosterols. It has been assumed that these compounds have the same metabolism in the human upper gastrointestinal tract and that they follow the same fate as lipids. However, a literature review shows that the metabolism of HLFMs in the upper gastrointestinal tract depends on each HLFM species. For example, some HLFM esters are hydrolyzed mainly by pancreatic lipase, others by bile salt-stimulated lipase; some HLFMs are apparently absorbed by passive diffusion, others by a transporter. Also, although some factors (HLFM molecular species, fat, food matrix) affect absorption efficiency of most HLFMs, other factors (fibers, microconstituents) apparently affect absorption only of some HLFMs. The mnemonic acronym SLAMENGHI, previously proposed to list the factors affecting the bioavailability of carotenoids, was used here to review current knowledge of the factors suspected to affect the intestinal absorption of HLFMs. The available data reveal numerous gaps in the knowledge of the metabolism of HLFMs and the factors that affect their absorption. These gaps need to be filled to be able to formulate HLFMs so as to promote greater absorption efficiency.

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.