Tea and coffee brews are not dietary sources of vitamin K-1 (phylloquinone)

Higher Habitual Dietary Flavonoid Intake Associates With Less Extensive Abdominal Aortic Calcification in a Cohort of Older Women

BACKGROUND

The extent of abdominal aortic calcification (AAC) is a major predictor of vascular disease events. We have previously found regular apple intake, a major source of dietary flavonoids, associates with lower AAC. Whether total dietary flavonoid intake impacts AAC remains unknown. Here, we extend our observations to habitual intakes of total flavonoids, flavonoid subclasses, and specific flavonoid-containing foods, with the odds of extensive AAC.

METHODS

We conducted cross-sectional analyses on 881 females (median [interquartile range] age, 80 [78-82] years; body mass index, 27 [24-30] kg/m²) from the PLSAW (Perth Longitudinal Study of Ageing Women). Flavonoid intake was calculated from food-frequency questionnaires. Calcifications of the abdominal aorta were assessed on lateral lumbar spine images and categorized as less extensive or extensive. Logistic regression was used to investigate associations.

RESULTS

After adjusting for demographic, lifestyle and dietary confounders, participants with higher (Q4), compared with lower (Q1) intakes, of total flavonoids, flavan-3-ols, and flavonols had 36% (odds ratio [95% CI], 0.64 [0.43-0.95]), 39% (0.61 [0.40-0.93]) and 38% (0.62 [0.42-0.92]) lower odds of extensive AAC, respectively. In food-based analyses, higher black tea intake, the main source of total flavonoids (75.9%), associated with significantly lower odds of extensive AAC (2-6 cups/d had 16%-42% lower odds compared with 0 daily intake). In a subset of nonconsumers of black tea, the association of total flavonoid intake with AAC remained (Q4 versus Q1 odds ratio [95% CI], 0.11 [0.02-0.54]).

CONCLUSIONS

In older women, greater habitual dietary flavonoid intake associates with less extensive AAC.

A potential biotechnological process for the sustainable production of vitamin K1

The primary objective of this review is to propose an approach for the biosynthesis of phylloquinone (vitamin K₁) based upon its known sources, its role in photosynthesis and its biosynthetic pathway. The chemistry, health benefits, market, and industrial production of vitamin K are also summarized. Vitamin K compounds (K vitamers) are required for the normal function of at least 15 proteins involved in diverse physiological processes such as coagulation, tissue mineralization, inflammation, and neuroprotection. Vitamin K is essential for the prevention of Vitamin K Deficiency Bleeding (VKDB), especially in neonates. Increased vitamin K intake may also reduce the severity and/or risk of bone fracture, arterial calcification, inflammatory diseases, and cognitive decline. Consumers are increasingly favoring natural food and therapeutic products. However, the bulk of vitamin K products employed for both human and animal use are chemically synthesized. Biosynthesis of the menaquinones (vitamin K₂) has been extensively researched. However, published research on the biotechnological production of phylloquinone is restricted to a handful of available articles and patents. We have found that microalgae are more suitable than plant cell cultures for the biosynthesis of phylloquinone. Many algae are richer in vitamin K₁ than terrestrial plants, and algal cells are easier to manipulate. Vitamin K₁ can be efficiently recovered from the biomass using supercritical carbon dioxide extraction.

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.

Old and new oral anticoagulants: Food, herbal medicines and drug interactions

The most commonly prescribed oral anticoagulants worldwide are the vitamin K antagonists (VKAs) such as warfarin. Factors affecting the pharmacokinetics of VKAs are important because deviations from their narrow therapeutic window can result in bleedings due to over-anticoagulation or thrombosis because of under-anticoagulation. In addition to pharmacodynamic interactions (e.g., augmented bleeding risk for concomitant use of NSAIDs), interactions with drugs, foods, herbs, and over-the-counter medications may affect the risk/benefit ratio of VKAs. Direct oral anticoagulants (DOACs) including Factor Xa inhibitors (rivaroxaban, apixaban and edoxaban) and thrombin inhibitor (dabigatran) are poised to replace warfarin. Phase-3 studies and real-world evaluations have established that the safety profile of DOACs is superior to those of VKAs. However, some pharmacokinetic and pharmacodynamic interactions are expected. Herein we present a critical review of VKAs and DOACs with focus on their potential for interactions with drugs, foods, herbs and over-the-counter medications.

Updates on the clinical evidenced herb-warfarin interactions

Increasing and inadvertent use of herbs makes herb-drug interactions a focus of research. Concomitant use of warfarin, a highly efficacious oral anticoagulant, and herbs causes major safety concerns due to the narrow therapeutic window of warfarin. This paper presents an update overview of clinical findings regarding herb-warfarin interaction, highlighting clinical outcomes, severity of documented interactions, and quality of clinical evidence. Among thirty-eight herbs, Cannabis, Chamomile, Cranberry, Garlic, Ginkgo, Grapefruit, Lycium, Red clover, and St. John's wort were evaluated to have major severity interaction with warfarin. Herbs were also classified on account of the likelihood of their supporting evidences for interaction. Four herbs were considered as highly probable to interact with warfarin (level I), three were estimated as probable (level II), and ten and twenty-one were possible (level III) and doubtful (level IV), respectively. The general mechanism of herb-warfarin interaction almost remains unknown, yet several pharmacokinetic and pharmacodynamic factors were estimated to influence the effectiveness of warfarin. Based on limited literature and information reported, we identified corresponding mechanisms of interactions for a small amount of “interacting herbs.” In summary, herb-warfarin interaction, especially the clinical effects of herbs on warfarin therapy should be further investigated through multicenter studies with larger sample sizes.

Intake of dietary phylloquinone and menaquinones and risk of stroke

Background

Dietary vitamin K intake is thought to decrease the risk of cardiovascular disease (CVD) by reducing vascular calcification, although vitamin K is also involved in coagulation. Studies investigating the association between phylloquinone intake and risk of stroke are scarce, and the relation with menaquinones has not been investigated to date.

Methods and Results

We investigated the association between intake of phylloquinone and menaquinones and stroke in a prospective cohort of 35 476 healthy subjects. Information on occurrence of stroke was obtained by linkage to national registries, and stroke was further specified into ischemic and hemorrhagic stroke. Vitamin K intake was estimated using a validated food‐frequency questionnaire. Multivariate Cox proportional hazards models adjusted for cardiovascular risk factors, lifestyle, and other dietary factors were used to estimate the associations. During a follow‐up of 12.1±2.1 years, 580 incident cases of stroke were identified, 163 of which were hemorrhagic and 324 were ischemic. Phylloquinone intake was not associated with risk of stroke with a hazard ratio (HR) of 1.09 (95% CI: 0.85 to 1.40, P_trend 0.41) for the highest versus lowest quartile. For intake of menaquinones similar results were found, with an HR_{Q4 versus Q1} of 0.99 (95% CI: 0.75 to 1.29, P_trend 0.82). When specifying hemorrhagic and ischemic stroke or menaquinone subtypes, no significant associations were detected.

Conclusion

In our study, neither dietary phylloquinone nor dietary menaquinones intake were associated with stroke risk.

A Possible Effect of Concentrated Oolong Tea Causing Transient Ischemic Attack-Like Symptoms

Aims

Tea (green, oolong, and black) is the second most widely consumed beverage worldwide, second only to water. Aside from a few reported adverse effects, tea, particularly green tea, appears to be beneficial for human health. In the case described herein, a male experienced several transient ischemic attack-like symptoms immediately following the consumption of a cup of high quality oolong tea. A thorough medical evaluation uncovered no evidence of such an attack and leads to the suggestion of a heretofore unreported response to oolong tea.

Presentation of Case

A 72-year old male with hypertension and atrial fibrillation, who takes valsartan/hydrochlorothiazide to control hypertension and warfarin to reduce the risk of thrombosis and thromboembolism, presented at the emergency room of a local hospital describing several transient ischemic attack-like symptoms immediately after consuming a cup of oolong tea. His symptoms included presyncope, disequilibrium, bilateral hand parathesias, mild dysphasia, and visual problems (but apparently not presbyopia or amaurosis fugax), all of which had disappeared in approximately two hours after drinking the tea. (Mild presyncope was previously noted by the patient when ingesting a strong green tea.) No unusual features emerged from his physical examination, and his blood work was unremarkable except for elevation of his partial thromboplastin time (39 sec) and prothrombin time (22.5 sec), giving an international reference of 2.0, all consistent with the effects of warfarin. A battery of tests by the emergency room physician, a cardiologist, and a neurologist, e.g. electrocardiogram, brain computerized tomography, 2-dimensional transthoracic echocardiogram, brain magnetic resonance imaging, with and without 20 ml Gadolinium, and a magnetic resonance angiogram, confirmed the earlier diagnosis of atrial fibrillation but disclosed no additional malfunction in his heart. His brain showed no evidence of a prior hemorrhage, and his carotid arteries were clear.

Methodology and Results

Analysis of the oolong tea by high performance liquid chromatography and mass spectrometry identified the major catechins and two methylxanthines, caffeine and theophylline, as well as other constituents, but there was no evidence of any extraneous chemicals that could lead to the symptoms.

Conclusion

In view of the rapid onset of symptoms after the consumption of oolong tea, bilateral as opposed to unilateral parathesis, and the absence of any evidence of a hemorrhage or the presence of impurities in the tea, we suggest that the transient ischemic attack-like symptoms could possibly be attributable to one or more components of the oolong tea and was not an atypical magnetic resonance imaging-negative transient ischemic attack.

Drug and dietary interactions of warfarin and novel oral anticoagulants: an update

Clinicians and patients around the world have been intrigued by the concept of developing an oral anticoagulant with a broad therapeutic window and few drug and dietary interactions that can be administered at fixed doses with no or minimal monitoring. The recently approved oral direct thrombin inhibitor dabigatran, along with the emerging oral anti-factor Xa inhibitors, rivaroxaban, apixaban, and edoxaban, have been developed to address many of the shortcomings of warfarin therapy. As warfarin is associated with extensive food and drug interactions, there is also a need to consider such interactions with the new oral anticoagulants. While to date few drug and dietary interactions have been reported with the new oral anticoagulants, it is still early in their development and clinical use cycle. Pharmacokinetic and pharmacodynamic profiles will have to be closely accounted for when determining the likelihood of a potential drug interaction prior to therapy initiation. As the list of drugs and supplements that interact with warfarin is continuously expanding, and the knowledge on drug interactions with the novel oral anticoagulants is still in its infancy, clinicians need to be vigilant when initiating any of these agents or when any changes in the patient's medication profile occur and perform a close screening for potential drug and dietary interactions. The objective of this paper is to give an update on drug and dietary interactions with warfarin and the novel oral anticoagulants, dabigatran, rivaroxaban, apixaban, and edoxaban.

A high menaquinone intake reduces the incidence of coronary heart disease

BACKGROUND AND AIM

Vitamin K dependent proteins have been demonstrated to inhibit vascular calcification. Data on the effect of vitamin K intake on coronary heart disease (CHD) risk, however, are scarce. To examine the relationship between dietary vitamins K(1) and K(2) intake, and its subtypes, and the incidence of CHD.

METHODS AND RESULTS

We used data from the Prospect-EPIC cohort consisting of 16,057 women, enrolled between 1993 and 1997 and aged 49-70 years, who were free of cardiovascular diseases at baseline. Intake of vitamin K and other nutrients was estimated with a food frequency questionnaire. Multivariate Cox proportional hazards models were used to analyse the data. After a mean+/-SD follow-up of 8.1+/-1.6 years, we identified 480 incident cases of CHD. Mean vitamin K(1) intake was 211.7+/-100.3 microg/d and vitamin K(2) intake was 29.1+/-12.8 microg/d. After adjustment for traditional risk factors and dietary factors, we observed an inverse association between vitamin K(2) and risk of CHD with a Hazard Ratio (HR) of 0.91 [95% CI 0.85-1.00] per 10 microg/d vitamin K(2) intake. This association was mainly due to vitamin K(2) subtypes MK-7, MK-8 and MK-9. Vitamin K(1) intake was not significantly related to CHD.

CONCLUSIONS

A high intake of menoquinones, especially MK-7, MK-8 and MK-9, could protect against CHD. However, more research is necessary to define optimal intake levels of vitamin K intake for the prevention of CHD.

High dietary menaquinone intake is associated with reduced coronary calcification

BACKGROUND

Dietary vitamin K is thought to decrease risk of cardiovascular disease by reducing coronary calcification, but inconsistent results are reported. This may be due to different effects of vitamin K(1) (phylloquinone) and vitamin K(2) (menaquinone, MK), but few studies included both.

METHODS

We investigated the association of intake of phylloquinone and menaquinone, including its subtypes (MK4-MK10), with coronary calcification in a cross-sectional study among 564 post-menopausal women. Phylloquinone and menaquinone intake was estimated using a food-frequency questionnaire.

RESULTS

Sixty-two percent (n=360) of the women had coronary calcification based on 1.5-mm thick slices. Phylloquinone intake was not associated with coronary calcification with a relative risk (RR) of 1.17 (95%-confidence interval: 0.96-1.42; p(trend)=0.11) of the highest versus lowest quartile. Menaquinone intake was associated with decreased coronary calcification with an RR of 0.80 (95%-CI: 0.65-0.98; p(trend)=0.03).

CONCLUSION

This study shows that high dietary menaquinone intake, but probably not phylloquinone, is associated with reduced coronary calcification. Adequate menaquinone intakes could therefore be important to prevent cardiovascular disease.

Warfarin and its interactions with foods, herbs and other dietary supplements

Despite its complex pharmacokinetic and pharmacodynamic profile, warfarin is still one of the most widely used oral anticoagulant agents. Attaining optimal anticoagulation with this agent is clinically challenging in view of its many food and drug interactions. Inappropriate anticoagulation control can expose patients to an increased risk of bleeding or thromboembolic complications, due to over and underanticoagulation, respectively. Fluctuations in dietary vitamin K intake can have a significant effect on the degree of anticoagulation in patients treated with warfarin. In addition, the explosion in use of various dietary supplements and herbal products can lead to undesired outcomes on anticoagulant levels. The aim of this review is to discuss the scope and the potential clinical impact of the most commonly reported food, dietary supplement and herbal interactions with warfarin therapy. Practical steps for patients and providers to minimise these interactions are highlighted.

Vitamin K intake and calcifications in breast arteries

OBJECTIVES

Vitamin K is an important co-factor in the production of proteins that inhibit vascular calcification. A low dietary Vitamin K intake has been associated with aortic and coronary calcifications and an elevated cardiovascular risk. Calcifications in the arteries of the breasts have also been associated with cardiovascular risk, but whether there is a relation with a low Vitamin K intake has not yet been studied.

METHODS

We conducted a cross-sectional study among 1689 women, aged 49-70 years. Dietary Vitamins K1 and K2 intake was calculated from a validated food frequency questionnaire. Breast arterial calcifications (BAC) were assessed on standard screening mammograms by two independent radiologists. With a general linear model mean Vitamins K1, K2 and Vitamin K2 subtypes were calculated for women with BAC and without, adjusted for age, smoking, diabetes, intake of saturated fat, mono-unsaturated fat, poly-unsaturated fat and protein- and calcium-intake.

RESULTS

BAC was less common in the highest (9%) quartile of Vitamin K2 intake, compared to the lowest (13%) (OR 0.7, 95% CI 0.5-1.1) and not different across quartiles of Vitamin K1 intake. Mean Vitamin K2 levels and mean levels of Vitamin K2 subtypes MK-5 through MK-10 were lower in the participants with BAC (p=0.01) compared to participants without BAC. However, after adjustment for aging, smoking, diabetes and dietary factors the association of mean Vitamin K2 intake with BAC was no longer significant.

CONCLUSION

Calcifications in breast arteries are not associated with a lower dietary intake of Vitamin K.

Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study

Vitamin K-dependent proteins, including matrix Gla-protein, have been shown to inhibit vascular calcification. Activation of these proteins via carboxylation depends on the availability of vitamin K. We examined whether dietary intake of phylloquinone (vitamin K-1) and menaquinone (vitamin K-2) were related to aortic calcification and coronary heart disease (CHD) in the population-based Rotterdam Study. The analysis included 4807 subjects with dietary data and no history of myocardial infarction at baseline (1990-1993) who were followed until January 1, 2000. The risk of incident CHD, all-cause mortality, and aortic atherosclerosis was studied in tertiles of energy-adjusted vitamin K intake after adjustment for age, gender, BMI, smoking, diabetes, education, and dietary factors. The relative risk (RR) of CHD mortality was reduced in the mid and upper tertiles of dietary menaquinone compared to the lower tertile [RR = 0.73 (95% CI: 0.45, 1.17) and 0.43 (0.24, 0.77), respectively]. Intake of menaquinone was also inversely related to all-cause mortality [RR = 0.91 (0.75, 1.09) and 0.74 (0.59, 0.92), respectively] and severe aortic calcification [odds ratio of 0.71 (0.50, 1.00) and 0.48 (0.32, 0.71), respectively]. Phylloquinone intake was not related to any of the outcomes. These findings suggest that an adequate intake of menaquinone could be important for CHD prevention.

Lifestyle and diet as risk factors for overanticoagulation

The risk of hemorrhage when using coumarin anticoagulants sharply increases when the International Normalized Ratio (INR) is > or =6.0. We performed a case-control study among outpatients of an anticoagulation clinic to identify sociodemographic-, lifestyle-, and dietary factors related to overanticoagulation. Three hundred cases with an INR > or =6.0 were compared with 302 randomly selected matched controls with an INR within the target zone. Age, sex, and level of education were not associated with overanticoagulation. Body mass index was negatively related to overanticoagulation, a beneath-average level of physical activity was positively related to overanticoagulation and never-smokers were more likely to have an INR > or =6.0 compared with smokers. Habitual alcohol consumption, even heavy drinking, was not related to overanticoagulation. However, a recent decrease of alcohol intake increased the risk of an INR > or =6.0. In addition, weight loss and a vacation were risk factors for overanticoagulation. Dietary factors were not associated with overanticoaguation. If risk factors can not be avoided, increased monitoring of INR values could prevent overanticoagulation and potential bleeding complications.

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.

Probable antagonism of warfarin by green tea

OBJECTIVE

To report a case of the inhibition of the effect of warfarin by green tea.

CASE SUMMARY

A 44-year-old white man was receiving warfarin for thromboembolic prophylaxis secondary to a St. Jude mechanical valve replacement in the aortic position. The patient had an international normalized ratio (INR) of 3.20 approximately one month prior to entering our clinic, and an INR of 3.79 on entering our clinic. Twenty-two days later his INR was 1.37. One month later the patient's INR was 1.14. It was subsequently discovered that the patient began drinking one-half to one gallon of green tea per day about one week prior to the INR of 1.37. On discontinuation of the green tea, the patient's INR increased to 2.55.

DISCUSSION

Warfarin produces anticoagulation by inhibiting production of the vitamin K-dependent clotting factors (i.e., factors II, VII, IX, X). The exogenous administration of vitamin K inhibits the effect of warfarin and reduces a patient's degree of anticoagulation. Green tea can be a significant source of vitamin K and thus antagonize the effect of warfarin.

CONCLUSIONS

Warfarin is a highly effective oral anticoagulant, but it requires close monitoring to prevent complications. Patients receiving warfarin need to be routinely questioned about their intake of vitamin K-containing foods and beverages.

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.