When Danish scientist Henrik Dam fed a cholesterol-free weight loss plan to child chicks in his lab about 90 years in the past, he observed extreme bleeding in a few of them. It didn’t cease after he changed the ldl cholesterol. Dam in the end concluded the bleeding was associated to a “depletion of an anti-hemorrhagic compound,” which he referred to as vitamin Okay (for “koagulation,” as spelled in Danish). For that discovery, Dam received the Nobel Prize in Physiology or Medication in 1943.
Most individuals find out about nutritional vitamins A, B, C, D and/or E, however vitamin Okay slips beneath the dietary radar. But it’s important for all times as a result of it is required for blood to clot usually. Now scientists at the moment are realizing there may be extra to find out about this much less appreciated nutrient.
Right this moment, the Jean Mayer USDA Human Diet Analysis Heart on Growing older at Tufts College homes the one analysis workforce on the planet targeted completely on vitamin Okay vitamin. I’m a analysis scientist on that workforce. We examine how meals offers vitamin Okay to assist wholesome getting older.
Why is vitamin Okay vital?
Over the previous few a long time, scientists found vitamin Okay-dependent proteins in lots of tissues all through the physique. This means vitamin Okay has physiological roles nicely past blood clotting. For instance, in arterial tissue, proteins depending on vitamin Okay can assist forestall calcification. That is crucial, as a result of arterial calcification can result in coronary heart assaults.
With out vitamin Okay, these proteins can not forestall calcification. And since these proteins are current in cartilage and bone, we’re additionally learning how these vitamin Okay-dependent proteins could also be concerned in osteoarthritis.
Simply as there are a number of types of B nutritional vitamins, there are additionally a number of types of vitamin Okay. Scientists know of at the very least 12. Phylloquinone, often known as vitamin K1, is synthesized by vegetation. Inexperienced leafy greens, like spinach and collard greens, and vegetable oils, like soybean and canola oil, comprise excessive quantities of phylloquinone.
Menaquinones, a category of vitamin Okay compounds often known as vitamin K2, are present in variable quantities in animal-based meals, reminiscent of dairy meals and some meats. Menaquinones are additionally produced by intestinal microbiota, though their dietary worth is unsure.
Our lab has measured the quantity of vitamin Okay in hundreds of meals generally consumed in North America. In partnership with the U.S. Division of Agriculture, this data is publicly obtainable on the USDA’s Meals Knowledge Central web site, essentially the most complete vitamin database on the planet. Over 350,000 meals are profiled.
A objective of our analysis is to ascertain a really helpful dietary allowance for vitamin Okay. In North America, present dietary suggestions for vitamin Okay are known as “enough consumption,” the quantity assumed to guarantee dietary adequacy. An enough consumption is ready when inadequate scientific proof exists to offer a extra exact really helpful dietary allowance. For males over 18, the enough consumption for vitamin Okay is 120 micrograms a day. For ladies, it’s 90 micrograms a day. One cup of uncooked spinach accommodates 145 micrograms of phylloquinone. Sufferers who’re taking warfarin must seek the advice of with their healthcare skilled for steering on their vitamin Okay intakes.
Clotting abnormalities because of low dietary vitamin Okay intakes are extraordinarily uncommon as a result of almost everybody consumes sufficient vitamin Okay in his or her weight loss plan to keep up regular coagulation. Though rising proof suggests low vitamin Okay intakes might affect well being outcomes unrelated to coagulation, proper now this proof doesn’t assist the necessity to take vitamin Okay dietary supplements, although they’re available on the market. Menaquinone dietary supplements have develop into notably fashionable as a result of there are claims they have distinctive well being advantages that phylloquinone doesn’t.
Nonetheless it is vitally troublesome to isolate the impact of a nutrient on a well being consequence, and much more troublesome to suggest complement use primarily based on the research which have been finished up to now. Massive medical trials should be designed to deal with the query. These trials, which might price tens of millions, haven’t but been performed with vitamin Okay. The smaller trials which have been finished don’t meet the requirements of scientific rigor required to advertise vitamin Okay dietary supplements at the moment.
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As our analysis continues, we attempt for a greater understanding of vitamin Okay’s function in human well being past coagulation. We need to understand how a lot vitamin Okay is required to guard in opposition to age-related illness and incapacity. Nonetheless, till we’ve got extra sturdy proof that dietary supplements are wanted, it’s safer, and extra pleasing, to acquire vitamin Okay from meals.
Any opinions, findings, conclusions, or suggestions expressed on this publication are these of the creator and don’t essentially replicate the views of the USDA.