Vitamin K: A little-known but noteworthy nutrient
Scientists discover the mysteries of vitamin Okay at Tufts College’s USDA Human Diet Analysis Heart on Ageing. Credit score: Deb Dutcher/USDA Human Diet Analysis Heart on Ageing/Tufts College, CC BY-SA

When Danish scientist Henrik Dam fed a cholesterol-free food 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 known as vitamin Okay (for “koagulation,” as spelled in Danish). For that discovery, Dam gained the Nobel Prize in Physiology or Drugs in 1943.

Most individuals learn about nutritional vitamins A, B, C, D and/or E, however Okay slips below 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 learn about this much less appreciated nutrient.

At this time, the Jean Mayer USDA Human Diet Analysis Heart on Ageing at Tufts College homes the one analysis group on the planet centered solely on vitamin Okay diet. I’m a analysis scientist on that group. We examine how meals offers vitamin Okay to assist wholesome getting old.

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 stop calcification. That is vital, as a result of arterial calcification can result in coronary heart assaults.

With out vitamin Okay, these proteins can’t stop 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 no less than 12. Phylloquinone, often known as vitamin K1, is synthesized by crops. Inexperienced leafy greens, like spinach and collard greens, and , 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, comparable to 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 1000’s of meals generally consumed in North America. In partnership with the U.S. Division of Agriculture, this data is publicly accessible on the USDA’s Meals Knowledge Central web site, essentially the most complete diet database on the planet. Over 350,000 meals are profiled.

What’s subsequent?

A objective of our analysis is to determine a beneficial 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 about when inadequate scientific proof exists to offer a extra exact beneficial dietary allowance. For males over 18, the enough consumption for vitamin Okay is 120 micrograms a day. For girls, it’s 90 micrograms a day. One cup of uncooked spinach comprises 145 micrograms of phylloquinone. Sufferers who’re taking warfarin have to 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 food plan to take care of regular coagulation. Though rising proof suggests low vitamin Okay intakes could affect unrelated to coagulation, proper now this proof doesn’t assist the necessity to take vitamin Okay dietary supplements, despite the fact that they’re available on the market. Menaquinone dietary supplements have grow to be notably widespread as a result of there are claims they have distinctive well being advantages that phylloquinone doesn’t.

Nevertheless it is extremely tough to isolate the impact of a nutrient on a well being consequence, and much more tough to suggest complement use based mostly on the research which have been executed to this point. Giant scientific trials have to be designed to deal with the query. These trials, which may price tens of millions, haven’t but been carried out with vitamin Okay. The smaller trials which have been executed don’t meet the requirements of scientific rigor required to advertise vitamin Okay dietary supplements presently.

As our analysis continues, we try for a greater understanding of vitamin Okay’s function in human well being past coagulation. We need to know the way a lot vitamin Okay is required to guard towards age-related illness and incapacity. Nevertheless, till we’ve extra strong proof that dietary supplements are wanted, it’s safer, and extra fulfilling, to acquire vitamin Okay from meals.

Is an excessive amount of vitamin C dangerous?

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