Vitamin D is most widely known as the sunshine vitamin because the body can make vitamin D when exposed to sunlight. Vitamin D plays an important role in supporting bone health, maintaining cardiovascular function and immune function, and promoting an overall sense of well-being.
Vitamin D is available in two different forms, D2 and D3. Vitamin D3 is the preferable form as it has been found to maintain vitamin D levels in the body for a longer period when compared to vitamin D2.
Vitamin K occurs in two main forms: K1 (phylloquinone), derived from foods such as green leafy vegetables and K2 (menaquinone), which is a group of related compounds differentiated by their side-chains. Numerous studies have shown that vitamin K2 as MK-7 is the more bioavailable form of the nutrient 7 and more powerfully influences bone building than K1. The combination of vitamin K2 with vitamin D3 has been suggested in recent studies to promote bone health.
Vitamin K Depletion
Although most people consume adequate dietary vitamin K to maintain sufficient blood clotting, most do not consume enough to meet cardiovascular and bone health needs. In fact, approximately 70% of the western population is deficient in vitamin K2. Compromised intestinal absorption can also lead to insufficient K2 levels leaving calcium available to be exported out of bone and into other tissues. Other medications such as antibiotics, cholesterol-lowering medications, and laxatives have also been found to contribute to a deficiency of vitamin K.
Building and maintaining healthy bones requires a number of key nutrients including vitamin K, for the proper binding of calcium to the bone matrix. A 2005 study from northern Finland found that those with greater levels of vitamin K-carboxylated osteocalcin had stronger bones than those with lower levels of the protein. A Japanese study found superior bone health among women who were frequent MK-7-rich natto eaters than those who were not. Another randomized study which split 172 women into a vitamin K2 group, a vitamin D3 group, a vitamin K2 and D3 group, and a placebo group for two years found that the combination of vitamin D3 and K2 had the most benefits for supporting bone health among the groups.
Cardiovascular Health and Blood Sugar Balance
Vitamin K plays a key role in supporting the cardiovascular system as well as blood sugar balance already within normal levels. In a large population study, researchers found that those who consumed high amounts of K2 had significantly better cardiovascular health markers compared to those given vitamin K1. Studies have also shown vitamin K supports healthy blood sugar metabolism.
New evidence also suggests vitamin K plays a central role in balancing immune health. Recent studies have shown that both vitamins D and K impart immune-modulating effects. In the Framingham Offspring Study, one of the longest standing studies on generational health, higher serum levels of vitamins D and K were associated with stronger immune function and a balanced inflammatory response. In a 2011 study, vitamin K was also found to suppress various markers of the immune system.