Vitamin K absorption
Although vitamin K is a fat soluble vitamin it appears its absorption can be reduced by other fat-soluble vitamins such as vitamin D, E, and A. As both vitamin D and K are important for bone health it may confusing whether you should take them together or separately.
What Vitamin K Does
Vitamin K is actually a group of structurally related, fat-soluble vitamins ranging from K1 to K10. Vitamin K1 is the primary dietary source vitamin K and is found in increased amounts and dark green leafy vegetables and in much lower levels in some vegetable oils. Vitamin K2 is typically found in small amounts of egg yolk, butter, some cheeses. Vitamin K1 is actually converted to vitamin K2 in the small intestines. Vitamin K2 has become a very popular supplement recently and is found in high amounts in a Japanese fermented soybean product called natto.
Vitamin K functions in our body to modify certain proteins made by the liver and other organs to ensure proper blood clotting and calcium utilization and distribution in our arteries and bones and elsewhere.
Evidence does exist that low vitamin K consumption may be associated with decreased bone mass and higher risk of hip fractures in elderly individuals. However, the research is not complete in this area and is ongoing. Studies have generally found that people taking a higher dose of vitamin K1 (1 mg) along with vitamin D and magnesium showed less bone loss than others taking the same supplements without vitamin K.
Individuals who are being treated with anticoagulants from diseases such as atrial fibrillation need to be careful with the amount of vitamin K they consume. Definitely work with your medical doctor on this.
In heart disease, low serum vitamin K levels have been associated with atherosclerosis. Higher intake of vitamin K to from the diet has been associated with reduced risk of coronary calcification and even mortality from heart disease. This information primarily came from the Rotterdam Heart Health study. The cheese most associated with vitamin K is Gouda.
Although a true deficiency of vitamin K is rare, it is true that other fat-soluble vitamins such as A, D, and E all compete against vitamin K for absorption in the small intestines. This is particularly true in people taking high amounts of vitamin E. One study found that it may be best to take vitamin K at least 3 hours apart from vitamin D for optimal absorption. Realize these are animal studies, but it is the best information we have to date. Finally, it is best to obtain vitamin K from your diet by eating foods such as turnip greens, spinach, broccoli, lettuce, cabbage, green peas, fermented soy beans, asparagus and other vegetables can provide vitamin K in good amounts. And don’t forget about some hard cheeses (gouda) that can also provide some vitamin K. And realize that meat, dairy, and egg yolks contain small amounts of vitamin K2.