Optimize Your K Vitamins

By Dr. Mercola

While the importance of vitamin D has become more fully appreciated, another vitamin that is just as important as vitamin D, vitamin K2, needs wider recognition. It’s a fat-soluble vitamin most well known for its role in blood clotting.

However, there are two primary kinds of vitamin K, and they serve very different functions.

Vitamin K1 is the primary form of vitamin K responsible for blood clotting, whereas vitamin K2 is essential for bone strength, the health of arteries and blood vessels, and plays a role in other biological processes as well, including tissue renewal and cell growth.

In the 2014 paper,¹ “Vitamin K: An old vitamin in a new perspective,” vitamin D expert Dr. Michael Holick and co-authors review the history of vitamin K and its many benefits, including its significance for skeletal and cardiovascular health. They also discuss important drug interactions.

Since there are no reported cases of overdose of vitamin K2, and appears to have no toxicity issues, it may be prudent to double or even triple your intake while pregnant. Cancer prevention is another health benefit of vitamin K2. The 2010 European Prospective Investigation into Cancer and Nutrition (EPIC) study¹⁹ found that high intake of vitamin K2 — not K1 — leads to reduced cancer risk, as well as a 30 percent lower risk of dying from cancer.²⁰

The evidence also suggests vitamin K2 may reduce your risk for non-Hodgkin lymphoma. Mayo Clinic researchers discovered that people with the highest intake of vitamin K2 had a 45 percent lower risk for this type of cancer, compared to those with the lowest vitamin K2 intake.²¹ They attribute this effect to vitamin K2’s ability to inhibit inflammatory cytokines, which are related to this type of lymphoma, and its role the life cycle of your cells. Researchers are also looking into other health benefits.

For example:

• Vitamin K2 has been shown to improve insulin sensitivity; people who get the most vitamin K2 from their foods are about 20 percent less likely to develop type 2 diabetes
• One 2012 study²² found vitamin K2 has the potential to improve disease activity in those with rheumatoid arthritis (RA)
• Another study,²³ found that vitamin K2 serves as a mitochondrial electron carrier, thereby helping maintain normal ATP production in mitochondrial dysfunction, such as that found in Parkinson’s disease
• According to Dr. Holick’s paper,²⁴ vitamin K2 has anti-inflammatory, anti-oxidative, and anticarcinogenic properties, and in addition to cancer and diabetes, MK-7 in particular may also offer benefits for age-related macular degeneration. Moreover, due to its structural similarity to coenzyme Q10, MK-7 may support ATP production in the respiratory chain

Are You Getting Enough Vitamin K?

Clearly, you want both vitamin K1 and K2, but you’re virtually guaranteed to not get enough K2 from your diet unless you eat the proper fermented foods. Dietary sources of vitamin K1 include:

• Kale
• Spinach
• Collard greens
• Broccoli
• Brussels sprouts

As for a clinically useful dosage of vitamin K2, some studies — including the Rotterdam study²⁵ — have shown as little as 45 micrograms (mcg) per day is sufficient. As a general guideline, I recommend getting around 150 mcg of vitamin K2 per day. Others recommend slightly higher amounts; upwards of 180 to 200 mcg. You can obtain healthy amounts (about 200 mcg) of K2 by eating 15 grams (half an ounce) of natto each day, or fermented vegetables. If you fermented them using a starter culture designed with vitamin K2-producing bacteria, one ounce will give you about 200 to 250 mcgs.

If you opt for a vitamin K2 supplement, make sure it’s MK-7. Also remember to take it with fat since it’s fat-soluble and won’t be absorbed otherwise. Fortunately, you don’t need to worry about overdosing on K2, as it appears to be completely non-toxic. People have been given a thousand-fold “overdose” over the course of three years, showing no adverse reactions (i.e., no increased clotting tendencies).

That said, people who are taking vitamin K antagonists, i.e. drugs that reduce blood clotting by reducing the action of vitamin K, are advised to avoid MK-7 supplements.²⁶ As a last tip, keep in mind that vitamin K2 may not necessarily make you “feel better” per se. Its internal workings are such that you’re not likely to feel the difference physically. Compliance can therefore be a problem, as people are more likely to take something that has a noticeable effect. This may not happen with vitamin K2, but that certainly does not mean it’s not doing anything.

Sources and References

• ^1, 24, 26 Dermo-Endocrinology 2014: 6(1)
• ^2, 25 Journal of Nutrition November 1, 2004: 134(11); 3100-3105
• ³ NattoPharma 2013
• ⁴ Newhope360 September 22, 2015
• ⁵ Int J Oncol September 2003
• ⁶ Am J Clinical Nutrition April 2008;87(4):985-992
• ⁷ Altern Med Rev August 2003
• ⁸ Journal of the American College of Cardiology 2015;65(13):1273-1282
• ⁹ Expert Review of Clinical Pharmacology 2015 Mar;8(2):189-99
• ¹⁰ Journal of Nutrition November 2004: 134; 3100-3105 (The Rotterdam Study)
• ¹¹ NutraIngredients.com February 12, 2009
• ¹² Thrombosis and Homeostasis May 2015: 113(5); 911–1157
• ¹³ Nutritional Outlook September 24, 2015
• ¹⁴ European Journal of Nutrition December 2004;43(6):325-335
• ¹⁵ Archives of Internal Medicine 2006; 166: 1256-1261
• ¹⁶ Osteoporosis International March 2015: 26(3): 1175–1186
• ¹⁷ Osteoporosis International September 2013: 24(9); 2499–2507
• ¹⁹ Am J Clin Nutr March 24, 2010
• ²⁰ Nutraingredients.com
• ²¹ Medical News Today April 20, 2010
• ²² Modern Rheumatology 2012 Nov 6. [Epub ahead of print]
• ²³ Science 2012 Jun 8;336(6086):1306-10.