Ask the Pharmacist

Q) I have heard some good things about vitamin K2. What can you tell me about it?

A) Vitamin K2 (menaquinone) is one of the least discussed and little known vitamins which is a shame given the large role it plays in maintaining and enhancing our health.

For the longest time, it has been lumped together with its more prominent relative Vitamin K1, a vitamin famous for rescuing patients whose blood has become too thin as a result of warfarin treatment. But K1 & K2 are in fact very different both in terms of their molecular structures as well as their impact on human health. They also differ in terms of what to eat in order to boost your levels as well as how likely you are to be deficient in either of them.

Whereas K1 comes from green leafy vegetables, an adequate supply of Vitamin K2 requires consuming meat, in particular organ meat. Other sources of K2 include egg yolks as well as high fat dairy products including hard cheeses made with whole milk.

For vegetarians, the only source of K2 is natto, a fermented soy food popular in eastern Japan. The source of the K2 is not the actual soy beans themselves (hence other more readily available soy products are not considered sources) but the particular species of bacteria used in the fermentation process.

While a deficiency in K1 is relatively rare, that is not believed to be the case for K2. Despite the fact it comes from animal sources and most of us eat plenty of that, experts feel that it is at all uncommon for people to have low K2 levels.

As for the benefits of K2, the list seems to be going by the year. It’s most prominent role may be in optimizing bone health. K2 activates osteocalcin (a protein secreted by our osteoblasts, the cells that build up our bones) which acts to draw calcium into our bones making them larger and stronger.

K2 also, when combined with Vitamin D3, slows down the activity of our osteoclasts, the cells that are responsible for eating away at our existing bone. The net effect is healthier bones that are less likely to fracture. Given its role, there is currently a lot of research going into whether we should start recommending K2 supplementation to those whose bones have been found to be too thin for their respective age (a condition known as osteopenia or, in its more severe form, osteoporosis). This function of K2 may well make calcium supplements a viable treatment option once again as well.

For years, people (mainly females) were told to consume extra calcium in the form of supplements in order to help combat these diseases. That recommendation changed dramatically due to a study in 2007 (when research showed that these supplements did not seem to lower the risk of hip fractures and may in fact increase it) and, in 2011, when it was discovered that calcium supplements, with or without vitamin D, seemed to significantly increase the risk of heart attack and stroke due to the accumulation of calcium deposits in our veins and arteries.

There are some researchers who speculate that this lack of benefit and increased cardiovascular risk associated with calcium may be due to a deficiency of K2 and a definitive answer to the positive would undoubtedly make K2 almost as well known as vitamins C or D.

Beyond its role in bone formation, vitamin K2 also plays a role in heart health. It helps trigger a protein called matrix gla protein (MGP) which is responsible for removing excess calcium that has accumulated in soft tissues such as arteries and veins. Clots in our vessels occur as a result of the buildup of atherosclerotic plaque. These plaques are composed mainly of fat, cholesterol and calcium. Hence, a reduction in calcium within these vessels should in turn reduce the size of our plaques and consequently also lower our risk of suffering from heart disease. This is supported by numerous studies that have found associations between diets that are low in vitamin K2 and mild to moderate artery disease and there is hope that further research will lead to K2 supplementation as a possible method to treat this disorder.

Other possible roles for K2 involve reducing the risk of kidney stones (once again related to its ability to keep dietary calcium from going to all the wrong places), stabilizing blood sugars (by aiding in the production of insulin and helping our body maintain its sensitivity to it), optimizing sexual health (it is involved in testosterone production), treating polycystic ovarian disease (by bringing the high levels of male hormones found in women with this disease back down to more normal levels), improving exercise performance (by enhancing your ability to utilize energy) and possibly reducing the risk of certain cancers by suppressing genes that trigger cells to become cancerous and enhancing other genes that seem to make cells more healthy.

At present, there is no recommendation as to how much vitamin K2 we should aim to get through our diets. Some have suggested 100-200ug per day (approximately the amount you would ingest from eating 6-12 ounces of dark chicken meat or 5-9 ounces of a hard cheese like Edam) but it is far too early in the research game to know if these are in fact accurate, beneficial or safe.

On the topic of safety, long term use of 45mg per day of K2 did not seem to be associated with serious side effects and this dose is more than 200 times the amount the researchers are suggesting as levels to try and attain in your diet. That being said, anyone taking blood thinners (and in particular warfarin) should not be altering their vitamin K1 or K2 levels via diet or supplementation without first consulting their family doctor or cardiologist given its role in helping blood clot.

For the rest of us, while vitamin K2 looks very promising, history tells us that medicine is littered with studies that show that vitamin supplementation generally doesn’t seem to produce the results we were hoping for (and in some cases may lead to a worsening of your health!). It is probably best to wait for now until we can better answer the many questions we still have.