The ABC's of Vitamins - Vitamin K

Well, it has been a while since my last post and for that I do apologize. As the weather warms up, my work load seems to increase (and not in that fun vacation sort of way, at least not yet!). But nonetheless, today marks the last of the vitamin series - vitamin K. Vitamin K was discovered back in 1929 and was first synthesized in a lab in 1939, so why is it that in 2009 so few people know anything about it?

Without sounding too much like a broken record, vitamin K is also the generic term for a group of compounds; the two natural forms being K1 and K2. (There are 3 more synthetic forms) K1 is also known as phylloquinone and comes from plants and is very biologically available. K2 is a family of menaquinones and are produced by bacteria, including those that live in your gut.

So, what's the big deal about vitamin K? The biggest, perhaps most important job is its role in blood coagulation. (It works with prothrombin and other proteins to cause coagulation) It also plays a role in bone metabolism which may help to prevent osteoporosis. SCIENCE ALERT: Both of these functions have to do with vitamin K's role as a co-factor for gamma-glutamyl carboxylase (the enzyme that catalyzes the conversion of bound glutamate (Glu) to gamma-carboxyglutamate (Gla) and the binding of calcium ions to the Gla giving it bioactivity - also known as the "vitamin K dependent glutamate gamma-carboxylation reaction").

The lack of vitamin K seems to lead to a higher incidence of calcified atherosclerotic plaques - not good. And newer research is looking into vitamin K's role in neuronal survival and its potential in the treatment or prevention of Alzheimer's.

Are you wondering "where can I get this wonderful vitamin"? Good, the best sources are green leafy vegetables like broccoli, kale, spinach, turnip greens, asparagus, and cabbage. Vitamin K, as an oil soluble vitamin, is also found in canola, soybean and olive oil. The recommended daily intake varies depending on age and gender, but is generally between 65 -120 micrograms per day. Most of us have no problem getting this amount from our diet, but those who are on a highly restricted diet, or are on sulfa drugs may need to supplement. Those who are on anticoagulant drugs should watch their intake of vitamin K containing foods, as vitamin K can interfere with their medication (make sure to talk to your doctor!).

So, we've covered the world of vitamins (sort of in the "Reader's Digest" kind of way) and I hope it makes you feel more comfortable about what you need, in what quantities, and why you need them. July is another crazy month for me at my job (and my committee work, and vacation, etc.) but I will try to get at least of couple of posts in. Please let me know what you want to learn about next - I'm open to ALL suggestions, so don't be afraid to ask!

The ABC's of Vitamins - Vitamin E

Vitamin E – this is another one of those vitamins that we all assume we know quite a bit about, so let’s see what you really do know about our next to last vitamin.

Vitamin E is not a single chemical, but rather two groups of compounds: tocopherols and tocotrienols; and within each of these there are 4 compounds (alpha, beta, delta, gamma) and their mirror images (known as isomers) – very confusing! The best bioactive form is alpha-tocopherol and that is what all of the various compounds are measured against. The natural form is d-alpha-tocopherol and the synthetic version is dl-alpha-tocopherol. It is one of the few vitamins that your body can distinguish between the natural and synthetic versions, but both are very bioactive and therefore effective.

The name “tocopherol” means “to bring forth in childbirth” in Greek and it is because the vitamin was discovered by feeding pregnant rats a specialized diet and finding that a previously unknown compound was needed for them to carry their fetuses to term. And although Vitamin E was once referred to as an “anti-sterility vitamin” it does not appear to help with that problem.

Vitamin E is stored in your adipose tissues because of its high lipid solubility. It is best known perhaps for its antioxidant properties; it is the major antioxidant found in the lipid portion of the cellular membranes in your body protecting them from peroxidation.

Vitamin E counteracts the artherogenic effects of the breakdown of good cholesterol (LDL) which involves too many processes too complicated to go into here (like nitric-oxide mediated arterial relaxation and inhibition of platelet aggregation), so let’s just suffice to say that Vitamin E is good for your heart and circulatory system.

It also helps with your immune system, especially when phagocytosis is involved, but you need to ingest levels 4-6 times higher that what normal diets contain. So in essence: the older you are – the more depressed your immune system gets – and the more vitamin E you should be consuming.

Good sources of vitamin E are grains, nuts, beans, seeds and their oils, eggs, and butter. This is unfortunate, because these are “fatty foods” that many people are cutting out of their diet, or at least cutting back on, and that means we are getting less vitamin E. The good news is that vitamin E from food sources is not toxic, so you can’t get too much of a good thing that way!

Well, how well did you do; did you know vitamin E as well as you thought? Good, next will be the last vitamin, vitamin K, one of the least well known of its brethren. However, it will be a couple of weeks between posts as I'm off to attend the Institute of Food Technologists conference tomorrow. And as always, let me know what you want to know about - we are about to move onto a new chapter and I want to make sure it is a chapter you want to read!