January 28, 2008
Vitamin D counteracts the development of atherosclerosis and prevents fatal complications of high blood pressure – but vitamin D deficiency is very widespread.
We are not done with vitamin D. More and more information is streaming in about this amazing substance, which is actually not a vitamin but a hormone created in skin exposed to sunlight.
Now we will look at vitamin D’s effects on the heart and circulation. It seems as though the risks of blood clots in the heart and the brain are far lower in people who get enough vitamin D, which is to say people who get more than most. This “vitamin” is especially effective at lowering the risk in people with high blood pressure.
This find appears in a recent report from Farmingham, a little town in Massachusetts where the health and lifestyles of thousands of people (and their descendents) has been registered since 1948 in order to find lifestyle related reasons for cardiovascular disease. The Farmingham study is, without a doubt, the most famous of its kind. When we today take for granted that exercise, healthy diet, and aspirin prevents cardiac death it is the Farmingham project that we should thank.
The report in question is on a part of the study involving 1,739 people aged 50 – 70 who were free of cardiovascular disease at the beginning of the study. From 1996 to 2000 their vitamin D status was measured with blood tests after which their health was monitored for an average of 5.4 years (up to 7.6 years). Who suffered blood clots?
Those who had the least vitamin D in the blood! After seven years blood clots in the heart or the brain (stroke) was registered in one in ten with vitamin D levels over 37 nmol/l, but in no less than one in four of those with levels under 37. After correcting for differences within the group such as age, sex, cholesterol levels, smoking, diabetes, and so on, the group with the highest vitamin D levels still had a cardiovascular risk 60 % less than that of the group with the lowest levels. If these numbers are right, vitamin D is more important for cardiovascular health than aspirin or cholesterol medicine.
Strong immune system
The beneficial effects of vitamin D seem to be even greater for those with high blood pressure, which is the most important cause of cardiovascular disease. Among participants with high blood pressure the risk for those with vitamin D levels over 37 was half that of those with levels under 37.
This result is similar to that of other studies which have shown that low vitamin D status and high blood pressure and clogged cardiac arteries are related. The Farmingham has an even stronger message: If you lack vitamin D you are at risk of a heart attack within the foreseeable future.
Does this mean that vitamin D prevents atherosclerosis? Yes, this seems to be the case. This fits in well with other known effects including: that vitamin D counteracts an important hormone (renin) which is responsible for raising blood pressure and that when heart cells which normally use vitamin D are prevented from using vitamin D (through genetic manipulation) in experiments on mice, blood pressure rises quickly.
Without eating fatty fish is you get almost no vitamin D from October to May. Deficiency is therefore very widespread. In a European study of teenage girls more than one out of every three had severe anemia (blood percent of under 25 nmol/l). Over 90% of these girls would have, if they lived in Farmingham, ended up in the study group with severe atherosclerosis.
How much vitamin D is it wise to take? There is no rule of thumb, but it should be considered that a typical vitamin pill contains 200 units whereas one out of every two adult Americans need 1,000 units in order to have an “acceptable” vitamin D status (which is a concentration of 75 nmol/l – most American researchers recommend 75 – 150 nmol/l). It is also understood that it is completely safe to take up to 2,000 units daily.
Luz Tavera-Mendoza and John White, two molecular biologists from the American McGill University have shown that vitamin D causes the skin and the immune system to form antibiotics (cathelicidin and more) which kill bacteria, including tuberculosis bacteria. This is probably the explanation for the earlier idea that it is possible to cure tuberculosis with sunlight. These two researchers have written an easy to read summery of recent research and even reveal what they take as supplements during the dark months.
Luz, who is a younger woman, takes 1,000 unites (25 micrograms).
John, who is a younger man, takes 4,000 units (100 micrograms).
By: Niels Hertz, MD
1. Wang TJ et al. Vitamin D deficiency and risk of cardiovascular disease. Circulation 2008;117:000-000.
2. Tavera-Mendoza L, White J. Celle defences and the sunshine vitamin. Scientific American 2007 (11):36-44.