Vitamin D associated with signficantly reduced risk of death from stroke : Nutrition & Supplements Forum : Active Low-Carber Forums

#1 ^

Fri, Oct-30-09, 11:43

Demi

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Vitamin D associated with signficantly reduced risk of death from stroke

Quote:

Vitamin D associated with signficantly reduced risk of death from stroke

Posted By Dr John Briffa
October 29, 2009

Regular readers will know that I have a particular interest in the role of sunlight in health, in large part due to its ability to stimulate vitamin D production in the body. Vitamin D, in turn, has been found to be association with a very wide variety of disease processes including cancer, diabetes, and multiple sclerosis. Back in 2007, one of my blogs focused on the relationship between vitamin D levels and risk factors for cardiovascular disease (e.g. heart disease and stroke). This study found that individuals with relatively low levels of vitamin D were at significantly increased risk of a variety of risk factors including high blood pressure, diabetes, obesity and raised levels of blood fats known as triglycerides.

I was therefore interested to read of a study published this week, that has found a relationship between vitamin D levels and cardiovascular disease [1]. This study involved following 6219 Finnish men and women for an average of about 27 years. In those with the highest levels of vitamin D, risk of death from cardiovascular disease was found to be 24 per cent than in those with the lowest vitamin D levels.

Cardiovascular disease death encompasses deaths due to heart disease and stroke. The authors of this study went further by looking at the relationship between vitamin D levels and these specific causes of death. They found no significant relationship between vitamin D levels and risk of death due to heart attack. However, there was a striking relationship between vitamin D levels and risk of death due to stroke. individuals with the highest vitamin D levels were at a 52 per cent reduced risk of dying from stroke compared to those with the lowest levels.

Now ‘epidemiological’ studies of this nature can only be used to show associations between things, and it is not certain whether optimising vitamin D levels actually reduces the risk of stroke. Ideally, any truly protective role of vitamin D needs to be proven with intervention studies (which, say, assess cardiovascular disease risk in individuals treated with vitamin D or placebo). In the meantime, I continue to attempt to optimise my vitamin D levels. If vitamin D turns out to help prevent stroke, then this optimising my vitamin D levels may turn out to be a very worthwhile endeavour (there is a strong history of stroke in my family).

References:

1. Kilkkinen A, et al. Vitamin D status and the risk of cardiovascular disease death. Am J Epidemiol 2009;170(8):1032-9

http://www.drbriffa.com/blog/2009/1...th-from-stroke/

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#2 ^

Fri, Oct-30-09, 14:20

Hutchinson Hutchinson is offline

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Remember this was a Finnish study and only ONE vitamin d sample was taken 27 yrs ago.
Trouble with a single test particularly where winter status is likely to be even lower than winter status in the UK is that it may give an unrealistic idea of levels either for the average status of that particular year or for each of the following 27 yrs. It would be far better if Spring Autum levels could be averaged and repeated at intervals over the study so we could be surer that those who were low originally remained so throughout the study.

Another concern is that they took the study population and divided it into equal 5 groups by vitamin D status but the vitamin D status of the highest group went from 62.0nmol/l ~ 180.0 nmol/l 22.4ng/ml ~ 72ng/ml

Readers of the Vitamin D thread will know that anything below 80nmol/l 32ng/ml is below the level at which calcium is absorbed optimally so everyone below that level is vitamin D insufficient. Therefore lumping the people between 62~80nmol/l into the high group is misleading because these people are still vitamin d insufficient (as actual measurable harm is occurring in their bones it would be fairer to say they are deficient. OK they are less deficient that the other 4 groups but including their results in the group of people with adequate status does adversely affect the benefits of adequate status. It is reasonable to expect that if instead of numerical quartiles the groups had been sorted by vitamin D status we may have been able to see if those with levels over 125nmol/l had fewer heart attacks than those with levels between 100~125 or between 80~90nmol/l.

It seems ridiculous to me to have people bordering on the toxicity level 180nmol/l lumped in with people who have not reached the lowest level of adequate status.

However despite my reservations the study is more evidence that higher vitamin d status is better than lower.