Heart Attacks, Cardiovascular Deaths and All-Cause Deaths*
In my November 2007 newsletter Sunlight and Health – How Sunlight Can Prevent Serious Health Problems, a lack of sunlight exposure with associated lower levels of vitamin D was listed as a risk factor in heart disease, heart attacks and hypertension.
This newsletter summarises two more studies that look at the association of low Vitamin D levels and disease.
A recent publication in the Archives of Internal Medicine (Vol.168, No.11, June 9, 2008) reports that low levels of vitamin D are associated with a higher risk of myocardial infarction (heart attack) when compared to those with normal levels of vitamin D.
The study was conducted at the departments of Nutrition and Epidemiology, Harvard School of Public Health, Boston, by Dr Edward Gionannucci and associates.
The background to the study was based on the premise that vitamin D deficiency may be involved in the development of atherosclerosis and coronary heart disease in humans.
It was a prospective study and involved 18,225 males in the Health Professionals Follow-up Study. The age range was 40-75 years. They were free of diagnosed cardiovascular disease at the time of blood collection. The follow-up period was 10 years. During that time, 454 developed “nonfatal myocardial infarction or fatal coronary artery disease”.
Vitamin D is 25-Hydroxyvitamin D (25(OH)D). Deficiency of 25(OH)D was set at 15ng/ml or less. Adequate 25(OH)D levels were 30ng/ml or greater. (In Australia the levels are measured in nmol/: 15ng/ml = 37.5nmol/L and 30ng/ml = 75nmol/L)
After adjustment for matched variables, men deficient in vitamin D were at increased risk of myocardial infarction (heart attack) compared to those considered to have adequate levels of vitamin D. The relative risk was 2.42 (95% confidence, 1.53-3.84, p less than .001). This means that those with a deficiency of vitamin D were 2.42 times more likely to have a heart attack compared to those with adequate levels, and the results were statistically significant.
There are many risk factors for heart disease. This study took these into account. After additional adjustment for family history of myocardial infarction, body mass index, alcohol consumption, physical activity, history of diabetes mellitus and hypertension, ethnicity, omega 3 intake, high and low lipoprotein cholesterol levels, and triglyceride levels, the relationship remained significant. The relative risk was 2.09 (95% confidence, 1.24-3.54, p = .02).
Even men with intermediate 25(OH)D levels were at elevated risk relative to those with adequate levels of 25(OH)D. With an average level of 22.5ng/ml (56nmol/L) the relative risk was 1.51.
The authors of the study concluded: “Low levels of 25(OH)D are associated with higher risk of myocardial infarction in a graded manner, even after controlling for factors known to be associated with coronary artery disease.”
The following issue of the same journal (Archives of Internal Medicine, Vol.168, No.12, June 23, 2008) confirmed the above findings, in this instance focussing on the cardiovascular mortality, and also the all-cause mortality, associated with low serum 25-Hydroxyvitamin D (25(OH)D) and 1,25-Dihydroxyvitamin D (1,25 (diOH)D) levels.
The study was a multi-university cooperation, with prime author Dr Harald Dobnig.
The background to this study was that low serum levels of vitamin D are associated with higher prevalence of cardiovascular risk factors and disease. The aim of the study was to determine whether endogenous vitamin levels of vitamin D are related to “all-cause and cardiovascular mortality”.
This study was also a prospective study and involved 3,258 consecutive male and female patients (mean age 62) scheduled for coronary angiography. Quartiles were formed according to 25(OH)D and 1,25(diOH)D within each month of blood collection. The main outcome measures were all-cause and cardiovascular deaths.
The follow-up period was 7.7 years. During that time, 737 patients (22.6%) died, including 463 deaths from cardiovascular causes.
Multivariate analysis removes any bias that other factors, such as age, obesity and ethnicity, may have on the result. Multivariate-adjusted hazard ratios (HRs) for patients in the lower two 25(OH)D quartiles (median 7.6 and 13.3 ng/ml or 19 and 33 nmol/L) were higher for all-cause mortality: HR 2.08 (95% confidence, 1.60-2.70 and HR 1.53 (95% confidence, 1.17-2.01) respectively. The HRs for cardiovascular mortality were also higher: HR 2.22 (95% confidence, 1.57-3.13) and HR 1.82 (95% confidence, 1.29-2.58) respectively. Both were compared to patients in the highest 25(OH)D quartile (median 28.4 ng/ml or 71 nmol/L).
Similar results were obtained for patients in the lowest 1,25(diOH)D quartile.
These results were independent of coronary artery disease and physical activity levels.
The authors of the study concluded: “Low 25(OH)D and 1,25(diOH)D levels are independently associated with all-cause and cardiovascular mortality.”
Sunlight exposure is the best way for the body to obtain vitamin D. The simple act of spending some time in the sun each day can drastically reduce your risk of major diseases like cancer and diabetes and, as the above reports demonstrate, heart disease. Study 2 found that low vitamin D levels more than doubled the risk of heart attack and death.
How does vitamin D help your heart?
There are a number of mechanisms triggered by vitamin D production that help fight heart disease including:
· An increase in your body’s natural anti-inflammatory cytokines
· The suppression of vascular calcification
· The inhibition of vascular smooth muscle growth
· The lowering of insulin resistance (the cause of the Metabolic Syndrome and a major risk factor in heart disease).
In my November 2007 newsletter Sunshine and Health, it was pointed out that a major on-going publicity campaign has been undertaken in Australia to convince us that staying out of the sun is necessary to avoid cancer, when actually the opposite is true. Why exchange the risk of a few harmless (excluding melanoma) skin cancers with that of serious life-threatening challenges like colon, breast and prostate cancers? It is estimated that for every one melanoma prevented by avoiding exposure to the sun, somewhere between 10 and 50 other cancers will occur as the result of relative lack of vitamin D from reduced sun (ultraviolet) exposure. A diet rich in fruit and vegetables, supplying high levels of natural antioxidants, as well as supplements of omega 3 fatty acids and vitamin C, are recommended to protect against the possible adverse effects of sunlight exposure on the skin.
You are encouraged to have your vitamin D levels tested. The test is a simple blood test, namely 25-Hydroxyvitamin D. The normal range is 51-140nmol/L. It is said that “Serum levels of greater than 75nmol/L indicate sufficient Vitamin D3, Relative insufficiency is 51-75nmol/L and deficiency is 50nmol/L or less.”
Sun exposure is always the best way of getting vitamin D. Sunlight exposure should always be less than that which would lead to sunburn. Mild redness of the skin is the most that should occur. Some people, linked to lifestyle and geographic location, may need to take a vitamin D3 supplement to maintain adequate levels. If this is so, you should be supervised by a knowledgeable health professional.
Please read this newsletter in association with my November 2007 newsletter Sunlight and Health - How Sunlight Can Prevent Serious Health Problems.
*Copyright 2009: The Huntly Centre.
Disclaimer: All material in the Huntlycentre.com.au website is provided for informational or educational purposes only. Consult a health professional regarding the applicability of any opinions or recommendations expressed herein, with respect to your symptoms or medical condition.
Back to the list Print friendly version