Low Vitamin D Levels Could Kill You
RESEARCHERS at Johns Hopkins are reporting what is believed to be the most conclusive evidence to date that inadequate levels of vitamin D lead to substantially increased risk of death. Their findings also provide a strong connection between low levels of vitamin D and heart disease.
The Johns Hopkins team analyzed a diverse sample of 13,000 initially healthy men and women participating in an ongoing national health survey and compared the risk of death between those with the lowest blood levels of vitamin D to those with higher amounts.
Of the 1,800 study participants known to have died by Dec. 31, 2000, nearly 700 died from some form of heart disease, with 400 of these being deficient in vitamin D. This translates overall to an estimated 26% increased risk of any death, though the number of deaths from heart disease alone was not large enough to meet scientific criteria to resolve that it was due to low vitamin D levels.
An unhealthy deficiency is considered blood levels of 17.8 nanograms per milliliter or lower.
"We think we have additional evidence to consider adding vitamin D deficiency as a distinct and separate risk factor for death from cardiovascular disease," says study co-lead investigator Erin Michos, M.D., M.H.S., "putting it alongside much better known and understood risk factors, such as age, gender, family history, smoking, high blood cholesterol levels, high blood pressure, lack of exercise, obesity and diabetes."
"Now that we know vitamin D deficiency is a risk factor, we can better assess how aggressively to treat people at risk of heart disease or those who are already ill and undergoing treatment," she says.
Test screening for nutrient levels is relatively simple, Michos adds. It can be part of routine blood work and done while monitoring other known risk factors, including blood pressure, glucose and lipid levels.
Michal Melamed, M.D., M.H.S., study co-lead investigator who started the research as a clinical fellow at Johns Hopkins, says no one knows yet why or how vitamin D may protect the heart, but she adds that there are plenty of leads in the better known links the vitamin has to problems with muscle overgrowth and high blood pressure, in addition to its control of inflammation, which scientists are showing plays a stronger role in all kinds of heart disease.
Boosting Vitamin D
Vitamin D is well known to play an essential role in cell growth, in boosting the body's immune system and in strengthening bones. The hormone-like nutrient controls blood levels of calcium and phosphorus, essential chemicals in the body.
Michos recommends that people boost their vitamin D levels by eating diets rich in such fish as sardines and mackerel, consuming fortified dairy and cereals, taking cod-liver oil and vitamin supplements. In warmer weather briefly exposing skin to the sun -- as little as 10 to 15 minutes of daily exposure -- can produce sufficient amounts of vitamin D to sustain health.
There is no evidence that more than 2,000 I.U. of supplements per day do any good. Study results show that heart disease death rates flattened out in participants with the highest vitamin D levels (above 50 nanograms per milliliter of blood), signaling a possible loss of the vitamin's protective effects at too-high doses.
More research is needed to determine the nutrient's precise biological action and the next steps are to test various high doses of vitamin D to find out if this results in fewer deaths and lower incidence of heart disease, including heart attack or moments of prolonged and severe chest pain. The team also plans to investigate what biological triggers, such as obesity or hypertension, might offset or worsen the action of vitamin D on heart muscle, or whether vitamin D sets off some other reaction in the heart.
Melamed says that because vitamin D levels are known to fluctuate in direct proportion with daily physical activity, the growing epidemic of obesity and indoor sedentary lifestyles lend more urgency to act on the vitamin D factor.
Knowledge of vitamin D3
Keywords for the information: