It is believed more than one in five Britons do not have enough vitamin D in their bodies, which has prompted calls to fortify foods in the UK with the fat-soluble compound. But whether vitamin D supplements can really help is still a hot topic, with some scientific circles arguing the benefits are uncertain. One Harvard professor presents two arguments highlighting the potential dangers of vitamin D over-supplementation.
The “sunshine vitamin”, so-called because it is produced in the skin through the action of sunlight, has long been known to help strengthen bones by increasing the body’s absorption of calcium and phosphorous.
Doctor JoAnn E. Manson, Professor of Women’s Health at Harvard Medical School, warns that high intake of the supplement can lead to a host of complications.
Doctor Manson’s insight stems from the recently published vitamin D and Omega-3 Trial, which comprised more than 25,000 participants nationwide.
The study, led by doctor Manson, found that higher intake of the vitamin did not always lead to improved health.
She noted: “More is not necessarily better, in fact, it could be worse.”
The study revealed that over-supplementation with vitamin D can be toxic.
It can lead to hypercalcemia, which is when too much calcium builds up in the blood, forming deposits in the arteries or soft tissues.
Symptoms of hypercalcemia include nausea, vomiting, weakness and kidney failure.
Reports have shown that toxicity from vitamin D occurs almost exclusively in people who take long-term high dose supplements.
The effects of intoxication can be felt over the course of several hours, since the vitamin is stored in body fat and released into the bloodstream slowly.
As a rule of thumb, vitamin D levels ranging between 40 and 80 ng/ml are considered healthy.
Doctor Manson explained: “While there is no question that vitamin D and calcium are essential to bone health, it appears that very high doses of vitamin D don’t provide further benefits for bone health and may actually have a harmful effect.”
A study investigating the effects of vitamin D over-supplementation found that individuals who received higher doses over a period of three years.
Doctor Mason, said it “found no improvement in bone density at the higher doses and even a suggestion that there might be some harm by reducing bone density.
“This is further evidence that high doses are not advisable. In terms of bone health, once you get to a certain level of intake, increasing that amount isn’t going to be beneficial.”