Shedding light on vitamin D deficiency ‘crisis’

Sunshine is our primary source of vitamin D. But unlike other nutrients there is no recommended daily allowance of vitamin D. By Brian Alexander
msnbc.com contributor
updated 8:45 a.m. ET Feb. 2, 2009


Brian Alexander
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The seizures gripped the nine-month-old baby boy as he slept.

In the beginning, the infant’s mother thought he was sick with a cold. But then he became feverish and developed diarrhea, along with a strange, bulging soft spot on his skull. According to a report in a recent issue of the New England Journal of Medicine, once the worried mother and her baby arrived at a hospital and doctors conducted a series of tests, she heard a diagnosis that had become vanishingly rare since the 1940s: her baby had rickets. Rickets is a skeletal disease that most often results from a lack of vitamin D. In the baby’s case, the condition was most likely caused by breast-feeding. Mothers often do not pass enough vitamin D to their babies from breast milk, which is why most pediatricians suggest vitamin D supplements, especially for breast-fed infants.

However, the vitamin D story is much bigger than an unexpected case of rickets. Deficiency in vitamin D, a fat-soluble supplement needed to maintain normal levels of calcium and phosphorus in the blood, does appear to be a growing problem. Some medical experts even claim we are suffering through a vitamin D deficiency "crisis." As urban societies grow and we scramble to protect ourselves from the cancer-causing rays of the sun — the primary source of the nutrient— too few of us have optimal levels of vitamin D in our bodies, some doctors say. For example, cases of rickets, sometimes in adults, are on the rise in developed countries, according to a government report.

The vitamin D craze has been building over the last few years, with low levels of the supplement being the blamed as a source of many of our ills. Depression? D can ease it. Chronic pain? Take D. It is said to prevent kidney disease, diabetes, osteoporosis, colon and breast cancer, cardiovascular disease, or even the common cold. Recently, a study linked low vitamin D levels to the rise in Caesarean births.

Some studies, mainly epidemiological research that hunts for associations between diseases and possible causes, would seem to support that enthusiasm. For example, Cedric Garland, professor of family and preventive medicine at the University of California San Diego School of Medicine and colleagues, found that "the serum level associated with a 50 percent reduction in risk [for colon cancer] could be maintained by taking 2,000 international units of vitamin D3 daily." Garland believes the good news is being suppressed.

“We are curing cancer and diabetes and nobody is doing anything about it,” Garland said. Well, not quite. Partly through the agitation of evangelists like Garland, along with the efforts of the indoor tanning industry, the vitamin companies, and medical testing outfits, the message has been heard. Patients are now getting their vitamin D status tested at such a rate Quest Diagnostics, the world’s largest medical testing company, reports double digit sales growth of vitamin D tests, which can cost upwards of $200.

How much is enough?
Meanwhile, skeptics doubt many of the health claims and question the need and even the validity of widespread testing. They recall how large doses of vitamins C and E were supposed to prevent cardiovascular disease. Beta-carotene was supposed to prevent lung cancer. Selenium kept prostate cancer at bay. None of it turned out to be true, and some of the advice even proved harmful.

Vitamin D was discovered 87 years ago by team of scientists at Johns Hopkins University who cured mice with rickets by feeding them cod liver oil. Oily fish like sardines remain one of the few natural food sources of vitamin D.

It was later found that certain wavelengths of ultraviolet light prompt our bodies to synthesize vitamin D, eventually making a hormone called calcitriol that, among other things, controls how the body uses calcium and mineralizes bone.