Vitamin D: The new wonder pill

If I tell you that there is one pill that can ease aches and pains, strengthen bones, slow down cancer, and prevent disease as varied as Type 1 diabetes, multiple sclerosis, and schizophrenia, I am sure that you would think that I have now accepted a job to promote a product of a health food company.

But these claims aren’t mine. A growing number of serious scientists are quite willing to speculate that a single compound may be able to accomplish all of these — and possibly more. They’re not talking about a new miracle drug, but a common nutrient: vitamin D, "the sunshine vitamin." It is the latest darling of nutrients.

For decades, nobody suspected that vitamin D could do anything better than strengthen bones. But today, it’s clear that D is a powerful agent with wide-ranging effects. It improves calcium absorption, controls the growth of cells, strengthens the immune system, and seems to rein in overzealous immune system cells that cause disease such as rheumatoid arthritis and multiple sclerosis. No wonder, to some scientists, the potential looks huge. "Even if two-thirds of these things don’t pan out, it’s still a blockbuster," says Dr. Robert Heaney, a professor of medicine at Creighton University in Omaha, Nebraska.

Growing Body Of Research

Vitamin D is the only vitamin that the body can make on its own, with a little help from rays of ultraviolet B light. Unlike other vitamins, which act like cogs to aid specific enzymes in the body, vitamin D cycles through the liver and kidneys to turn into a potent steroid hormone in the same chemical class as estrogen and cortisol. Whatever messages vitamin D carries, the whole body seems to listen. Scientists have found receptors that respond to it in just about every type of human cell, from brain to bones. The hormone can also switch at least 200 genes on and off.

Researchers aren’t even close to understanding all of its effects, but what they’ve seen so far has them buzzing. At a vitamin D scientific workshop last April, 37 speakers from around the world talked about their work, and "everybody there was excited," says Anthony Norman, a professor of biochemistry at UC Riverside in California. Here’s what research tells us about vitamin D so far:

• Fractures and falls. There is ample evidence that vitamin D can reduce the risk of breaking a hip. That’s because without vitamin D, calcium is not absorbed as well. However, much evidence also indicates that 400 international units (IU) of D – the current recommended daily value – has little effect beyond preventing osteomalacia, a bone-wasting disease characterized by bone pain, aches, and muscle weakness. Recent research suggests it takes doses of 700 to 800 IU a day to fight fractures. A 2005 study published in the Journal of the American Medical Association even found that an extra 700 to 800 IU of vitamin D, taken with or without calcium, can reduce the risk of hip fractures in post-menopausal women by 26 percent.

• Cancer. Emerging research continues to suggest significant anticancer benefits from vitamin D. Colon and prostate cancers have shown the strongest links, but D may also protect against breast, lung, and digestive cancers, apparently by stopping cell growth. Edward Giovannuci, MD of Harvard Medical School, speculates that at least 1,500 IU of vitamin D a day may be needed to curb cancer. Vitamin D may also affect cancer progression and treatment. In one study, men with the highest levels of D not only had a lower overall risk of prostate cancer, but a 77 percent lower risk of aggressive prostate cancer – the type likely to kill. Other research found that people who got the most vitamin D were more likely to survive after lung cancer surgery than those getting the least D.

• Inflammation. By helping quell inflammation, vitamin D may deter conditions like periodontal disease and arthritis. In a study of people aged 50 and older, those with the lowest blood levels of D were more likely to suffer loss of gum tissue than those with the highest levels. Other research has linked low blood levels of D with increased risk of both osteoarthritis and rheumatoid arthritis (RA). With researchers now believing inflammation may be at the core of not only arthritis but many diseases – even heart disease and cancer – D’s ability to ease inflammation could end up being its most important role.

• Immune malfunction. The link between RA and sub-par blood levels of D may be linked to the vitamin’s influence on immunity. RA develops when the body’s immune system mistakenly launches an attack on itself, especially the joints. Multiple sclerosis (MS), another autoimmune disorder, occurs when the body attacks its own nervous system. In one study, women who took at least 400 IU of D a day were 40 percent less likely to develop MS than those not taking a D supplement.

• Hormone and brain messengers. Vitamin D influences the functioning of some crucial substances, like insulin, renin, serotonin and estrogen. As an insulin stimulator, it helps deter diabetes. For example, a 2001 study found that giving Finnish children 2,000 IU of vitamin D each day starting at age one reduced the risk of type 2 diabetes by 80 percent. As a suppressor of the kidney hormone renin, it controls blood pressure. As a booster of the brain chemical serotonin, it may ease depression. And as a regulator of estrogen, it may help minimize premenstrual syndrome discomforts.

• Obesity. Excess body fat absorbs and holds onto vitamin D, so the body can’t use it. Moreover, not getting enough D seems to interfere with the workings of another hormone, leptin, which sends signals to the brain that you are full and you should stop eating. Repleting D to normal levels seems to restore leptin’s functioning.

Desirable D Dose

As excitement about vitamin D grows, so does the concern that many people may not be getting enough. In March, an article in the journal Mayo Clinic Proceedings, called vitamin D deficiency "a largely unrecognized epidemic in many populations worldwide." Heaney and other researchers believe the Food and Drug Administration should consider radically increasing the suggested daily dietary intake of the vitamin, which is currently set at 200 IU for anyone younger than 51, 400 IU for people 51 to 70, and 600 IU for those 71 and older. Almost all vitamin D experts believe people should get at least 1,000 IU a day – two-and-a-half times the current official recommendation for younger adults. And although these experts also feel that a much higher dose does not pose a toxicity risk, there is probably no reason to get more than 2,000 IU daily.

"I’m 99 percent sure that vitamin D deficiency is becoming common," says Dr. Walter Willett, a professor of epidemiology at Harvard University who has conducted several studies on the health effects of vitamin D. In one of them, he and his colleagues estimated that an extra 1,500 IU of vitamin D each day could reduce the risk of deadly cancers of the digestive system by 45 percent.

Where To Get It

So how should one get 800 IU to 1,000 IU a day? For many people, the largest source of vitamin D is their own skin. This dependence on sunshine presents several problems – there’s skin cancer and damage to worry about. Sunscreens are a dilemma, because they block UVB light.

How about eating more fruits and vegetables? That isn’t going to work either because vitamin D isn’t found in plants. Vitamin D may be yet another reason to eat fish, but you’d have to eat an awful lot to get as much vitamin D. Most multivitamins contain 400 IU of vitamin D, but you shouldn’t just take two because the vitamin A in the pill may interfere with vitamin D. Many calcium pills now contain about 200 IU of vitamin D, so a multivitamin and two calcium pills would get you 800 IU. For women, that’s not a bad way to go. For men, it may be. Professor Willett cites evidence for a possible link between high calcium intake and prostate cancer.

But not to worry. With evidence of the benefits of vitamin D growing, it will not take long before pure vitamin D pills of various sizes, shapes, and forms will be available at your nearest friendly neighborhood health store soon.