Wonder pill. Really.
EVEN the most brazen snake-oil salesman might blush at trying to sell the public on a pill to ease aches and pains, strengthen bones, slow down cancer and prevent diseases as varied as Type 1 diabetes, multiple sclerosis and schizophrenia.
But these claims aren’t the frothy hyperbole of a sideshow huckster. A growing number of serious scientists are quite willing to speculate that a single compound may be able to accomplish all of these feats -- and possibly more. They’re not talking about a new miracle drug, but a common nutrient: vitamin D, “the sunshine vitamin.”
Once seen as merely a defense against rickets, vitamin D has in recent years gained recognition as a major force that acts throughout the body. It improves absorption of calcium, controls the growth of cells (both healthy and cancerous), strengthens the immune system and seems to rein in overzealous immune system cells that cause diseases such as rheumatoid arthritis and multiple sclerosis.
Much of vitamin D’s potential is still just that: potential. But at this moment, 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, who specializes in osteoporosis.
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 many 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 international units (IU) for anyone younger than 51, 400 IU for people 51 to 70, and 600 IU for those 71 and older.
They cite studies such as one published earlier this year that found that cancer deaths were especially common in men with low levels of vitamin D, and a series of studies showing that high levels of vitamin D improved strength and prevented falls in elderly people.
“The daily allowances for vitamin D are outdated,” says Anthony Norman, a professor of biochemistry at UC Riverside. “I would recommend 1,000 IU per day for all ages, with a maximum of 2,000 IU. I’m considering taking 2,000 IU myself.” And, he adds, current evidence suggests that even 10,000 IU -- overkill by anyone’s standards -- would probably be safe.
“I’m 99% sure that vitamin D deficiency is becoming more common,” says Dr. Walter Willett, a professor of epidemiology and nutrition 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%.
Willett believes that more than 1 billion people on the planet -- including about two-thirds of whites and almost all blacks in America -- don’t have enough for optimal health. In recent years, shortages of the compound have even led to a resurgence of rickets, a childhood bone deformity, especially among dark-skinned babies who are exclusively breast-fed.
Growing body of research
Vitamin D is the only vitamin that the human body can make on its own, with a little help from rays of ultraviolet B light. On a sunny day, a fair-skinned person can make 10,000 to 20,000 IU in 15 minutes or less. Vitamin D is also available in fatty fishes such as salmon and mackerel and in fortified foods such as milk, orange juice and cereals.
The vitamin was discovered about 80 years ago, when doctors realized that both cod liver oil and sunlight could cure the rickets plaguing many poor children in northern cities. The race was on to find the common thread. The German organic chemist Adolf Windaus won that race -- and the Nobel Prize -- by isolating the vitamin in 1926.
For decades, nobody suspected that vitamin D could do anything other than strengthen bones. But today it’s clear that D is a powerful agent with wide-ranging effects. 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 in April, 37 speakers from around the world talked of their work, and “everybody there was excited,” Norman says.
Much of that excitement is centered around cancer research. Just like nearly all healthy cells, cancer cells have vitamin D receptors too -- and when D binds, it tells those cells to stop growing, a potentially life-saving command. In fact, a 2005 article in the Southern Medical Journal called vitamin D “one of the most potent inhibitors of both normal and cancer cell growth.”
This potential cancer-fighting power may help explain why cancers of the breast, colon or prostate tend to be more common, or more aggressive, in dark-skinned people, Norman says. It may also, he adds, help explain why people in northern states such as Maine or Minnesota -- where summers are short and sleeves, for most of the year, are long -- are more prone to these cancers than people in the sunny South.
Other quirks of geography offer compelling evidence for the importance of vitamin D, says Dr. Michael Holick, a professor of medicine, physiology and biophysics at Boston University School of Medicine and one of the most vocal proponents of the compound. People in sun-deprived regions are especially prone to schizophrenia, multiple sclerosis and Type 1 diabetes, he says.
In some cases, taking vitamin D supplements to compensate for a shortage of sunlight may stop such diseases before they start. A 2001 study found that giving Finnish children 2,000 IU of vitamin D each day starting at age 1 reduced the risk of Type 1 diabetes by 80%.
Generous amounts of D also seem to strengthen bones and prevent fractures. A 2005 study in the Journal of the American Medical Assn. found that an extra 700 to 800 IU of vitamin D, taken with or without calcium, reduced the risk of hip fractures in post-menopausal women by 26%.
Willett says that boosting levels of vitamin D can build bone density, strengthen muscles and, in some cases, help relieve unexplained aches and pains. A recent Mayo Clinic survey found that 93% of adults and children with unexplained pain were vitamin D deficient. Anecdotally, some people with pain report relief when they take vitamin D.
A simple experiment reported in March strongly suggests that vitamin D may help fend off dangerous infections. UCLA researchers mixed the bacterium that causes tuberculosis with blood samples from African Americans, a group that is especially vulnerable to the disease.
The blood was low in vitamin D, as it almost always is with dark-skinned people. When the researchers added a little vitamin D to the mix, disease-fighting cells that had previously sat dormant suddenly roared to life and started attacking the infection.
A call for caution
Nobody could blame the general public for rolling their eyes ever so slightly at the current fizz about vitamin D. Many vitamins and supplements have been over-hyped in the past. Vitamin E, for example, was once touted as a potent antioxidant that could prevent heart disease -- until a 2000 study found that vitamin E supplements didn’t offer any protection to patients at high risk for a heart attack or stroke.
And beta carotene once enjoyed a reputation as a cancer fighter -- until a study of more than 29,000 male smokers found that supplements of the vitamin actually increased the risk of lung cancer.
In fact, even vitamin D, along with calcium, failed to live up to expectations in the highly publicized Women’s Health Initiative, a long-term study of more than 160,000 women. As reported in February, supplements containing 1,000 milligrams of calcium and 400 IU of vitamin D (a modest dose, to be sure) didn’t significantly increase bone density or prevent fractures in post-menopausal women.
For these and other reasons, some scientists argue for circumspection.
Connie Weaver, a professor of food and nutrition at Purdue University who helped craft the current dietary guidelines for vitamin D, believes some researchers may be asking too much from the nutrient. “Too many people expect nutrients to work like drugs,” she says. “That kind of approach is likely to lead to disappointment.”
The guidelines for vitamin D may well have to be bumped upward, she says, but only after careful scientific consideration and more studies. “There’s a lot of good data that optimal vitamin D status may have many health benefits, but we don’t know what those optimal levels are,” she says.
Hector DeLuca, a professor of biochemistry at the University of Wisconsin at Madison and a prominent vitamin D researcher, says he’s open to the possibility that vitamin D can prevent cancer or autoimmune diseases, but he’s not yet convinced. He believes that the FDA should eventually raise the recommended dietary intake, perhaps to 2,000 IU a day. (“I see no risks, and it might well help,” he says.) But he’s concerned about possible toxicity if people take more than that.
At this time, it’s not especially easy for consumers to add large amounts of vitamin D to their diets. A cup of fortified milk contains less than 100 IU of vitamin D and a nice hunk of salmon can provide up to 400 IU. Typical multivitamins contain just 400 IU.
Vitamin companies have been slow to recognize the potential value -- and marketability -- of D. In fact, supplements that contain nothing but vitamin D have only recently hit the market. “I saw vitamin D on the shelf for the first time last week,” Heaney says.
Last week, the Institute of Medicine (which advises the government on medical matters) held a workshop to discuss vitamin D and a few other nutrients. Such meetings are often the first step toward new guidelines.
In the meantime, if people want to supplement their diet with D, scientists suggest aiming for between 1,000 and 2,000 IU a day from a combination of fish and fortified food and supplements, choosing the more common, animal-derived D3 form of the vitamin over another form, vitamin D2. (D2, made by plants, is less than one-third as potent as D3.)
Doctors can now measure a patient’s level of vitamin D with a simple blood test, but Heaney, for one, believes the tests are often unnecessary. At his osteoporosis clinic, he says, “we just assume that every patient is deficient.”