Vitamin D

Vitamin supplements have been both heralded and hyped over the years, only to ultimately fall from grace once research proves them to be little more than placebos in our quest for longer life or better health. But at least one substance may have true merit -- vitamin D. Long considered just a supplement consumed with calcium for bone health, this humble vitamin may have untapped potential in fighting or preventing disease, suggests an explosion of new research.

Vitamin D may be helpful in protecting highly active pre-teen and teen girls, such as those who play sports, from stress fractures, researchers reported Monday. The study was surprising because calcium has long been considered the nutrient most vital to bone health in children. But, in developing children, vitamin D intake may matter more. Researchers analyzed data from 6,721 girls ages 9 to 15 at the start of the study. The girls' intake of calcium, vitamin D and dairy products was recorded along with stress fractures, which are common sports-related injuries.

Vitamin D appears to lower the risk of colon, breast and ovarian cancer, say researchers who reviewed 63 studies, including several large long-term ones, on the relationship between vitamin D and certain cancers. "There's nothing that has this ability to prevent cancer," said researcher Dr. Cedric Garland, urging governments and public health officials to do more to fortify foods with vitamin D. The findings were published online in the American Journal of Public Health.

Vitamin D has emerged as something of a wonder supplement, according to the claims of dozens of studies published in the past few years. Researchers have suggested that adequate levels of the nutrient not only strengthen bones, but reduce the risk of cancer, heart disease and other conditions. Several studies also suggest Americans are not getting enough vitamin D, which is synthesized in the skin from sun exposure and found in certain foods, such as fortified milk and cereal, some types of fish and legumes.

Higher amounts of vitamin D could help make it easier to breathe, offering possible good news for smokers, asthmatics and other people with respiratory problems. Researchers at the University of Auckland in New Zealand found that people with higher levels of the vitamin in their systems showed better lung function than those with lower amounts. Although the vitamin, which people get mostly from sunlight, is linked to lung health, the exact relationship is unclear, they said.

New studies indicate that vitamin D, a nutrient made by the skin during exposure to sunlight, can lower the risk of breast cancer by 30% to 40% and perhaps even more. Epidemiologist Esther John of the North California Cancer Center said at a meeting of breast cancer experts that a study comparing the health habits of 133 breast cancer patients with women who did not have the disease found that exposure to sunlight significantly reduced the risk of breast cancer.

Vitamin D -- the fat-soluble vitamin that's technically a hormone -- is crucial for good bone health. Manufactured in the skin with the help of the sun's ultraviolet B rays, the vitamin regulates absorption and excretion of calcium. Because it's found in very few foods (fatty fish and cod liver oil are on the short list), most Americans, particularly the sun-deprived, get the vitamin from fortified milk and cereal products.

Hanging out in the sun, letting your face acquire that nice, ruddy glow, used to feel good. Then came all those depressing public health messages telling us that the sun was dangerous, that we should feel guilty about even the slightest tan. Well, fellow sun worshipers, the sad truth is that, as a general rule, we should still practice "safe sun" much of the time. But there's a new ray of hope--dare we say "sunshine"?

Scientists have long suspected that sunshine and vitamin D may protect against the development of multiple sclerosis; now they have additional evidence. Oxford University researchers hypothesized that if solar radiation is protective, multiple sclerosis patients probably would have less solar exposure -- and thus lower rates of skin cancer. They then examined skin cancer rates among more than 432,000 Oxford-area patients treated by England's National Health Service from 1963 to 1999.

It is simply not possible anymore to pick up a newspaper or turn on the television or especially to prowl the Internet without being confronted with incredible hype for this supplement or that dietary miracle. The magic bullet theory of health promotion is very seductive, and no one can be faulted for wanting it to be true.

Vitamin D works with calcium to strengthen bones. But adequate levels of vitamin D in the bloodstream also appear to boost the power of bisphosphonates, medications used to treat osteoporosis, according to research presented Monday. The study adds to the evidence that the current recommendations for vitamin D may be too low. Late last year, the Institute of Medicine issued a report that declined to make changes to the recommendation -- despite many new studies supporting the need for more vitamin D than is typically consumed.

We should get more vitamin D; no, we already get enough. A debate rages over how much vitamin D adults, children and pregnant women should consume for health benefits and disease prevention. Now research suggests that infants who are born with low levels of vitamin D may be at higher risk for lung infections caused by a common virus. In the new study published online Monday in Pediatrics , researchers in the Netherlands assessed vitamin D levels in 156 babies at birth by measuring concentrations in their cord blood.

Getting enough vitamin D may help prevent women from losing their vision in old age. That's the quick and easy conclusion from a new study, just perhaps not one that will require you to change your diet. In a study of 1,313 women ages 50 to 79, researchers from the University of Buffalo in New York found that women with adequate levels of vitamin D were at 48% decreased odds for developing age-related macular degeneration (AMD) compared with women with insufficient levels of the vitamin.

Vitamin D levels in most Americans are adequate, with only 8% of the population at risk for health problems because of low vitamin D, according to a government report. Vitamin D is one confusing nutrient. Numerous studies in recent years have linked deficiency to a range of health problems and disease risk, including cancer, autoimmune diseases and diabetes. The nutrient also has a well-defined role in bone health. Some doctors and researchers have called for an increase in the recommended dietary intake of vitamin D. But in a report released late last year, the Institute of Medicine declined to raise the values saying: "The IOM finds that the evidence supports a role for vitamin D and calcium in bone health but not in other health conditions.

Eggs are getting a bit of a reprieve on the cholesterol front. A U.S. Department of Agriculture report released Tuesday says eggs are lower in cholesterol and higher in vitamin D than previously thought.   The federal agency released these findings (helpfully publicized by the egg industry) after testing a random sample of eggs across the country and examining their nutrient value. It found the average large egg contained 185 milligrams of cholesterol (14% less than prior measures)

Even as a high-profile panel of experts recently disputed the conventional wisdom that Americans don't get enough vitamin D -- and that vitamin D deficiencies create greater risk of disease -- new research shows that newborns with low levels of vitamin D have higher rates of respiratory infection and wheezing than infants born with more vitamin D in their systems. There was no correlation, however, between low vitamin D levels and asthma. The study, published Monday in the journal Pediatrics, expanded on earlier work by Dr. Carlos Camargo of the Massachusetts General Hospital in Boston that had shown that babies born to mothers who took vitamin D supplements were less likely to develop wheezing during childhood.

People who take vitamin D tablets appear to be almost half as likely to get deadly pancreatic cancer as people who do not, researchers have found. Now they're checking to see whether getting the vitamin from food or sunlight also cuts the risk. The study suggests one easy way to reduce the risk of pancreatic cancer, the fourth-leading cause of death from cancer in the United States.

New research finds vitamin D deficiency surprisingly common among older adults, especially those in poor health, and concludes that even a daily multivitamin may not provide enough of this essential nutrient. A study of patients at a Boston hospital, reported today in the New England Journal of Medicine, found that more than half had too little vitamin D in their bodies, a condition that increases the risk of bone fractures and may have other ill effects, as well.

I was deeply saddened with the Institute of Medicine report that we are a healthy nation in regard to our calcium and vitamin D intakes ["Sweeping Away the Hype About Vitamin D," Dec. 6]. As a physician keenly interested in my patients' nutrition status and needs, I find the report flawed. By arbitrarily setting the lower limit of normal vitamin D blood level at 20 nanograms per milliliter, they are missing the borderline deficiency between 20 and 40 ng/ml. I recommend 2,000 international units of vitamin D per day to my adult patients.

The Institute of Medicine recently upended the health apple cart with a new study that says we don't need as much calcium or vitamin D as we've been told. In fact, taking the kind of megadose that makes you feel virtuous and keeps the supplement industry healthy can lead to kidney stones, with calcium, and kidney or heart damage, with D. If that sounds alarmist, let me quote directly from the Institute of Medicine's statement, which says that "some signals suggest there are greater risks of death and chronic disease associated with long-term high vitamin D intake.