February 29, 2004
As the sun begins to break through over Chicago, its warming rays are resuming a critical role that has lain dormant most of the winter, coaxing our skin to make vitamin D.
Emerging research indicates that vitamin D is more important to our health than previously thought, leading an increasing number of scientists to challenge whether the fear of sun exposure has made us cover up too much.
Doctors are finding an increase in vitamin D deficiencies, even as researchers discover remarkable results from the vitamin that affects nearly every tissue in the body.
Told their pain and muscle weakness would only get worse, and that they would likely remain in wheelchairs the rest of their lives, five patients in Buffalo decided to take a chance on large doses of vitamin D.
In 4 to 6 weeks they were up and about, saying goodbye to their wheelchairs and back to normal activities, pain free.
When women took vitamin D in multivitamin supplements over a long period of time, their risk of developing multiple sclerosis was reduced by 40 percent.
And a disturbing number of children who don't have enough vitamin D in their bodies are showing up with rickets, a crippling bone disorder thought to have been eradicated more than 70 years ago.
Dr. Craig Langman, a kidney and mineral metabolism expert at Children's Memorial Hospital and Northwestern University Medical School, sees a new case of rickets every week, triple the rate of five years ago.
"We're finding more and more kids are presenting with evidence of vitamin D malnutrition," said Langman, who noted that includes fractures and bone pain.
Vitamin D is a critical hormone that scientists are discovering helps regulate the health of more than 30 different tissues, from the brain to the prostate. It plays a role in regulating cell growth, the immune system and blood pressure, and in the production of insulin, brain chemicals and bone.
"We thought that vitamin D was a very narrow-acting substance," said Dr. Hector DeLuca of the University of Wisconsin, where vitamin D was first identified in the early 1900s, leading to the fortification of milk and some other foods that eliminated endemic rickets.
"The big surprise is that it's got a lot of important biological effects that probably contribute to our health and we're just now beginning to uncover them," said DeLuca. "Are we getting enough vitamin D? No we're not, especially in the winter."
Vitamin D is one of the body's many control systems. It acts like an emergency brake that helps stop cells from perilously misbehaving, as immune cells can do when they cause such autoimmune diseases as MS and as breast and prostate cells do when they turn cancerous.
This protection declines as vitamin D levels drop. University of Chicago microbiologist Yan Chun Li discovered just how that happens with high blood pressure. Vitamin D helps normalize blood pressure by keeping a pressure-increasing switch called renin in check.
Vitamin D's importance for health goes back more than 750 million years to the earliest life forms that left the ocean for the Earth's surface. All vertebrates today depend on sun exposure for vitamin D production.
The lack of vitamin D is known to cause rickets, osteoporosis and osteomalacia (soft bones). New research indicates that vitamin D malnutrition may also be linked to many chronic diseases such as cancer (breast, ovarian, colon and prostate), chronic pain, weakness, chronic fatigue, autoimmune diseases like multiple sclerosis and Type 1 diabetes, high blood pressure, mental illnesses--depression, seasonal affective disorder and possibly schizophrenia--heart disease, rheumatoid arthritis, psoriasis, tuberculosis and inflammatory bowel disease.
"A lot of people with aches and pains and marginal weakness could be helped by vitamin D supplements," said Dr. Paresh Dandona of the State University of New York at Buffalo who reported the first five cases of vitamin D deficient myopathy three years ago in the Archives of Internal Medicine.
Undiagnosed pain is the chief complaint of more than one-third of patients.
Studying 150 children and adults with undiagnosed pain, Dr. Greg Plotnikoff of the University of Minnesota discovered that 93 percent were severely or profoundly vitamin D deficient. All were put on prescription doses of the vitamin.
"One patient with chest pain had multiple balloon angioplasties and his pain never went away," Plotnikoff said. "He also had surgery for his low back pain but he didn't get any better.
"I measured his vitamin D level and it was basically zero," he said. "His chest and low back pain were not due to cardiac or spinal disease but to low vitamin D. We put him on prescription strength vitamin D and he got much better. We had spent over $200,000 on him in the hospital for these other procedures without doing a $20 blood test."
A study in the British medical journal Lancet found that infants receiving 2,000 IU of vitamin D daily were protected from developing Type 1 diabetes. Various forms of vitamin D have become a major treatment for psoriasis and preliminary evidence suggests it reduces blood pressure, reduces hip fracture risks in older people and improves symptoms of rheumatoid arthritis and multiple sclerosis.
"Our study supports a possible role for vitamin D in the prevention of MS," said epidemiologist Kassandra Munger of the Harvard School of Public Health. "Further studies are needed to confirm the findings, but taking a multiple vitamin as part of a healthy diet can't hurt."
Researchers are finding that the current recommended daily allowances of vitamin D--ranging from 200 international units for infants, children and adults up to age 50 years; 400 IU for men and women from 50 to 70; and 600 IU for people older than 70--are probably far lower than the minimum amount necessary for optimum health.
Scientists are quick to warn that although people may need more vitamin D, mostly in the form of supplements in higher latitudes where sunlight is weak during winter months, they should consult a physician before consuming large doses. Taking too much vitamin D can elevate levels of calcium in the blood, a potentially serious condition that can lead to nausea, vomiting, or even death. It is especially easy for children to overdose on vitamin D supplements.
Dr. Michael F. Holick of Boston University Medical Center, one of the world's foremost vitamin D experts, recommends 1,000 IU daily for everyone through a combination of safe exposure to sunlight and supplements.
Summertime sun exposure on the face, arms and hands around noon for only 5 to 15 minutes for people with light skin 2 to 3 times a week provides sufficient vitamin D, he said.
Blacks have the highest risk for vitamin D deficiency because dark skin needs 5 to 10 times more sunlight than white to produce the same amount of the vitamin. One study found that 42 percent of African-American women in the U.S. were vitamin D deficient.
Chronic diseases associated with vitamin D deficiency are 25 to 50 percent more frequent in northern climates than among people living closer to the sunny equator, where humans first evolved. As people migrated away from the equator, it is thought, skin evolved lighter shades to absorb more sunlight for vitamin D production.
Vitamin D is not available in most foods (oily fish, egg yolks, liver and cod liver oil have some), but it is abundantly made when sunlight strikes the skin, which normally produces about 90 percent of the body's store of the vitamin.
People living in northern latitudes don't get enough sun from December through February to make vitamin D. A person living in Chicago, Boston, Detroit or New York can stand naked outside all day in the winter and not make any vitamin D, said Holick, author of "The UV Advantage."
Even in summer the skin's vitamin D-making ability gets dampened from the increasing use of sunscreen, leading a growing number of health experts to challenge the advice given over the last two decades to avoid the sun at all costs in order to reduce skin cancer risk.
"The amount of vitamin D in our diet is totally inadequate," Holick said. "We are in an era of sunphobia--that is not being exposed to any direct sunlight--that's being promoted widely by the dermatology community and it's probably hurting people's health more than it's helping them."
"That message needs to be modified and moderated to a more sensible approach so that people can get a little bit of safe sun," he said.
The evidence is overwhelming that excessive sun exposure causes skin cancer. More than 1 million cases of squamous and basal cell cancers, which are highly treatable, are expected this year, according to the American Cancer Society. Solar exposure is also blamed for the anticipated 55,100 cases of melanoma in 2004 and 7,910 deaths. Melonama, a potentially deadly skin cancer, usually occurs years after severe sunburns in childhood.
On the other hand, increasing but less conclusive evidence suggests that adequate vitamin D levels from healthy sun exposure may reduce the risk of many other cancers.
A recent study of more than 430,000 death certificates showed that people who had more exposure to sunlight had a 26 percent lower risk of death from colon and breast cancer, said D. Michal Freedman, an epidemiologist at the National Cancer Institute.
Testifying in October at a "Vitamin D and Health in the 21st Century" conference called by the National Institutes of Health's Office of Dietary Supplements, William B. Grant, a retired NASA senior scientist and solar radiation expert, said his studies determined that lack of vitamin D accounts for 45,000 cancer deaths annually and 165,000 new cancer cases.
The conference was prompted by growing concerns of widespread vitamin D inadequacy and how to strike a balance between supplements, dietary fortification, tanning booths and sun exposure, said NIH nutritionist Mary Frances Picciano.
"If you go to the literature where people are talking about sunlight and cancer risk, nobody mentions that you need sun for vitamin D," she said. "By the same token if you go to the vitamin D literature where people are talking about skin irradiation to get vitamin D, nobody talks about cancer.
"One of the first things that might be necessary is to get the skin cancer people together with vitamin D requirement people," Picciano said. "There are questions that need to be addressed before meaningful public health policy can go forward."
Emphasis on vitamin D growing
New research puts a greater importance on vitamin D, which the body develops from sunlight exposure. Vitamin D's main function is to maintain normal levels of calcium and phosphorus in the blood.
VITAMIN D SOURCES
- Multivitamin supplements
- Sunlight: Ultraviolet rays trigger the formation of vitamin D in the skin, accounting for 90 percent of the daily recommended intake.
5 to 10 minutes of sun exposure between 10 a.m. and 2 p.m. daily in the summer are recommended. Particularly in northern areas, it is difficult to produce in the winter.
- Foods: Milk and cereals are fortified. Oily fish naturally contain vitamin D.
FOOD SOURCE INTERNATIONAL UNITS
Cod liver oil (1 tbs.) 1,360
Salmon, cooked (3 1/2 oz.) 360
Milk, nonfat, reduced, whole (1 cup) 98
Dry cereal (3/4 cup) 40-50
DAILY ALLOWANCE RECOMMENDATIONS
In international units (IU), by age
50 to 70: 400
Older than 70: 600
Many vitamin D experts recommend 1,000 IU daily for everyone.
Vitamin D-related health risks
Rickets: A disease in which children's bones soften, break.
Osteopororis: A condition characterized by fragile bones.
Osteomalacia: A bone-thinning disorder in adults that is similar to rickets.
Vitamin D malnutrition also may be linked to diseases such as cancer,
multiple sclerosis, Type 1 diabetes and high blood pressure.
National Institute of health, National Osteoporosis Society
Copyright © 2004, Chicago Tribune