Vitamin Information Center

Mothers everywhere probably will not be surprised to hear that they were right. Drinking your milk is, of course, good for you. Not only is milk chock-full of calcium, most milk has been fortified with vitamin D — and both nutrients are necessary for good bone health, among other things. And in recent years, a growing body of research has caused experts to conclude that many adults, particularly those over 50, are not getting enough calcium or vitamin D, says Dr. Michelle Germain, a part-time faculty member in the Department of Gynecology and Division of Urogynecology at Greater Baltimore Medical Center.

What is vitamin D?

Vitamin D is a fat-soluble vitamin. It is absorbed from food through the GI [gastrointestinal] tract and also is made by the body. The body needs it because it helps with absorption of calcium and phosphorus, both of which the body needs for bone health.

You said that, in addition to absorbing vitamin D from food, the body also manufactures it. How does the body make vitamin D?

The skin manufactures the vitamin D with the help of ultraviolet rays from the sun. So you need sun exposure to make it. Once we have vitamin D in our bodies, the liver and the kidneys convert the vitamin D into the active form that is used for bone health.

What foods contain vitamin D?

Cod-liver oil is the best way to get vitamin D, but we don’t see many people taking that these days. So other really great sources of vitamin D are fish, such as salmon, mackerel and tuna, and vitamin D-fortified foods, such as dairy products and cereals.

What happens if we don’t get enough vitamin D?

You can become vitamin D-deficient. Children can develop “rickets,” in which the bone doesn’t properly mineralize, and the children develop very soft bones and deformities of their skeleton. In adults, too little vitamin D can lead to osteoporosis. [Too much vitamin D, on the other hand, can make the intestines absorb too much calcium.]

How pervasive is rickets?

In developed countries like the United States, it is pretty uncommon because we fortify so many foods with vitamin D. But there has been a resurgence of rickets in African-American infants and children in poorer states, especially in the South such as Tennessee and Mississippi. The resurgence is being caused by poverty and poor nutrition. It also has to do with darker pigmentation of the skin, which converts sunlight less effectively into vitamin D.

Rickets also is more prevalent in immigrants from Africa, the Middle East and Asia because of their diets before they arrive in the United States and because they may not have enough money to afford good nutrition once here. Again, if they have darker skin, they are not converting UV rays into vitamin D as effectively as people with lighter skins.

Are there other populations for which vitamin D is particularly important?

Older women. If older women are vitamin D-deficient then they are at increased risk for osteoporosis. This is of special concern for menopausal women because once their estrogen levels drop, they begin to lose bone. The vitamin D is necessary to absorb calcium and utilize it in bone formation. And people who have any kind of gastrointestinal illness like Crohn’s disease or celiac disease or any kind of liver disease also are at increased risk for vitamin D deficiency.

Are there any symptoms of vitamin D deficiency that might occur before bone loss?

Unfortunately, there are really no symptoms of it until you are diagnosed with osteoporosis.

What do you tell your patients about vitamin D?

Children and young adults need to consume a diet that is rich in vitamin D-fortified foods. At least 15 minutes of exposure to sunlight twice a week should be adequate to make sufficient amounts of vitamin D. But I also tell them that if you put on sunscreen with an SPF greater than 8, it can interfere with making vitamin D, so diet is very important. Particularly in winter, they should concentrate on eating a diet with plenty of vitamin D-rich foods.

What do you tell adults?

If a woman has osteoporosis, she should ask the doctor if she is potentially vitamin D-deficient. Very often, after a woman has a hip fracture, we check her vitamin D level, and it turns out to be ridiculously low. So, if you have osteoporosis or a fracture, ask about your vitamin D level.

How much vitamin D do we need?

Last year, the National Osteoporosis Foundation released new recommendations about vitamin D. The National Institutes of Health also are due to release this spring new guidelines. According to the National Osteoporosis Foundation, adults under age 50 need 400 to 800 IU [International Units] of vitamin D3 daily. [Also called cholecalciferol, vitamin D3 is the kind of vitamin D that best enhances healthy bones.] And menopausal women and adults over the age of 50 need 800 to 1,000 IU of vitamin D3 daily.

Dr. Robert Heaney, professor of internal medicine at St. Louis University School of Medicine, says 40 percent of his patients get too little vitamin D. He fears the condition could result in health problems as people age.

That corresponds with the 40 percent of Americans and more than 500 million worldwide who get too little vitamin D to stay healthy, according to the World Health Organization.

Vitamin D is known as the “sunshine vitamin” because people normally would get most of what they need from exposing their skin to the sun. UVB rays turn cholesterol in the skin into vitamin D.

And that’s the snag. As scientists find that vitamin D helps conditions from bones to heart health, physicians are rethinking the guidelines for sun exposure — to the chagrin of doctors who believe that’s an invitation to more skin cancer.

Fish oils, fish and fortified dairy products are the main vitamin D sources in food. “But you can eat fish every day of the week and be deficient in vitamin D,” Heaney says. “Vitamin D is difficult to get from food.”

Indeed, the American Vitamin D Council cites research that 10 to 15 minutes in the sun makes up to 12,000 IU (international units) of vitamin D. A sunburn can make up to 50,000. A multivitamin may have 400 IU, which is the recommended daily amount of vitamin D for adults, according to the National Institutes of Health.

Dr. John Cannell, founder of the American Vitamin D Council, says vitamin D is much more valuable than a tool to build bones and teeth. Researchers say vitamin D affects more than 1,000 genes, including ones that resist illness such as colds and even cancer.

“We never put together before that we get colds in the winter and not in the summer when we get more vitamin D in the summer,” Cannell said.

THE SNAG

Doctors who fight skin cancer fear that young people will start sunbathing — and sunburning — again, or use tanning beds to up their dose of vitamin D.

Dr. Susan Bayliss, professor of dermatology at the Washington University School of Medicine, recommends food supplements over increased sun

exposure. UVB and UVA sun rays remain culprits for skin cancer.

“The dilemma is that if you have really fair skin and red hair and freckles, it’s probably better to take your vitamin D in by mouth and put your sunscreen on,” says Bayliss, who also is director of pediatric dermatology and practices at St. Louis Children’s Hospital and the Center for Advanced Medicine.

People with more pigment (melanin) in the skin can tolerate more sun, she says.

AUSTRALIA’S DILEMMA

Heaney says that Australians, who have the highest rate of skin cancer in the world, years ago heeded the word about skin cancer and got out of the sun. But in only a few years, the rate of rickets — a disease of softened bones and bowed legs caused by vitamin D deficiency — increased.

Physicians who advocate more sun say vitamin D made with sunshine never reaches toxic levels. “Vitamin D gets to the useful level, then the sunshine destroys the surplus,” he says.

ELSEWHERE

As health experts wonder what to do with the new findings, they are examining vitamin D intake standards.

For example, the one-size-fits all approach is obsolete. Vitamin D intake recommendations change the closer you live to the equator. People who live in St. Louis don’t get the same amount of sun as southern neighbors, but we do get more sun that our northern states.

The Canadian Cancer Society, for example, last year raised its recommendation for daily vitamin D supplement intake to 1,000 IU per day, more than twice the 400 IU recommended daily for U.S. adults.

SUNSHINE

For some, getting more sun is a back-to-basics measure.

Dr. John Morley, head of geriatrics at St. Louis University, says, “In our nursing homes, people are supposed to be on 800 IU a day,” he said. Still, “about 40-50 percent are vitamin D deficient by the criteria you have to measure the vitamin D. For people 25, that’s not so important and can be corrected. But at 60 or 65 you’re more likely to have falls and deterioration in your functional status, more injuries, hip fractures.”

Nursing homes where he consults now put residents in the sun about 30 minutes a day. The policy led to fewer falls and fractures as well as better health and mood.

“Even with lousy sunlight, if you get people out a half-hour a day, and they’re not covered up and they get some sun, they’ll do OK,” Morley says. “Since we’ve been doing that, we’ve noticed a marked decrease in fractures in the nursing homes, and we now have a rule in the nursing homes, you have to check the vitamin D and make sure the people get (the vitamin) and calcium at an appropriate level.

“But so many people don’t get any sunlight, and that’s particularly true with older people.”

SAFE STEPS

Physicians agree on some issues:

– Vitamin D is essential and needs to be maintained and monitored.

– Sunbathing for a long time in direct summer sun is still a bad thing. “You can get outside, even wearing a hat and expose the arms,” says Dr. Veronica McGregor, an endocrinologist with St. John’s Mercy Medical Center in West County. “About 10 to 15 minutes two or three times a week. It doesn’t take much sun to get adequate vitamin D.”

– Check food labels on supplements because not all vitamin D is the same, Heaney says. You’ll find two types. The best is “cholecalciferol,” the form that occurs naturally and exists mainly in fish oils. It can be synthesized. The second type, “ergocalciferol, is an inexpensively produced vitamin D but may be only 30 percent as effective as the other form. A label that doesn’t specify is probably the lesser form, Heaney says.

– Cod liver oil is the best single source of vitamin D besides sunshine. One tablespoon can deliver 340 percent of the daily recommended vitamin D.

– Don’t rely on fortified dairy products. “Those levels were established (decades ago) to address problems with rickets in children,” Heaney says. “They don’t supply enough for an adult.”

– Tanning beds aren’t the answer. They may not be balanced properly between UVB and UVA rays. Too much UVA is not beneficial.

– Talk to your doctor about a vitamin D test. People most likely to have deficiencies are people who get little sun and anyone who has a family history of bone-density problems.
Source: St. Louis Post-Dispatch

Want to live longer? Get moving

The report was published in the Journal of the American Medical Association.

People dealt with vitamin D deficiency at the turn of the 20th century. Who ever thought we’d be talking about rickets in 2008?

By Jennifer Fisher Wilson

Despite its familiarity, vitamin D is pretty puzzling. Not really a vitamin at all, it is actually a fat-soluble nutrient that is a prohormone (a precursor substance to a hormone). Milk is fortified with it, but it does not come in most other dairy products like cheese, yogurt, and ice cream, and it occurs in significant levels naturally in only a few foods like fatty fish and fish oils. To fulfill the recommended daily intake with milk alone may take as much as 6 to 8 glasses, far more than most people drink, and so most people get the majority of their vitamin D from sun exposure. But wearing sunscreen significantly impairs the sun’s ability to activate vitamin D — wearing SPF 8 can reduce the skin’s ability to produce vitamin D by about 95 percent.

Until recently, nobody thought much about whether they got enough vitamin D from drinking milk or other foods or from the sun. But getting the so-called “sunshine vitamin” does matter because it plays a far more complex role in our health than anyone could have imagined just a decade or two ago.

Of course scientists have known for a long time that vitamin D is important to keeping bones strong. Vitamin D signals the body to absorb calcium from food and so maintains normal blood calcium levels. When there isn’t enough vitamin D, the body doesn’t absorb enough calcium from the diet, and it instead removes calcium from stores in the bones, making them weak or brittle. Bone diseases linked to vitamin D deficiency include: rickets, the bone-deforming and potentially fatal condition that afflicted children for ages; osteomalacia, a muscle-weakening, bone-softening form of rickets that occurs in adults; and osteoporosis, the brittle bone disease.

Vitamin D’s role in bone health was pretty much the limit of scientific understanding back in the early 1990s when I met Michael F. Holick, professor of medicine, physiology, and biophysics at Boston University School of Medicine. The endocrinologist and vitamin D specialist met me in his office and told me about the discovery of vitamin D during the industrial age, when smoggy skies blocked the sun’s rays from people’s skin and led to an epidemic of rickets. Rickets mostly disappeared once doctors started prescribing cod liver oil and sunshine, and especially once governments mandated that milk be fortified with vitamin D in the 1930s. It doesn’t take much vitamin D to prevent rickets.

In between talking about vitamin D, Holick talked about his schooling in Wisconsin, about ice skating with his wife on their first date, about his adventures in industry developing a vitamin D-based psoriasis lotion, and about the glorious view of Boston from his office window. He introduced me to patients in his clinic that had bone disorders like osteoporosis. And he explained how rickets was now mostly confined to family pets like his own family’s iguana. Holick cured his captive reptile by serving it cream cheese and lettuce sandwiches, and by shining a sun lamp into the cage.

I was taken with this charismatic, energetic scientist. For a while I even tried to sell magazines an article on how to save pet iguanas from rickets. I was, not surprisingly, unsuccessful. But given time, a far larger and richer story about vitamin D has emerged, and much of it has come out of Holick’s office.

For one thing, rickets never really went away. Soon after our meeting, medical journals started reporting on cases diagnosed among children living in northern cities, as well as on a rise in cases of its adult form, osteomalacia. Scientists started to wonder if vitamin D deficiency was more common than they thought. A research group in Baltimore found that more than half of homebound adults over the age of 65 were severely vitamin D deficient.

To get sense of the scope of vitamin D deficiency in the wider community, Holick and colleagues measured vitamin D levels in younger people living in Boston. They found that it was surprisingly common. About 36 pecent of young adult city dwellers that worked office jobs were vitamin D deficient at the end of winter, and 11 percent were so at the end of summer. The emerging research also indicated that people with darker skin were more likely to be deficient than people with lighter skin, because they needed more time in the sun to convert vitamin D into an active hormone. Also, people who were overweight were more likely to be deficient, a result of the vitamin D becoming harder for the body to access from fat cells.

Suddenly, people again started paying attention to long-taken-for-granted vitamin D. Holick and others declared that the country was in the middle of a silent epidemic of vitamin D-deficiency, and warned that the health effects could be subtle but far-reaching. To combat the epidemic, Holick came out in 2004 with a book called The UV Advantage, which recommends sun exposure of 15 to 20 minutes a day while de-emphasizing skin cancer concerns. Some of his colleagues recoiled from his advice, feeling that people would take it as permission to sunbathe. After it also came to light that Holick received funding from the Indoor Tanning Association, he was forced to resign from the dermatology department at Boston University Medical School. (He still holds other positions there.)

Holick defended himself, saying his situation was no different than other doctors taking pharmaceutical money, and pursued his studies. Today he is still considered a leading expert in demystifying vitamin D. Building on what is now more than 30 years of research, last year he published a capstone review article in the New England Journal of Medicine that delineated just how important vitamin D is to the healthy body — and how many people need more of it.

Scientists now understand that most tissues and cells in the body have vitamin D receptors, including several that possess the machinery to convert it to the active form in the body. It is also now commonly believed that vitamin D helps maintain muscle strength and immune capability while also decreasing the risk for various chronic illnesses, including cardiovascular diseases, autoimmune diseases such as diabetes type 1 and multiple sclerosis, and various cancers including colon, ovarian, breast, and prostate. Among the evidence is the fact that the further away from the equator — and the sun — that people live, the greater their chance of developing some of these health problems. (Some very northern cultures like the Inuit naturally compensate for the reduced sun exposure with a diet rich in fish oil.)

The work is not without its doubters. A National Cancer Institute study based on survey data has found no relationship between vitamin D levels and the overall risk of dying from cancer based on a 10-year follow-up, although it did find an association between decreased risk of colorectal cancer death and higher vitamin D levels. The findings are not completely clear because of the complex contributions to risk from total diet and lifestyle.

Large studies are also still needed to confirm the strength of the links between vitamin D and chronic diseases. In recent years such studies of several other vitamins turned out to be disappointing for their role in improving health. But remember, vitamin D is not a classic vitamin, and so these vitamin studies may not be relevant.

Only time and additional studies will elucidate further whether we should be paying more attention to vitamin D. Maybe eventually it will become clearer whether we should be worrying less about skin cancer and more about whether our skin is soaking up enough rays to fulfill our sunshine vitamin quota.

In the meantime, I wonder if Holick still has that iguana — they can live for 20 to 30 years — and whether it really beat rickets for good. • 19 March 2008

SOURCES: “Vitamin D deficiency in homebound elderly persons.” Gloth FM 3rd, Gundberg CM, Hollis BW, et al. JAMA. 1995;274:1683-6. “Vitamin D insufficiency among free-living healthy young adults.” Tangpricha V, Pearce EN, Chen TC, & Holick MF. Am J Med. 2002;112:659-62. “Vitamin D Deficiency.” Holick MF. N Engl J Med 357; 266-81. Prospective Study of Serum Vitamin D and Cancer Mortality in the United States, Freedman DM, Looker AC, Chang S-C, & Graubard BI, J Natl Cancer Inst 2007; 99:1594-1602

Lisa Bell, Know Your Numbers

Vitamin D is the only vitamin you don’t have to get from food, because it is also a hormone.

You need at least 200 IUs of vitamin D each day.

You can eat it, take a supplement, or let your body manufacture it when you are in the sun, but however you get it, you need vitamin D for strong muscles, bones, and teeth.

Doctors say it is just as important as calcium, because without D, your body can’t absorb the calcium.

If you are under 50 years old, you need 200 IU’s every day — 400 if you’re 50 to 70 years old and 600 if you’re over 70.

A little bit of sun or fortified dairy products are the easiest ways to get your vitamin D.