Vitamin D deficiency: the silent epidemic.

This year, more than a million Americans will break a bone because of osteoporosis. A fractured spine can cause permanent pain. A fractured hip can lead to permanent disability...or death.

Too little calcium makes our bones brittle. But it's not the only cause.

A silent epidemic of vitamin D deficiency is also to blame, says Michael F. Holick, director of the Vitamin D, Skin and Bone Research Laboratory at Boston University Medical Center.

Why? Milk is the only food that's fortified with vitamin D, but adults don't drink much. Exposure to sunlight makes vitamin D, but--in most of the country--not in the winter.

"Older people are not getting enough vitamin D to satisfy their bodies' requirements," says Holick.

One reason: "They're less likely to go outside because they're worried about skin cancer and wrinkles."

Q: Why do people need vitamin D?

A: Its principal function is to maintain blood calcium in the normal range. It does that largely by telling the intestine to absorb more calcium from the food we eat. If you're not getting enough calcium from your diet, vitamin D removes calcium from your bones. The body will keep blood calcium normal at any expense because calcium is critically important to keep your mind, lungs, muscles, and heart functioning.

Q: Why do you say that there is a silent epidemic of vitamin D deficiency among order people?

A: There's a multitude of evidence. In both Europe and the U.S., blood levels of a key form of vitamin D [25-hydroxy] are much lower in the wintertime, when they border on deficiency.

In a study done at Tufts University, women who were given 700 IU a day of vitamin D lost less bone than those who got 100 IU a day.(1) We also found that women in the Bangor, Maine, area lost, on average, about three percent of their bone mass during the winter. The bone loss was related to a decrease in their vitamin D levels. They recovered part of the loss during the summer.(2)

And we have evidence that upwards of 40 percent of the adult population over age 50 that we see in our Bone Health Care Clinic is deficient in vitamin D.

Q: Are those people typical?

A: Yes. A study at Massachusetts General Hospital found the same thing when it tested adults over 50 who came into the hospital for any reason. Thirty to forty percent were borderline to overtly vitamin-D-deficient. And vitamin D deficiency usually has no symptoms, so it's silent.

Q: What damage does vitamin D deficiency cause?

A: Children get rickets. They have short stature, bowlegs or knock-knees, and deformities of the skull. In the 1930s, we eradicated rickets as a significant health problem by fortifying milk with vitamin D.

But in the 1950s, some European countries added too much vitamin D and children began to get intoxicated. There was such a panic that they prohibited the addition of vitamin D to foods. That's why rickets continues to be a health problem in France and Great Britain.

Q: What about adults?

A: As you age, you lose bone. Women lose more than men because menopause accelerates bone loss. But men lose about one percent of their bone mass per year after about age 55 or 60.

If you're vitamin-D-deficient, you're not getting enough calcium into the body to satisfy its needs. That appears to be true no matter how much calcium you consume. Therefore, your body removes calcium from your bones. So vitamin D deficiency accelerates bone loss and increases the risk of fracture at an earlier age.

Q: And that leads to osteoporosis?

A: Yes. We have pretty good evidence, in the U.S. and especially in Europe, that when you evaluate patients coming into the hospital with hip fracture, on average about 30 to 40 percent are vitamin-D-deficient. Vitamin D deficiency also causes osteomalacia, or adult rickets, which is a mineralization defect.

Osteomalacia is insidious because it can cause intense and gnawing bone pain. We see it in about one to two percent of the people who come to our Bone Health Care Clinic. If we treat them with vitamin D, the pain starts to disappear over several months.

BROKEN BONES

Q: How common is osteoporosis?

A: An estimated 25 million Americans suffer from it. Five million are men and 20 million are women. About 1.25 million skeletal fractures--including 300,000 hip fractures--occur annually in the U.S. as a result of osteoporosis.

Q: And many fractures are debilitating?

A: Yes. If you have a spinal fracture, you could end up with permanent lower back pain or sciatica because of nerve compression. You lose height, which leads to a loss of self-esteem so you're not as likely to spend time outdoors or to be as active or social as you used to be.

Hip fracture is a different story. Within 90 days of a hip fracture, about 10 to 15 percent of patients will die due to complications, and about 20 percent will die within the first year. Fifty percent will never regain the quality of life they had before.

Q: They end up in nursing homes?

A: Yes, or debilitated. About $6 billion is spent annually for the acute care of hip fractures. That includes surgery and rehabilitation, not the long-term consequences due to other complications, immobility, and chronic care.

MILK & SUNLIGHT

Q: Why are people getting so little vitamin D?

A: The principal cause is that most foods have little or no vitamin D and few foods except milk are fortified with it. Many people over the age of 50--probably over the age of 20--don't drink milk.

The second cause of vitamin D deficiency is that older people are worried about skin cancer and wrinkles, so they wear a lot more clothing and they wear sunscreen. Both will prevent you from making vitamin D in your skin. Q: How does sunlight create vitamin D? A: When skin is exposed to sunlight, the highest energy ultraviolet light, called UV-B, penetrates into the skin. It converts a precursor into vitamin D, which is then activated, first in the liver and then in the kidneys.

Q: How much sunlight do people need?

A: That's the famous question. And my famous answer is I can't tell you exactly. It depends on the time of day, season of the year, where you live, and how easily you get sunburned. We recommend that people expose their hands, face, and arms two to three times a week to 50 to 70 percent less sun than would cause a sunburn. If you know you'll get a sunburn after 30 minutes of June sunlight at noon, then we would recommend five to ten minutes, max. without a sunscreen.

Q: Why does the season matter?

A: In Boston, you can't make any vitamin D from November through February because the angle of the sun markedly limits the amount of UV-B radiation that can reach the earth's surface. In Edmonton, Canada, you can't make any from mid-October through mid-April [see "Head for the Equator"]. If you make enough vitamin D during the summer, you can store it in your fat and use it during the wintertime. But older people usually can't make enough.

In Los Angeles and farther south, you can make vitamin D year round. In fact, we suspect that at a latitude of 34 degrees--that's around Atlanta--you can, too. But it depends on cloudiness, the time of day, and how much pigmentation is in your skin. The fairer you are, the more you make.

You also can't make any vitamin D before seven or eight in the morning and after four or five in the afternoon, no matter where you live.

Q: Do all sunscreens block vitamin D?

A: If you wear a sunscreen with SPF [sun protection factor] 8, it prevents 95 percent of your skin's production of vitamin D. When you get to SPF 30, production is almost zero.

Q: Can't excess sun cause skin cancer?

A: Yes, but you have to put it into perspective. Young children, teenagers, and young adults get more than enough sunlight anyway. But for an older person, who could fracture a hip tomorrow, the benefits of a little bit of sunlight to promote bone health far outweigh the risks.

Q: And older people make less vitamin D?

A: Yes. There's about a three- to four-fold decrease in the precursor of vitamin D in the skin of people over the age of 70. And when we irradiated them with UV light, the vitamin D levels in their blood increased only about one-third as much as they did in young medical students [See "More Years, Less D"].

Q: Why not just take a basic multivitamin with 400 IU of vitamin D and forget about the sun?

A: We see patients at our clinic who take a multivitamin every day and they're still not getting an adequate amount of vitamin D. My belief is that people over the age of 50 need 400 to 600 IU a day, and that for people over 70 it could be as high as 800 IU. Last August, the National Academy of Sciences raised the new recommendations for vitamin D to 400 IU a day for people aged 51 to 70 and 600 IU for people aged 71 or older.

Q: So you recommend sun not a supplement?

A: I recommend a little bit of sunlight. To be outside and to walk is good for older people because it increases their muscle tone, maintains bone strength, and provides vitamin D. If they want to take a multivitamin on top of that, all the better.

Q: Should they worry about taking too much?

A: Not from food or the sun. Even if you drank a quart of milk or were exposed to sunlight on the beach for half a day, you'd never become intoxicated with vitamin D. Your body destroys any extra vitamin D it makes from exposure to sunlight. There are only 400 to 600 IU in a quart of milk. Adults would have to take at least 2,000 IU a day for half a year to a year before they'd become intoxicated with D. Children up to one year could be intoxicated if they ingested 1,000 IU a day for a prolonged period.

Q: What are the symptoms of vitamin D toxicity?

A: Blood calcium goes up so people become confused and fatigued, they complain of constipation, and they may develop kidney stones or calcified kidneys and kidney failure. There is no good evidence that too much vitamin D raises blood cholesterol. That's been put to rest.

Q: Can people get enough vitamin D from four cups of milk a day?

A: It could be there, but don't count on it. We tested milk purchased at supermarkets nationwide and in Western Canada in 1991 and 1993.(3) Seven out of ten samples contained less than 80 percent of the amount of vitamin D that was listed on the label. Half didn't even contain 50 percent. And 14 percent of the skim milk samples contained no detectable vitamin D.

Q: Are any other dairy foods fortified with vitamin D?

A: No. A lot of people assume that milk, yogurt, ice cream. and cheese are the same. While they're all good sources of protein and calcium, only milk has vitamin D.

The only natural food sources are cod liver oil and some fatty fish, but unless you're eating them two or three times a week, you're not getting enough vitamin D. Eggs also have some, but not much. Some breads and cereals are now being fortified with vitamin D, but in small quantities.

WHAT TO DO

Q: Should people get a blood test for vitamin D?

A: Yes, especially adults over the age of 50. Vitamin D deficiency is silent. There's no way of detecting it without measuring 25-hydroxyvitamin D--that's the form that's made in the liver. You never measure the fully active form--1,25-dihydroxyvitamin D--because it's tightly regulated by the body. Doctors often test the active vitamin D by mistake.

Q: How high should your 25-hydroxy level be?

A: Most commercial labs say that 10 to 15 nanograms per milliliter is the lower range of normal. We believe the lowest you should reach is 20 if you're over age 50. You should have the test done in mid-winter because that's the best time to detect vitamin D deficiency. But if you're at risk, it's best to get tested at the beginning of winter, so you can treat any deficiency with a vitamin D supplement.

Q: Should women also get their bone density measured?

A: Yes. All women over the age of 50 should consider having a bone mineral density study, so they know where they are when they're going into menopause. They should have another one two years later. If they're taking estrogen to prevent bone loss, measuring bone density makes it easier to keep taking the estrogen because they see its benefit.

BEYOND BONES

Q: A recent study suggested that vitamin D can slow the progression of arthritis. What do you think?

A: I'm highly skeptical. Until I see it repeated in two or three good studies, I'd say it's too early to make any recommendations to take vitamin D to treat arthritis.

Q: How about reports that vitamin D prevents breast or colon cancer?

A: They're also highly speculative. All we know for sure is that activated vitamin D inhibits the growth of cancer cells in test tubes. But that means you'd have to make more of the active form of vitamin D when you make or ingest more vitamin D. This doesn't happen.

So we don't know if vitamin D reduces the risk of colon or breast cancer. A large government-funded study called the Women's Health Initiative is looking at this issue.

Q: Can vitamin D creams treat psoriasis?

A: Yes, but you need a prescription medication for an active vitamin D analog, which is called Dovonex. You can't do it on your own by taking excessive amounts of the regular vitamin D or using a cream that contains it. We've also tried activated vitamin D on eczema, and it's not effective.

[GRAPH OMITTED]

(1) Amer. J. Clin. Nutr. 61: 1140, 1995.

(2) Bone and Mineral 25: 83, 1994.

(3) New Eng. J. Med. 326: 1178, 1992 and 329: 1507, 1993.

RELATED ARTICLE: THE BOTTOM LINE

Vitamin D

* Expose your non-sunscreened hands, face, and arms to the sun for about ten to fifteen minutes (depending on skin sensitivity to sunburning, latitude, and time of day) two to three times a week between 8 a.m. and 4 p.m.

* If you're 70 or younger, get 100 percent of the Daily Value (400 IU) for vitamin D from a multivitamin, other supplements, or four glasses of milk a day.

* If you're over 70, get a total of 600 IU of vitamin D a day.

* Make sure you're not getting more than 1,000 IU of vitamin D a day from all your supplements and your food. Calcium supplements often contain vitamin D (check the label).

Calcium

* Get enough calcium either from a supplement or from foods like 1% or skim milk, low-fat yogurt, reduced-fat cheese, leafy green vegetables, fortified orange juice, or tofu (if it's made with calcium sulfate).

* Shoot for:

--1,000 mg a day if you're 19 to 50, and

--1,200 mg a day if you're over 50.

Michael F. Holick is the director of the Vitamin D, Skin and Bone Research laboratory and Chief of Endocrinology, Nutrition and Diabetes at Boston University Medical Center.