As a registered dietician, one of the questions I routinely ask my patients on their initial consultations is: “Do you know your vitamin D status?”

Why, you may ask yourself, does this matter?

Over the last couple of years, vitamin D has come out of the closet, leaping to the forefront of many nutrition discussions. You might even say it’s the vitamin du jour. It has always been associated with bone strength, of course, but recently it’s been connected with so many health conditions it could make your head spin.

Current research has linked vitamin D shortages to heart disease (today’s headline), certain cancers (see above), diabetes, obesity, depression, and multiple sclerosis. The problem, though, is that the outcome of various research studies differ, and there’s still no overall consensus on what vitamin D does and doesn’t do.

What do I need to know? The first thing I recommend to patients is to get their vitamin D levels checked. Ask your doctor to test for 25-hydroxyvitamin D. Blood levels of less than 30 nanograms per milliliter are considered deficient, but many experts agree that a level of 50 nanograms per milliliter is ideal.

How do I get enough D? As you might imagine, I always like to recommend food first. Foods that contain vitamin D include fatty fish (like salmon, tuna, or mackerel), liver, and egg yolks, and vitamin D-fortified milk. But in all honesty, it’s hard to meet your daily needs with food alone. As for the sun, yes, it does convert a cholesterol substance found in the skin into vitamin D. But baking in the sun, especially without sunscreen (which is the way you’d need to do it) adds a whole new host of problems—wrinkles and possible skin cancer among them. And as you get older, your body absorbs less vitamin D from this exposure.

How much supplement should I take? Current U.S. guidelines call for 200 IU (international units) from birth through age 50, 400 IU from 51 through age 70, and 600 IU from 71 on. But with all the recent research, many experts, including the American Medical Association, have suggested that these dosages are too low and are urging the government to revisit the guidelines.

To prevent fractures, the National Osteoporosis Foundation recommends that healthy adults over age 50 get at least 800-1000 IU daily. According to The Institute of Medicine, an amount of 2,000 IU daily is the upper limit that should be taken in supplement form. But research published since 1997 suggests that for adults, this upper limit is probably overly conservative, and that vitamin D toxicity is unlikely in healthy people at intake levels lower than 10,000 IU a day. (Even so, it’s good to keep in mind that when it comes to supplementing with any vitamin, the right amount is good, but a lot is not necessarily better. And it can be dangerous.)

So what’s the bottom line? Get your vitamin D level checked. If lab results are low to normal, consider a supplement of 1,000-2,000 IU daily. On the other hand, if results show a deficiency, 2,000 IU per day may not be enough to raise your level and give you the full benefits of this vitamin. Many doctors are advising patients to take much higher dosages with careful monitoring of blood and urine levels for excess calcium. If you’re vitamin D-deficient, consult with your doctor about the correct level of supplementation, and make sure to set a retest date. Although the latest research may need more follow-up, there’s one thing we do know: it’s important to get enough vitamin D.

Keri Gans is a Registered Dietitian in private practice in Manhattan. She is a Spokesperson for the American Dietetic Association Spokesperson (ADA), an ADA Delegate for NY State, and a Past President of the New York State Dietetic Association. She is a member of the WVFC Medical Advisory Board.

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  • Paul Maher March 24, 2010 at 1:00 am

    The evidence for the benefits from vitamin D is nothing short of astonishing and keeps coming in. From helping to ward off cancer to possibly curing the common cold to preventing influenza and other positive findings, the sunshine vitamin has a bright future indeed. When you throw in that because of poor diet and a modern lifestyle which decreases exposure to sunshine average vitamin D levels are likely lower than in the past, it is not a stretch to speculate that very many of the diseases of modern society may be directly related to or partially influenced by a deficiency of this lion of a vitamin. There is a little bit of an intro to the topic here,
    and here
    if anyone is interested, also the web abounds with resources on the topic. Oh yeah and bone health effects that have been known about for a while longer.

    So get out and enjoy the sun on your face this Spring, won’t even cost you a dime.

  • b. elliott March 21, 2010 at 1:25 pm

    I remember in the ’70s, women of a certain age got Vitamin D injections for vitality and youthfulness. Was this bunk and/or is this still something that is done?

  • Joy Fromm March 19, 2010 at 12:41 pm

    I am confused about Vit D. I take microcristaline hydroxiapatite for my calcium. It contains vit d3. There are many vit d numbers. I have not seen D alone.
    What do you suggest I do?

    Thank you