Want to get enough vitamin D? Try supplements — or sunshine

Beverly Merz

Executive Editor, Harvard Women's Health Watch

This morning, I swallowed a small translucent capsule I’d popped out of the blister pack I keep next to the coffee pot. I’m not sure what’s in this little pill, but I’ve taken one with breakfast every day for more than two years and will keep taking them for at least two more years.

Like almost 26,000 other women and men, I’m part of the VITamin D and OmegA-3 TriaL, otherwise known as the VITAL study. Every day we take identical pills, but half of us are getting 2,000 IU of vitamin D and the rest of us are taking a placebo. We’re also taking another capsule that contains either a gram of omega-3 fatty acids or a placebo. We don’t know which groups we’re in — and neither do the researchers.

I volunteered for the study because I had read so many promising reports about vitamin D and had a lot of questions: Does it prevent heart attacks and strokes? Does it reduce the risk of cancer? Does it prevent bone fractures? The VITAL study was designed to answer all three. By the end of 2017, we’ll know who got vitamin D and who got the placebo, and whether the vitamin D group had lower rates of those health problems than the placebo group. We’ll also have similar information about the effects of the omega-3 fatty acid capsules, and the effects of vitamin D in combination with them.

Why VITAL is vital

So far, numerous small studies have failed to show conclusively that taking vitamin D supplements prevents cardiovascular disease or cancer, and in 2014 the US Preventive Services Task Force determined that there isn’t enough evidence to recommend vitamin D supplements to stave off either condition.

Although vitamin D has is essential to bone health, a controlled clinical trial published in JAMA Internal Medicine this week found that a vitamin D supplements didn’t build bone in postmenopausal women with blood levels of vitamin D below the 30 ng/mL–the threshold generally considered necessary for good health. In that study, researchers at the University of Wisconsin randomly assigned 260 women to three groups: one got either 800 IU daily and a placebo twice a month; one got a placebo daily and 50,000 IU of vitamin D twice a month; the third got placebos daily and twice a month. The study lasted a year. The researchers found that neither dose of vitamin D had a significant effect on bone mass, falls or fractures.

The Wisconsin study may not have used the right doses of vitamin D or lasted long enough, says Dr. JoAnn Manson, chief of the Division of Preventive Medicine at Harvard-affiliated Brigham and Women’s Hospital. Dr. Manson is also a principal investigator of the VITAL study. “VITAL is large enough to demonstrate even small-to-moderate benefits of vitamin D supplementation,” she says. She adds that the VITAL study dose of 2,000 IU daily ensures that the vast majority of participants in the vitamin D group will have blood levels of vitamin D above 30 ng/mL, while virtually none will have blood levels high enough to cause adverse effects. In addition, VITAL’s five-year duration is long enough to determine whether 2,000 IU of vitamin D protects against falls and fractures as well as cardiovascular disease and cancer. Other large, long-term studies using similar doses of vitamin D are also getting under way in Finland, the United Kingdom, and Australia.

Shining some light on vitamin D deficiency

While you’re waiting for answers from the big studies, you may also want to try getting a little sunshine — a tactic that seems almost subversive these days. A commentary published online in June by the Journal of the American College of Nutrition points out that vitamin D isn’t actually a vitamin, but a hormone manufactured in our skin with the aid of the sun’s radiation. They say that many people have blood levels below 30 ng/mL because they don’t get enough sun exposure, and that the sun’s health benefits have been clouded by decades of unnecessarily harsh warnings that have us either slathering ourselves with sunscreen or staying indoors during peak sun hours. The researchers maintain that it is possible to absorb enough sunlight to achieve adequate vitamin D levels without increasing your risk of skin cancer. (However, they don’t guarantee that you’ll be immune to wrinkles, age spots, and other effects of sun exposure.)

(Their advice may not be of much help to the United Kingdom, however. Their government’s  Scientific Advisory Committee on Nutrition has just declared that, because the sun over the British Isles is so unreliable as a source of vitamin D, all citizens are advised to take a daily vitamin D supplement of 10 micrograms — the equivalent of 400 IU.)

Endocrinologist Michael Holick, director of the Bone Health Care Clinic at Boston Medical Center, was one of the commentary’s authors. Dr. Holick has made many of the discoveries that explain how vitamin D is produced and how it works in our bodies. He explains that several factors determine how much vitamin D we make, including age, skin pigmentation, the latitude at which we live, and the angle of the sun in the sky. He offers a simple prescription for vitamin D production: Go out in the sun between 10 a.m. and 3 p.m. with at least 10% of your skin exposed. Stay out long enough to absorb the sun but not long enough to be burned. (This approach is reliable for most regions of the U.S., but only during the summer months. In other seasons, the body makes little if any vitamin D from the sun at latitudes above 37 degrees north in the United States.)

An app for all seasons

If all this sounds a little iffy, you can download dminder — an app for smartphones and tablets that is based on Dr. Holick’s research. Dminder calculates how much sunlight you can absorb without risking skin cancer. You enter information on your age, height, weight, and skin type into the app, and grant it access to your device’s GPS. The app will let you know if the sunlight is adequate for vitamin D production and calculate how many IUs of vitamin D you’re making while you’re outside. It will also warn you when it’s time to run for the shade. You can download this app from the App Store or Google Play. Just search on “dminder.”

What to do about vitamin D?

Whether to choose supplements or sunlight to get your vitamin D quota might be worth discussing with your doctor. Whatever you decide, it’s still important to get the recommended daily dose of vitamin D: 400 IU for infants; 600 IU for children and adults through age 70; and 800 IU for people ages 71 and older.


  1. Saso

    i have read in one article that this vitamin helps also in prevention of colon cancer,metabolic disorders and Rickets ( syndrome that affects children who have vitamin D deficiency and include deformities of the joints and bones, poor growth and development.)

  2. Robert Oh

    I’m surprised that this article did not mention natural FOOD sources of Vitamin D. Primarily Wild Salmon and mushrooms. There are other sources than just supplements and sunshine, and these foods have the highest sources. Other sources, include eggs, other fish and other mushrooms.

  3. Fred

    That app for sunshine levels sounds like a great idea. I was reading about the importance of healthy levels of sunshine for vitamin D but I was confused about how to measure exactly how much sun is needed. I would definitely download that app. Where we are the sun is not at all strong in the winter so I take supplements, but when traveling it would be good to know how much sun I should be getting.

  4. Clarence anak david singen

    Vitamin C very important for our body.

  5. Steven

    vitamin C is also really important

  6. Neha Sahaay

    Great article!!! Thanks for letting us know the importance and sources of vitamin D. It has proved to be great help.

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  10. Dana

    Same problem here as Richard.

  11. Kumar

    Day to day many peoples not getting all vitamins especially Vitamin -D, All peoples should aware about this lack of vitamin-d. Pls make healthy life with wealth.

  12. Sam Wik

    Well I think sunshine is the best source to get vitamin D …. wouldn’t have to take any supplement ….. just woke up early in morning & take regular work in the sunlight within the first hour of the day !!!

  13. Arian Ward

    I’m not a healthcare practitioner, altho many friends and colleagues have come to me for healthcare advice over the years because of my special interest in and decades of study and use of integrative medicine. I believe integrative medicine is the best future alternative path for healthcare in all aspects: reducing and stabilizing costs; filling the increasing gaps in coverage for certain geographic areas, specialties, demographic segments, and forms of coverage (insurance, Obamacare, Medicare, Medicaid, etc.); overcoming the deficiencies of a system biased towards profits over the social good particularly over the holistic health of any individual, a system heavily influenced and in some cases, totally controlled by special interests like big PHARMA, the AMA and other powerful professional groups/lobbies, and big medical corporations that now control most U.S. hospitals and who also now own a majority of U.S. allopathic clinics (and still increasing with no regulatory constraints on mergers and acquisitions and their resultant monopolies or trusts – the #1 reason for healthcare costs in the U.S. being at least 3x more expensive per capita than any other country on earth with healthcare quality/results worse than all other countries of comparable wealth/prosperity ); a bias towards looking at the body as a biomechanical device that can be viewed and fixed one part or subsystem at a time rather than holistically where only by viewing and acting upon the whole system – all aspects or subsystems of the body, mind, feelings, spirit, can you gain systemic, long term healing and well being, …. Integrative medicine is just what the name implies – the integration of CAM (complementary and alternative medicine) with allopathic/conventional/mainstream medicine, as well as the integration of all practice areas/specialties in a much more collaborative way even just within allopathic medicine compared to the fragmented, poorly connected system we have today. I provide this intro as my credentialing for being more than the average patient but less than a formally educated, certified healthcare practitioner.

    I’ve learned integrative medicine the hard way, out of necessity since it is almost non-existent today in the U.S. and in most of the world. If I wasn’t doing the integration across all the different practice areas and practitioners I’ve seen across the entire country and even a few overseas, I would have died long ago because of the number of life threatening illnesses, or at least I would have been severely limited in my work and lifestyle due to the number of debilitating conditions I’ve had and still have for the most part.

    Coming from this point of view (remember I’m not a doctor and legally can’t give medical advice, another crazy part of the U.S. medical system that no other part of the world requires), here are my personal opinions and practices in the subject area of this article:

    I have osteopenia due to long term use of steroids for ulcerative colitis. Another allopathic failure in prescribing steroids without prescribing bone building supplements to compensate for the steroids leaching calcium out of my bones and teeth. Result was osteoporosis in my bones, and my teeth losing so much of their calcium they fell apart and I’ve had to have over half of my teeth pulled, when they couldn’t be repaired, or crowned. But I’ve since diligently self-prescribed and adminstered bone building supplements – calcium and other minerals and Vitamin D, + Vitamin C to assist with absorption. As a result, I’ve improved my bone density back to normal in some bones and osteopenia in the others, with none still showing the lowest density – osteoporosis.

    Unfortunately, I had untreated or undertreated high blood pressure for too long and it resulted in kidney degeneration = chronic kidney disease. Since calcium is one of the toughest substances for the kidneys to process, I have been told by a nephrologist (specialist in the urinary tract, incl. kidneys) to stop taking all supplemental calcium to help stop my rapidly worsening kidney disease. He has recommended that I take 2000 iu daily of Vitamin D instead. My PCP (primary care physician) who is more holistic/integrative than my nephrologist, told me I can take as much as 5000 iu daily of Vit D. She also told me to increase my load bearing exercise, by wearing ankle weights when I go for my daily hike. Basically, what load bearing exercise like lifting or carrying weights does is trigger the body’s automatic response of increasing bone mass to enable it to handle the increased load without bone fractures. She says that combo of vitD + load bearing exercise should be enough to compensate for not taking supplemental calcium and to prevent further loss of bone density. The body will increase its absorption of the needed vitamins and minerals from what I eat, which should be sufficient since I eat a balanced, healthy diet.

    Bottom line – I’ve been told and my experience has demonstrated that the recommended daily dose of Vitamin D cited in this article is FAR TOO LOW. Instead, I should be taking 2000-5000 iu daily + include load bearing exercise in my daily routine.

  14. Richard Goodbrand

    Did a search in the IPAD App Store for ‘dminder’ and nothing was found. Does it go by another name? Or does it only work for US ?

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