Do Vitamin D Supplements Help Your Bones? Not According To A New Study

Before you spend any money to buy and take Vitamin D supplements to help your bones, you may want to bone up on the available scientific evidence.

That’s what Mark J Bolland, PhD and Andrew Grey, MD from the University of Auckland in New Zealand and Alison Avenell, MD from the University of Aberdeen in Scotland did. They conducted a systematic review and meta-analysis of randomized controlled trials of adults that evaluated the ability of vitamin D supplements to prevent bone loss, fractures, and falls. This meant searching the scientific literature for such studies, combining or pooling together similar studies, and then analyzing whether they showed any  actual effects. They then published their findings in a reputable peer-reviewed scientific journal: The Lancet Diabetes and Endocrinology. Emphasis on the words “reputable”, “peer-reviewed”, and “scientific”. How well did Vitamin D fare? Is there a grade worse than D?

The systematic review part of the study found 81 randomized controlled trials that included a total of 53, 537 participants. The meta-analysis part, which was the pooling together of similar studies and doing statistical analyses of the results, found nothing, zilch, nada, bupkis. No significant effect on the risk of any fractures, hip fractures, or falls. No significant effect on bone mineral density in the lumbar spine or the femoral neck. No real difference if participants took high or low dose vitamin D supplements. The researchers concluded that “there is little justification to use vitamin D supplements to maintain or improve musculoskeletal health. This conclusion should be reflected in clinical guidelines.” Not very good for vitamin D supplements. 

Of course, these results are not saying that vitamin D is useless. Vitamin D helps your body absorb calcium and build and maintain your bones. It also blocks your parathyroid gland from releasing parathyroid hormone, which breaks down your bones. The question is whether taking those Vitamin D supplements has any beneficial effect.

There are various natural ways that you can get vitamin D. For example, if you are not a vampire, you can go out into the sun. Your skin produces vitamin D when it is exposed to ultraviolet (UV) light. Sure too much sunlight may put you at risk for skin cancer. But you are not a potato. No matter how Goth you want to look, you need to get adequate amounts of sun. The general recommendation is that you should get at least 5 to 30 minutes of sun exposure twice a week to your face, arms, legs, or back. This should be without sunscreen and between the hours of 10 am and 3 pm. Trying to get sun exposure at 2 am doesn’t work in most places. Using a spray-on tan does not count as sun exposure.

Then there are natural vitamin D sources from food. Look at this table from the National Institutes of Health (NIH) Office of Dietary Supplements:

As you can see in the third column of this table, eating just 3 ounces of salmon should give you 112% of the vitamin D that you need for the day. Eating 7 tablespoons of margarine can also get you over the 100% mark, but doing so in general is not advisable.

If you want to see the recommended dietary allowances, how much vitamin D you should get each day through your diet, take a look at the following table from the NIH:

As you can see, your dietary needs go up when you get older. First they jump after you reach one year of age. (Yes, it’s all downhill after that first birthday.) Then over age 70, you may need even more because your body gets less efficient at processing vitamin D. If you have darker skin, you also may need a little more vitamin D. So tall, dark and handsome can also mean tall, dark, handsome, and needing to get more sun and eat more dairy.

Getting vitamin D from supplements can be very different from getting vitamin D naturally. It isn’t clear how much your body actually absorbs vitamins from supplements compared to vitamins from foods. The question is whether taking supplements has any positive health effects or if they just make your pee and poop more expensive.

Before you waste your money on supplements, check with your doctor to see if you really need anything beyond the natural sources of vitamin D. Sure there are some medical conditions or situations that may require extra vitamin D like when your gastrointestinal tract cannot absorb vitamin D well (e.g., with inflammatory bowel disease or after undergone gastric bypass surgery) or you can’t get adequate sun exposure (e.g., being homebound or being Dracula). Otherwise, until science proves otherwise, vitamin D supplements may just be vitamin “d’oh” when it comes to bone health.