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Can vitamin D supplements prevent cancer, protect your heart and step up physical performance? Read on to see what science has to say.

has a good reputation. It purportedly is a multitasker with the ability to boost your immune system, improve physical performance, maintain a healthy heart, support strong bones and lower your cancer risk. But is it true or is it hype?

The fact is we all need vitamin D 鈥� it helps our bodies absorb calcium, which helps us build strong bones. It also plays a role in keeping our muscles, nerves and immune system functioning properly. We can get vitamin D from the foods we eat, from exposure to the sun or from . Here鈥檚 a look at what vitamin D supplementation can and can鈥檛 do for your health.

Claim: Vitamin D supplements boost your immune system.

Because of vitamin D鈥檚 role in regulating your immune system, it鈥檚 natural that scientists are exploring whether vitamin D supplementation can prevent viral infections. One small study of schoolchildren found that those who took vitamin D supplements were less likely to get the flu than those who didn鈥檛 take the supplements, while another of adults found no difference in the rate of upper respiratory infections.

Verdict: The jury is still out.

Claim: Vitamin D supplements improve heart health.

This idea was an outgrowth of an interesting scientific observation: 鈥淪ince the early part of the 21st century, there has been compelling epidemiological evidence that suggests that vitamin D deficiency is a risk factor for heart attack, stroke, congestive heart failure and other medical conditions that increase an individual鈥檚 risk factors for heart disease,鈥� says Helga Van Herle, MD, a cardiologist with the 喵咪社区 Cardiac and Vascular Institute, part of聽喵咪社区.

But just because vitamin D deficiency is associated with heart disease, it doesn鈥檛 necessarily mean that vitamin D supplementation will lower that risk.

鈥淚n fact, a recent large of randomized controlled trials failed to show that vitamin D supplementation protects against cardiovascular events, stroke or heart attack,鈥� Dr. Van Herle says.

While vitamin D supplements may not decrease your risk of heart disease, lifestyle habits, like physical activity, quitting smoking and a heart-healthy diet, can.

Verdict: False.

Claim: Vitamin D supplements support bone health.

According to the National Institutes of Health (NIH), vitamin D enhances the absorption of calcium in the gut (which explains why it鈥檚 often used to fortify milk). On top of that, it ensures that the body has what it needs for bone mineralization, which keeps them strong.

But, when it comes to vitamin D supplementation, it鈥檚 difficult to know whether it improves bone health, because most research to date looks at vitamin D plus calcium. Among those studies, there is evidence that vitamin D plus calcium can slightly increase bone mineral density throughout the skeleton, according to the NIH; however, a large found that vitamin D alone doesn鈥檛 decrease the risk of bone fractures.

Verdict: The jury is still out.

Claim: Vitamin D supplements improve physical performance.

Unfortunately, a daily vitamin D supplement will not make you a better athlete. An of randomized controlled trials found that vitamin D supplementation does not improve physical performance in athletes.

Verdict: False.

Claim: Vitamin D supplements lower your cancer risk.

So far, the evidence on vitamin D supplements and cancer is conflicting. Some have found an association between lower vitamin D levels and an increased risk of colorectal cancer, but association doesn鈥檛 mean causation. A large randomized controlled found that vitamin D and calcium supplementation did not lower the risk of colorectal cancer in women, and yet another found no effect of vitamin D supplementation on cancer risk overall. Perhaps this is why the American Academy of Family Physicians and the do not recommend vitamin D supplementation for this purpose.

Verdict: The jury is still out.

So, what鈥檚 the bottom line when it comes to vitamin D supplements and your health? While research seems to have ruled out any benefit for heart health and physical performance, more studies are needed to make any definitive conclusions about its impact on your immune system, bone health and cancer risk.

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