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8 Benefits of Vitamin D—and How to Get More in Your Diet

Vitamin D—nicknamed the "sunshine vitamin" due to its ability to be made in the presence of sunlight—is a major player in keeping the human body healthy. Its main job, according to the National Institutes of Health's Office of Dietary Supplements (ODS) is to promote calcium absorption, making it necessary for bone growth and bone remodeling (when mature bone tissue is removed and new bone tissue is formed). Because of that, a lack of vitamin D can lead to thin, brittle, or misshapen bones. But vitamin D offers a range of other benefits too, for both physical and mental health. Here are eight vitamin D benefits you need to know about—including ways to get more of the vitamin in your daily diet.

Vitamin D Strengthens Your Bones

Vitamin D is known for its bone-building and strengthening powers. "Vitamin D promotes the absorption of calcium in your gut, which ultimately allows for normal mineralization of your bones," Jackie Newgent, RDN, culinary nutritionist, and author of The Clean & Simple Diabetes Cookbook, told Health. Basically, the calcium that benefits your bones wouldn't be able to do its job without vitamin D. "You need vitamin D for bone growth—and to prevent bones from becoming brittle." When teamed with calcium, it can help prevent osteoporosis, a disease that signifies that the density and quality of bone are reduced, Newgent added.

Vitamin D Can Help Strengthen Muscles

Along with its bone-building abilities, vitamin D is also influential in strengthening muscles, according to a 2018 study in the Journal of the Academy of Orthopaedic Surgeons. "Lack of vitamin D in the body can increase the risk of having weak muscles, which in turn increases the risk of falls," Lana Nasrallah, MPH, RD, clinical dietician at UNC Health, told Health. This is especially important for the elderly. "Vitamin D may help increase muscle strength thus preventing falls, which is a common problem that leads to substantial disability and death in older adults," Nasrallah said.

Vitamin D Can Support the Immune System and Fight Inflammation

Vitamin D can also help build immunity, Nasrallah said. "It can support the immune system by fighting off harmful bacteria and viruses." In fact, this role in possibly preventing infections has become a critical concern during the COVID-19 pandemic, as researchers are interested in its potential role in infection outcomes. "There is particular interest in its role in viral infections such as influenza and coronavirus," Barry Boyd, MD, RDN, a Yale Medicine hematologist, oncologist, and nutritionist, told Health. He pointed to a 2017 BMJ analysis of 25 randomized control trials comparing vitamin D supplements to placebos, which found that vitamin D reduced the risk of acute respiratory infection with either daily or weekly vitamin D supplementation, particularly in individuals who were deficient in it.

A study in a 2017 Journal of Osteopathic Medicine found that high latitudes and winter season are risk factors for low vitamin D, as well as influenza, and other respiratory illness and adverse outcomes. "We now are seeing a similar pattern with higher mortality rates in COVID-19 infections," though more research still needs to be done to determine whether the link is causal or merely a correlation," said Dr. Boyd.

Vitamin D Can Help Support Oral Health

While there is not a lot of research on Vitamin D's role in oral health, a 2020 review in Nutrients concluded that because vitamin D helps our body absorb calcium, it may lower the risk of tooth decay, cavities, and gum disease.

Vitamin D May Help Prevent Type 1 and Type 2 Diabetes

While studies are not conclusive, vitamin D may be helpful for preventing both type 1 and type 2 diabetes, said Newgent.

One such study, published in 2019 in the European Journal of Endocrinology, found that 6 months of vitamin D supplementation increased insulin sensitivity in people with diabetes or at high risk of the disease. This effect could halt the development of diabetes or slow down the progression in those who already have it.

Vitamin D May Help Treat Hypertension

A 2019 review published in the journal Current Protein & Peptide Science suggests that vitamin D may play a role in the treatment of high blood pressure—one of the markers of cardiovascular disease—said Newgent. According to the authors of the review, "even short-term vitamin D deficiency may directly raise BP [blood pressure] and promote target organ damage." The researchers went on to add that, "due to the high correlation between vitamin D and hypertension, vitamin D supplementation therapy may be a new insight in the treatment of hypertension."

Vitamin D May Help With Weight Loss

Dr. Boyd pointed out that obesity is a known risk factor for low vitamin D levels—which means more vitamin D may help with weight loss. A small 2013 study in Nutrition Journal found that taking a combination of vitamin D and calcium, in particular, helped overweight and obese participants shed pounds when combined with a calorie-restricted diet.

However, additional research concerning vitamin D for weight loss has produced mixed results. According to the ODS, "available research suggests that consuming higher amounts of vitamin D or taking vitamin D supplements does not promote weight loss."

Vitamin D May Help Battle Depression

The sun can brighten up your mood, and so can vitamin D. According to a 2017 review article in the journal Neuropsychology, researchers found "a significant relationship between depression and vitamin D deficiency." While they acknowledged that more research is needed to define the exact workings of it—such as, if low vitamin D levels are a cause or effect of depression—the authors recommend "screening for and treating vitamin D deficiency in subjects with depression" noting that it is an "easy, cost-effective and may improve depression outcome."

How To Get More Vitamin D

Despite being readily available through sunlight, some foods, and supplementation, many Americans are still getting inadequate amounts of vitamin D.

According to the ODS, approximately 25% of Americans do not have sufficient vitamin D. The daily recommendation for adults age 19 to 70, as well as pregnant and breastfeeding women, is 15 mcg (600 IU) per day; Adults over 70 should get 20 mcg (800 IU).

Because you can't necessarily find out if you have a vitamin D deficiency on your own, the best thing to do is to consult a medical expert, said Cynthia Sass, RD, MPH, contributing nutrition editor for Health. "Ideally the best approach is to have your blood vitamin D level tested to find out if your blood vitamin D level is within the adequate range," she explained. "This determines if a supplement is needed in order to achieve adequate blood vitamin D status, and if so, the proper dosage of supplemental vitamin D."

If you find out you are deficient or lacking in vitamin D intake, there are a few key ways you can up your daily dosage—starting with getting around 20 minutes of sunlight several times a week, according to Newgent. "The major cause of vitamin D deficiency is inadequate exposure to sunlight, an increasing feature in modern life," said Dr. Boyd. But remember: You still need to wear sunscreen whenever you step outside—even to get vitamin D.

Aside from the sun, you can also get extra vitamin D through a few foods, like fatty fish (including salmon, tuna, mackerel, and sardines) and mushrooms (some of which are exposed to ultraviolet (UV) light to increase vitamin D levels), said both Dr. Nasrallah and Newgent. Foods like milk, orange juice, yogurt, and breakfast cereals can also be fortified with vitamin D.

And of course, you can always go the supplement route, in the form of vitamin D3, if your healthcare provider thinks it's necessary. According to Dr. Boyd, many doctors now consider a daily dose of 1000-2000 IU of D3 safe and will assure optimal levels for most adults. As for when to take it, because Vitamin D is fat soluble, Dr. Boyd suggested pairing it with your largest meal of the day, "containing fat to assure maximal absorption." But again, check in with your provider before you decide to try vitamin D in supplement form.


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