Our wellness advice is expert-vetted. Our top picks are based on our editors’ independent research, analysis, and hands-on testing. If you buy through our links, we may get a commission. Reviews ethics statement Vitamin D can do wonders for your physical and mental health. Here's how to get more and things to consider before you start. It's no surprise that supplements have gained in popularity in recent years. If feeling better and living longer can be achieved by simply taking a pill, why wouldn't we all jump at the chance?Enter vitamin D, a key nutrient that doesn't just support healthy immune function but also bolsters our bones, our brains and more. Before you start popping vitamin D supplements, though, you should know what to expect — and the potential risks. Your body needs vitamin D for a number of its critical processes, from building healthy bones to regulating certain cellular functions. It affects your brain, skin, muscle function and more. As far as bone health goes, vitamin D plays an important role because it maintains calcium and phosphorus balance by promoting absorption. Vitamin D is usually added to milk to increase the absorption of calcium, which occurs through the small intestine. Vitamin D comes in two primary forms: D2 (ergocalciferol) and D3 (cholecalciferol). They function fairly similarly in your body, although D3 is more bioavailable and, therefore, more effective in raising and maintaining adequate vitamin D levels in the bloodstream. Good news: Your body actually has the ability to make vitamin D on its own when a chemical in your skin gets direct sunlight. Bad news: Most people can't make as much vitamin D as their bodies need. This becomes particularly true with limited sun exposure during the winter months when the days shorten and you spend less time outdoors. Others at higher risk for developing vitamin D deficiency include those who have dark skin, fat malabsorption disorders, inflammatory bowel disease or are elderly. Without enough of this vitamin, you're more prone to stress fractures. Some people also experience fatigue, aches and pains with vitamin D deficiency. If you think you might have this deficiency, ask your doctor to order a blood test. They can help you determine if you're low on this vitamin and, if so, the best way to increase your levels. Some people benefit from adding more vitamin D-rich foods and drinks to their diet, while others need vitamin D supplements. If you want a safe, risk-free way to get more of this nutrient into your body, stock up on foods with lots of vitamin D. Some naturally occurring sources include:You can also find foods and drinks fortified with this vitamin. Remember, your body can't absorb calcium without it. As a result, you'll often find it in milk and yogurt. Check the packaging. It should specifically say something like "fortified with vitamin D." You might also find D-fortified cereals, oatmeal and orange juice. In other words, food manufacturers have seemingly decided that a healthy dose of vitamin D is a great way to start the day. Also, these foods are fortified because they are affordable and accessible to most people. You can also get vitamin D from sunlight. Sunscreen blocks this bodily process, though. To protect yourself from skin cancer while increasing your vitamin D production, you might consider a limited amount of time outdoors (like 15 minutes) without sunscreen each day. If you got a blood test and found that you're low in this vitamin, you can try moving to a D-rich diet and getting some sun. If another test reveals that you're still low, though, it's likely time to start exploring the many vitamin D supplement benefits. Whether you combine food and sunlight or add vitamin D supplements to your diet, getting enough of this nutrient makes a big difference for your body. Specifically, sufficient vitamin D can deliver:Studies show that vitamin D plays a critical role in your body's calcium absorption. And as you probably already know, calcium means strong, healthy bones. That's why doctors often prescribe vitamin D supplements for kids with rickets and people with inherited bone disorders. Since all of us have bones, it's worth double-checking that you're getting enough. Sufficient vitamin D can help to prevent and manage osteoporosis.Across the country, heart disease is the leading cause of death. While many factors come into play here, studies have linked low levels of vitamin D and:If you're looking for a way to defend yourself against some of the most common health conditions in the country, it might be time to consider these major vitamin D supplement benefits. While low vitamin D levels can make you more likely to get sick, the opposite is also true. This vitamin works to activate your T cells, which help your body fight infection. That means vitamin D supplement benefits include a reduced likelihood of getting sick, along with the potential to shrink your risk for deregulated immune system conditions like rheumatoid arthritis, asthma and diabetes. Studies link insufficient vitamin D and depression. What's more, even if you're not living with major depressive disorder, low levels of vitamin D can contribute to depressive symptoms like low mood and apathy. Speaking of your brain, vitamin D might help. Studies seem to demonstrate a correlation between vitamin D insufficiency and decreased cognitive function. Beyond that, early research suggests that low levels of vitamin D can contribute to cognitive decline as we age. In short, those vitamin D supplements may help you stay sharp now and through the years. All of this said, you can certainly have too much of a good thing when it comes to vitamin D supplements. While experts recommend around 600 international units of vitamin D a day for most adults, taking 4,000 IU a day or more is considered unsafe, particularly for those supplementing without known vitamin deficiency. These high doses, especially over a longer period of time, are linked to:Taking too much vitamin D can lead to hypercalcemia, which means you have too much calcium in your blood. This can cause kidney stones and contribute to hardening in your blood vessels, lungs and heart. Excess vitamin D supplements can upset your stomach, leading to nausea and vomiting. In fact, if you recently started taking these supplements and have been feeling queasy, it could be a sign that you're overdoing it. Taking extremely high levels of vitamin D can cause toxicity. One of the primary symptoms of vitamin D toxicity is intense dehydration. While some of the biggest vitamin D supplement benefits center around your brain, too much can cause the opposite effect. People taking an excess amount often report disorientation and confusion. Before you start taking vitamin D supplements, get a blood test from your doctor. They can tell you if you're vitamin D deficient. And even if you are, adjusting your diet and spending a short amount of time outdoors each day without sunscreen may be enough to tip the scales. These options remove the risk of vitamin D toxicity. If you're still low in this key nutrient after eating more D-rich foods and getting some sun, supplements can help. Your body needs vitamin D to keep your bones strong, bolster your immune response and support your heart and brain health. Just make sure you keep an eye on your intake levels. Around 600 to 800 IU a day should be plenty, unless your doctor instructs you otherwise.