Ever notice how a few minutes in morning sun can lift your mood and make you feel good? Part of that is Vitamin D — the “sunshine vitamin.” Unlike most vitamins we get only from food, our bodies can make Vitamin D when skin is exposed to sunlight.
Vitamin D comes in two forms. D2 (ergocalciferol) is usually found in fortified foods and some plants like mushrooms. D3 (cholecalciferol) is the form our skin makes from sunlight and is also found in animal foods such as fatty fish, egg yolks, and cheese. Both types help keep the body working well.
This vitamin plays many important roles. It helps the body absorb calcium, keeping bones strong and lowering the risk of osteoporosis. It supports the immune system, helps muscles function, influences mood and brain health, and plays a part in heart health by helping regulate blood pressure.
Low Vitamin D can cause noticeable symptoms. Many people feel persistent tiredness or weakness that doesn’t improve with rest. Bone or back pain and muscle weakness are common because of reduced calcium absorption and muscle function. Some studies link low Vitamin D to mood changes like depression, though this is a complex area still under study. Over time, chronically low Vitamin D may raise the risk of conditions such as heart disease, certain cancers, and cognitive decline.
Sunlight is our main source of Vitamin D, but it’s a balance. Moderate sun exposure helps the body make Vitamin D and may protect against some cancers, while too much UV exposure raises the risk of skin cancer. Short periods of sun around midday several times per week can be enough for many people, but factors like skin tone, age, location, and the UV index affect how much time is needed. Protect your skin from excessive sun with clothing, shade, and sunscreen when you’ll be exposed longer.
Some people are more likely to be deficient. Older adults make less Vitamin D in their skin. People with darker skin need more sun exposure to produce the same amount because higher melanin reduces UV absorption. Spending most time indoors and living in places with little sun, especially far from the equator or with long winters, also increase the risk. Regular, thorough sunscreen use can reduce Vitamin D production as well.
You can raise Vitamin D levels in several ways: safe sun exposure, eating Vitamin D-rich foods like salmon, mackerel, sardines, egg yolks, and fortified dairy or plant milks, or taking supplements when needed. If you think you might be low, a blood test measuring 25-hydroxyvitamin D will show your status. Talk to a healthcare provider before starting supplements to get the right dose for you.
While rare, too much Vitamin D can be harmful. Excessive supplement use can cause hypervitaminosis D, leading to high blood calcium (hypercalcemia). Early signs include nausea, vomiting, weakness, and loss of appetite. More serious effects are frequent urination, excessive thirst, constipation, confusion, kidney stones, and damage to the heart or kidneys. Sun exposure alone rarely causes toxicity because the body regulates production, so the main risk comes from taking too many supplements.
Vitamin D is a quiet but powerful part of good health. With safe sun habits, a diet that includes Vitamin D-rich foods, and supplements when recommended, you can keep levels in a healthy range and support your bones, muscles, immune system, and overall wellbeing.
