Your skin produces vitamin D from exposure to sunlight. However, if you protect your skin from ultraviolet light, which is vital, you may not make enough vitamin D. Very few foods naturally provide vitamin D. As a result, it's hard to get enough through your diet. Fortified foods, such as milk and other dairy products, cereals and orange juice are the primary sources of vitamin D for most Americans, according to the Office of Dietary Supplements. If you don't consume a sufficient amount of foods fortified with vitamin D, you may need to take supplements to avoid health problems caused by a deficiency, such as osteoporosis, heart disease and rickets.
Visit your doctor for a simple blood test to determine whether you are deficient in vitamin D before taking supplements. You shouldn't take supplements if your vitamin D levels are normal because too much vitamin D in your system can become toxic.
Check the supplement label for the USP Verified symbol, which shows the product was tested for quality. The label also lists the form of vitamin D in the supplement. They may contain vitamin D-3, called cholecalciferol, or vitamin D-2, which is ergocalciferol. The Office of Dietary Supplements reports that both forms are equal in their ability to increase levels of vitamin D.
Eat a diet high in magnesium, vitamin A and zinc. These nutrients are needed to support vitamin D's ability to function properly, according to the Vitamin D Council. Magnesium is found in green leafy vegetables, nuts and whole grains. You can boost zinc by eating meat, poultry, seafood and beans. For vitamin A, eat meat, dairy products and orange, yellow and dark green vegetables.
Watch for symptoms of vitamin D toxicity, such as poor appetite, weight loss and frequent urination. In severe cases, high levels of vitamin D can cause an irregular heart beat. To avoid toxicity, never consume more than 100 micrograms, or 4,000 international units of vitamin D daily.
Seek medical attention if you develop symptoms of kidney stones, such as pain in your belly, back, groin or testicles, blood in your urine, chills, fever and nausea. Getting too much vitamin D from supplements can raise your levels of calcium, which increases the risk of kidney stones. Excess calcium can also lead to damage to your heart, blood vessels and kidneys.
Audit your other prescription medications. Corticosteroid, anti-seizure and cholesterol-lowering medications interfere with the absorption of vitamin D. Consult your health care provider to be sure you take the right supplemental dose to counterbalance the impact of these medications.
Speak with your doctor about increasing your dose of vitamin D if you currently suffer from rickets, osteoporosis or other chronic diseases that may be associated with vitamin D, such as heart disease and multiple sclerosis. In some cases, supplementation with high doses may help treat these conditions, according to the Linus Pauling Institute.
The recommended dietary allowance of vitamin D is 15 micrograms or 600 international units daily. Most single-ingredient vitamin D supplements available over the counter contain 10 micrograms or 400 international units of the vitamin. You can take vitamin D supplements with or without food. Follow the directions on the product label.