Medically reviewed by Richard Fogoros, MD
Vitamin D is an essential fat-soluble vitamin that your body needs to regulate calcium absorption. Deficiency can result in weakened, brittle bones. Children who don’t get enough may end up with a disease called rickets, and adults with vitamin D deficiency are at a greater risk for osteoporosis.
The adequate daily intake of vitamin D is from 200 to 600 International Units (IU); however, some experts believe those numbers should be increased. Three ounces of salmon contains about 800 IU, a cup of milk has just over 100 IU, and one serving of fortified breakfast cereal usually has about 40 IU vitamin D.
Symptoms of Vitamin D Deficiency
People with vitamin D deficiency may experience bone pain and muscle weakness although the symptoms may be very mild at first.
Children who have rickets suffer from soft bones and skeletal deformities. Deficiency in adults will cause osteomalacia, which is a condition that makes your bones weak. Your health care provider can order tests that measure the levels of 25-hydroxyvitamin D.
Insufficient levels of vitamin D in the blood have been associated with a variety of other health conditions such as diabetes, hypertension, multiple sclerosis and some forms of cancer. However, more research is needed to determine if vitamin D can prevent or treat any of these disorders.
Causes of Vitamin D Deficiency
Not eating foods that contain vitamin D and not getting enough sun exposure may lead to vitamin D deficiency. Breastfed infants, older adults, housebound individuals, and people with dark skin are at higher risk of vitamin D deficiency.
Individuals who have fat absorption problems due to conditions such as Crohn’s disease, cystic fibrosis, gastric bypass surgery, or have liver or kidney conditions may not get enough vitamin D from their diets.
You need sun exposure to make vitamin D, but it only takes 5 to 30 minutes of sun exposure on your face, arms, legs, or back twice each week without sunscreen to stimulate sufficient vitamin D production. Excessive sun exposure increases your risk of skin cancer, so it’s important to use sunscreen and limit your use of tanning beds.
Vitamin D is not naturally present in many foods; however, oily fish and especially cod liver oil are rich in vitamin D. Beef liver, eggs, and cheese also contain small amounts. Vitamin D is added to some foods like milk and fortified breakfast cereals.
Can You Get Too Much Vitamin D?
Your body stores fat-soluble vitamins such as vitamin D, but excessive sun exposure will not cause vitamin D toxicity. It would be tough to get too much vitamin D from foods—even fortified foods—unless you consume large amounts of cod liver oil.
Vitamin D is available as an over-the-counter supplement. But since your body stores fat-soluble vitamins for a long time, taking large amounts of vitamin D can lead to toxicity that causes nausea, vomiting, loss of appetite, constipation, weakness, and weight loss.
High blood levels of vitamin D may also raise your blood levels of calcium, possibly resulting in mental confusion and abnormal heart rhythms. So, if you have any health conditions, it’s important to speak with your doctor before taking vitamin D supplements. And follow the label directions unless your healthcare provider tells you differently.