Vitamin D Deficiency

Vitamin D deficiency is one of the most common nutritional deficiencies worldwide. Nearly 42% of adults in the United States have a vitamin D deficiency, with rates rising to almost 63% in Hispanic adults and 82% in African American adults. Vitamin D helps your body absorb calcium, which is one of the main building blocks of bone, and also has a role in your nervous, muscle, and immune systems.

Vitamin D deficiency is the state of having inadequate amounts of vitamin D in your body, which may cause health problems like brittle bones and muscle weakness. There may be no symptoms and doctors don't routinely check vitamin D levels, so many people are deficient and don't realize it. While the condition can affect anyone, certain populations may be at higher risk, including older adults, people with limited sun exposure, those with darker skin pigmentation, and individuals following restricted diets. The majority of patients with vitamin D deficiency are asymptomatic.

The two main causes of vitamin D deficiency are not getting enough vitamin D in your diet and/or through sunlight, and your body not properly absorbing or using vitamin D. Due to fear of developing skin cancer most people avoid the sun exposure. To prevent vitamin D deficiency, one should spend 15 to 20 minutes daily in the sunshine with 40% of the skin surface exposed. However, many factors can interfere with adequate vitamin D production or absorption.

People who work indoors, wear extensive clothing, regularly use sunblock, are dark skinned, obese, aged or consciously avoid the sun, are at risk of vitamin D deficiency. As people age, it's harder for their skin to produce adequate amounts of vitamin D, which may lead to deficiency. Additionally, certain medical conditions may increase the risk, including kidney or liver disease, digestive disorders that affect fat absorption, and certain medications. Vitamin D deficiency is more common among people who are lactose intolerant, have a milk allergy, or follow an ovo-vegetarian or vegan diet. Deficiency may also occur in people who have limited exposure to sunlight, those whose kidneys cannot convert 25(OH)D to its active form, or those who cannot absorb vitamin D efficiently in the digestive tract.

Healthcare providers don't usually order routine checks of vitamin D levels, but they might need to check your levels if you have certain medical conditions or risk factors for vitamin D deficiency and/or have symptoms of it. Testing may be particularly beneficial for individuals experiencing unexplained bone pain, muscle weakness, frequent infections, or persistent fatigue. Testing may be done on people who are at high risk for vitamin D deficiency, such as those who are over the age of 65 (both skin production of vitamin D and gut absorption of vitamin D becomes lower as we get older) or are obese.

Other situations where testing might be considered include having a family history of osteoporosis, following a restricted diet with limited vitamin D-rich foods, spending most time indoors, or taking medications that may interfere with vitamin D absorption. People with certain chronic conditions, such as kidney disease, liver disorders, or digestive issues, may also benefit from regular monitoring of their vitamin D status.

Most experts agree that 25(OH)D of < 20 ng/ml is considered to be vitamin D deficiency whereas a 25(OH)D of 21-29 ng/ml is considered to be insufficient. The goal should be to maintain both children and adults at a level > 30 ng/ml to take full advantage of all the health benefits that vitamin D provides. Many experts recommend a level from 20 and 40 ng/mL or 60 and 100 nmol/L. Others recommend a level from 30 to 50 ng/mL (75 to 125 nmol/L).

Low vitamin D results may indicate the need for lifestyle changes such as increased sun exposure, dietary modifications, or supplementation. If calcium levels are also low, this may suggest that the deficiency is already affecting the body's ability to maintain proper mineral balance. Higher than normal levels are typically the result of excessive supplementation and may require adjustment of vitamin D intake. Talk to your health care provider about the meaning of your specific test results, and whether you may need vitamin D supplements.

Maintaining adequate vitamin D levels often involves a combination of safe sun exposure, dietary choices, and possibly supplementation. You can get vitamin D in three ways: through your skin, from your diet, and from supplements. Your body forms vitamin D naturally after exposure to sunlight. However, too much sun exposure can lead to skin aging and skin cancer, so many people try to get their vitamin D from other sources. Foods that naturally contain vitamin D include fatty fish, egg yolks, and liver, while many foods like milk and cereals are fortified with vitamin D.

Regular physical activity, particularly weight-bearing exercises, can help support bone health alongside adequate vitamin D levels. For individuals at higher risk of deficiency, working with a healthcare provider to develop an appropriate supplementation plan may be beneficial. If you are diagnosed with the condition and follow treatment recommendations, you will likely be able to increase your intake to an acceptable level, which should eliminate any symptoms or long-term problems.