Getting enough vitamin D through food and sunlight helps prevent deficiency. Some health conditions, like cystic fibrosis, Crohn’s disease and celiac disease, keep your intestines from absorbing vitamin D well.
Older adults have less ability to make vitamin D in response to sunlight. Some medicines (such as cholesterol, anti-seizure and steroid medicines) can also affect how much vitamin D is active in the body.
Symptoms
Vitamin D is well-known for supporting bone health, but it also plays an important role in regulating the body’s immune system and nerve cell function. It is produced by the skin when exposed to direct sunlight, and it’s found in a few foods, including fatty fish, fortified milk and some mushrooms. The body can’t absorb calcium — the primary component of bones — without Vitamin D.
A deficiency of the vitamin can lead to a number of symptoms, including softening of the bones (osteomalacia), frequent infections and fatigue. Researchers are increasingly discovering that a healthy level of vitamin D may help reduce the risk of certain health problems, including type 1 diabetes and rheumatoid arthritis.
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Some people are more at risk of vitamin D deficiency than others. Young children who don’t spend enough time outdoors, older adults who spend more time indoors and people with certain medical conditions are more likely to have low levels of the nutrient. In addition, some people with gastrointestinal tract diseases, such as celiac disease or Crohn’s disease, and those who have undergone bariatric surgery are at greater risk because they have less efficient digestive systems and may be unable to absorb the vitamin D they consume.
In babies and children, Vitamin D deficiency can cause rickets, a condition in which the bone tissue doesn’t mineralize properly, resulting in soft bones and skeletal deformities. It can also lead to failure to thrive, hypocalcemic seizures, tetanic spasms, neurodevelopmental delays and dental abnormalities.
A deficiency of the vitamin can also affect wound healing. A 2019 study found that people who have low vitamin D concentrations are more likely to experience delayed healing after an injury or surgery. This is because the nutrient is required for making compounds that help with the formation of new tissues and skin. Researchers are continuing to investigate whether Vitamin D levels may be linked to the risk of autoimmune disorders, such as rheumatoid arthritis and type 1 diabetes, but more research is needed in this area before firm conclusions can be drawn. As the Vitamin D Deficiency Prevention and Treatment campaign points out, it’s possible to prevent a deficiency by improving your diet and increasing your time in the sun. A GP can advise on this and prescribe a vitamin D supplement, which should be taken as directed.
Causes
Vitamin D is made in the skin by absorbing sunlight, and it’s also present in a small number of foods, including fortified products. It’s a fat-soluble vitamin, meaning it’s stored in the body and not eliminated when you eat. A deficiency can be caused by not getting enough sun, having a condition that limits the gut’s ability to absorb fat or other nutrients, having surgery that bypasses part of the digestive tract, taking medications such as anti-convulsants and glucocorticoids, and age.
People with darker skin may need more time in the sun to make enough vitamin D. The skin’s ability to produce vitamin D decreases as people get older. People who are obese have a harder time making enough vitamin D, because they can’t store as much of it. And some conditions can interfere with how well the gut absorbs vitamin D and its active form, calcitriol (25(OH)2D).
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A deficiency may not cause any symptoms at all. But over time it increases the risk of long term health problems. These include osteoporosis, a condition that weakens bones and makes them more likely to break. It can also increase the risk of a bone disease called osteomalacia, which causes bones to become soft and painful. A deficiency can lead to a loss of balance and coordination and muscle weakness, which can affect daily activities.
Other conditions that can lead to vitamin D deficiency include some types of cancer, heart disease, depression, multiple sclerosis, type 2 diabetes, and slow wound healing. The most accurate way to check for vitamin D deficiency is with a blood test, but it’s not always covered by insurance and can cost up to $200.
The best treatment is to get more sun, if possible. If you can’t, talk to your doctor about taking a supplement that contains calcium and vitamin D. Be sure to follow the dosage instructions, because too much vitamin D can have serious side effects. High levels can increase the risk of forming kidney stones and can raise blood calcium levels to dangerously high levels, which can lead to nausea, vomiting, frequent urination, and high blood pressure.
Treatment
While vitamin D breaks the rules of the other vitamins in that it is both a nutrient and a hormone, its importance cannot be overstated. It helps regulate calcium levels and maintains bone health, especially in children. A severe deficiency leads to rickets in children and osteomalacia in adults. These conditions cause soft, brittle bones that can lead to bone deformities and fractures. The deficiency can also lead to secondary hyperparathyroidism, a condition in which the parathyroid glands produce too much of the hormone parathyroid hormone (PTH).
If a deficiency is suspected, a simple blood test will confirm it. The test measures the level of 25(OH)D, which is a form of Vitamin D that your body uses to regulate calcium and build bone density. Wrist X-rays may also be done to assess the severity of the deficiency by looking for changes in the shape of the wrist bones.
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A diet that is low in vitamin D-rich foods can contribute to the deficiency, but other factors can also play a role. People with dark skin who have a harder time absorbing Vitamin D from sunlight, and those who avoid the sun due to a history of skin cancer or cultural or religious beliefs, are at risk for a deficiency. So are people who live in areas with little sunshine or spend most of their lives indoors, such as the elderly and those who are housebound.
Some medical conditions also reduce your body’s ability to absorb Vitamin D from food. For example, Crohn’s disease, ulcerative colitis, and celiac disease prevent your digestive system from absorbing fats, including the Vitamin D that is found in some foods. Kidney and liver disease can also decrease your body’s ability to change vitamin D into a usable form. So can obesity, which causes your body’s fat cells to bind with vitamin D and prevent it from getting into the bloodstream.
A doctor can prescribe you a vitamin D supplement, usually cholecalciferol, to treat the deficiency. This is available in tablet and liquid form. You can also get it in an injection, which is useful if you’re at risk for the deficiency and have difficulty taking tablets or remembering to take them regularly.
Prevention
Vitamin D is well-known for keeping bones strong, but it also plays an important role in the immune system. A 2019 study linked low vitamin D levels to an increased risk of respiratory infections. Primary care doctor Mindy Lacey, MD, says she screens patients for vitamin D deficiency if they complain of fatigue, muscle weakness or changes in mood.
A healthy diet can help prevent vitamin D deficiency. Eat foods rich in the vitamin, such as fatty fish like salmon, tuna and mackerel, fortified milk and cereals, and orange juice. Also get some moderate sun exposure – but only for short periods of time, as excessive sun exposure can lead to skin cancer.
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Certain diseases and conditions increase the likelihood of having a low vitamin D level, including inflammatory bowel disease (Crohn’s and colitis) and celiac disease, which limit fat absorption. People with a history of kidney or liver disease may also have low vitamin D levels because the liver and kidneys create enzymes that change sunlight and food into the biologically active form of the vitamin.
In children, low vitamin D levels can cause rickets and in adults, osteomalacia (softening of the bones). Symptoms of both disorders include bone pain, tenderness or weakness, but they are generally not serious and can be treated with medication.
Fortunately, preventing vitamin D deficiency is easy, especially if you’re at higher risk. Get some moderate sunlight each day, avoiding the peak hours of 10 a.m. to 4 p.m. and wear protective clothing if you have to be outdoors for long periods of time. Choose a sunscreen with an SPF of 30 or more, and avoid spending too much time in the sun when it’s at its strongest. In addition, take a daily supplement of vitamin D. Your doctor can recommend the best dosage for you, which is typically ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3). If you take a supplement, follow your doctor’s instructions carefully. You may need to get more calcium in your diet, as well. This helps keep your bones and teeth healthy.
