What are the symptoms of vitamin D deficiency?

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The symptoms of vitamin D deficiency are important to be aware of, because if you’re not getting enough of this nutrient it could lead to soft bones, known as rickets in children, and osteomalacia in adults.

So why do we need vitamin D? According to a spokesperson from the Academy of Nutrition and Dietetics, this fat-soluble nutrient aids in the absorption of calcium and phosphorus in our bodies, bringing these minerals to our bones and teeth and helping to regulate how much calcium remains in our blood.

“Together with calcium, vitamin D helps protect against the loss of bone mass,” they say. “It also helps muscles to function and allows the brain and body to communicate through nerves. The immune system also uses vitamin D to help fight off invading bacteria and viruses.”

Registered dietitian Jen Bruning, a spokesperson for the Academy of Nutrition and Dietetics, also adds: “There may also be a role for vitamin D in inflammation reduction as well as helping to control the growth of cancer cells and preventing depression.”

The body naturally produces vitamin D when exposed to sunlight, but we can also get it from certain foods and the best vitamin D supplements. But research in the National Institutes of Health found that 42% of Americans aren’t getting enough vitamin D, and people with darker skin need longer to synthesize enough of it.

In this article, experts explain more about the symptoms of vitamin D deficiency and what you can do to avoid it.

What causes vitamin D deficiency?

The amount of vitamin D your skin makes depends on several things, including skin pigmentation, the time of day and season, and even where you live. Using sunscreen, while important to prevent skin cancer, can also decrease how much vitamin D your body gets.

Bruning told Live Science: “Estimates suggest that around 1 billion people worldwide have a vitamin D deficiency. In many adults, this may not present with any clear signs or symptoms.”

Jen Bruning
Jen Bruning ,MS, RDN, LDN

Jen Bruning is a spokesperson for the Academy of Nutrition and Dietetics and the director of Nutrition and Brand Innovation at Incite Strategic Partners. She is a graduate of Saint Louis University and earned a master's degree from Colorado State University.

Soft bones (rickets/osteomalacia)

“In children, deficiency can lead to a condition called rickets, or softening of the bones, due to low calcium levels that results in bent or easily broken bones,” says Bruning. “In adults, bone loss can occur and present as osteomalacia.” 

Rickets in children can be treated when caught early, typically with a regimen of dietary changes and/or supplementation as directed by a physician, plus sunlight exposure. Left untreated, rickets can result in bone deformities.

“Osteomalacia, the softening of the bones seen in older adults, can lead to easily broken bones, which are more difficult to recover from as we age,” she adds.

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Muscle cramps, fatigue and weakness

According to Bruning, muscle cramps from vitamin D deficiency can lead to undue injury, and fatigue and weakness from vitamin D deficiency is dangerous as it increases the chances of losing balance, falls, broken bones, head strikes or other injuries.  

“Since vitamin D deficiency in adults is more common in older adults, these side effects can be more dangerous in those who may already be frail,” she says. “The amount of calcium in our bloodstream is very important, and so if we do not get enough calcium from food, it is pulled from our bones. This can also happen with vitamin D deficiency – because we need it to be able to absorb calcium.”

How to know if you have a vitamin D deficiency

You can find out if you have a vitamin D deficiency with a simple blood test. Your healthcare professional may also order an X-ray to check the strength of your bones. You may then be told to take a course of vitamin D tablets or liquids. 

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How to get more vitamin D

If you want to get more vitamin D from food, up your intake of fatty fish such as salmon and mackerel, a spokesperson from the Academy of Nutrition and Dietetics told Live Science. “Beef liver, cheese and egg yolk provide small amounts, while mushrooms also contain this vitamin if grown under UV lights.” 

Most milk and some cereals are fortified with vitamin D, as well as many plant-based drinks. Orange juice, yogurt and cheese may be fortified — you can find out by looking at the Nutrition Facts Label on packaging.

“Some individuals may need extra vitamin D, such as older adults, breastfed infants, people with dark skin, those with certain medical conditions including liver disease, cystic fibrosis, celiac disease and Crohn's disease, and those with obesity or who have had gastric bypass surgery. Always check with your health care provider before taking a vitamin D supplement.”

Bruning adds: “Work with a registered dietitian or your country’s equivalent, or your physician, to determine what forms of vitamin D, at what dosage, may be best for you based on your individual needs.”

Maddy Biddulph

Maddy has been a writer and editor for 25 years, and has worked for some of the UK's bestselling newspapers and women’s magazines, including Marie Claire, The Sunday Times and Women's Health. Maddy is also a fully qualified Level 3 Personal Trainer, specializing in helping busy women over 40 navigate menopause.