Vitamin D is an essential nutrient kids need for healthy growth and development. It builds strong bones and teeth, boosts calcium and phosphorus absorption, supports the immune system, and can even influence mental health. But despite how important it is, many kids don’t get enough of it. Unlike most vitamins and minerals that we mainly get from our food, vitamin D is mostly absorbed through our skin when we're exposed to sunlight. 

Unless your kids are soaking up rays without sunscreen, dodging clouds, or avoiding smog, they’re probably not getting enough. And to make matters more challenging, very few foods naturally contain vitamin D. So, let’s dive into everything you need to know about vitamin D deficiency, which kids are at risk, common signs and symptoms, and how to make sure they get enough of this essential nutrient.

What causes vitamin D deficiency in kids?

Every kid needs vitamin D to stay healthy. Babies under 12 months need 400 IU of vitamin D each day, while toddlers and older kids need 600 IU daily. But some things can make it harder for kids to get enough vitamin D, like:

Food intolerances and restrictions 

Children with food intolerances, sensitivities, or allergies are at a higher risk for vitamin D deficiency, especially those with a milk allergy, lactose intolerance, or who follow a mostly plant-based diet. In the U.S., most whole milk is fortified with around 120 IU of vitamin D per cup, so if your child isn’t drinking milk, their risk of deficiency increases. Plus, foods like fatty fish, beef liver, and egg yolks contain small amounts of vitamin D. If your child follows a vegetarian or vegan diet, they’re likely missing out on these key animal sources of vitamin D.

Eat less food

Young children, especially toddlers, tend to have smaller appetites, reflective of their change in growth. They’re still growing, but not as quickly as their first year of life. This slower growth means they need less food to fuel their bodies, so they might eat smaller portions. If their overall food intake is limited, they might not get enough of the nutrients they need, including vitamin D.

Fussy eating

Picky eaters often stick to a narrow range of foods, which can make it tough for them to get enough vitamin D and overall nutrition.

Signs of vitamin D deficiency

If you're worried your child has a vitamin D deficiency, it's likely because you've noticed something unusual about their health, mood, or behavior. Here are some common signs and symptoms of vitamin D deficiency:

Low energy

In some children, vitamin D deficiency can present as fatigue. Even after getting enough sleep, they may feel constantly tired or lack the energy to participate in their usual activities.

Poor immune function 

Our bodies need vitamin D to help the immune system fight off infections. It reduces inflammation and plays a role in preventing respiratory infections and autoimmune diseases. Plus, some studies suggest that vitamin D deficiency can increase risks of common illnesses.

Dental problems 

If your child complains of a toothache or their teeth start turning brown, it’s probably time to go to the dentist. Just like vitamin D supports bone health, it’s also important for tooth mineralization. Without enough of it, children could possibly develop cavities, weak or fractured teeth, and even "rachitic teeth," or weak teeth, a condition similar to rickets but affecting the teeth. 

Sleep issues

Not getting enough sleep is tough for anyone, but as a parent, you really notice it when your kid is throwing tantrums every ten minutes or seems extra moody and cranky. Interestingly, vitamin D influences sleep, and if your child isn’t getting enough of it, they might face sleep issues like waking up in the middle of the night, having trouble falling asleep, or not sleeping as long as they should.

How to keep your kids from getting vitamin D deficient

The good news? You don’t have to be a gourmet chef to get more vitamin D into your child’s diet. Vitamin D isn’t found in many foods, and even the ones that do have it—like fortified milk, fatty fish, beef liver, egg yolks, and mushrooms—only provide small amounts. So, relying on food alone can be tough. If the sun has been hiding lately, or it’s just tough to get enough time outside, ask your child's pediatrician if a vitamin D supplement might be beneficial.

If your pediatrician thinks it could help, you have some options. When choosing a vitamin D supplement, you can either pick one that’s just vitamin D on its own or a multivitamin that includes it (especially useful for picky eaters!). With either one, look for one with cholecalciferol or vitamin D3, the active form of vitamin D, and the easiest one to absorb.