Vitamin D Deficiency in Kids: Signs, Symptoms, and More

Vitamin D deficiency impacts more than 1 billion people worldwide.

It’s common in both developed and undeveloped countries and is a major public health concern in all age groups, including children(1, 2).

Vitamin D deficiency can negatively affect a child’s growth, immune response, mental health, and more, which is why proper treatment is important (3).

This article explains how vitamin D deficiency impacts kids, how much vitamin D they need, and how vitamin D deficiency is treated in infants, children, and teens.

Vitamin D needs for babies, children, and teens

You need vitamin D throughout your life, from infancy through older age.

Your body needs it to maintain optimal calcium and phosphorus levels, as well as for the development of immune cells, bone mineralization, regulation of the production of inflammatory proteins, and much more(2, 4).

Vitamin D is especially important during infancy and childhood because it’s essential for the growth and development of the skeletal system.

Because of the vitamin’s significant role in maintaining critical bodily processes, having low or deficient levels can greatly impact your health.

Even though experts argue that current vitamin D recommendations are generally too low to maintain optimal levels, daily intake recommendations are the same for children, teens, adults, and those who are pregnant and breastfeeding or chestfeeding (5, 6).

Babies have lower vitamin D needs than children and adults. The term “adequate intake” (AI) is used for vitamin D recommendations in infants. This is because there is insufficient evidence to develop a recommended dietary allowance (RDA) for that age group.

Infant AIs for vitamin D are based on the amount of vitamin D needed to maintain vitamin D levels above 20 ng/mL (50 nmol/L) and support growth. The RDA is the average daily intake sufficient to meet the nutrient requirements of nearly all healthy people.

The following charts show the current daily intake recommendations for vitamin D for children in the United States (5):

RDAs for vitamin D are listed in both micrograms (mcg) and international units (IU); 1 mcg vitamin D is equal to 40 IU.

Keep in mind that not all experts agree on these recommendations.

For example, the Endocrine Society — an international medical organization — claims that to maintain vitamin D levels above 30 ng/mL (75 nmol/L), adults likely need at least 1,500–2,000 IU (37.5–50 mcg) per day of vitamin D supplements (5).

They also state that children and teens may need at least 1,000 IU (25 mcg) per day (5).

Regardless, it’s clear that many adults and children don’t get enough vitamin D through their diet and that deficiency is common among all age groups.

Are certain children more at risk for developing vitamin D deficiency?

Certain children are more at risk for developing low vitamin D levels due to factors like (7):

• skin color
• body weight
• sunlight exposure

Children and teens who have higher levels of body fat are at higher risk of developing a vitamin D deficiency than kids who have standard body fat levels (8).

Additionally, kids with darker skin tones are significantly more likely to develop a vitamin D deficiency. In fact, people with darker skin need up to 15 times more sun exposure to produce the same amounts of vitamin D as people with lighter skin (7).

These things also increase a child’s risk for developing a deficiency (7):

• living in a cold climate
• getting limited sun exposure
• taking certain medications, like anticonvulsants
• having medical conditions that impact vitamin D absorption or utilization, like Crohn’s disease or cystic fibrosis

Vitamin D deficiency is common in all age groups, including infants, children, and teens. Certain kids, like those with darker skin tones, those with more body fat, and those who get limited sun exposure, are more likely to develop a deficiency.

How does vitamin D deficiency impact children? Signs and symptoms

A healthcare professional can diagnose vitamin D deficiency through a blood test. Just like adults, children are considered to be deficient if their levels fall below 20 ng/mL (50 nmol/L) (6, 8, 9).

Levels of 21–29ng/ml (52–72 nmol/L) are considered insufficient.

Although there is some debate over what constitutes an optimal level of vitamin D in the blood, values above 30ng/ml (75 nmol/L) are generally considered sufficient (10, 11, 12).

Vitamin D insufficiency and deficiency can go unnoticed because noticeable symptoms typically don’t manifest until a severe deficiency develops. Also, symptoms can be nonspecific, making it hard for parents or caregivers to detect a deficiency.

This is why having your child’s doctor regularly test their vitamin D levels is important, especially if your child is considered at risk for developing a deficiency.

Babies

Vitamin D deficiency is common in infants worldwide, with prevalence rates ranging from 2.7% to 45% (13).

Babies up to 2 years old are at a higher risk for developing this deficiency because they’re generally exposed to less sunlight than adults.

Plus, exclusively breastfed or chestfed babies who are not supplemented with vitamin D may not get enough of the vitamin.

To avoid developing a vitamin D deficiency, the American Academy of Pediatrics recommends that exclusively and partially breastfed infants receive a 400 IU vitamin D supplement every day, beginning in the first few days of life (14).

If a baby develops vitamin D deficiency, it could cause (15, 16):

• seizures due to low calcium levels
• growth failure
• irritability
• lethargy
• muscle weakness
• frequent respiratory infections

Extreme vitamin D deficiency can lead to rickets, a bone condition that can cause growth abnormalities and joint deformities. Rickets is most likely to impact babies and young children of 6–23 months and adolescents ages 12–15 (17, 18).

Rickets refers to defective mineralization, or calcification, of bones before the closure of the epiphyseal plates. Epiphyseal plates, commonly known as growth plates, are sections of cartilage located at the ends of the long bones of children and teens.

Children and teens

Although the prevalence of vitamin D deficiency in children and teens varies by geographic region, studies estimate a prevalence rate of about 15% in children ages 1 through 11 and 14% in children and teens ages 12 through 19 (19).

Children and teens who have overweight or obesity are much more likely to be deficient in vitamin D than children who are considered to be at a healthy weight (19).

In younger children, vitamin D deficiency can cause a number of symptoms, including (1, 7):

• irritability
• developmental delays
• bone fractures
• slow growth
• muscle pain

It’s important to note that vitamin D deficiency may be more apparent in young children than adolescents, as many teens who are deficient are asymptomatic or have vague symptoms.

For example, adolescents may have pain in weight-bearing joints like the knees as well as pain in the back, calves, and thighs. They may experience pain when climbing stairs, when running, or when standing up from a squatting position (20).

The pain is typically non-radiating and accompanied by bone tenderness. Symptoms like facial twitching and spasms in the hands and feet are less common symptoms of vitamin D deficiency in adolescents.

If this deficiency goes undetected, it could lead to bone demineralization and fractures, convulsions, and damage to the heart (20).

Because vitamin D deficiency can also present with vague symptoms like pain, lethargy, and irritability, teens who have it could be misdiagnosed with conditions like depression or fibromyalgia (20, 21).

As mentioned, severe vitamin D deficiency could lead to rickets in children if left untreated. In adolescents, it can cause rickets or osteomalacia.

Rickets is defective mineralization or calcification of bones that occurs before the closure of the epiphyseal plates, or growth plates. In contrast, osteomalacia is a softening of the bones that occurs after the closure of the growth plates.

Growth plates typically close between ages 13 to 15 in girls and between the ages 15 to 17 in boys. This means that both rickets and osteomalacia can occur in teens, depending on their age and growth pattern (22).

Vitamin D symptoms can be vague. Infants may present with growth failure, irritability, lethargy, muscle weakness, and frequent respiratory infections, while teens may present with pain in weight-bearing joints like the knees, as well as pain in the back, calves, and thighs.

How is vitamin D deficiency in children and teens treated?

Treatment for vitamin D deficiency depends on age. It’s treated differently in infants than in older children and teens.

Your child’s healthcare professional will determine the most appropriate protocol for treating vitamin D deficiency. Their treatment plan may differ from the recommendations listed below due to factors like:

• underlying medical conditions
age
• deficiency severity

For example, the following are global recommendations for treating vitamin D deficiency rickets in infants and children (23):

• Under 3 months old: 2,000 IU (50 mcg) oral supplements daily for 3 months
• Infants between 2 and 12 months old: 2,000 IU (50 mcg) oral supplements daily for 3 months or a single dose of 50,000 IU (1,250 mcg)
• Children 12 months to 12 years old: 3,000–6,000 IU (75–150 mcg) oral supplements daily for 3 months or a single dose of 150,000 IU (3,750 mcg)
• Children over 12 years old: 6,000 IU (150 mcg) oral supplements daily for 3 months or a single dose of 300,000 IU (7,500 mcg)

After vitamin D levels have normalized, it’s recommended that babies under 12 months old receive a daily maintenance dose of 400 IU (10 mcg), while children 1 year or older receive a daily dose of 600 IU (15 mcg) (23).

It’s also recommended that children and teens with vitamin D deficiency rickets maintain a daily calcium intake of at least 500 mg per day.

In teens, vitamin D deficiency may be treated with 300,000 IU (7,500 mcg) given either as weekly doses or multiple daily doses, such as (20):

Other common treatment options for teens is an oral dose of 50,000 IU (1,250 mcg) vitamin D once weekly for 8 weeks or a mega dose of 300,000 IU (7,500 mcg) every 3 to 4 months (20).

After vitamin D levels have returned to an expected range, your teenager’s healthcare professional may recommend an appropriate daily dose to maintain healthy levels — for example, a daily maintenance dose of 1,500–2,000 (37.5–50 mcg) (20).

Keep in mind that treatment plans can vary significantly depending on the severity of the vitamin D deficiency, the child’s age, medical conditions, and more.

Your child’s physician will determine the best way to treat a vitamin D deficiency based on their needs and overall health. You should never try to treat a vitamin D deficiency without consulting your child’s healthcare professional.

Children, especially babies and younger children, are more at risk for developing vitamin D toxicity from inappropriate supplement doses.

While vitamin D toxicity is rare in the pediatric population, it can be life threatening. So, parents and caregivers should never give a child high dose vitamin D supplements unless prescribed by a healthcare professional (24).

If you’re concerned your child may be low or deficient in vitamin D, make an appointment with their pediatrician so they can undergo appropriate testing and get the right care.

How children can maintain optimal vitamin D levels

Remember, the only way to tell if your child is deficient in vitamin D is to have a healthcare professional perform a blood test.

If they are low or deficient in vitamin D, your child’s healthcare professional will recommend the most appropriate treatment based on their level of deficiency and other factors.

Once their vitamin D levels return to usual, your child’s healthcare professional may recommend a daily maintenance dose to maintain optimal levels. This dose will depend on your child’s age and other factors like:

• skin color
diet
• medication use
• medical diagnoses

In addition to supplements, there are certain foods that are high in vitamin D that can be added to kids’ diets to help maintain healthy vitamin D levels.

Kid-friendly foods that are high in this vitamin include (5):

• wild-caught salmon
• herring
• sardines
• egg yolks from pastured chickens or chickens fed vitamin D-fortified feed
• vitamin-D enriched foods like milk and yogurt

Also, letting your child play outside in the sun is a helpful way for them to maintain healthy vitamin D levels, though using appropriate sun protection is important.

Studies suggest that using sunscreen on children during the summer months allows enough sunlight to be received by the skin to maintain typical serum levels while still limiting the risk of sunburn (25).

Treatment for vitamin D deficiency depends on factors like age, the severity of the deficiency, underlying medical conditions, and more. Your child’s doctor will determine the best treatment protocol based on your child’s specific needs.

The bottom line

Vitamin D deficiency is common in all age groups, including children.

Symptoms related to this deficiency differ depending on a child’s age and are often vague, making it hard to detect without proper testing by a healthcare professional.

Treatment for vitamin D deficiency differs by age. For example, infants require lower doses of the vitamin compared with older children and teens.

Because vitamin D deficiency is common — especially in kids who have more body fat, certain medical conditions, and darker skin tones — it’s important to have your child’s vitamin D levels tested regularly.