Vitamin D deficiency affects over 1 billion individuals globally, making it a significant health concern that transcends borders.

This deficiency is prevalent in both developed nations like Australia and Canada, as well as in developing countries such as India and Japan, impacting all demographics, including children. In particular, a lack of vitamin D can hinder a child's growth, impair their immune system, and influence their mental well-being, highlighting the necessity for effective treatment.

This article will delve into the effects of vitamin D deficiency on children, outline the recommended daily intake for various age groups, and discuss treatment options available for infants, children, and adolescents.

Vitamin D Requirements for Infants, Children, and Adolescents

Vitamin D is essential throughout your life, starting from infancy and continuing into old age. This vital nutrient is necessary for maintaining optimal levels of calcium and phosphorus, supporting the development of immune cells, promoting bone mineralization, regulating inflammatory protein production, and much more.

The significance of vitamin D is amplified during infancy and childhood, as it plays a crucial role in the growth and development of the skeletal system. Insufficient or deficient levels of this vitamin can severely affect overall health due to its critical contributions to various bodily processes.

Despite ongoing discussions among experts regarding the adequacy of current vitamin D recommendations, the daily intake guidelines remain consistent for children, teenagers, adults, and those who are pregnant or breastfeeding. It is important to note that infants have lower vitamin D requirements compared to older children and adults. For infants, the term “adequate intake” (AI) is utilized instead of the more commonly known recommended dietary allowance (RDA) due to insufficient evidence to establish an RDA for this age group.

The AIs for infants are determined based on the amount of vitamin D necessary to maintain levels above 20 ng/mL (50 nmol/L) and support healthy growth. In contrast, the RDA represents the average daily intake required to meet the nutritional needs of nearly all healthy individuals.

The following table outlines the current daily intake recommendations for vitamin D for children in the United States:

It's worth noting that RDAs for vitamin D are expressed in both micrograms (mcg) and international units (IU), with 1 mcg of vitamin D equating to 40 IU. However, it is essential to acknowledge that not all experts are in agreement regarding these recommendations.

For instance, the Endocrine Society, a global medical organization, asserts that to maintain vitamin D levels above 30 ng/mL (75 nmol/L), adults may require at least 1,500–2,000 IU (37.5–50 mcg) of vitamin D daily. They also recommend that children and teenagers should aim for a minimum of 1,000 IU (25 mcg) per day. It is evident that many individuals, regardless of age, often do not obtain sufficient vitamin D through their diets, leading to a widespread deficiency.

Sources of Vitamin D

Only a select few foods are rich in vitamin D, including:

• trout
• salmon
• fortified milk
• certain egg yolks

This makes it challenging to meet daily vitamin D needs, particularly for children. While sunlight can help fulfill part of the daily requirement for this vitamin, the exact amount of sun exposure necessary to maintain optimal levels in both adults and children remains unclear. Factors such as the season, cloud cover, sunscreen application, and skin pigmentation can influence UV exposure and vitamin D synthesis in the skin.

Consequently, children residing in colder climates and those with darker skin tones are at a heightened risk of having insufficient vitamin D levels.

Are Certain Children More Vulnerable to Vitamin D Deficiency?

Some children face a greater risk of developing low vitamin D levels due to several factors, including:

• skin color
• body weight
• sunlight exposure

Children and teenagers with higher body fat percentages are more susceptible to vitamin D deficiency than their peers with standard body fat levels. Additionally, those with darker skin tones are significantly more prone to this deficiency. Research indicates that individuals with darker skin may require up to 15 times more sun exposure to synthesize the same amount of vitamin D as those with lighter skin.

Other factors that can increase a child's risk of vitamin D deficiency include:

• living in colder climates
• limited sun exposure
• taking specific medications, such as anticonvulsants
• having health conditions that affect vitamin D absorption or utilization, such as Crohn’s disease or cystic fibrosis

Vitamin D deficiency is prevalent across all age groups, including infants, children, and teenagers. However, certain individuals, particularly those with darker skin, higher body fat, and limited sun exposure, are more likely to experience this deficiency.

Understanding the Impact of Vitamin D Deficiency on Children: Symptoms and Signs

A healthcare professional can accurately diagnose vitamin D deficiency in children through a simple blood test. Similar to adults, a child is deemed deficient if their vitamin D levels are below 20 ng/mL (50 nmol/L). On the other hand, levels ranging from 21 to 29 ng/mL (52 to 72 nmol/L) indicate insufficiency.

While there is ongoing discussion about what constitutes an optimal vitamin D level, values exceeding 30 ng/mL (75 nmol/L) are generally accepted as sufficient. It is important to note that vitamin D insufficiency and deficiency can often go unnoticed because significant symptoms usually arise only when the deficiency becomes severe. Additionally, the symptoms can be nonspecific, which complicates the ability of parents and caregivers to recognize a deficiency.

This emphasizes the importance of having regular blood tests for vitamin D levels conducted by your child’s healthcare provider, particularly if your child is at an increased risk of developing a deficiency.

Infants

Globally, vitamin D deficiency is prevalent among infants, with rates varying from 2.7% to 45%. Infants under the age of two are particularly vulnerable to this deficiency due to their limited exposure to sunlight compared to adults.

Moreover, exclusively breastfed (or chestfed) infants who do not receive vitamin D supplements may not obtain sufficient amounts of this vital nutrient. To prevent vitamin D deficiency, health experts, such as the American Academy of Pediatrics, recommend that exclusively and partially breastfed infants receive a daily supplement of 400 IU of vitamin D starting in the first few days of life.

In cases where an infant develops a deficiency, the following health issues may arise:

• Seizures resulting from low calcium levels
• Impaired growth
• Irritability
• Lethargy
• Muscle weakness
• Increased susceptibility to respiratory infections

Severe vitamin D deficiency can lead to rickets, a bone condition that results in growth abnormalities and joint deformities. This condition predominantly affects infants and young children aged 6 to 23 months, as well as adolescents between 12 and 15 years old.

Rickets refers to improper mineralization or calcification of bones before the closure of the epiphyseal plates, commonly known as growth plates. These plates are segments of cartilage found at the ends of long bones in children and teenagers.

Older Children and Adolescents

The prevalence of vitamin D deficiency among children and teens can differ based on geographic location. Studies suggest an estimated deficiency rate of around 15% in children aged 1 to 11 and about 14% in those aged 12 to 19.

It is also observed that children and teens with overweight or obesity are significantly more likely to face vitamin D deficiency compared to those maintaining a healthy weight. In younger children, the deficiency can manifest through various symptoms, such as:

• Irritability
• Delays in development
• Bone fractures
• Slower growth rates
• Muscle pain

It's crucial to recognize that vitamin D deficiency symptoms may be more apparent in younger children than in teenagers. Many adolescents who are deficient might remain asymptomatic or exhibit vague symptoms. For example, they may experience discomfort in weight-bearing joints such as the knees, as well as pain in the back, calves, and thighs. This discomfort may become noticeable during activities like climbing stairs, running, or rising from a seated position.

The pain is generally non-radiating and may accompany tenderness in the bones. Rarely, symptoms such as facial twitching and spasms in the hands and feet can occur in adolescents. If vitamin D deficiency remains undetected, it could lead to severe complications like bone demineralization and fractures, convulsions, and potential cardiac issues.

As vitamin D deficiency can present with ambiguous symptoms such as fatigue, lethargy, and irritability, there is a risk of misdiagnosis in teens, with conditions like depression or fibromyalgia being mistaken for a nutritional deficiency. As previously mentioned, untreated severe vitamin D deficiency may lead to rickets in children and, in adolescents, it can result in either rickets or osteomalacia.

Rickets involves improper mineralization or calcification of bones prior to the closure of the growth plates, while osteomalacia refers to the softening of bones that occurs after these plates have closed. Growth plates usually close between the ages of 13 and 15 in girls and between 15 and 17 in boys, indicating that both rickets and osteomalacia can potentially affect teenagers, depending on their age and growth patterns.

Symptoms of vitamin D deficiency can be quite subtle. Infants may show signs such as impaired growth, irritability, lethargy, muscle weakness, and frequent respiratory infections, while teenagers may report discomfort in weight-bearing joints, along with pain in their back, calves, and thighs.

How is Vitamin D Deficiency in Children and Teens Treated?

Treatment for vitamin D deficiency varies significantly based on the individual's age, leading to distinct approaches for infants compared to older children and teenagers. To determine the most suitable treatment for your child, their healthcare provider will evaluate a range of factors, which may include:

• existing medical conditions
• age
• severity of the deficiency

For instance, here are some widely accepted global guidelines for managing vitamin D deficiency rickets in infants and children:

• Infants under 3 months: 2,000 IU (50 mcg) of oral supplements daily for a duration of 3 months
• Infants aged 2 to 12 months: 2,000 IU (50 mcg) of oral supplements daily for 3 months, or a single dose of 50,000 IU (1,250 mcg)
• Children aged 12 months to 12 years: 3,000–6,000 IU (75–150 mcg) of oral supplements daily for 3 months, or a single dose of 150,000 IU (3,750 mcg)
• Children older than 12 years: 6,000 IU (150 mcg) of oral supplements daily for 3 months, or a single dose of 300,000 IU (7,500 mcg)

Once vitamin D levels have normalized, it is advisable for babies under 12 months to receive a daily maintenance dose of 400 IU (10 mcg), while children aged 1 year and above should take a daily dose of 600 IU (15 mcg). Furthermore, it is essential for children and teens diagnosed with vitamin D deficiency rickets to maintain a daily calcium intake of at least 500 mg.

In adolescents, vitamin D deficiency can be treated with 300,000 IU (7,500 mcg) administered either as weekly doses or as several daily doses. For example:

Other frequently used treatment methods for teenagers include an oral dose of 50,000 IU (1,250 mcg) of vitamin D once a week for 8 weeks, or a mega dose of 300,000 IU (7,500 mcg) every 3 to 4 months. Once vitamin D levels have returned to the expected range, your teen’s healthcare provider may suggest an appropriate daily maintenance dose to sustain healthy levels, such as a daily intake of 1,500–2,000 IU (37.5–50 mcg).

Keep in mind that treatment strategies can differ greatly based on the severity of the vitamin D deficiency, the age of the child, and their overall health profile. It is crucial to consult with your child’s physician to determine the most effective way to address vitamin D deficiency tailored to their individual needs. Self-treatment without professional guidance is not advisable.

Particularly for children, especially infants and younger kids, there is a heightened risk of vitamin D toxicity from incorrect supplement dosing. While vitamin D toxicity remains rare in children, it can pose serious health risks. Therefore, parents and caregivers should only administer high-dose vitamin D supplements if prescribed by a healthcare professional.

If you suspect that your child may have low or deficient vitamin D levels, it is imperative to schedule an appointment with their pediatrician for proper testing and care.

How Children Can Maintain Optimal Vitamin D Levels

It is important to remember that the only definitive way to ascertain if your child is deficient in vitamin D is through a blood test conducted by a healthcare professional. Should they be found to have low or deficient levels, your child’s healthcare provider will recommend the most suitable treatment based on the severity of the deficiency and other influencing factors.

Once vitamin D levels stabilize, their healthcare provider may suggest a daily maintenance dose to uphold optimal levels, which will be contingent on your child's age and variables such as:

• skin pigmentation
• dietary habits
• medication usage
• existing medical conditions

Apart from supplements, incorporating foods rich in vitamin D into your child’s diet can also be beneficial for maintaining healthy levels. Some kid-friendly foods high in vitamin D include:

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

Encouraging your child to play outdoors in the sunlight is another effective strategy to help them maintain adequate vitamin D levels, though it is crucial to ensure they use appropriate sun protection. Studies have shown that applying sunscreen on children during summer months allows for sufficient sunlight exposure to the skin to sustain normal serum levels while mitigating the risk of sunburn.

The Bottom Line

Vitamin D deficiency is a widespread issue affecting individuals across all age groups, including children. The symptoms associated with this deficiency can vary significantly based on the child’s age and are often nonspecific, which makes early detection challenging without appropriate testing conducted by a healthcare professional.

When it comes to treatment, the approach to addressing vitamin D deficiency varies according to age. For instance, infants typically require lower dosages of this essential vitamin compared to older children and adolescents. Given the prevalence of vitamin D deficiency—particularly in children who have higher body fat percentages, specific medical conditions, or darker skin tones—it is crucial to monitor your child's vitamin D levels regularly through testing.