Sources and Testing of Vitamin D

Maintaining healthy vitamin D levels is vital at every stage of life, but it becomes especially crucial during childhood and infancy. This fat-soluble vitamin plays a key role in developing strong bones, supporting immune function, and even influencing mood and energy levels.

In today’s modern lifestyle—with indoor schooling, increased screen time, and changing dietary habits—many children and infants are unknowingly falling short of this essential nutrient. Here’s what every parent needs to know about ensuring their child gets enough vitamin D.

Vitamin D helps the body absorb calcium and phosphorus—two minerals critical for healthy bones and teeth. In children, a deficiency can lead to rickets, a condition characterized by soft, weak bones. But its role doesn’t end there. Vitamin D also:

Ensuring adequate vitamin D intake is a combination of smart sun exposure, nutrition, and, in some cases, supplementation. Here's how you can approach each:

Our skin naturally produces vitamin D when exposed to ultraviolet B (UVB) rays from the sun. For most people, 10–30 minutes of direct sun exposure a few times a week—on the face, arms, and legs—is enough. However, this can vary depending on:

In infants, limited sun exposure is often advised to protect their sensitive skin. As a result, diet and supplements become even more important.

While few foods naturally contain vitamin D, some are fortified or naturally rich in it:

For children who are picky eaters or follow a plant-based diet, getting enough vitamin D from food alone can be difficult.

In many cases, vitamin D supplements are necessary—especially for children with low sun exposure or dietary limitations. Doctors often recommend vitamin D3 (cholecalciferol) over D2, as it’s more effective at raising and maintaining blood levels.

Always consult a pediatrician before starting supplements, especially if your child is on medication or has underlying health conditions.

Despite best efforts, deficiency can go unnoticed until symptoms arise. Regular testing can help detect low levels early and prevent long-term complications.

This is the most commonly used and accurate test. It measures total vitamin D levels in the body from all sources—sunlight, food, and supplements. Results are typically categorized as:

Routine testing is especially advised for:

This test measures the active form of vitamin D in the blood. It’s less commonly used but may be ordered for individuals with kidney problems or other complex medical conditions affecting vitamin D metabolism.

Vitamin D isn’t just a seasonal concern or a dietary footnote—it’s a cornerstone of long-term health for growing children. Ensuring adequate levels through a balanced mix of sun exposure, smart nutrition, and, when needed, supplements can make all the difference.

If you’re unsure about your child’s vitamin D status, don’t wait for symptoms to appear. A simple blood test can provide clarity and help you take action early—giving your child the strong foundation they deserve.