Does Your Kid Need More Vitamin D in Winter?

The winter season brings plenty of opportunity for snuggling up indoors with your little one, but the chilly weather and snowy winds also mean less time outdoors.

Vitamin D is a powerful micronutrient, responsible for bone and teeth health, muscle and nerve function, immune system support, and even mood regulation. In children, this essential nutrient also helps prevent rickets, a rare soft-bone disease caused by severe vitamin D deficiency.

Most vitamin D intake in children and adults comes from sun exposure, which is abundant during the summer but often lacking during the winter. While adults and children can also get vitamin D from certain foods, and babies can get it from formula, supplementation may be recommended in certain cases.

We’ll break down how much vitamin D babies and children actually need at different ages, which foods naturally contain, or are fortified with, vitamin D, and when supplements may be helpful or necessary.

Vitamin D for Kids: What Does Vitamin D Do for Babies?

The main purpose of Vitamin D for babies is that it helps their tiny bodies absorb calcium and phosphorus from what they consume, be it solid food, breast milk, or formula. These minerals help growing bones develop properly, allow muscles to contract and relax as they should, and support the signals that travel between the brain and nerves.

For babies and children, these minerals are essential for healthy development, especially as they go through phases of rapid growth, and without enough vitamin D, the body cannot absorb them properly.

There are certain circumstances that make it harder for children to receive enough vitamin D. These include being born prematurely, living in northern latitudes, being exclusively breastfed, and having darker skin pigmentation. So, if children meet any of these criteria, extra precautions should be taken to ensure they are getting enough vitamin D.

Rickets is a serious outcome of a prolonged vitamin D deficiency in little ones. The risk can be heightened by certain conditions, especially those that can influence how the body absorbs vitamin D, like celiac disease, inflammatory bowel disease, cystic fibrosis, or certain kidney problems.

Beyond rickets, vitamin D deficiency symptoms in babies can also include developmental delays, muscle weakness, and increased vulnerability to infections. An adequate vitamin D intake can prevent these outcomes, allowing little ones to grow big and strong during their formative years.

Which leads us to the main question presented in the article: Does your baby need more vitamin D in the winter?

How Babies Get Vitamin D in Winter Naturally?

While sunlight is the body’s primary natural source of vitamin D, shorter days, weaker sun rays, and limited skin exposure make dietary sources far more important during this season.

Before babies can consume solids, they get most of their vitamin D from fortified infant formula and supplement drops for breastfed infants. Once solids are introduced, around the 6-month mark, parents can include vitamin D-rich foods in their child's diet.

Some of the foods richest in vitamin D are fatty fish such as salmon, tuna, and swordfish, as they store vitamin D in their fat. Cod liver oil is another highly concentrated natural source and has been used for generations to help prevent vitamin D deficiency.

However, because cod liver oil also contains high levels of vitamin A, it should only be used for babies and young children under medical guidance.

Another lesser-known natural source of vitamin D is sun-dried or UV-exposed mushrooms. When mushrooms are exposed to sunlight during growth or drying, they produce vitamin D in a way similar to human skin. While mushrooms are not usually a major part of an infant’s diet, they can be incorporated into family meals for older babies and toddlers.

In addition to naturally occurring sources, there are also vitamin D–fortified foods. In many countries, cow’s milk and some plant-based milk alternatives are fortified with vitamin D, as well as certain brands of orange juice.

While the aforementioned vitamin D foods for kids can help boost intake during the winter months, remember to only introduce them when age-appropriate. While these natural and fortified food sources can support vitamin D intake, they rarely provide enough on their own to meet an infant’s daily needs during winter because babies eat small portions and have limited dietary variety.

For this reason, dietary sources are best viewed as a helpful complement to a vitamin D–fortified formula or supplementation.

Why Winter Increases the Risk of Vitamin D Deficiency in Kids?

Unlike many nutrients that come primarily from food alone, vitamin D is largely synthesized in the skin when it is exposed to ultraviolet B (UVB) rays from the sun.

Experts agree that there are various factors that can influence how much vitamin D humans get through sun rays alone. As stated in this study, "Sunlight exposure-induced vitamin D synthesis is influenced by many important variables including the season of the year, time of day, latitude, altitude, air pollution, skin colour, age, area of skin exposed, clothing habits, sunscreen use, sunlight passing through glass and plastic, and aging."

Season plays a particularly important role because, during the winter months, the sun sits lower in the sky. This lower angle significantly reduces the amount of UVB radiation that reaches the Earth’s surface, especially in northern regions. Paired with the fewer outdoor activities, shorter daylight hours, and bundled clothing, it is easy to see why there are plenty of barriers to getting adequate sun exposure during the colder months.

Vitamin D Needs for Breastfed Babies in Winter

If you’re wondering how much vitamin D for children and babies is needed, the answer depends on a child’s age, how they’re fed, and their overall nutritional intake.

For example, while breast milk is perfectly designed to meet most of a baby’s nutritional requirements, it naturally contains very small amounts of vitamin D.

This means that even babies who are exclusively breastfed may not receive enough vitamin D from breast milk alone, regardless of how nutritious the mother’s diet is.

Health authorities in many countries recommend that vitamin D for breastfed babies be given through a daily vitamin D supplement of 400 IU starting soon after birth and continuing until your little one hits their first birthday. The most common form of supplementation comes in vitamin D drops for breastfed babies. These are easy to administer and generally regarded as safe.

Vitamin D Needs for Formula-Fed Babies in Winter

Formula-fed babies generally receive more vitamin D from their diet than breastfed babies because infant formula is fortified with vitamin D by design.

In most cases, babies who consume approximately 32 ounces (about 1 liter) of vitamin D–fortified formula per day will meet their daily vitamin D requirements without the need for additional supplementation.

However, not all formula-fed babies consistently drink this amount, especially younger infants or babies who are combination fed. Babies who drink less than the recommended volume of formula may still need a vitamin D drops for babies to bridge the gap.

Vitamin D Supplement for Babies: Are They Safe?

Vitamin D supplements for kids and babies are widely considered safe when used as directed.

Most vitamin D supplements for little ones come in liquid form and are designed to provide the recommended daily dose in just one drop or a small measured amount, making them easy to administer.

Directions for vitamin D baby drops should be followed, as safety concerns typically arise only when it's given in excessive amounts over long periods. For this reason, it is also best to avoid combining multiple vitamin D sources without guidance.

If you are administering vitamin D drops for kids or babies, it is best to consult your pediatrician for guidance.

Conclusion: Should You Increase Vitamin D Dose for Kids During Winter?

For most babies and children, the recommended daily dose of vitamin D does not need to increase in winter, as long as they are consistently meeting established intake guidelines.

The standard recommendations are designed with seasonal changes in mind, accounting for reduced sun exposure during colder months. Rather than increasing the dose, the focus should be on ensuring consistency by making sure vitamin D supplements are given daily and that dietary sources are reliably included when age-appropriate.

Answering Your Questions

Below, we’re answering some of the most common concerns about vitamin D intake for babies.

How Do Babies Born in Winter Get Vitamin D?

Newborns are not exposed to direct sun, and winter UVB rays are too weak in many regions to support vitamin D production in the skin during the winter. Breast milk naturally contains very little vitamin D, so breastfed babies are generally recommended to receive a daily vitamin D supplement beginning shortly after birth. Formula-fed babies can meet their needs through fortified formula, but only if they are consuming enough volume.

Do Babies Get Enough Vitamin D from Sunlight in Winter?

In most cases, babies do not get enough vitamin D from sunlight during the winter months. The sun sits lower in the sky, which significantly reduces the UVB rays needed for vitamin D synthesis, particularly in northern climates. Beyond that, cold weather means babies are covered in layers, hats, and blankets, leaving very little skin exposed.

Pediatric sun-safety guidelines also recommend avoiding direct sun exposure for young infants. Because of these factors, healthcare providers do not recommend relying on sun exposure alone to meet a baby’s vitamin D needs during this season.

What Are the Symptoms of Low Vitamin D in Babies During Winter?

Vitamin D deficiency in babies can be difficult to spot early on, as symptoms are often subtle or absent at first. Over time, low vitamin D levels may affect growth and bone development, leading to softer bones, delayed physical milestones, or reduced muscle tone. Some babies may also seem more prone to infections. In more severe or prolonged cases, deficiency can result in rickets, a condition that causes weakened bones and skeletal changes.