It’s winter: Are children getting enough Vitamin D?

January 13, 2021
Laird Harrison

Contemporary PEDS Journal, Vol 38 No 1, Volume 38, Issue 01

How changing seasons affect children’s nutrition.

Most pediatricians have no trouble recommending healthy diets for their patients. However, as the days grow shorter and colder, children’s nutritional needs can change in ways that not everyone takes into account. Exposed to less sunlight, children may not make enough vitamin D. Natural production of melatonin shifts. As everyone spends more time indoors, influenza and upper respiratory infections become more common. Fresh fruits and vegetables may be harder to find. And in 2020, the rising incidence of COVID-19 has added a new risk to consider.

Human beings evolved outdoors eating fresh foods, and vitamin D deficiency may have resulted from our switch to living indoors and eating processed food. Considerations about supplementation with this nutrient start before conception and continue throughout a lifetime.

It’s not clear yet whether supplementing the diets of breastfeeding mothers can provide adequate vitamin D to their infants. Due to the risk of skin cancer, the American Academy of Pediatrics (AAP) recommends against sun exposure for infants. That leaves vitamin D supplements given directly to the breastfeeding infant as the best option.

Children aged 1 year and older may get enough vitamin D in their diets. Natural sources of vitamin D in food include salmon (wild is better than farmed), canned sardines, canned tuna, canned mackerel, and shiitake mushrooms. Most milk and some other foods are fortified with this nutrient. If, however, children aren’t getting enough vitamin D through food, they may need supplements, especially in winter, says Dr Cora Collette Breuner, professor of adolescent medicine at the University of Washington in Seattle, and a member of the American Academy of Pediatrics (AAP) Council on Integrative Health. “In areas where there is not a lot of sunshine and children have a lactose intolerance or they’re super picky eaters, and they won’t consume milk or calcium-containing vegetables, or they don’t eat fish, what do you do in those families? I believe it’s appropriate to supplement vitamin D and calcium.”

There is little risk of over-supplementing with vitamin D, and the AAP recommends that infants aged younger than 1 year take a supplement of 400 IU/day of vitamin D. The RDA is 600 IU for children aged 1 year and older.1

The best documented consequence of vitamin D deficiency in children is rickets. Many studies have also linked the deficiency to an increased risk of respiratory tract infections including influenza, and even COVID-19. Although preliminary trials have suggested that vitamin D supplements can reduce the risk of some of these infections, the evidence is not yet strong enough to result in recommendations.2 The evidence for other supplements in preventing or treating respiratory tract infections has also not risen to the level where strong recommendations can be made, though the data for zinc is strong, Breuner says.

With less sunlight, patterns of natural melatonin production shift as well, Breuner says. This may be a consideration when children are taking melatonin for sleep disorders. Some research has explored the use of melatonin as a treatment for seasonal affective disorder as well. However, the AAP currently recommends melatonin only as a short-term therapy for sleep disturbances while the underlying causes of the problem—such as poor sleep hygiene—are addressed.2

Pediatricians should investigate their patients’ lifestyle and supplements before making recommendations, Breuner says. “People self-medicate their children all the time,” she says. “They don’t know what to do to prevent their kids getting COVID, not getting enough sleep, not eating organic foods. Parents just throw up their hands and say, ‘We’ll give them a multivitamin and we’re good.’” In her experience, parents of children with complex medical needs are even more likely to use alternative or complementary medicine, typically without telling their pediatrician.

Parents may feel especially inclined to hand their kids a bottle of vitamins in the winter in northern latitudes, when the selection of fresh fruits becomes less appealing. The 2017-2018 National Health and Nutrition Examination Survey, showed that 23.8% of children and teenagers were taking multivitamins.3

The problem with this one-size-fits-all approach is that it doesn’t take into consideration what else a child may be consuming. Often children taking multivitamins still end up deficient in some nutrients while exceeding recommended levels of others. That’s why Breuner and the academy take a “less is more” approach when it comes to most supplements. Breuner also cautions against extrapolating from the research on adults. “The premise of pediatrics is they’re not little adults, so you can’t do that,” she says.

References

1. HealthyChildren.org. 2016. Vitamin D: On The Double. Accessed December 11, 2020. https://www.healthychildren.org/English/healthy-living/nutrition/Pages/Vitamin-D-On-the-Double.aspx#:~:text=All%20non%2Dbreastfed%20infants%2C%20as,a%20supplement%20containing%20that%20amount

2. Esparham, A., 2020. Melatonin And Children’s Sleep. [online] HealthyChildren.org. Accessed December 1, 2020. https://www.healthychildren.org/English/healthy-living/sleep/Pages/Melatonin-and-Childrens-Sleep.aspx

3. Stierman B, Mishra S, Gahche JJ, Potischman N, Hales CM. Dietary Supplement Use in Children and Adolescents Aged ≤19 Years — United States, 2017–2018. MMWR Morb Mortal Wkly Rep 2020;69:1557–1562.

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