A gem: Vitamin D and Flu Season

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Modern kids tend to spend much less time outdoors than kids did a few generations ago – and that change could make a particularly big difference in the winter months, with today’s kids often not making the amount of vitamin D they need for optimum health. Some have observed that kids who don’t get enough vitamin D may get 3 times as many colds and flus than others in their class. Could simply taking a vitamin D supplement slash respiratory infections in kids?

A careful 2010 study suggests the answer is yes.

More than 300 school children were given either 1200 IU of vitamin D3 or a placebo for 4 months during the winter, in a forward-looking, randomized double-blind trial. To be precise with the results, researchers who didn’t know which group each child was in tested the kids for laboratory-confirmed influenza A using nasal swabs. The results were impressive.

Taking the vitamin D supplement cut the rate of influenza A by 1/3. Among kids who hadn’t been taking vitamin D in a multivitamin or by itself before the study, taking the vitamin D supplement made an even bigger difference, dropping the rate of influenza A by 2/3.

In the absence of time in the sun, it typically takes 1000 IU a day of vitamin D3 to get optimal blood levels. Most multivitamins have no more than 400 IU vitamin D (and it’s often just D2) – but kids shouldn’t take more than one serving of a multivitamin daily because of all the other ingredients. A glass of milk has about 100 IU, but kids shouldn’t drink 6 to 10 glasses a day. Playing in the sunshine with the skin exposed can give at least 20,000 IU.

Personally, I also take vitamin D dots most days, unless I’m sure I’ve had plenty of time in the sun.

One little change could make a big difference in your child’s school year – and yours.

M. Urashima, T. Segawa, M. Okazaki, M. Kurihara, Y. Wada, and H. Ida Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren Am. J. Clinical Nutrition, May 1, 2010; 91(5): 1255 - 1260
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Comments

Anonymous's picture

Vitamin D

Dr. Greene, How much of Vitamin D should a 9 mth old baby have daily? any special brand?

Reply

Vitamin D and Babies

For kids under one year, the AAP recommends getting 400 IU of vitamin D supplementation every day, unless they are getting at least 32 ounces a day of formula (which already has vitamin D supplementation added in). This amount seems about right to me, based on today's best available evidence, though it wouldn't surprise me if we learn in the future that more would be better.
Anonymous's picture

Unsure

My pediatrician said that my 6-year-old daughter doesn't need a supplement if she drinks milk. Are there harmful side effects of too much D if I decide to supplement in the winter?

Reply

Milk and Vitamin D

Kids who drink 32 ounces a day of milk, they are getting the minimum recommended amount of vitamin D. The AAP recommends supplementing with an additional 400 IU of vitamin D for all kids over 12 months old who are not getting 32 ounces a day of milk (and only recommends 16 to 24 ounces of milk a day, depending on age, so presumably this would be most kids). The kids in the above study who had the big benefit were getting a supplement of 1200 IU a day. In general, the biggest benefits seem to come between 1000 and 2000 IU daily, a level that is quite safe. I usually suggest a supplement of 1000 IU, which ensures that kids get plenty, and still isn't too much if they drink milk and even if they get a multivitamin with 400 IU of vitamin D. Of course, sunshine can be an even better way to get vitamin D. Admittedly, it can be tough to get kids outside enough between 10 am and 3pm - especially in the winter. Here's tips for how much it would take: http://www.drgreene.com/blog/2008/11/15/getting-enough-sunshine-vitamin