Step aside vitamin C! New research suggests that daily vitamin D supplement that may help prevent the flu, particularly in kids and teens.
We know that we’re more likely to get sick in the winter, and we also know that we get vitamin D primarily from sun exposure. Is this a coincidence? One theory behind the seasonality of the flu is that lower levels of vitamin D during the winter lead to lower immunity. Indeed, research has shown at least two ways in which Vitamin D boosts our immune systems. First, it enhances the strength of our white blood cells, whose primary function is to fight off invaders — such as flu viruses. Second, it has anti-inflammatory properties, which means that it can lessen symptoms when you have been infected with a virus. Children are especially at risk for seasonal flu because their immune systems are less mature, and because flu can spread around a crowded classroom with ease.
In this study, 334 Japanese schoolchildren aged 6 to 15 were divided into two groups. One group received a 1,200 IU vitamin D supplement daily for four months (December to March), while the other group received a placebo daily. Both groups were assessed for flu symptoms during the four-month study period. Since regular vitamin D supplementation for three months is shown to stabilize vitamin D blood levels, the study’s four-month duration would presumably be long enough to observe a potential protective effect of the vitamin. And that’s apparently what the researchers saw: by the end of the four months, there were 42 percent fewer cases of seasonal flu in the children receiving the vitamin supplement compared to those on placebo. Furthermore, children with a previous diagnosis of asthma were 83 percent less likely to have an attack if they were taking the vitamin D supplement compared to asthmatic children taking the placebo. This observation is consistent with the findings of a recently study we covered suggesting that vitamin D can help prevent asthma attacks.
As always, caution should be taken when interpreting these results. The parents were instructed to bring the pill bottles to every follow up clinic visit so that the remaining pills could be counted. This was how adherence to the program was measured instead of taking blood samples and analyzing for vitamin D level. This is significant because that means there is no biological proof that the children in the test group had higher blood levels of vitamin D than the placebo group. It should also be noted that this study’s dose of 1,200 IU Vitamin D exceeds the adequate intake for children currently established by the Institute of Medicine (200 IU). However, experts widely regard this recommended level to be too low, and the American Academy of Pediatrics (AAP) advises at least 400 IU daily for infants, children and adolescents. Furthermore, daily doses up to 2000 IU are considered to be perfectly safe by the Institute of Medicine for children aged 1 and older.
While getting a flu shot is still the best insurance against getting the flu, maybe popping a daily vitamin D supplement is another weapon we have in our battle to stay healthy this winter.