Vitamin D3 supplements may be as effective as flu vaccine at reducing the risk of flu during the winter, particularly in school children, a new Japanese study suggests.
The study showed among school children taking 1200 IU per day of vitamin D3 supplements, 10.8 percent of children had influenza A compared to 18.6 percent of controls. This means that vitamin D3 reduced the risk of the flu by 48 percent, which could be comparable to the efficacy of flu vaccine.
The randomized, double-blind, placebo-controlled trial was conducted by Mitsuyoshi Urashima, MD, PhD, from Jikei University School of Medicine, Minato-ku, in Tokyo, Japan and published online in the March 10, 2010 issue of the American Journal of Clinical Nutrition.
For the trial, Urashima and colleagues compared 167 children taking 1200 IU per day of vitamin D3 supplements with 167 children who did not take the supplement to evaluate the difference in the incidence of influenza A between Dec 2008 and March 2009.
Vitamin D is important for innate immunity against microbes and viruses because vitamin D helps produce antibacterial peptides which fight viruses and microbes and prevent infections including flu, according to Dr. John Cannell, MD, one of the most knowledgeable vitamin D experts and director of vitamin D Council, a non-profit organization that aims to educate the public about the importance of the sunshine vitamin.
However, trials on the effect of vitamin D on risk of flu are rare.
“To our knowledge, no rigorously designed clinical trials have evaluated the relation between vitamin D and physician diagnosed seasonal influenza,” Urashima and colleagues write in their report.
According to the researchers, vitamin D supplement was particularly effective in children who had not been taking other vitamin D supplements and in those who started nursery school after age 3 years. The reduction in the flu risk among those groups was 67 percent!
In addition, vitamin D supplements help prevent asthma attacks . Of children with diagnosed asthma, 2 children taking vitamin D supplementation experienced asthma attacks compared to 12 children in the placebo group. The risk for asthma attacks in the vitamin D group was reduced by 83 percent.
Dr. Cannell says in his newsletter last year that two physicians, one in Wisconsin and the other in Georgia, reported to him that few of their patients/residents who maintained a high level of serum vitamin D acquired swine flu last year while many of other patients and medical workers who did not take vitamin D to maintain high vitamin D levels got swine flu and other flu viruses.
Epidemiological studies have revealed a strong association between vitamin D deficiency and high incidence of flu. The new trial adds to a growing body of evidence to demonstrate that this vitamin D helps prevent infections.
Recently, Carsten Geisler and colleagues at the University of Copenhagen have confirmed that vitamin D plays an important role in activating immune defenses against infectious diseases like flu.
They explained the role vitamin D plays in the immune responses as follows:
First when the naive T cell recognizes foreign invaders like bacteria or viruses with T cell receptor (TCR), it sends activating signals (1) to the vitamin D receptor gene. The VDR gene then starts producing DVR protein, which binds vitamin D in the T cell (3) and becomes activated. Then the vitamin D bound and activated DVR gets into the cell nucleus and activates the gene for PLC-gamma1 (5), which in turn produces PLC-gamma1 protein (6) and “the T cells can get started”.
Here are some basics about vitamin D:
Vitamin D deficiency: Vitamin D deficiency is common, particularly in those who stay indoors all the time and people with dark skin. This condition is more common in the winter and in people who live in the Northern hemisphere. Normally, exposure to sunlight at noon time for 15 to 20 minutes would trigger production of sufficient vitamin D. According to Dr. John Cannell, the normal range of 25(OH)D should be 50 to 80 ng per mL blood.
Vitamin D deficiency symptoms: Unlike vitamin C, vitamin D deficiency does not result in obvious symptoms. Some people with the condition may experience bone pain and muscle weakness. Because of this, vitamin D deficiency is determined by the measured serum level of this vitamin.
Consequences of vitamin D deficiency: It has been clear that vitamin D deficiency plays an important role in many diseases including heart disease, hypertension, arthritis, chronic pain, depression, inflammatory bowel disease, obesity, premenstrual syndrome, muscular weakness, fibromyalgia , Crohns disease, multiple sclerosis, autoimmune illness, and cancer, according to Vitamin D Council. If you suffer one or more diseases listed here, you are likely vitamin D deficient.
Vitamin D foods: Only a few foods contain vitamin D. Oily or fatty fish like salmon is a good source of vitamin D. Cod liver oil produced today contains some, but not much vitamin D. In addition, cod liver oil contains high levels of vitamin A, which can sabotage the work of vitamin D, making it a less reliable source. Vitamin D is supplemented in some foods and beverages such as milk, orange juice, cereal and others. However, the level in the fortified foods is generally very low; one needs to drink 20 glasses of milk to get sufficient amounts of vitamin D.
Vitamin D levels and overdose: It is recognized that up to 10,000 IU per day is safe. Dr. Cannell says one needs at least 5,000 IU per day from all sources to meet his physiological needs.