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Influenza reduced by 1.7 with 1200 IU D3, also reduced related asthma by 6X – RCT May 2010

Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren.

Am J Clin Nutr. 2010 May;91(5):1255-60. Epub 2010 Mar 10.
Urashima M, Segawa T, Okazaki M, Kurihara M, Wada Y, Ida H.
Division of Molecular Epidemiology, Jikei University School of Medicine, Nishi-shimbashi 3-25-8, Minato-ku, Tokyo 105-8461, Japan. urashima at jikei.ac.jp

BACKGROUND: To our knowledge, no rigorously designed clinical trials have evaluated the relation between vitamin D and physician-diagnosed seasonal influenza.
OBJECTIVE: We investigated the effect of vitamin D supplements on the incidence of seasonal influenza A in schoolchildren.

DESIGN: From December 2008 through March 2009, we conducted a randomized, double-blind, placebo-controlled trial comparing vitamin D(3) supplements (1200 IU/d) with placebo in schoolchildren. The primary outcome was the incidence of influenza A, diagnosed with influenza antigen testing with a nasopharyngeal swab specimen.

RESULTS: Influenza A occurred in 18 of 167 (10.8%) children in the vitamin D(3) group compared with 31 of 167 (18.6%) children in the placebo group [relative risk (RR), 0.58; 95% CI: 0.34, 0.99; P = 0.04].

The reduction in influenza A was more prominent in children who had not been taking other vitamin D supplements (RR: 0.36; 95% CI: 0.17, 0.79; P = 0.006) and who started nursery school after age 3 y (RR: 0.36; 95% CI: 0.17, 0.78; P = 0.005).
{64% reduction in influenza A by those taking 1200 IU of vitamin D compared to children not taking any vitamin D}

In children with a previous diagnosis of asthma, asthma attacks as a secondary outcome occurred in 2 children receiving vitamin D(3) compared with 12 children receiving placebo (RR: 0.17; 95% CI: 0.04, 0.73; P = 0.006).

CONCLUSION: This study suggests that vitamin D(3) supplementation during the winter may reduce the incidence of influenza A, especially in specific subgroups of schoolchildren. This trial was registered at https://center.umin.ac.jp as UMIN000001373. PMID: 20219962


Report on the trial

Vitamin D3 Supplements in Winter May Help Protect Against Influenza A, Laurie Barclay, MD


April 2, 2010 — Vitamin D3 supplementation during the winter is linked to lower incidence of influenza A, particularly in specific subgroups of schoolchildren, according to the results of a randomized, double-blind, placebo-controlled trial reported online in the March 10 issue of the American Journal of Clinical Nutrition.

"To our knowledge, no rigorously designed clinical trials have evaluated the relation between vitamin D and physician diagnosed seasonal influenza," write Mitsuyoshi Urashima, MD, PhD, from Jikei University School of Medicine, Minato-ku, in Tokyo, Japan, and colleagues. "We investigated the effect of vitamin D supplements on the incidence of seasonal influenza A in schoolchildren."

Schoolchildren were randomly assigned to receive vitamin D3 supplements (1200 IU/day) or placebo from December 2008 through March 2009. The main endpoint of the study was the incidence of influenza A, diagnosed by influenza antigen testing (rapid influenza diagnostic test [RIDT]) on a nasopharyngeal swab specimen.

In the vitamin D3 group, 18 (10.8%)of 167 children had influenza A, as did 31 (18.6%) of 167 children in the placebo group (relative risk RR, 0.58;95% confidence interval [CI], 0.34 - 0.99; P = .04). The association of decreased influenza A incidence with vitamin D supplements was stronger in children who had not been taking other vitamin D supplements (RR, 0.36; 95% CI, 0.17 - 0.79; P = .006) and in those who started nursery school after age 3 years (RR, 0.36; 95% CI, 0.17 - 0.78; P = .005).

Among children with a previous diagnosis of asthma,

  • 2 children in the vitamin D3 group vs
  • 12 children in the placebo group

had asthma attacks as a secondary outcome (RR, 0.17; 95% CI, 0.04 - 0.73; P = .006).

"This study suggests that vitamin D3 supplementation during the winter may reduce the incidence of influenza A, especially in specific subgroups of schoolchildren," the study authors write. "....Moreover, asthma attacks were also prevented by vitamin D3 supplementation."

Limitations of this study include small sample size, lack of data on serum 25-hydroxyvitamin D or on urinary calcium data, and lack of information on the presence or development of influenza A antibodies.

"Future studies should include a larger sample size of schoolchildren without comorbidities to determine the optimal dose and duration of vitamin D supplementation by measurement of serum 25-hydroxyvitamin D, serum and urinary calcium, and titers of antibody to influenza levels," the study authors conclude.

Jikei University School of Medicine supported this study. The study authors have disclosed no relevant financial relationships.


See also VitaminDWiki

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Natural News - Sept 2010

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