Low Vitamin A, C Intake Tied to A...( But British team says findings don't ...),Health

But British team says findings don't prove cause and effect

THURSDAY, April 16 (HealthDay News) -- People who don't get enough of the antioxidant vitamins A and C in their diet may be at increased risk for asthma, British researchers say.

The pooled results of 40 studies conducted between 1980 and 2007 showed that people with asthma had a significantly lower dietary intake of vitamin A than those without the disease. The average intake among those with asthma was 182 micrograms a day, which is between a quarter and a third of recommended daily intake.

The review authors also found that people with severe asthma had a significantly lower intake of vitamin C (about half the recommended daily intake) than those with mild asthma. In addition, low circulating levels of vitamin C in the blood and lower dietary intake of foods containing vitamin C were associated with a 12 percent increased risk of asthma.

There was no association between vitamin E intake and asthma risk, but blood levels of vitamin E were much lower among people with severe asthma than in those with mild asthma. Those with severe asthma had an average vitamin E intake of 2 milligrams/day, which is 20 percent lower than the daily recommended amount, the review authors said.

These findings don't prove cause and effect, but they do challenge a study published last year that found no association between antioxidants and asthma risk, said Dr. Jo Leonardi-Bee, of the division of epidemiology and public health at the University of Nottingham in the United Kingdom, and colleagues.

"Overall, our findings from [the current] systematic review and meta-analysis indicate that low levels of vitamin C intake, and to a lesser extent vitamin A, are consistently associated with asthma risk to a degree that, if causal, would be sufficient to be clinically relevant," they concluded.

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