People with asthma tend to eat low levels of two key vitamins, A and C, researchers warned today.
Researchers said the link would be “clinically relevant” if the low levels of vitamins contributed to asthma.
Another possibility is that some people with asthma have restricted diets because of the link between the disease and allergy.
The researchers at Nottingham University, UK, set out to test the conclusions of a study last year when researchers concluded there was no link between vitamins and asthma.
Writing in the journal Thorax, researchers said they had found 40 studies of the issue in the last 30 years.
They found that people with severe asthma consumed about half the recommended daily amount of vitamin A – and all patients, on average, had reduced levels of vitamin A.
People with low levels of vitamin C were also 12 per cent more likely than others to have asthma.
And people with severe asthma also consumed less vitamin E than people with mild asthma.
Researcher Dr Jo Leonardi-Bee writes: “Overall, our findings from 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.”
Thorax 2009; doi 10.1136/thx.2008.101469
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