Dietary fiber may protect against development of asthma

Consuming a high-fiber diet protects against the development of asthma, according to a study recently published in Nature Communications.

Asthma remains a highly prevalent disease in the Western World. The reason behind this high prevalence is poorly understood. “Understanding and addressing the reasons underlying the increase in prevalence may help to reduce the rates of asthma in the future,” lead study author Alison Thorburn, PhD, an immunologist and microbiologist from Monash University, Victoria, Australia, recently told Medical Economics via email.

“To date, the prevailing explanation has been ‘the hygiene hypothesis,’ which suggests that the high prevalence of asthma is due to a decline in family size and improved hygiene," Thorburn said. "At the same time we must consider the role of diet. Interestingly, the nutritional transition that occurred in the Western World since the 1960s correlates with the increased prevalence of asthma. This made us ask the question: ‘What is it about the Western diet that has led to the increased prevalence of asthma?’”

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Many studies implicate obesity, as well as a high-fat, low-fruit and vegetable diet with higher prevalence of asthma, according to Thorburn. “On the other hand, a Mediterranean diet, which is high in fruit and vegetables, is associated with lower prevalence of asthma. Interestingly, the consumption of dietary fiber is reduced in severe asthmatics. These and other data suggest that the diet - particularly dietary fiber - and the gut microbiota may play an important role in the development of asthma.”

In the study, Thorburn and her colleagues utilized animal models of asthma and showed that the mice that were fed a high-fiber diet were protected against the development of asthma. In addition, they showed that when pregnant mice ate a high-fiber diet, their offspring were protected against the development of asthma.

Thorburn and colleagues then analyzed blood from pregnant women and found that high-fiber consumption was associated with increased levels of the anti-inflammatory molecule acetate. They then found that mothers with high acetate levels had reduced risk of their children developing asthma.

“Fiber protects both yourself and your offspring against the development of asthma,” says Thorburn. “Fiber is particularly important for supporting the growth of bacteria in the gut that produces acetate, which helps regulate the immune response. Knowing this, physicians may play a key role in reducing the rates of asthma and other inflammatory diseases.”

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The study goes on to show that acetate affected the expression of genes in the offspring involved in inflammation, so that they were less likely to get asthma after they were born.

“The mechanism underlying these findings involves increasing T regulatory cell number and function through epigenetic mechanisms, which enhance immune regulation to prevent inflammation.

“This information is pertinent for physicians because they can use this evidence to educate their patients on the importance of consuming adequate amounts of dietary fiber,” Thorburn says. “In doing so, physicians have the potential to reduce the development of asthma and other inflammatory diseases.”