As the weather warms, avoiding the flu may not be your top concern. Nevertheless, researchers are already investigating ways to prepare for next season, finding in a recent animal study that a certain dietary fiber may help protect against the flu. For the study, which was published in Immunity, researchers fed mice a low-fiber diet supplemented with either cellulose (control), a fiber that is mostly non-fermentable by intestinal bacteria, or inulin, a fiber that is highly fermentable by intestinal bacteria. The by-products of inulin fermentation are known to promote healthy immune function. Then, the researchers infected the mice with the flu virus. Seven days later, they tested the animals’ lung function and markers of immune function. They found that, compared with the animals on the cellulose-supplemented diet, the animals on the inulin-supplemented diet had a higher survival rate due to a more balanced immune response to the flu. Specifically:
The cellulose-fed mice experienced a harmful, excessive immune response causing inflammation and tissue damage in their lungs, while the inulin-fed mice experienced a strong anti-viral immune response with milder inflammation and less damage to their lung tissue.
The mice fed the inulin-supplemented diet had increased populations of beneficial intestinal bacteria and higher blood levels of immune-enhancing fermentation by-products.
This study suggests that the highly fermentable fiber inulin may help fight the flu, but more research is needed to confirm this benefit in humans. In the meantime, dietary fiber in general may support our health in other ways, by improving weight management and lowering blood pressure, among other things. So, don’t skimp on high-fiber foods like vegetables, fruits, legumes, and whole grains. And if you’d like to get more inulin into your diet, look to chicory root, Jerusalem artichoke, banana, onion, and garlic.