Dr's Casebook: Your gut flora loves walnuts

Dr Keith Souter writes: Fascinatingly, research suggests that the benefits come about because walnuts feed and encourage good gut bacteria, so it is a good thing to keep the gut microflora happy.

Each time you eat a high-fat meal, fat molecules trigger an inflammatory reaction that reduces the elasticity of your arteries. They stiffen and become less able to expand when you exercise. Over time, this repeated damage contributes to hardening of the arteries and, ultimately to heart disease.

The inner lining of the arteries produces a substance called nitric oxide that is needed to keep the arteries flexible. When we eat high-fat meals, the fat molecules temporarily halt the production of nitric oxide, which prevents the arteries from increasing blood flow in response to physical activity.

One of the nutrients found in walnuts is arginine, an amino acid used by the body to produce nitric oxide. Walnuts also contain antioxidants and alpha-linolenic acid (ALA), a plant-based omega-3 fatty acid, which also helps nitric oxide production.

Current medical research shows that if we can maintain good gut bacteria it reduces the risk from many conditions. Nutritional research has shown that eating walnuts daily as part of a healthy diet is associated with increase in certain bacteria that can help promote health.

By putting volunteers on different diets and comparing their levels of gut bacteria, scientists found that a walnut-containing diet was associated with higher proportions of Eubacterium eligens, a bacterium that is associated with lower risk of high blood pressure. Also, there were higher levels of Lachnospiraceae, which also is known to help lower blood pressure and cholesterol. Lastly, they seemed to correlate with higher levels of Roseburia, which are associated with gut lining protection.

So, in addition to taking foods like live yoghurt that give you good bacteria, walnuts feed and help the good bacteria to thrive. So, as long as you are not allergic to nuts, to get these health benefits simply replace your comfort snacks with a couple of ounces of walnuts a day.