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Walnuts improve the microbiome and lipid markers

Traditional dietary recommendations to improve the microbiome center on fermented foods like sauerkraut and kimchi, and prebiotic foods like Jerusalem artichoke and avocados. Now we can add walnuts to the list.

Walnuts are a rich source of omega-3 fatty acids, antioxidants, and phytochemicals. Now it has been shown that they can improve gut microbiome composition and diversity, according to a recent randomized controlled trial reported at the American Heart Association meeting. Interestingly, these changes in gut flora may account for the effects of walnut consumption on reducing LDL cholesterol, triglycerides, and apolipoprotein B (also known as “apo B”, a protein that may better predict heart disease risk than traditional cholesterol measures).

The study included 204 healthy men and women randomized to an 8 week diet including one a half ounces of walnuts daily or an equal calorie nut-free control diet. Stool samples showed that the walnut-eating group developed larger quantities of bacteria like Ruminococcus and Bifidobacteria. These bacteria are known to produce beneficial compounds known as short-chain fatty acids, especially butyric acid, which feed the intestinal cells and reduce inflammation. In addition, potentially harmful species like Clostridium were decreased, compared with those on the control diet.

Secondary data looking at cholesterol revealed that LDL cholesterol fell by an average of 7.4 mg/deciliter after 8 weeks of walnut consumption; triglycerides fell by 5 mg/deciliter and apolipoprotein B also decreased by 6.7 mg/deciliter. All of these changes were statistically significant.

This human trial confirms earlier animal research showing that walnuts beneficially altered the gut microbial composition. Eating walnuts has also been associated with reduced cardiovascular disease risk, slower tumor growth in animals and improved brain health. We need more studies to look at the long-term effects on the microbiome of walnut consumption, but until then, walnuts offer a nutrient-rich addition to your diet that is likely to have beneficial effects on your microbiome and multiple different areas of health.


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