WALNUT consumption as part of a healthy diet has been associated with increased levels of certain bacteria in the gut microbiome contributing to heart-health benefits and reducing the risk of heart disease.
Recent research at Penn State University, Pennsylvania, USA, has shown that eating walnuts daily in conjunction with a healthy diet exerts cardiovascular benefits. The researchers recruited 42 participants who were either overweight or obese and between the ages of 30 and 65. Two weeks prior to the start of the study the participants were placed on an average American diet (‘run-in’ diet) and were then randomly assigned to one of the three study diets. All diet groups included less saturated fats than the run-in diet. The first diet incorporated whole walnuts, the second the same amount of α-linolenic acid and polyunsaturated fatty acids without walnuts, and the last partially substituted oleic acid for the same amount of α-linolenic acid found in walnuts, without walnuts. In all three diets, saturated fats were replaced with walnuts or vegetable oil and the participants followed each diet for 6 weeks with a 1 week break between diet periods.
Fecal samples were collected 72 hours before participants finished the run-in diet and each of the three study diet periods to analyse gastrointestinal bacteria. Results showed that after the walnut diet, there were increased levels of gut bacteria that have been associated with health benefits such as eubacteria eligens and Butyricicoccus. Eubacterium were associated with changes in various measures of blood pressure, indicating that increased levels of eubacterium contribute to greater reductions in those risk factors. Furthermore, increased levels of Lachnospiraceae were linked to a significant decrease in blood pressure, total cholesterol, and non-high-density lipoprotein cholesterol. These finding imply that the cardiovascular benefits seen after the walnut diet are attributable to changes in the microbiome.
Assistant Prof Petersen, Penn State, concluded that: “Substantial evidence shows that small improvements in diet greatly benefit health. Eating two to three ounces of walnuts a day as part of a healthy diet could be a good way to improve gut health and reduce the risk of heart disease.”