Wan and colleagues recently published their study in Gut examining the impact of fat on gut microbiota, the fecal metabolome, as well as cardiometabolic risk factors in a healthy young population living in China. The primary aim of this randomized controlled feeding trial was to determine if a low-fat diet was more effective than a high-fat diet in helping participants lose weight. Subjects were randomized into one of three isocaloric dietary interventions: low fat (20% fat, 14% protein, 66% carbohydrate), moderate fat (30% fat, 14% protein, 56% carbohydrate), and high fat (40% fat, 14% protein, 46% carbohydrate). Fiber provided in all diets was similar to baseline at 14 grams per day (low fiber). Subjects were followed for 6 months and stool was collected at baseline and at the end of the trial.
All groups lost weight, but the low-fat group lost the most. Interestingly, the study found that the high-fat diet led to unfavorable changes in the microbiota, the metabolome as well as pro-inflammatory markers, however, it is important to note that the type of fat the researchers modified in their dietary intervention was soybean oil, rich in omega 6 fatty acids or linoleic acid (LA). The researchers found increased levels of arachidonic acid (precursors of inflammatory compounds derived from LA) in the high fat group.
The results of this study are limited in terms of generalizability, and because the study was conducted in a young and healthy population, it is hard to say how these diet changes would affect other groups of people.
I will continue to recommend the Mediterranean-style eating pattern, which has been associated with favorable changes in the microbiota and metabolome as well as positive effects on health and wellness. A Mediterranean diet is rich in fiber, fruits, vegetables, nuts, seeds, whole grains, legumes, olive oil (high in omega 3 fatty acids), and encourages moderate to low intake of fish, dairy, and meat.
Kelly Issokson, MS, RD, CNSC
Registered Dietitian, Nutrition and Integrative IBD Program
Disclosures: Issokson reports no relevant financial disclosures.