The incorporation of red meat in higher-HEI diets supports brain-health critical nutritional adequacy, and gut microbial diversity

We evaluated whether red meat could be integrated into a high Healthy Eating Index (HEI) diet to improve brain health-critical nutrient adequacy without compromising diet quality, mental health, or gut microbiota. Using data from 3,643 adults in the American Gut Project, participants were stratified into four groups: high-HEI (≥ 80) with red meat (HH-R), high-HEI without red meat (HH-NR), low-HEI (< 80) with red meat (LH-R), and low-HEI without red meat (LH-NR). Both high-HEI groups maintained healthy BMI values regardless of red meat intake. HH-R had higher protein intake and lower carbohydrate intake, with saturated fat levels within recommended limits. Brain health-critical micronutrient adequacies (selenium, vitamin B12, zinc, calcium, vitamin D3, choline) were significantly higher in HH-R ( p  < 0.001). Higher HEI scores, irrespective of red meat consumption, were associated with reduced odds of depression (logOR= -2.22), PTSD (logOR= -3.80), and bipolar disorder (logOR= -5.90). Gut microbiota diversity and richness were highest in HH-R, with increased Bacteroides caccae (p _adj = 0.003) and Clostridium hathewayi (p _adj < 0.001), while HH-NR showed higher Bifidobacterium adolescentis and Bacteroides eggerthii (p _adj < 0.001). Therefore, these findings suggest that the inclusion of lean red meat in a high-HEI diet improves brain health-supporting micronutrient adequacy without adverse effects on mental health or microbial diversity.