Red meat linked to better brain health and gut microbes

A large-scale study of more than 3,600 people shows that red meat, when eaten as part of a balanced diet, can enhance brain-supporting nutrients like B12 and zinc without disrupting gut microbes or raising mental health risks.

Study: Red meat consumption in higher healthy eating index diets is associated with brain health critical nutritional adequacy, and fecal microbial diversity. Image credit: Katarzyna Hurova/Shutterstock.com

A recent study published in Scientific Reports investigated whether red meat intake in low and high healthy eating index (HEI) diets is associated with fecal microbial diversity composition and brain health-critical nutritional adequacy.

Diet has a crucial yet underrecognized role in mental health. A balanced diet with optimal levels of essential micronutrients, such as zinc, iron, folate, and vitamins B12 and D, is consistently associated with a lower risk of anxiety, cognitive decline, and depression. Deficiencies in these micronutrients disrupt neurogenesis, signaling that regulates mood, cognition, and metabolic pathways. Red meat is a significant source of micronutrients.

Red meat has faced scrutiny due to associations with cancer and cardiovascular disease. Nevertheless, studies have often failed to account for diet quality and differentiate unprocessed from processed meat. High-HEI diets are linked to a reduced risk of mental health disorders; however, whether red meat in HEI-matched diets improves micronutrient adequacy and supports mental health or fecal microbial diversity has yet to be evaluated.

About the study

In the present study, researchers explored the associations of red meat in low and high-HEI diets with micronutrient adequacy and fecal microbiota composition. They used data from the American Gut Project (AGP), which recruited participants in the United States (US) and internationally. Participants provided fecal samples and completed metadata questionnaires.

Dietary intake information was collected using the food frequency questionnaire. Diet quality was assessed using the 100-point HEI, comprising adequacy components (whole grains, total fruits, total protein foods, and plant/seafood proteins) and moderation components (added sugars, sodium, refined grains). DNA was extracted from fecal samples.

The V4 region of the 16S rRNA was amplified and sequenced. Mann-Whitney U-test and t-test were used to evaluate differences between dietary groups. Shannon diversity index was used to examine α-diversity; Bray-Curtis distance and Jaccard index were used to assess β-diversity. Linear discriminant analysis was performed to evaluate differential taxonomic abundance.

Findings

The study used data from 3,643 participants from the AGP and stratified them into four groups based on their red meat intake and HEI score. These groups were high-HEI with red meat (HH-R), low-HEI with red meat (LH-R), high-HEI without red meat (HH-NR), and low-HEI without red meat (LH-NR), with 319, 2,121, 325, and 878 participants, respectively. The HH-R group was marginally older than the HH-NR group. Similarly, the LH-R group was older than the LH-NR group.

Further, HH-R participants showed a slightly higher mean body mass index (BMI) than HH-NR subjects (23.8 vs 23.0), although both remained in the healthy BMI range. Likewise, the LH-R group had a higher mean BMI than the LH-NR group. Of note, high-HEI groups had a lower BMI than low-HEI groups. Further, macronutrient profiles were distinct between HH-NR and HH-R groups, while energy intake did not differ. On the other hand, the LH-R group had significantly higher energy intake than the LH-NR group.

Total carbohydrate intake was lower in HH-R and LH-R groups compared to HH-NR and LH-NR groups. Protein intake was higher in LH-R and HH-R groups compared to LH-NR and HH-NR groups. Notably, dietary fiber intake was below adequate levels in all groups. In both low- and high-HEI groups, red meat consumers consistently had higher intakes of certain brain health-critical micronutrients than non-consumers.

Intake levels of vitamin B12, zinc, selenium, calcium, vitamin D, choline, and iron in red meat consumers exceeded those of non-consumers. In contrast, folate intake was lower in red meat consumers than in non-consumers. Notably, while vitamin D intake was significantly higher in red meat consumers, it was below the recommended levels in all groups. Similarly, calcium intake was below the recommended levels, with the HH-R group approaching the threshold.

Despite elevated intakes of specific micronutrients among red meat consumers, consumption was below the tolerable upper intake level for nearly everyone. Higher HEI scores were inversely associated with the prevalence of virtually all neurodevelopmental and mental health disorders evaluated, including depression, bipolar disorder, and migraines. Significant inverse associations were also found for attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder. Further, the HH-R group exhibited the highest phylum diversity, while the LH-NR group had the lowest.

There were no differences in α-diversity measures between high-HEI groups. Conversely, the LH-R group had significantly higher α-diversity than LH-NR. There were no significant differences in β-diversity. However, differences in the relative abundance of individual species were evident; the HH-R group showed higher relative abundance of Clostridium hathewayi and Bacteroides caccae, and the HH-NR had higher abundance of Bacteroides eggerthii and Bifidobacterium adolescentis. The study also reported shifts in numerous other bacterial taxa, including reductions in some Blautia, Roseburia, and Veillonella species among red meat consumers, as well as increases in Collinsella aerofaciens.

Conclusions

Red meat intake within a high-HEI diet was associated with a modestly higher BMI but still within a healthy range and was not linked to adverse changes in fecal microbiota. Instead, it was associated with improved micronutrient adequacy.

Both high-HEI groups had favorable macronutrient profiles, with red meat contributing to improved nutritional adequacy. Higher HEI was associated with a lower prevalence of neurodevelopmental and mental health disorders, regardless of red meat intake, with the high-HEI diet preserving a favorable fecal microbial profile.

The authors caution that the cross-sectional design, self-selected sample, and potential reverse causation limit causal interpretation. They also disclosed that the National Cattlemen’s Beef Association funded the study, though they had no role in study design or analysis.

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