How your diet transforms your brain
The brain-gut connection has profoundly revolutionized our understanding of the interplay between diet, cognitive function, and emotional well-being. Recent research has emphasised the powerful impact of our nutritional choices on critical aspects of brain health, such as learning, memory, and mental resilience. For instance, sugar consumption is linked to reduced cognitive abilities, while eating saturated fats correlates with reduced memory and learning. In addition, an unhealthy diet is a risk factor for a wide range of psychiatric disorders, including depression, anxiety, sleep problems, and Alzheimer’s disease.
Large-scale exploration of food preferences
This study involved 181,990 participants (mean age 70.7 ± 7.7 years and 57.08% women) recruited from the UK Biobank, a long-term prospective biobank study. Researchers determined participants’ food preferences using 140 food and beverage items. Through principal component analysis and hierarchical clustering, they identified four distinct food preference patterns in participants: starch-free or reduced-starch diets (18.09%), vegetarian diets (5.54%), high-protein and low-fibre diets (19.39%), and balanced diets (56.98%).
Next, they investigated how these diets affect mental health, cognitive function, blood and metabolism biomarkers, brain magnetic resonance imaging, mental disorders, genome-wide association analysis, and gene expression. Mental health assessments focused on anxiety symptoms, depressive symptoms, mental distress, psychotic experiences, self-harm, and trauma. Cognitive functions such as fluid intelligence, pair-matching, reaction time, and symbol-digit substitution were also tested.
Dietary effects on the brain
Participants with a balanced diet had better mental health and higher cognitive functions than those in the other three subgroups. Participants with vegetarian or high-protein and low-fibre diets showed higher levels of anxiety and depression compared to individuals with a balanced diet. Vegetarians also had a greater risk of developing eating disorders. Additionally, those on starch-free or reduced-starch and high-protein and low-fibre diets had an increased risk of stroke.
Participants with different diets displayed distinct brain MRI patterns that may shape mental health and cognitive functions. Those with a high-protein and low-fibre diet had less grey matter in the post-central gyrus region of the brain, and vegetarians had more grey matter in the thalamus and precuneus regions compared to individuals with a balanced diet.
Finally, genome-wide association analyses identified 16 genes that differed between participants with a high-protein and low-fibre diet and those with a balanced diet. Those 16 genes are involved in mental health and cognitive processes.
Not so fast
The four dietary patterns identified among participants were related to food preferences rather than actual food consumption; subtle differences could influence the observed relationships. Everyone enrolled in this study was healthy, introducing a selection bias that may have impacted the results. Tryptophan with omega-3 and omega-6 fatty acids, which are directly involved in mood regulation as components for serotonin synthesis, are missing from these dietary patterns. In addition, mental health factors were assessed using simplified measures.
Why does it matter?
Understanding how food choices impact our health, particularly brain health, is essential to creating dietary strategies that encourage eating nutritious foods that support better brain function. These findings suggest that teaching healthy eating habits at a young age could promote better food choices and support brain health throughout life.
Take home messages
2. Diet influences the brain’s ability to change and adapt, which can lead to structural changes that affect mental health and cognitive function.
3. Genetic associations with dietary patterns suggest that specific genes may promote health and support brain function.
Guest author: Solène Grosdidier, PharmD, PhD
Reviewer: Barbara Fahmy, MS OTR, MPA
This article was written as part of a series of ‘journal club’ summaries for Scientific Writers Ltd and is based on the following publication.
First Author: Zhang R, et al.
Journal: Nature Mental Health
Date online: 01 April 2024
