The practice of vegetarianism, rooted in religious and cultural traditions, has gained recognition for its potential health benefits, although concerns about nutritional deficiencies persist. Amidst its growing popularity, a study suggests that genetics might play a role in influencing one’s dietary choices, shedding light on the genetic factors that may steer individuals toward a vegetarian lifestyle.
The Study Overview
This study drew upon participant data from the UK Biobank (UKB), a comprehensive health research database housing half a million individuals aged 40-69. The UKB collected data through physical examinations, sample collections, and detailed questionnaires, which included inquiries about dietary habits to identify vegetarians.
The UKB, operating under the approval of the North West Multi-center Research Ethics Committee, allows researchers to utilize its data without requiring additional ethical clearance. All data remain fully anonymized, and participants initially provided electronic consent, with the option to opt out at any time.
Genotyping and quality control processes were applied to the ethnically diverse participant pool using the UK Biobank Lung Exome Variant Evaluation (UK BiLEVE) and UK Biobank Axiom Array (UKB Axio). Imputation was performed on genotyped data, yielding over 93 million genetic markers.
After additional in-house quality controls and stringent criteria, the study analyzed 340,754 samples, with 9,740,199 genetic variants considered for investigation.
Phenotype processing divided quality-controlled data into vegetarians and non-vegetarians based on responses from two distinct questionnaires. The analysis identified 5,324 participants as vegetarians and 329,455 as non-vegetarians.
Genome-wide analysis utilized the Scalable and Accurate Implementation of a GEneralized mixed model (SAIGE), accounting for factors such as age and sex. Further analyses employed the Functional Mapping and Annotation platform (FUMA).
Key Findings
In this study, vegetarians were defined as individuals who had abstained from consuming animal flesh or related products for at least one year. These individuals were identified through a touchscreen questionnaire, assessing their dietary habits over the past year, and a 24-hour recall questionnaire, detailing food intake from the previous day.
Vegetarians, in comparison to non-vegetarians, tended to be younger, predominantly female, exhibited lower body mass indices, and hailed from less affluent backgrounds. Genome-wide association studies (GWAS) for vegetarianism displayed a mild inflation, possibly due to case-control imbalances despite rigorous analytical measures.
A gene-property analysis pinpointed 30 general tissue types influenced by the phenotype, with notable activity observed in brain-related tissues. Several genes linked with vegetarianism were particularly active in the brain, and single nucleotide polymorphisms (SNPs) associated with vegetarianism also correlated with traits related to lipid metabolism and brain function.
One prominent SNP on chromosome 18 was identified, along with closely related SNPs within genes like RIO kinase 3 (RIOK3), NPC intracellular cholesterol transporter 1 (NPC1), required for meiotic nuclear division 1 homolog (RMC1), and transmembrane protein 241 (TMEM241). Notably, NPC1, associated with SNPs with high functional significance, plays a crucial role in intracellular cholesterol and glycolipid transport.
The disruptions in NPC1 function are responsible for most cases of Niemann-Pick disease type C, a condition characterized by cholesterol buildup in tissues, primarily affecting the nervous system. These findings suggest potential connections between vegetarianism, lipid metabolism, and their impact on brain activity.
In total, 202 significant variants associated with 11 genes were linked to vegetarianism. Further scrutiny using the FUMA platform identified 37 genomic risk loci for vegetarianism, connecting 842 SNPs and 59 genes to these regions.
This study provides valuable insights into the genetic factors that might influence an individual’s inclination toward a vegetarian diet, emphasizing the intricate interplay between genetics, dietary choices, and health outcomes. Further research in this domain promises to deepen our understanding of the genetic underpinnings of dietary preferences.