Genetic Variant Linked to Onion Preference Associated with Lower Blood Pressure and Reduced Type 2 Diabetes Risk

A new study published in BMC Medicine has found that a specific genetic variant in an olfactory receptor gene, OR2T6 (搜索)搜索该靶点, which predisposes individuals to enjoy onions, is associated with lower blood pressure and a reduced risk of type 2 diabetes (搜索)搜索该疾病. The international research effort, led by scientists at the Monell Chemical Senses Center查看公司主页 in Philadelphia, the National Institutes of Health, the University of Queensland, the University of Bristol, and the QIMR Berghofer Medical Research Institute, introduces a sophisticated new method for determining whether certain foods may be genuinely beneficial to health.

The study addresses a longstanding challenge in nutrition science: observational studies often find that people who eat more vegetables are healthier, but these individuals also tend to exercise more, smoke less, and have higher incomes, making it difficult to establish causation. Randomized controlled trials—the gold standard for establishing causality—are rarely feasible in dietary studies due to long follow-up periods, high costs, and logistical constraints.

"Long-term, randomized controlled trials are simply not feasible in nutrition, and the findings of observational studies—such as a recent study that found vitamin E supplements lower heart disease risk—are often not replicable through large-scale clinical trials. We used Mendelian randomization—genetic analysis—to address this challenge," said Danielle Reed, PhD, Monell Chief Science Officer and co-author of the study.

Harnessing the Genetics of Taste and Smell

Mendelian randomization leverages the natural randomness of genetic inheritance: the version of a gene a person inherits at birth is determined by chance, not by lifestyle or health status. By using genetic variants as proxies, or "instruments," for dietary habits, the researchers were able to test causal questions about food and health. They focused specifically on genes encoding taste and smell receptors in the mouth and nose.

"We wanted instruments that were biologically meaningful, rooted in the fundamental biology of how we experience food," Reed said. "Taste and smell genes gave us exactly that: a way into the causal question of diet and health that doesn't depend on people accurately remembering what they ate, or on the assumption that their diet has or hasn't been changed by disease."

The team screened over 1,200 genetic variants across 325 taste and smell receptor genes using data from the UK Biobank, a landmark study of nearly 500,000 British adults. They identified 268 genetic variants across 117 taste and smell receptor genes that were associated with preferences for 96 different foods, ranging from garlic and grapefruit to horseradish, broad beans, and aniseed.

Rigorous Validation Across Populations

The researchers confirmed their findings in a completely separate, younger cohort—the Children of the 90s study from Bristol, UK—and verified that the same genes also influenced how much of each food people actually consumed. They further ruled out genetic variants that might be confounded by wealth or social factors.

After this rigorous filtering process, 25 robust genetic instruments for 20 different foods remained. The standout finding centered on OR2T6 (搜索)搜索该靶点, an olfactory receptor gene linked to how much a person likes onions. This variant predicted onion liking in both older and younger adults, predicted onion consumption, and showed no associations with social deprivation or unrelated health conditions.

Quantifiable Health Benefits

Using the OR2T6 (搜索)搜索该靶点 variant as a genetic proxy for onion preference, the researchers tested whether a genetically driven tendency to eat more onions affects health outcomes. They found that people with the genetic variant linked to greater onion liking had, on average, lower systolic blood pressure (approximately 1.3 mmHg per point on the liking scale) and lower diastolic blood pressure (approximately 0.7 mmHg). They also had a roughly 14% reduced risk of developing type 2 diabetes (搜索)搜索该疾病.

Notably, there was no effect on body mass index, blood fats, or blood sugar levels, suggesting that the observed benefits are not simply a reflection of onion eaters being generally healthier people.

Biological Plausibility and Cautious Interpretation

Onions are rich in quercetin查看药品详情 and other compounds with known anti-inflammatory and cardiovascular properties, providing a plausible biological explanation for the findings. Previous laboratory and small human studies have hinted at onions' potential health benefits, but this new evidence leveraging genetics provides much stronger grounds for taking those effects seriously.

Despite the promising results, the study authors urge caution. "Our findings suggest that onion consumption may help lower blood pressure and reduce the risk of type 2 diabetes (搜索)搜索该疾病, but this study alone isn't enough to recommend that people eat more onions specifically for these purposes," said Daniel Liang-Dar Hwang, PhD, lead study author and genetic epidemiologist at the Institute for Molecular Bioscience at the University of Queensland.

A New Framework for Nutritional Epidemiology

By anchoring genetic instruments in the biology of taste and smell, the approach is more resistant to the confounding and reverse causation that have plagued nutritional epidemiology for decades. "What we've built is essentially a new way of asking whether a food is genuinely good for you," Reed said. "Previous methods often used statistical signals that turned out to be picking up on the fact that sick people change their diets, which sends the analysis in the wrong direction. Grounding the instruments in chemosensory biology helps avoid that trap."

The work was supported by the Australian Research Council Discovery Early Career Researcher Award, NHMRC Leadership Fellowship, the National Institute of Alcohol Abuse and Alcoholism, the Intramural Research Program of the National Institutes of Health, the National Institute on Deafness and Other Communication Disorders, the Rockefeller University Heilbrunn Nurse Scholar Award, the NIH Distinguished Scholars Program, the UK Medical Research Council and Wellcome, the University of Bristol, and the Monell Chemical Senses Center查看公司主页.