Researchers studied 140 foods. Only one was consistently linked to lower blood pressure

A new study suggests that a genetic preference for this popular allium could be linked to better heart health markers.

Key Points

• New research found that a genetic tendency to prefer onions was associated with lower blood pressure and a reduced risk of type 2 diabetes, though the findings need further study.
• Researchers developed a framework using taste and smell genes to better understand how food preferences may influence chronic disease and help distinguish cause from correlation.
• Among the 140 foods analyzed, onions were the only food whose results remained consistent across multiple analyses, including in a younger age group.

Love the scent and taste of a freshly cut onion atop your salad, in your sandwich, or, heck, just plain on its own? That could be a great sign for your blood pressure.

In June, researchers led by a team at the University of Queensland published their study in BMC Medicine on the association between loving onions and blood pressure. More specifically, the team examined taste and smell genes to determine whether specific foods are linked to specific diseases — work they say could help scientists better understand how diet drives chronic disease in the future.

"Determining if a specific food causes or is linked to a disease is a significant challenge in nutrition epidemiology," Dr. Liang-Dar Hwang of UQ's Institute for Molecular Bioscience said in a statement. "We have built a framework guided by taste and smell genes to help scientists better understand how diet contributes to chronic disease."

Hwang further explained that taste and smell are major biological drivers that influence what we eat. Understanding how those genes shape our food choices could help researchers "cut through the complexity of distinguishing causation from correlation," he said.

To examine the link between some people's taste for onions and their blood pressure readings, the team used data from the UK Biobank database and developed a genetic framework based on more than 1,200 genetic variants across 325 taste and smell receptor genes, assessing their associations with preferences for and intake of 140 foods.

The work drew on data from more than 160,000 adults ages 37 to 73, making the findings fairly robust. The team then assessed those results against a separate group of 25-year-olds from the Avon Longitudinal Study of Parents and Children to confirm that the genetic patterns held across age groups.

Related: How to Chop an Onion Without Crying, According to Experts

They also combined the findings with a statistical approach called Mendelian Randomization, which uses natural genetic differences between people to help scientists distinguish cause from correlation in health research. This helps them by essentially standing in for the kinds of controlled experiments that are nearly impossible to run in nutrition science, where studies rely on volunteers to self-report their dietary habits, which are often unreliable.

"MR nutrition research is expanding, with studies clarifying causal effects of coffee, alcohol, and milk intake," Hwang said. "Despite these advances, MR examinations of food and dietary patterns remain challenging due to difficulties in identifying valid genetic markers that reliably reflect what people eat."

Among all the foods tested, onions were the standout. While other foods had strong genetic associations, onions were the only ones whose results held up across every check, including replicating the finding in a younger age group and aligning with how much onion people actually ate.

The research found that a genetic predisposition to liking onions was associated with lower systolic and diastolic blood pressure and a reduced risk of type 2 diabetes.

The bottom line on onions and blood pressure

While the new findings are intriguing, they don't change current advice for managing blood pressure. Health experts still recommend eating a diet rich in fruits, vegetables, whole grains, beans, nuts, and lean proteins while limiting sodium, added sugars, and saturated fat. The Dietary Approaches to Stop Hypertension (DASH) eating plan is one of the most well-studied diets for lowering blood pressure and emphasizes a variety of vegetables — including onions — as part of an overall healthy eating pattern. If you already enjoy onions, they're a flavorful way to add more vegetables to your meals, but they shouldn't replace blood pressure medication or other proven lifestyle habits.

Of course, the researchers aren’t saying you should run to the grocery store right now to stock up on a bushel of onions. Instead, they explained, their work is intended to demonstrate that the framework works. They still need to replicate these findings in a larger, more diverse group before drawing any final conclusions. Still, it's a start.

Related: Your Sliced Onions Are Spoiling Faster Than They Should — Here's the Fix

"Our research shows taste and smell genes are promising tools for studying links between diet and disease and can help strengthen evidence about cause and effect in nutrition research," Hwang said. "This is important as we need better ways to understand how diet influences diseases such as diabetes, heart disease, and cancer."

Reviewed by

Lauren Manaker MS, RDN, LD, CLEC: Lauren is an award-winning registered dietitian and three-time book author, with more than 22 years in the field.

Read the original article on Food & Wine