If you enjoy the scent of garlic and onions sizzling in oil, a recent study from Japanese researchers may make you reconsider how you cook these kitchen staples. The research indicates that cooking garlic and onions in vegetable oil at high temperatures could generate harmful trans-fatty acids (TFAs), which may negatively impact your heart health.
What are TFAs and Why Should You Care?
TFAs are unhealthy fats that can accumulate along the walls of arteries, restricting blood flow and increasing the risk of heart disease and heart attacks. While we often associate TFAs with processed foods, this study suggests you could be creating them right at home while cooking.
Unsaturated fatty acids (UFAs), typically considered healthy, can undergo a chemical transformation called trans-isomerisation when heated to temperatures above 150°C. This process turns UFAs into TFAs, making them harmful to health.
How Garlic and Onions Play a Role
Researchers from Meijo University focused on how sulfur-containing compounds in garlic, onions, leeks, and scallions could accelerate the formation of TFAs when cooked at high temperatures. They found that cooking these sulfur-rich vegetables in oils like soybean and olive oil could significantly increase the production of TFAs.
According to Dr. Masaki Honda, who led the study:
“Cooking polysulfide-rich vegetables such as garlic and onions in vegetable oil at high temperatures can generate TFAs. The study demonstrates that garlic and onions significantly promote the trans-isomerisation of UFAs.”
The Science Behind It
To simulate real cooking scenarios, the team tested various ingredients like garlic, onions, leeks, cabbage, broccoli sprouts, and oils such as soybean and olive oil. They discovered that temperatures above 140°C were key for this chemical reaction to occur. Even antioxidants like alpha-tocopherol (a form of Vitamin E) couldn’t completely prevent the formation of TFAs, though they did help reduce some of the isomerisation.
Should You Be Concerned?
The researchers caution that while TFAs are released in small amounts during typical cooking, cooking with high-sulfur vegetables such as garlic and onions may increase your intake of TFAs. However, the release of these harmful fats under normal cooking conditions is minimal.
Why Does This Matter?
TFAs are a significant health concern globally. According to the World Health Organization (WHO), over 278,000 deaths annually are linked to TFAs, which is why the WHO recommends limiting TFA consumption to less than 1% of your daily energy intake.
Cooking Tips for the Health-Conscious
- Avoid high temperatures: Try not to heat oils beyond 150°C.
- Opt for medium heat: Sauté garlic and onions at moderate temperatures instead of deep frying.
- Incorporate antioxidants: Add antioxidant-rich ingredients to your meals to help minimize TFA formation.
While you don’t have to abandon garlic and onions entirely, being mindful of cooking temperatures can help you enjoy their flavor without compromising your health.
