A recent study has uncovered a surprising link between cooking garlic and onions at high temperatures and the production of trans fats, a major culprit behind cardiovascular diseases.
This study, conducted by a research team headed by Dr. Masaki Honda of Meijo University in Japan, was featured in the January 2025 issue of the international academic journal Food Research International.
The World Health Organization (WHO) estimates that trans fatty acids (TFAs) claim over 278,000 lives globally annually. The WHO advises keeping TFA intake below 1% of daily calories to combat this.
Trans fatty acids are found in fried fast foods, margarine, butter, oil, biscuits, and cakes. They are mainly created during the hydrogenation process of vegetable oils but can also be formed during home cooking.
Dr. Honda’s team delved into how compounds like isothiocyanates and polysulfides affect the transformation of unsaturated fatty acids (UFAs) into their trans counterparts during cooking. They used lab techniques and real-world cooking simulations to get the whole picture.
The researchers also explored whether antioxidants like α-tocopherol could help reduce this unwanted transformation.
The study’s findings demonstrated that sulfur compounds found in vegetable oils considerably accelerate heat-induced trans-isomerization of UFAs when cooked at temperatures higher than 140 degrees. Antioxidants considerably decrease the isomerization of unsaturated fatty acids but do not prevent polysulfide-induced isomerization.
When you’re sautéing garlic and onions in vegetable oil at high temps, you might be unknowingly whipping up a batch of trans fats.
Cooking with sulfur-rich ingredients could ramp up your trans fat intake without realizing it.
“We need to rethink our everyday cooking habits to minimize trans fat formation,” Dr. Honda warns. “Be extra cautious when working with ingredients naturally high in sulfur compounds.”
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