Numerous studies have linked fried food to an increased risk of cardiovascular disease. Trans fatty acids — a type of “unhealthy” fat — are usually to blame. A new study suggests that cooking food at high temperatures — like roasting or deep-frying — might cause the release of toxic chemicals that could heighten your risk of heart disease.

When food is prepared at temperatures above 150 degrees Celsius, or 302 degrees Fahrenheit, its chemical structure changes, releasing toxins that include trans fatty acids, according to researchers from the University of Edinburgh. The team said fried food was “particularly problematic” because the oils break down and form trans fatty acids.

The team reviewed studies that investigated the effects of the contaminants on humans and animals — including possible links to cardiovascular disease. Specifically, the researchers wanted to understand why people of certain ethnicities or cultures are more prone to heart disease. They suspected cooking methods are part of that reason.

For instance, frying or roasting foods is common in South Asian countries, leading to higher levels of trans fatty acids. The effect is especially prominent when frying oils are reused. Heart disease rates are lower in China, where food is prepared through braising, steaming or boiling. The study showed these lower-heat cooking methods don’t create such elevated levels of toxins.

The researchers say they don’t know why some ethnic groups are more prone to heart disease. They hope their findings can help reduce heart disease and related complications among at-risk cultures within a generation.