Warnings about saturated fat's impact on heart health need to be revisited as flaws were revealed in the 1950s studies that shaped these thoughts, according to new research from the Ateneo de Manila University.

In 1953, physiologist Ancel Keys published a study linking high saturated fat and cholesterol intake to increased blood cholesterol levels and heart disease, despite lacking solid evidence.

He introduced the Keys equation, aiming to mathematically predict cholesterol levels based on saturated fat and cholesterol intake.

Ateneo de Manila University professor and chemist Dr. Fabian M. Dayrit and American physician Dr. Mary T. Newport, have recently called into question such claim and the Keys equation in their review paper entitled, "The Lipid-Heart Hypothesis and the Keys Equation Defined the Dietary Guidelines but Ignored the Impact of Trans-Fat and High Linoleic Acid Consumption."

The researchers pointed out that the Keys erroneously conflated the saturated fats found in meat and dairy with the harmful industrial trans-fats commonly used in margarine and shortening. Keys also included coconut oil in the warning.

They argued that this has led to flawed dietary recommendations that overly emphasize heart disease while neglecting the roles of trans-fats in conditions like cancer and obesity, which have been on the rise since Keys' time.

"Numerous observational, epidemiological, interventional, and autopsy studies have failed to validate the Keys equation and the lipid-heart hypothesis," the researchers said in their paper.

"Nevertheless, these have been the cornerstone of national and international dietary guidelines,” they added.

Their study highlighted that trans-fats, commonly found in processed foods, are strongly linked to heart disease.

These industrial fats were widely consumed during the 20th century but ignored in dietary guidelines that were based on Keys’ claims.

The researchers also critiqued the unregulated promotion of polyunsaturated fats — specifically linoleic acid, commonly found in soybean oil and other vegetable oils — which can lead to an imbalance in omega-6 and omega-3 fatty acids and increase the risk of chronic inflammation and other health issues.

Dayrit and Newport argued that dietary guidelines based on Keys’ lipid-heart hypothesis were outdated and not supported by scientific evidence.

They also stressed the importance of distinguishing between different types of fats to develop more informed dietary recommendations.