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Research argues that heart health guidelines on saturated fat are outdated

New study rewrites decades of medical misunderstanding of saturated fat and heart disease
In 1900, infections were the top three causes of death. Between 1900 and 1940, public health infection control measures led to dramatic reductions in all-cause deaths in all age groups, and life expectancy steadily increased. Fewer deaths were attributed to heart disease in infants, children, and young adults, and many more people survived to middle and old age with proportionately more deaths attributed to heart disease rather than infection. Thus, there appeared to be an epidemic of heart disease in middle-aged and older men. However, fewer middle-aged and older men were dying prematurely, and most were dying from causes other than heart disease. (y = years). Credit: Nutrients (2024). DOI: 10.3390/nu16101447

Warnings against saturated fat on heart health need to be revisited as flaws were revealed in the seminal 1950s studies on which these warnings were based, according to new research coming out of the Ateneo de Manila University.

In 1953, spurred by an apparent surge in heart disease in the US, physiologist Ancel Keys published a study that introduced the “lipid-heart hypothesis.” He claimed without evidence that high saturated fat and cholesterol in the diet raise cholesterol levels in the blood and contribute to heart disease. He developed what is now known as the Keys equation, where he sought to mathematically predict serum cholesterol levels based on saturated fat and cholesterol intake.

However, Ateneo de Manila University professor and chemist Dr. Fabian M. Dayrit, and American physician Dr. Mary T. Newport, have recently called into question the lipid-heart hypothesis and the Keys equation in their review paper, titled “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 work is published in the journal Nutrients.

Newport and Dayrit pointed out that 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 argue that this misunderstanding has led to flawed dietary recommendations, including a disproportionate focus on heart disease at the expense of research into the role of trans-fats in cancer, obesity, and other metabolic disorders. These conditions have been steadily on the rise in the decades since Keys published his findings.

“Numerous observational, epidemiological, interventional, and autopsy studies have failed to validate the Keys equation and the lipid-heart hypothesis. Nevertheless, these have been the cornerstone of national and international dietary guidelines,” the researchers said in their paper.

The study highlights that trans-fats, commonly found in processed foods, are strongly linked to heart disease. These industrial fats were widely consumed during the twentieth century but ignored in dietary guidelines that were based on Keys’ claims.

It also critiques 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.

In conclusion, Dayrit and Newport argue that dietary guidelines based on Keys’ lipid-heart hypothesis are outdated and not supported by scientific evidence. They also underscore the need to distinguish between different types of fats and take a more nuanced approach to dietary recommendations.

More information:
Mary T. Newport et al, The Lipid–Heart Hypothesis and the Keys Equation Defined the Dietary Guidelines but Ignored the Impact of Trans-Fat and High Linoleic Acid Consumption, Nutrients (2024). DOI: 10.3390/nu16101447

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Ateneo de Manila University

Citation:
Research argues that heart health guidelines on saturated fat are outdated (2024, October 22)
retrieved 26 October 2024
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