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Published: 13 July 2023

Linolic Acid: A Narrative Review of the Effects of Increased Intake in the Standard American Diet and with Chronic Disease

Abstract

The intake of linoleic acid (LA) has increased dramatically in the standard American diet. LA is generally promoted as supporting human health, but there exists controversy regarding whether the amount of LA currently consumed in the standard American diet supports human health. The goal of this narrative review is to explore the mechanisms that underlie the hypothesis that excessive LA intake may harm human health. While LA is considered to be an essential fatty acid and support health when consumed in modest amounts, an excessive intake of LA leads to the formation of oxidized linoleic acid metabolites (OXLAMs), impairments in mitochondrial function through suboptimal cardiolipin composition, and likely contributes to many chronic diseases that became an epidemic in the 20th century, and whose prevalence continues to increase. The standard American diet comprises 14 to 25 times more omega-6 fatty acids than omega-3 fatty acids, with the majority of omega-6 intake coming from LA. As LA consumption increases, the potential for OXLAM formation also increases. OXLAMs have been associated with various illnesses, including cardiovascular disease, cancer, and Alzheimer’s disease, among others. Lowering dietary LA intake can help reduce the production and accumulation of OXLAMs implicated in chronic diseases. While there are other problematic components in the standard American diet, the half-life of LA is approximately two years, which means the damage can be far more persistent than other dietary factors, and the impact of reducing excessive LA intake takes time. Therefore, additional research-evaluating approaches to reduce OXLAM formation and cardiolipin derangements following LA consumption are warranted.

Keywords: linoleic acid (LA); seed oils; cardiolipin; oxidized linoleic acid metabolites (OXLAMs); 4-hydroxynonenal (HNE); omega-3; omega-6

The biggest category of increased calories for Americans over last 60 years comes from vegetable oils!!!

Nevertheless, Teicholz says seed oils and subsidized foods are just “part of the story,” and maintains that evidence showing seed oils are causal for diabetes and obesity is not strong enough. It’s the proliferation of packaged, processed foods, that has caused our health crisis, she says. And yes, government is to blame for that, too.

Obesity rates were in the low teens up until 1980, Teicholz says. “If you look at [footage of people] from the Seventies, people are thin. Everybody in line to watch a Star Wars movie — they’re all thin.”

But then, at the turn of the decade, there was a sharp, sudden turn upward in American obesity rates, and diabetes and other chronic diseases followed. In 1980 the USDA introduced its “Dietary Guidelines,” which determine the shape of all federal food programs. The Guidelines have come to be “the single most influential lever over what Americans eat,” says Teicholz.