US nutritionists call for dietary guideline limits on saturated fat intake to be lifted
BMJ 2020; 371 doi: https://doi.org/10.1136/bmj.m4226 (Published 29 October 2020) Cite this as: BMJ 2020;371:m4226
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Dear Editor:
Perhaps the most troubling aspect of the saturated fat controversy is that it has persisted for decades. Meanwhile, as the whole World gets fatter and sicker, a pandemic viral infection (the COVID-19 crisis) has been superimposed on top of a chronic inflammatory disease pandemic. In light of what follows, one wonders what sort of mortality humanity would be experiencing these days from COVID-19 complications if the anti-saturated fat campaign had been nipped in the bud.[1]
Excerpt: Humans have 1 to 5 kilograms of linoleic acid stored in fat. In this stored form it's safe, but it's released by lipases in pancreatitis and in COVID-19. The lethal dose of linoleic acid is 280 milligrams per kilogram -- just 23 grams for a person weighing 80 kilos. Similarly, in the case of oleic acid, only very low doses are needed for lethality... UFAs also affect obesity, and not all obesity is the same. It is the UFA component in obesity that determines the degree of harm in the event of acute lipolysis as in severe COVID-19 or acute pancreatitis. A larger proportion of UFA accumulation in adipose fat -- even when the overall fat amount is lower, as in a leaner person -- may be more harmful during acute lipolysis than a greater proportion of saturated fat."[2]
Earlier in the article, researchers at the Mayo Clinic in Scottsdale, Arizona analyzing global COVID-19 mortality data and comparing it with 12 risk factors for mortality reportedly "found unsaturated fat intake to be associated with increased mortality. This was based on the dietary fat patterns of 61 countries in the United Nations' Food and Agricultural Organization database. Surprisingly, they found saturated fats to be protective."[2]
A question comes to mind. Is there a plausible explanation for this observation? Another excerpt: "...mechanistically, unsaturated fatty acids (UFAs) can rapidly depolarize mitochondria, inhibit mitochondrial complexes I and V, and decrease levels of adenosine triphosphate. They also trigger the release of calcium from an endoplasmic reticulum and increase cytokines and inflammatory markers."[2]
I found this comment in a 2010 research paper published by Norwegian animal scientists. "The degree of fatty acid unsaturation of mitochondrial membrane lipids has been found to be one of those biochemical parameters that are most strongly correlated with longevity, when different species of mammals and birds are compared, with a low degree of fatty unsaturation being correlated with less lipid peroxidation and a longer normal life-span."[3]
For more on mitochondrial membrane lipid responses to excessive polyunsaturated fat intake, I recommend a video presentation by Colorado Ophthalmologist Chris Knobbe.[4]
Web page references
1. https://www.aocs.org/stay-informed/inform-magazine/featured-articles/big...
2. https://www.medpagetoday.com/reading-room/aga/lower-gi/86940
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2875212/
4. Chris A. Knobbe - Omega-6 Apocalypse: From Heart Disease to Cancer and Macular Degeneration - AHS19. YouTube 12 October 2019
Competing interests: No competing interests
Dear Editor
As correctly stated in the article, “US nutritionists call for dietary guideline limits on saturated fat intake to be lifted”, to inform its recommendations, the 2020 Dietary Guidelines Advisory Committee conducted an updated, robust and thorough systematic review. In conducting this analysis, the Committee was building upon the work of the 2015 Advisory Committee, which conducted an extensive review that included literature dating back to the 1960s.
Competing interests: No competing interests
The letter to Congress
Dear Editor
Here is a link to the letter, mentioned in the original article, which was sent to Congress by nutrition scientists and former members of the US dietary guidelines committee calling for a rethink on the restrictions placed on saturated fat intake.
https://static1.squarespace.com/static/5a4d5666bff20053c65b7ff2/t/5f6e2f...
Regards
Maryanne Demasi, PhD
Competing interests: No competing interests