The seed oils debate boils down to the fact that we don't have a complete data set from which to derive conclusions about what constitutes a healthy polyunsaturated fatty acid intake. That said, I recently learned to do Perplexity AI querys. My aim is to sort the science so as to determine which conclusions about linoleic acid intake are experiment-based and which are inference-based. Here is my most recent question: "Is there any human experimental evidence that increasing linoleic acid intake beyond 10% energy improves gut microbiome function?"
AI Response:
1) No human experimental trial has shown that pushing linoleic acid (LA) intake above about 10% of energy improves gut microbiome function; available data either do not isolate LA at that level or suggest potential dysbiosis at high LA loads. Current controlled work on oils in humans focuses mainly on mixed unsaturated fat or omega‑3–rich oils, not on high-LA-specific benefits for microbiota. https://www.nature.com/articles/s41522-022-00287-y
A recent trial comparing different edible oils reported broadly similar microbiota shifts across oils, with somewhat faster responses when alpha‑linolenic acid (ALA) was higher, again without demonstrating a specific benefit of high LA itself. https://www.nature.com/articles/s41522-022-00287-y
3) High‑LA soybean oil diets in mice (formulated to resemble current American intakes) shorten colonic crypts, alter barrier-related HNF4α isoforms, increase LA-derived oxylipins, and increase susceptibility to colitis, consistent with a detrimental, not beneficial, microbiome–host profile.
The same high‑LA soybean oil model encourages growth of adherent‑invasive E. coli that uses LA as a carbon source and is linked to an “unhealthy gut,” again pointing away from a microbiome benefit of high LA exposure.
4) Reviews on dietary lipids and the microbiome conclude that total fat load and SFA vs unsaturated balance clearly shape microbiota, but specify adverse gut effects for high-LA seed oil patterns rather than improvements when LA is raised above typical levels.
Small-intestinal work shows that linoleic acid is directly toxic to some beneficial Lactobacillus species (for example L. reuteri), with these taxa needing specific adaptations to survive LA exposure, implying that excess luminal LA can be hostile to key commensals.
5) Epidemiologic and metabolic trials support cardiometabolic benefits of higher LA intake, but they have not concurrently characterized gut microbiome composition or function at ≥10% energy LA as a primary endpoint.
No human study was identified in which LA was deliberately titrated above 10% of energy, with all other fats controlled, and gut microbiome outcomes were measured in a way that would allow concluding that such high LA improves microbiome function relative to lower LA intakes.
6) In sum, there is currently no human experimental evidence that increasing LA intake beyond 10% of energy improves gut microbiome function; mechanistic and animal data instead raise concerns about adverse microbiome and barrier effects at high LA exposure.
You and other scientists are clearly swimming upstream right now, but I am immensely grateful for your tireless efforts. Happy Holidays, and may you find time for rest and renewal.
The seed oils debate boils down to the fact that we don't have a complete data set from which to derive conclusions about what constitutes a healthy polyunsaturated fatty acid intake. That said, I recently learned to do Perplexity AI querys. My aim is to sort the science so as to determine which conclusions about linoleic acid intake are experiment-based and which are inference-based. Here is my most recent question: "Is there any human experimental evidence that increasing linoleic acid intake beyond 10% energy improves gut microbiome function?"
AI Response:
1) No human experimental trial has shown that pushing linoleic acid (LA) intake above about 10% of energy improves gut microbiome function; available data either do not isolate LA at that level or suggest potential dysbiosis at high LA loads. Current controlled work on oils in humans focuses mainly on mixed unsaturated fat or omega‑3–rich oils, not on high-LA-specific benefits for microbiota. https://www.nature.com/articles/s41522-022-00287-y
2) Human interventions with plant oils (olive, blended oils, perilla, etc.) show changes in diversity and specific taxa, but they manipulate a mix of MUFA and PUFA and do not isolate LA effects above 10% of energy as a primary variable. https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2024.1473648/full
A recent trial comparing different edible oils reported broadly similar microbiota shifts across oils, with somewhat faster responses when alpha‑linolenic acid (ALA) was higher, again without demonstrating a specific benefit of high LA itself. https://www.nature.com/articles/s41522-022-00287-y
3) High‑LA soybean oil diets in mice (formulated to resemble current American intakes) shorten colonic crypts, alter barrier-related HNF4α isoforms, increase LA-derived oxylipins, and increase susceptibility to colitis, consistent with a detrimental, not beneficial, microbiome–host profile.
The same high‑LA soybean oil model encourages growth of adherent‑invasive E. coli that uses LA as a carbon source and is linked to an “unhealthy gut,” again pointing away from a microbiome benefit of high LA exposure.
4) Reviews on dietary lipids and the microbiome conclude that total fat load and SFA vs unsaturated balance clearly shape microbiota, but specify adverse gut effects for high-LA seed oil patterns rather than improvements when LA is raised above typical levels.
Small-intestinal work shows that linoleic acid is directly toxic to some beneficial Lactobacillus species (for example L. reuteri), with these taxa needing specific adaptations to survive LA exposure, implying that excess luminal LA can be hostile to key commensals.
5) Epidemiologic and metabolic trials support cardiometabolic benefits of higher LA intake, but they have not concurrently characterized gut microbiome composition or function at ≥10% energy LA as a primary endpoint.
No human study was identified in which LA was deliberately titrated above 10% of energy, with all other fats controlled, and gut microbiome outcomes were measured in a way that would allow concluding that such high LA improves microbiome function relative to lower LA intakes.
6) In sum, there is currently no human experimental evidence that increasing LA intake beyond 10% of energy improves gut microbiome function; mechanistic and animal data instead raise concerns about adverse microbiome and barrier effects at high LA exposure.
You and other scientists are clearly swimming upstream right now, but I am immensely grateful for your tireless efforts. Happy Holidays, and may you find time for rest and renewal.
Thanks for sharing your knowledge and experience, Dr. Love. Happy Holidays