The liver clears hormones, endotoxin, and metabolic waste, synthesizes Cholesterol, proteins, and bile salts, and stores glycogen. Mainstream hepatology treats cirrhosis, fatty liver, and enzyme leaks as organ-specific disease.

Ray Peat places liver function at the center of thyroid hormone conversion (T4 to T3), Estrogen inactivation, endotoxin clearance, and stress tolerance.[1][2]

The liver is the major source of the acute phase proteins, and it is constantly burdened by toxins absorbed from the bowel; disinfection of the bowel is known to accelerate recovery from stress.

— Ray Peat

[3]

The liver converts cholesterol to bile salts for elimination; thyroid hormone speeds that pathway. Broda Barnes and Peat note hypothyroid patients often show elevated cholesterol and carotenemia (yellowish tint) when the liver clears carotene slowly.[4][5]

Impairing factors: alcohol, excess PUFA the liver cannot oxidize or store safely, iron overload, chronic Endotoxin from gut, and hypothyroid sluggishness. Hypothyroidism can cause enzyme leakage from liver and other organs on standard blood tests.[6]

Protective themes: Coffee, niacinamide, Gelatin/glycine and saturated fats (increase albumin, reduce fibrosis in models he cites), lowering endotoxin and PUFA, Aspirin in inflammatory contexts, adequate protein and thyroid support.[7][8]

Peat limits organ-meat liver to modest portions because of iron and phosphate load. See Cholesterol, Hypothyroidism, Iron, Harm reduction.

Alcohol, glutamate, and Kupffer cells

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Binge drinking upregulates hepatocyte VGLUT3, releasing glutamate that activates Kupffer-cell mGluR5/NOX2, driving nitric oxide–mediated inflammation and hepatocyte death, a direct hepatotransmitter pathway alongside gut LPS.[9]

Alcohol and saturated long-chain fats

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Alpha-tocopherol for six months improved steatosis, transaminases, and apoptosis markers in HIV patients with non-alcoholic steatohepatitis when newer antifibrotic trials exclude them.[10] In ethanol-fed mice, dietary palmitic and stearic acids reduce gut bacterial translocation and plasma endotoxin, preserve intestinal occludin and limit claudin-2 upregulation, reverse ethanol-induced dysbiosis (restoring Firmicutes and Lactobacillus), and protect against alcoholic steatohepatitis, whereas short-chain fatty acids improve barrier integrity but do not prevent liver injury.[11]

Amin A. Nanji's rat studies are the largest body of work on this specific substitution. Rats fed ethanol alongside tallow (largely saturated) developed none of the features of alcoholic liver disease, while rats fed the same ethanol dose alongside corn oil (largely PUFA) developed the full picture; lard, an intermediate mix, gave an intermediate result.[12] Switching rats already on a fish-oil/ethanol diet to a saturated palm-oil-based diet after 6 weeks reduced hepatic lipid peroxidation and reversed the liver injury already present, framed by the authors as a first candidate dietary treatment for alcoholic liver disease rather than just a prevention strategy.[13] A later study in the same model found the saturated-fat diet down-regulated cyclooxygenase-2 and TNF-alpha and reversed existing fibrosis, tying the protective effect to lower inflammation rather than just less lipid peroxidation.[14] A companion study switched already-injured rats onto medium-chain triglycerides instead of a saturated long-chain source and got a faster, more complete result: near-normal histology within two weeks, clearly ahead of vitamin E alone over the same period, tracked to reduced lipid peroxidation.[15]

This animal work now has a human trial behind it. A 60-day randomized trial in patients with severe alcoholic hepatitis compared clarified butter (ghee, saturated) against soybean oil (PUFA) at matched calorie and protein intake. The saturated-fat group had markedly lower 60-day mortality (12.2% vs 33%), a shift toward favorable commensal gut bacteria, lower TNF-alpha and NF-κB, higher IL-10 and adiponectin, and better MELD, Child-Pugh, and FIB-4 scores at follow-up, the animal mechanism playing out directly in patients rather than just protecting rats.[16]

Endotoxin and HDL3

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Portal endotoxin from gut injury or dysbiosis drives hepatic inflammation when HDL3 production is reduced; HDL3 binds LPS and limits inflammatory activation in bowel-resection, high-fat-diet, and alcoholic liver disease models.[17]

Gut microbiota, NLRP12, and hepatocellular carcinoma

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NLRP12 suppresses liver-cancer-promoting JNK signaling in hepatocytes; without NLRP12, gut-derived LPS reaching the liver via the bloodstream drives JNK activation and tumor growth, and depleting gut bacteria with antibiotics dramatically reduced tumor growth in NLRP12-deficient mice.[18]

SHBG as metabolic biomarker

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Hepatic miR-93 promotes metabolic dysfunction-associated steatotic liver disease pathogenesis, linking microRNA signaling to NAD+-sensitive fatty-liver progression.[19]

IBD and systemic mitochondrial failure

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When enterocyte mitochondria fail, dietary fat accumulates in intestinal epithelium instead of reaching peripheral tissues, feeding hepatic lipid overload and central obesity.[20] Inflammatory bowel disease patients show reduced plasma TCA-cycle metabolites, respiratory-complex activity, and ATP; succinate and IDH2 fall with disease activity and CRP, indicating systemic bioenergetic collapse alongside gut inflammation.[21]

Blood endotoxin rose with NAFLD severity from simple steatosis through NASH and advanced fibrosis, correlating with BMI, CRP, and markers of metabolic and liver dysfunction.[22]

Roundup at doses far below regulatory limits perturbed rat hepatic gene expression toward lipotoxic and fibrotic pathology with mitochondrial respiratory-chain suppression.[23]

Cirrhosis and arachidonic metabolites

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Mitochondrial NAD+ content in hepatocytes gates regenerative capacity after partial hepatectomy; SLC25A51 controls the mitochondrial NAD+ pool in vivo.[24] In decompensated cirrhosis, elevated 20-HETE (an arachidonic-acid metabolite) tracks mitochondrial membrane depolarization, ROS, and ATP failure in peripheral leukocytes, linking PUFA-derived lipid mediators to organ failure rather than fibrosis alone.[25] Hepatic sex hormone-binding globulin (SHBG) production reflects liver metabolic state: monosaccharide-induced lipogenesis in hepatocytes suppresses SHBG gene expression, and this regulation is independent of circulating insulin levels; low SHBG therefore signals disordered hepatic sugar metabolism before overt liver disease.[26] SHBG and albumin are both liver-synthesized proteins; low levels of either predict adverse outcomes and correlate with insulin resistance and type 2 diabetes risk in epidemiological work cited alongside this mechanism.

Exhaustive eccentric exercise and liver stress

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Exhaustive eccentric exercise (e.g. prolonged running) raised liver enzymes and worsened lipid profiles in overweight women with NAFLD, and vitamin D supplementation partly protected against these exercise-induced liver changes, showing that "healthy" endurance exercise can acutely stress an already-compromised liver.[27]

Herbal and dietary supplement liver injury

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A United Network for Organ Sharing (UNOS) registry study of liver-transplant waitlist patients from 1995 to 2020 found that herbal and dietary supplements accounted for a rapidly growing share of non-acetaminophen drug-induced acute liver failure, rising from about 3% of such cases in the earliest study period to roughly a quarter of them by 2016-2020.[28] The trend tracks the growth of the supplement industry itself and is a reminder that "natural" products are not automatically liver-safe, especially concentrated botanical extracts taken outside clinical supervision.

Ketogenic diet and liver enzymes

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A published case report followed a 57-year-old woman with obesity who started a ketogenic diet of eggs, cheese, butter, oil, nuts, and leafy greens; four months later her liver enzymes and LDL cholesterol had risen sharply and abdominal ultrasound showed a heterogenous, echogenic liver consistent with non-alcoholic fatty liver disease. Stopping the diet brought a modest improvement within two weeks, with liver enzymes normalizing over eight months and LDL over a year.[29] A single case does not establish how often a ketogenic diet provokes this pattern, but it documents that a high-fat, carbohydrate-free diet can measurably stress the liver in a previously stable patient.

References

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  1. ↑ "Thyroid: Therapies, Confusion, and Fraud," Ray Peat article
  2. ↑ "Ray Peat, PhD on Endotoxin"
  3. ↑ "Leakiness, aging, and cancer," Ray Peat article
  4. ↑ "Thyroid: Therapies, Confusion, and Fraud," Ray Peat article
  5. ↑ "The Cholesterol and Thyroid Connection"
  6. ↑ "Leakiness, aging, and cancer," Ray Peat article
  7. ↑ "Leakiness, aging, and cancer," Ray Peat article
  8. ↑ "Ray Peat, PhD on Endotoxin"
  9. ↑ Yang S, Kim W, Ryu D, et al. "Binge drinking, VGLUT3 glutamate, and hepatic inflammation," Nat Commun. 2025. doi:10.1038/s41467-025-60820-3.
  10. ↑ Loria P, et al. "Vitamin E for HIV-associated NASH," Liver Int. 2020. PMID 31651429.
  11. ↑ Chen P, et al. "Supplementation of saturated long-chain fatty acids maintains intestinal eubiosis and reduces ethanol-induced liver injury," Cell Host Microbe. 2014;16(1):5-16. PMID 25239591.
  12. ↑ Nanji AA, Mendenhall CL, French SW. "Beef fat prevents alcoholic liver disease in the rat," Alcohol Clin Exp Res. 1989;13(1):15-19. PMID 2646971.
  13. ↑ Nanji AA, Sadrzadeh SM, Yang EK, Fogt F, Meydani M, Dannenberg AJ. "Dietary saturated fatty acids: a novel treatment for alcoholic liver disease," Gastroenterology. 1995;109(2):547-554. PMID 7615205.
  14. ↑ Nanji AA, Zakim D, Rahemtulla A, et al. "Dietary saturated fatty acids down-regulate cyclooxygenase-2 and tumor necrosis factor alfa and reverse fibrosis in alcohol-induced liver disease in the rat," Hepatology. 1997;26(6):1538-1545. PMID 9397995.
  15. ↑ Nanji AA, Yang EK, Fogt F, Sadrzadeh SM, Dannenberg AJ. "Medium chain triglycerides and vitamin E reduce the severity of established experimental alcoholic liver disease," J Pharmacol Exp Ther. 1996;277(3):1694-1700. PMID 8667240.
  16. ↑ Tripathi H, Benjamin J, Sharma S, et al. "Saturated fat favorably alters the gut microbiota and improves survival in patients with severe alcoholic hepatitis: a randomized controlled trial," abstract, The Liver Meeting (AASLD), Boston, MA, 2023.
  17. ↑ Randolph GJ, et al. "Apolipoprotein A-I binding protein restricts HDL3-mediated protection against endotoxin-induced liver injury," Science. 2021;374(6567):eabe6729. doi:10.1126/science.abe6729.
  18. ↑ Udden SMN, Kwak YT, Zaki H, et al. "NLRP12 suppresses hepatocellular carcinoma via downregulation of cJun N-terminal kinase activation in the hepatocyte," eLife. 2019. doi:10.7554/eLife.40396.
  19. ↑ Lee S, et al. "Hepatic miR-93 in MASLD," Metabolism. 2025. doi:10.1016/j.metabol.2025.156266.
  20. ↑ Moschandrea C, et al. "Mitochondrial dysfunction and dietary lipid processing," Nature. 2023. doi:10.1038/s41586-023-06857-0.
  21. ↑ Dudzińska M, et al. "Mitochondrial dysfunction in inflammatory bowel disease," J Inflamm Res. 2025. doi:10.2147/JIR.S487349.
  22. ↑ Soppert J, et al. "Blood endotoxin in NAFLD staging," Clin Gastroenterol Hepatol. 2023. PMID 36470528.
  23. ↑ Mesnage R, et al. "Transcriptome effects of ultra-low dose Roundup," Environ Health. 2015. doi:10.1186/s12940-015-0056-1.
  24. ↑ Mukherjee S, Baur JA, et al. "Mitochondrial NAD+ limits liver regeneration," Nat Metab. 2025. doi:10.1038/s42255-025-01408-5.
  25. ↑ López-Vicario C, et al. "Lipid mediator-mitochondrial network in cirrhosis," Nat Commun. 2026. doi:10.1038/s41467-026-73386-5.
  26. ↑ Selva DM, et al. "Monosaccharide-induced lipogenesis regulates the human hepatic sex hormone-binding globulin gene," J Clin Invest. 2007;117(12):3979-3987. PMID 17992261.
  27. ↑ Rahimpour S, Hoseini R, Behpour N, et al. "Alterations of liver enzymes and lipid profile in response to exhaustive eccentric exercise: vitamin D supplementation trial in overweight females with non-alcoholic fatty liver disease," BMC Gastroenterol. 2022. doi:10.1186/s12876-022-02457-w.
  28. ↑ PMID 34331346, Liver Transplantation, 2022.
  29. ↑ Anekwe CV, Chandrasekaran P, Stanford FC. "Ketogenic Diet-induced Elevated Cholesterol, Elevated Liver Enzymes and Potential Non-alcoholic Fatty Liver Disease," Cureus. 2020;12(1):e6605. doi:10.7759/cureus.6605. PMID 32064187.