Nonalcoholic Fatty Liver Disease

Etiology, possible causes, and treatment considerations for NAFLD

Abstract

Nonalcoholic fatty liver disease (NAFLD) is subdivided into nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). In the United States, prevalence of NAFLD is 10% to 46% of the population. Worldwide prevalence is 6% to 35% (median 20%). There is a need to increase understanding of liver disease and its many causes, which will help to improve patient outcomes and reduce the stigma many patients experience. This article discusses epidemiology, etiologies, suspected pathogenesis, and risk factors, along with conventional and naturopathic therapeutic treatment options. 

Introduction

Nonalcoholic fatty liver disease (NAFLD) refers to the presence of hepatic fat in people who do not consume alcohol. NAFLD is now the most common cause of abnormal liver biochemistry in North America and likely in the United Kingdom, and while the cause is not always identified, it is known to be associated with some drugs, genetic defects, obesity, insulin resistance, and type 2 diabetes.1 NAFLD may progress to cirrhosis and is likely an important cause of cryptogenic cirrhosis.2,3
In the United States, prevalence of NAFLD is 10% to 46% of the population.4 Worldwide prevalence is 6% to 35%, with a median of 20%.5 Given the ethnic diversity of individuals in the US population, the prevalence varies among different ethnic groups. For example, in a 2004 study in the journal Hepatology, the authors concluded that
The frequency of hepatic steatosis varied significantly with ethnicity (45% in Hispanics; 33% in whites; 24% in blacks) and sex (42% in white men; 24% in white women). The higher prevalence of hepatic steatosis in Hispanics was due to the higher prevalence of obesity and insulin resistance in this ethnic group.6
NAFLD is subdivided into nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). The former is present without significant liver inflammation, while the latter is consistent with hepatic inflammation that may not be distinguishable histologically from alcoholic steatohepatitis.7
There is a need to increase the understanding of liver disease and its many causes, which will help to improve patient outcomes and reduce the stigma many patients experience. Currently, there is a perception that most liver diseases are due to alcohol or hepatitis8; yet in medicine today, NAFLD is considered as the hepatic manifestation of one of several major risk factors. These include central obesity, type 2 diabetes mellitus, dyslipidemia, and metabolic syndrome.9
Besides the aforementioned risk factors, patients with NAFLD (particularly those with NASH) often have one or more of the following comordities10,11: obesity, systemic hypertension, and type 1 diabetes.

Nonalcoholic Fatty Liver Disease

The pathogenesis of nonalcoholic fatty liver disease is not fully understood. One of the leading theories involves insulin resistance as a key mechanism leading to hepatic steatosis and perhaps also steatohepatitis. Another theory postulates that NAFLD is caused by oxidative stress secondary to steatohepatitis. Hepatic iron,12 leptin,13 antioxidant deficiencies,14 and intestinal bacteria15 have all been noted to be part of the pathogenesis of NAFLD.
Most individuals with NAFLD are asymptomatic, although some with NASH may complain of vague right upper abdominal discomfort, fatigue, and/or malaise.16 In clinical reality, NAFLD typically comes to the attention of the healthcare practitioner because laboratory testing reveals elevated liver aminotransferases. On physical exam, some patients may have hepatomegaly due to the fatty infiltration.7 Hepatic steatosis can also be detected incidentally on abdominal imaging.
“In clinical reality, nonalcoholic fatty liver disease typically comes to the attention of the healthcare practitioner because laboratory testing reveals elevated liver aminotransferases.”
Normal aminotransferase enzymes do not exclude those with NAFLD, but they present with mild to moderate
elevations in aspartate aminotransferase (AST) and alanine aminotransferase (ALT).17When elevated, these aminotransferases may be 2 to 5 times the upper limit of normal with a ratio of less than 1, whereas in alcoholic fatty liver disease, the ratio is typically greater than 2. It should be noted that the degree of aminotransferase elevation does not predict the degree of hepatic inflammation or fibrosis. Furthermore a normal ALT does not exclude histological injury.18 Other laboratory findings that may be found are an abnormal or high end of normal gamma γ-glutamyl transferase (GGT).19,20

Treatment Consideration

Numerous therapies have been investigated for the NAFLD treatment. Weight loss is the only therapy with reasonable evidence suggesting it is beneficial and safe, although emerging data supports nutritional interventions. Conventionally, the following strategies are typically employed:
  • Weight loss for patients who are overweight or obese;
  • Hepatitis A and B vaccinations, except in those with serologic evidence of immunity21;
  • Treatment of risk factors for cardiovascular disease; and
  • Abstention from alcohol.
Pharmacological agents, such as pioglitazone, are not recommended. Numerous other drugs have been examined for the treatment of NASH. While some have shown initial promise, none have been sufficiently studied.
I have routinely screened my patients with high normal GGT levels, in isolation or in conjunction with high normal or elevated AST and/or ALT levels, with a liver ultrasound and have frequently seen evidence of NAFLD on the radiology report. Typically, the patient’s medical doctor has dismissed this finding, as if there was nothing to be done about it besides weight loss (if indicated).
This is where nutritional and nutraceutical therapies have an enormous role to play. A diet rich in organic fruits and vegetables (the more varied the colors, the better) and avoidance of refined, processed, and charred foods are beneficial.22 I also recommend that my patients avoid trans fats and saturated fats,23 along with nitrates/nitrates and high fructose corn syrup.24-26 I recommend that they consume green tea, fresh fish, and liver-supportive foods. (Note of caution in regards to fish: Be aware of the mercury and other contaminants present in some fresh fish. The US Environmental Protection Agency is an excellent resource on safe fish consumption.27) Liver-supportive foods include high sulfur foods like garlic and onions, as well as cruciferous vegetables28-30 like Brussels sprouts, cabbage, cauliflower, and broccoli. Other nutritious liver-supportive foods include artichokes, turmeric, beets, and green tea.31-34
The following nutrients have shown the greatest clinical efficacy in addressing and even reversing the spectrum of NAFLD. In my practice, I have seen positive results in as little as 3 months, but typically it takes 9 to 12 months to see the most restoration and reversal of NAFLD.
  • Tocotrienols: 200 mg twice daily with food.34 Gamma-tocotrienol, but not alpha-tocopherol, attenuates triglycerides accumulation by regulating fatty acid synthase and carnitine palmitoyltransferase enzymes, leading to a reduction of hepatic inflammation and endoplasmic reticulum stress.35
  • N-acetyl-cysteine (NAC): 600 mg twice daily, best taken on an empty stomach.36 NAC blocks the propagation of lipid peroxidation.37
  • Omega 3 essential fatty acids: 2 g to 4 g daily.38 Omega 3 polyunsaturated fatty acids are known to downregulate sterol regulatory element binding protein 1c and upregulate peroxisome proliferator activated receptor α, which would favor fatty acid oxidation and reduce steatosis.39
  • Silybum marianum (milk thistle): 280 mg to 360 mg daily.40 Phytosomes provide the greatest bioavailability.41 Silymarin interferes with leukotriene formation in Kupffer cell cultures, thus inhibiting hepatic stellate cell activation.42
  • L-carnitine: 1 g twice daily.43 L-carnitine plays a critical role in fatty acid oxidation of energy regulation. It serves as a carrier to facilitate the transport of long-chain fatty acids through the mitochondrial membrane and to undertake free fatty acid b-oxidation.44
  • Choline: 250 mg to 1,000 mg daily.45 The precise mechanism of choline is unknown, except for its methyl donor properties and the observation that those with genetic polymorphisms involved in choline biosynthesis are associated with an increased risk of developing fatty liver.46
  • Betaine: 20 g daily (1-6 g/d may beneficial if used in conjunction with other therapies).47 Betaine, when used in rats with alcohol-induced steatohepatitis, led to an increase in S-adenosyl-l-methionine, which in turn led to a reduction in hepatic steatosis.47
  • Vitamin E (as RRR-α-tocopherol): 400 IU twice daily with food.48 Although well studied, I don’t utilize this treatment by itself due to increased risk for adverse cardiovascular events49 and gamma-tocopherol depletion50 at this dose. Mixed tocopherols have also shown efficacy in NAFL.35 Vitamin E is an effective defense mechanism against lipid peroxidation.51 Lipid peroxidation is increased in NAFLD and can promote inflammation and tissue damage.52
Other less-studied nutrients with potential benefits in the treatment of NAFLD include pantethine or pantothenic acid, taurine, magnesium, zinc with copper, vitamin B6, biotin, manganese, and lysine.53

Conclusion

Given the relatively high US prevalence of non-alcoholic fatty liver disease, along with its strong correlation in conditions such as metabolic syndrome, types I and II diabetes, obesity and dyslipidemia, evidence-based naturopathic strategies and interventions lay the framework for these treatments to take center stage.

References

  1. Sazci A, Ergul E, Aygun C, Akpinar G, Senturk O, Hulagu S. Methylenetetrahydrofolate reductase gene polymorphisms in patients with nonalcoholic steatohepatitis (NASH). Cell Biochem Funct. 2008;26(3):291-296.
  2. Caldwell SH, Oelsner DH, Iezzoni JC, Hespenheide EE, Battle EH, Driscoll CJ. Cryptogenic cirrhosis: clinical characterization and risk factors for underlying disease. Hepatology. 1999;29(3):664-669.
  3. Caldwell SH, Crespo DM. The spectrum expanded: cryptogenic cirrhosis and the natural history of non-alcoholic fatty liver disease. JHepatol. 2004;40(4):578-584.
  4. Lazo M, Hernaez R, Eberhardt MS, et al. Prevalence of nonalcoholic fatty liver disease in the United States: the Third National Health and Nutrition Examination Survey, 1988-1994. Am J Epidemiol. 2013;178(1):38-45.
  5. LaBrecque D, Abbas Z, Anania, F, et al. World Gastroenterology Organisation Global Guidelines: Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis. June 2012. Available at:http://www.worldgastroenterology.org/assets/export/userfiles/2012_NASH%20and%20NAFLD_Final_long.pdf. Accessed July 14, 2014.
  6. Browning JD, Szczepaniak LS, Dobbins R, et al. Prevalence of hepatic steatosis in an urban population in the United States: impact of ethnicity. Hepatology. 2004;40(6):1387-1395.
  7. Ludwig J, Viggiano TR, McGill DB, Oh BJ. Nonalcoholic steatohepatitis: Mayo Clinic experiences with a hitherto unnamed disease. Mayo Clin Proc. 1980;55(7):434-438.
  8. Osorio Calixtro L, Patiño Trinidad T, Tagle Arróspide M, Huayanay Falconi L. Perceptions, knowledge and attitudes about liver disease in healthy adults attending health facilities in stratum A, B and C [in Spanish]. Rev Gastroenterol Peru. 2010;30(2):126-132.
  9. Younossi ZM, Stepanova M, Afendy M, et al. Changes in the prevalence of the most common causes of chronic liver diseases in the United States from 1988 to 2008. Clin Gastroenterol Hepatol. 2011;9(6):524-530.e1; quiz e60.
  10. Alberti KG, Eckel RH, Grundy SM, et al; International Diabetes Federation Task Force on Epidemiology and Prevention; National Heart, Lung, and Blood Institute; American Heart Association; World Heart Federation; International Atherosclerosis Society; International Association for the Study of Obesity. Harmonizing the metabolic syndrome: a joint interim statement of the International Diabetes Federation Task Force on Epidemiology and Prevention; National Heart, Lung, and Blood Institute; American Heart Association; World Heart Federation; International Atherosclerosis Society; and International Association for the Study of Obesity. Circulation.2009;120:1640-1645.
  11. Meigs James. Metabolic syndrome and the risk for type 2 diabetes. Expert Rev Endocrin Metab. 2006;(1): 1:57-66.
  12. Viganò M, Vergani A, Trombini P, Paleari F, Piperno A. Insulin resistance influence iron metabolism and hepatic steatosis in type II diabetes. Gastroenterology. 2000;118(5):986-987.
  13. Angulo P, Alba LM, Petrovic LM, Adams LA, Lindor KD, Jensen MD. Leptin, insulin resistance, and liver fibrosis in human nonalcoholic fatty liver disease. J Hepatol. 2004;41(6):943-949.
  14. Baskol G, Baskol M, Kocer D. Oxidative stress and antioxidant defenses in serum of patients with non-alcoholic steatohepatitis. Clin Biochem. 2007;40(11):776-780.
  15. Miele L, Valenza V, La Torre G, et al. Increased intestinal permeability and tight junction alterations in nonalcoholic fatty liver disease.Hepatology. 2009;49(6):1877-1887.
  16. Bacon BR, Farahvash MJ, Janney CG, Neuschwander-Tetri BA. Nonalcoholic steatohepatitis: an expanded clinical entity.Gastroenterology. 1994;107(4):1103-1109.
  17. Charatcharoenwitthaya P, Lindor KD, Angulo P. The spontaneous course of liver enzymes and its correlation in nonalcoholic fatty liver disease. Dig Dis Sci. 2012;57(7):1925-1931.
  18. Mofrad P, Contos MJ, Haque M, et al. Clinical and histologic spectrum of nonalcoholic fatty liver disease associated with normal ALT values. Hepatology. 2003;37(6):1286-1292.
  19. Banderas DZ, Escobedo J, Gonzalez E, Liceaga MG, Ramírez JC, Castro MG. γ-glutamyl transferase: a marker of nonalcoholic fatty liver disease in patients with the metabolic syndrome. Eur J Gastroenterol Hepatol. 2012;24(7):805-810.
  20. Irie M, Sohda T, Iwata K, et al. Levels of the oxidative stress marker γ-glutamyltranspeptidase at different stages of nonalcoholic fatty liver disease. J Int Med Res. 2012;40(3):924-933.
  21. US Centers for Disease Control and Prevention. Vaccines that might be indicated for adults based on medical and other indications. 2014. Available at: http://www.cdc.gov/vaccines/schedules/hcp/imz/adult-conditions.html. Accessed July 14, 2014.
  22. Gaunt IF, Grasso P, Gangolli SD. Brominated maize oil. I. Short-term toxicity and bromine-storage studies in rats fed brominated maize oil. Food Cosmet Toxicol. 1971;9(1):1-11.
  23. Leamy AK, Egnatchik RA, Young JD. Molecular mechanisms and the role of saturated fatty acids in the progression of non-alcoholic fatty liver disease. Prog Lipid Res. 2013;52(1):165-174.
  24. Loomba R, Sanyal AJ. The global NAFLD epidemic. Nat Rev Gastroenterol Hepatol. 2013;10(11):686-690.
  25. Freedman ND, Cross AJ, McGlynn KA, et al. Association of meat and fat intake with liver disease and hepatocellular carcinoma in the NIH-AARP Cohort. J Natl Cancer Inst. 2010;102(17): 1354-1365.
  26. Tetri LH, Basaranoglu M, Brunt EM, Yerian LM, Neuschwander-Tetri BA. Severe NAFLD with hepatic necroinflammatory changes in mice fed trans fats and a high-fructose corn syrup equivalent. Am J Physiol Gastrointest Liver Physiol. 2008;295(5):G987-G995.
  27. US Environmental Protection Agency. What you need to know about mercury in fish and shellfish. Available at:http://water.epa.gov/scitech/swguidance/fishshellfish/outreach/advice_index.cfm. Accessed July 18, 20014.
  28. Whitfield JB. Gamma glutamyl transferase. Crit Rev Clin Lab Sci. 2001;38(4):263-355.
  29. American Institute for Cancer Research. AICR’s foods that fight cancer: broccoli and cruciferous vegetables. http://www.aicr.org/foods-that-fight-cancer/broccoli-cruciferous.html. Accessed July 14, 2014.
  30. Zhou R, Lin J, Wu D. Sulforaphane induces Nrf2 and protects against CYP2E1-dependent binge alcohol-induced liver steatosis. Biochim Biophys Acta. 2014;1840(1):209-218.
  31. Gebhardt R, Fausel M. Antioxidant and hepatoprotective effects of artichoke extracts and constituents in cultured rat hepatocytes.Toxicol In Vitro. 1997;11(5):669-672.
  32. Kim SW, Ha KC, Choi EK, et al. The effectiveness of fermented turmeric powder in subjects with elevated alanine transaminase levels: a randomised controlled study. BMC Complement Altern Med. 2013 Mar 8;13:58.
  33. Krajka-Kuźniak V, Paluszczak J, Szaefer H, Baer-Dubowska W. Betanin, a beetroot component, induces nuclear factor erythroid-2-related factor 2-mediated expression of detoxifying/antioxidant enzymes in human liver cell lines. Br J Nutr. 2013;110(12):2138-2149.
  34. Xu R, Ye H, Sun Y, Tu Y, Zeng X. Preparation, preliminary characterization, antioxidant, hepatoprotective and antitumor activities of polysaccharides from the flower of tea plant (Camellia sinensis). Food Chem Toxicol. 2012;50(7):2473-2480.
  35. Magosso E, Ansari MA, Gopalan Y, et al. Tocotrienols for normalisation of hepatic echogenic response in nonalcoholic fatty liver: a randomised placebo-controlled clinical trial. Nutr J. 2013;12(1):166.
  36. Muto C, Yachi R, Aoki Y, Koike T, Igarashi O, Kiyose C. Gamma-tocotrienol reduces the triacylglycerol level in rat primary hepatocytes through regulation of fatty acid metabolism. J Clin Biochem Nutr. 2013;52(1):32-37.
  37. Khoshbaten M, Aliasgarzadeh A, Masnadi K, et al. N-acetyl-cysteine improves liver function in patients with non-alcoholic fatty liver disease. Hepatitis Mon. 2010;10(1):12-16.
  38. Parker HM, Johnson NA, Burdon CA, Cohn JS, O’Connor HT, George J. Omega-3 supplementation and non-alcoholic fatty liver disease: a systematic review and meta-analysis. J Hepatol. 2012;56(4):944-951.
  39. Pettinelli P, del Pozo T, Araya J, et al. Enhancement in liver SREBP-1c/PPAR-alpha ratio and steatosis in obese patients: correlations with insulin resistance and n-3 long-chain polyunsaturated fatty acid depletion. Biochim Biophys Acta. 2009;1792(11):1080-1086.
  40. Abenavoli L, Aviello G, Capasso R, Milic N, Capasso F. Milk thistle for treatment of nonalcoholic fatty liver disease. Hepatitis Mon. 2011;11(3):173-177.
  41. Kidd P, Head K. A review of the bioavailability and clinical efficacy of milk thistle phytosome: a silybin-phosphatidylcholine complex (Siliphos). Altern Med Rev. 2005;10(3):193-203.
  42. Dehmlow C, Erhard J, de Groot H. Inhibition of Kupffer cell functions as an explanation for the hepatoprotective properties of silibinin.Hepatology. 1996;23(4):749-754.
  43. Malaguarnera M, Gargante MP, Russo C, et al. L-carnitine supplementation to diet: a new tool in treatment of nonalcoholic steatohepatitis—a randomized and controlled clinical trial. Am J Gastroenterol. 2010;105(6):1338-1345.
  44. Ahmad S. L-carnitine in dialysis patients. Semin Dial. 2001;14(3):209-217.
  45. Nehra V, Angulo P, Buchman AL, Lindor KD. Nutritional and metabolic considerations in the etiology of nonalcoholic steatohepatitis. Dig Dis Sci. 2001;46(11):2347-2352.
  46. Song J, da Costa KA, Fischer LM, et al. Polymorphism of the PEMT gene and susceptibility to nonalcoholic fatty liver disease (NAFLD).FASEB J. 2005;19(10):1266-1271.
  47. Abdelmalek MF, Angulo P, Jorgensen RA, Sylvestre PB, Lindor KD. Betaine, a promising new agent for patients with nonalcoholic steatohepatitis: results of a pilot study. Am J Gastroenterol. 2001;96(9):2711-2717.
  48. Sanyal AJ, Chalasani N, Kowdley KV, et al. Pioglitazone, vitamin E, or placebo for nonalcoholic steatohepatitis. N Engl J Med.2010;362(18):1675-1685.
  49. Lonn E, Bosch J, Yusuf S, et al. Effects of long-term vitamin E supplementation on cardiovascular events and cancer: a randomized controlled trial. JAMA. 2005;293(11):1338-1347.
  50. Jiang Q, Christen S, Shigenaga MK, Ames BN. gamma-tocopherol, the major form of vitamin E in the US diet, deserves more attention.Am J Clin Nutr. 2001;74(6):714-722.
  51. Sies H, Stahl W, Sundquist AR. Antioxidant functions of vitamins. Vitamins E and C, beta-carotene, and other carotenoids. Ann N Y Acad Sci. 1992 Sep 30;669:7-20.
  52. Dowman JK, Tomlinson JW, Newsome PN. Pathogenesis of non-alcoholic fatty liver disease. QJM. 2010;103(2):71-83.
  53. Gaby AR. Nutritional Medicine. Concord, NH: Fritz Perlberg; 2011.

Original Posting

On July 25, 2016   /   Articles