To date, nonalcoholic fatty liver disease (NAFLD) is the most common cause of liver disease in the Western world and may affect as many as 30% of US adults.1 NAFLD is often described as the liver’s manifestation of metabolic syndrome affecting 75% of the persons who are overweight and 90% of those who are obese.2 As a result of the rising incidence in obesity, and gradual changes in hepatic structure and function as we age, the risk of liver disease and related mortality increases.
NAFLD is a condition where too much fat is stored in the liver, and as the name implies, it is not or is only marginally related to alcohol intake. A type of NAFLD, nonalcoholic steatohepatitis (NASH) results from liver cell damage and inflammation as well as excess fat stored in the liver. And, once NASH occurs, the inflamed and damaged liver cells can undergo fibrosis and in some cases, lead to hepatic cancer.
Prevalence of NAFLD is highest in Hispanic Americans followed by European descent and African American. In a study of 26,567 subjects undergoing medical check-ups, the presence of NAFLD was 31 percent in men and 16 percent in women.3 Being overweight in childhood increased the risk as an adult. A 2005 school-based study of children in California, Louisiana, Minnesota, and Texas found the incidence of fatty liver among 17 to 18 year olds to be 23 percent.4 Studies have also suggested that NAFLD is more prevalent in women with a history of polycystic ovary disease (PCOS) and are post-menopausal as opposed to premenopausal women. The proinflammatory state of PCOS may increase the incidence of NASH in these women.
Signs and Diagnosis
In the early stages, persons with NAFLD may be asymptomatic or presenting with an increased sensation of pressure over the right upper quadrant of the abdomen, plus weakness and or fatigue until the disease has progressed. An initial diagnosis of NAFLD is usually established by radiologic studies that show >5% accumulation of fat in the liver in the absence of other causes of fatty liver such as alcohol abuse.6 Elevated levels of liver enzymes, gamma-glutamyl transpeptidase (GGT) and alkaline phosphatase (ALP), and low vitamin D are three laboratory indicators of a malfunctioning or damaged liver.
There is growing evidence that NAFLD is a multisystem disease affecting regulatory pathways and extra-hepatic organs. Signs of metabolic syndrome, excess abdominal fat, elevated blood pressure, and/or insulin resistance or elevated fasting blood sugar, raise the risk for NAFLD. There is a very high prevalence of NAFLD in persons with type 2 diabetes and in those with dyslipidemia. NAFLD increases risk of type 2 diabetes in those without the disease, or cardiovascular diseases, or chronic kidney disease. Although, the primary pathology in NAFLD affects hepatic structure and function resulting in morbidity and mortality from cirrhosis, liver failure, and cancer, the majority of deaths among NAFLD patients can be linked to CVD.6
Reversing NAFLD and NASH
To date, no medications have been approved to treat NAFLD or subsequent NASH, although some, including pioglitazone, typically used for treating type 2 diabetes, are being study. Statins have demonstrated (in some small studies), a reduction in liver enzymes and improved liver tissue in those with NAFLD and NASH. Lifestyle modifications are the most recommended and successful treatments for NAFLD.2 “Without doubt simple sugars and stripped refined carbohydrates have a greater impact on NAFLD due to their impact on insulin and blood glucose levels.”2,7 A 5-10% loss of body weight has been shown to decrease hepatic fat, hepatic inflammation, and promotion of regression of fibrosis. Vigorous physical activity for 75 minute per week can reduce fat deposits in the liver and improve insulin sensitivity. The most significant improvements in persons with NAFLD are seen in those who combine dietary changes with physical activity.
Chemical damage is possible from environmental toxins such as common household chemicals, pesticides such as Round-up, plastics containing bisphenol A (BPA), smoking, medications including acetaminophen and other nonsteroidal anti-inflammatory drugs (NSAIDS), and antifungal drugs. Some dietary supplements are toxic to the liver such as high dose vitamin A and iron; the herbal supplements kava, skullcap, and yohimbe; and plants, including poisonous mushrooms and some plants of the nightshade family such as frequent amounts of potatoes, eggplant, and tomatoes, to name a few. Avoiding or limiting exposure to these substances can help prevent future damage and reduce already existing damage.1
Nutrition and Lifestyle Therapies
Key dietary changes that are essential to the management of NAFLD, and prevention of NASH include:
- Choose a diet that is rich in fruits and vegetables (except as mentioned), primarily those that are clean and pesticide free, as promoted by the Environmental Working Group: Dirty Dozen and Clean Fifteen
- Include whole grains and clean proteins from plant and animal based foods
- Reduce calories each day to achieve a 10 percent weight loss if needed
- Avoid sugars and simple carbs
- Limit alcohol intake
- Go to your physician and have your liver enzymes checked
- Be active – exercise vigorously most days of the week
- If diabetic, control blood sugar levels to reach an optimum A1c
- Limit exposure to environmental toxins
- Monitor prescription and over the counter NSAIDS medications, including dietary supplements and herbal medications (mentioned above), in conjunction with your medical provider
by Sarah Laidlaw, MS, RDN, CDE
- Kirkpatrick K, Hanouneh I. Skinny Liver. Philadelphia, PA; Da Capo Press; 2017.
- Wisoky J, Paul S. The rising incidence of non-alcoholic fatty liver disease. The Nurse Practitioner. 2017:42: 15-20.
- Masuoka HC, Chalasani N. Non-alcoholic fatty liver disease: an emerging threat to obese and diabetic individuals. Ann N Y Acad Sci. 2013:1281: 106–122.
- Schwimmer JB, McGreal N, Deutsch R, Finegold MJ, Lavine J. Influence of gender, race, and ethnicity on suspected fatty liver disease in obese adolescents. Pediatrics. 2005: 115:5; e561-e565. DOI: 10.1542/peds.2004-1832
- Gutierrez-Grobe Y, Ponciano-Rodríguez G, Ramos MH, Uribe M, Méndez-Sánchez N. Prevalence of Non-alcoholic fatty liver disease in premenopausal, postmenopausal and polycystic ovary syndrome. The role of estrogens. Ann Hepatol. 2010;9:402-409.
- Byrne C, Targher G. NAFLD: A multisystem disease. J Hepatol. 2015:62: S47–S64.
- Personal communication with author, Kristen Kirkpatrick, February 25, 2018.