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World J Gastroenterol. Aug 7, 2011; 17(29): 3377-3389
Published online Aug 7, 2011. doi: 10.3748/wjg.v17.i29.3377
Nutrition and physical activity in NAFLD: An overview of the epidemiological evidence
Shira Zelber-Sagi, Vlad Ratziu, Ran Oren
Shira Zelber-Sagi, Ran Oren, The Liver Unit, Department of Gastroenterology, Tel Aviv Sourasky Medical Center, 64239 Tel-Aviv, Israel
Shira Zelber-Sagi, School of Public Health, Faculty of Social Welfare and Health Sciences, University of Haifa, 31905 Haifa, Israel
Vlad Ratziu, Université Pierre et Marie Curie, Hôpital Pitié Salpêtrière, 75013 Paris, France
Ran Oren, The Sackler Faculty of Medicine Tel-Aviv University, 64239 Tel-Aviv, Israel
Author contributions: The majority of the paper was written by Zelber-Sagi S, with significant contributions from Ratziu V and Oren R.
Correspondence to: Shira Zelber-Sagi, RD, PhD, The Liver Unit, Department of Gastroenterology, Tel Aviv Sourasky Medical Center, 64239 Tel-Aviv, Israel.
Telephone: +972-3-6973984 Fax: +972-3-6974622
Received: October 27, 2010
Revised: February 15, 2011
Accepted: February 22, 2011
Published online: August 7, 2011

Nonalcoholic fatty liver disease (NAFLD) has been recognized as a major health burden. The high prevalence of NAFLD is probably due to the contemporary epidemics of obesity, unhealthy dietary pattern, and sedentary lifestyle. The efficacy and safety profile of pharmacotherapy in the treatment of NAFLD remains uncertain and obesity is strongly associated with hepatic steatosis; therefore, the first line of treatment is lifestyle modification. The usual management of NAFLD includes gradual weight reduction and increased physical activity (PA) leading to an improvement in serum liver enzymes, reduced hepatic fatty infiltration, and, in some cases, a reduced degree of hepatic inflammation and fibrosis. Nutrition has been demonstrated to be associated with NAFLD and Non-alcoholic steatohepatitis (NASH) in both animals and humans, and thus serves as a major route of prevention and treatment. However, most human studies are observational and retrospective, allowing limited inference about causal associations. Large prospective studies and clinical trials are now needed to establish a causal relationship. Based on available data, patients should optimally achieve a 5%-10% weight reduction. Setting realistic goals is essential for long-term successful lifestyle modification and more effort must be devoted to informing NAFLD patients of the health benefits of even a modest weight reduction. Furthermore, all NAFLD patients, whether obese or of normal weight, should be informed that a healthy diet has benefits beyond weight reduction. They should be advised to reduce saturated/trans fat and increase polyunsaturated fat, with special emphasize on omega-3 fatty acids. They should reduce added sugar to its minimum, try to avoid soft drinks containing sugar, including fruit juices that contain a lot of fructose, and increase their fiber intake. For the heavy meat eaters, especially those of red and processed meats, less meat and increased fish intake should be recommended. Minimizing fast food intake will also help maintain a healthy diet. PA should be integrated into behavioral therapy in NAFLD, as even small gains in PA and fitness may have significant health benefits. Potentially therapeutic dietary supplements are vitamin E and vitamin D, but both warrant further research. Unbalanced nutrition is not only strongly associated with NAFLD, but is also a risk factor that a large portion of the population is exposed to. Therefore, it is important to identify dietary patterns that will serve as modifiable risk factors for the prevention of NAFLD and its complications.

Keywords: Nonalcoholic fatty liver disease, Nutrition, Physical activity, Weight reduction, Fat, Carbohydrates, Soft drinks, Nutrients