Nutrition and physical activity in NAFLD: An overview of the epidemiological evidence

Abstract

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.

A case–control study on the effect of metabolic gene polymorphisms, nutrition, and their interaction on the risk of non-alcoholic fatty liver disease

“…However, we were unable to demonstrate any beneficial effect of vegetable consumption on disease risk. As mentioned, several reports summarized in a recent review (Zelber-Sagi et al 2011) agree on the effect of unhealthy dietary pattern rich in fat and poor in vegetables, on the risk of NAFLD. Our results confirm such observation, though we were unable to estimate the effect of vegetables and pulses independently of the effect of fruit.…”

“…Among the lifestyle factors, poor dietary habits and lack of physical activity engagement have been recently reported as risk factors for NAFLD onset (Loomba and Sanyal 2013). High carbohydrate and fructose consumption, as well as high red meat and low fish intake, have been associated with an increased risk of NAFLD and overall inflammation at liver biopsy (Solga et al 2004;Zelber-Sagi et al 2011;Tappy and Le 2012). Few reports, however, have examined the interaction between nutritional factors and genes involved in the oxidative stress in the pathogenesis of NAFLD so far (Bell et al 2011;Daly et al 2011;Hardwick et al 2013).…”

Lifestyle intervention in non-alcoholic fatty liver disease in Chengyang District, Qingdao, China

“…Lastly, medication". More emphasis was placed on policies for physical activities and exercise [22][23][24][25] . Our study result is consistent with this view.…”

Reversing Advanced Hepatic Fibrosis in NASH: Clearly Possible, but Widely at Hand?

“…Moreover, the results support the often challenging but fundamental tenets of NASH management to advise aggressive lifestyle changes with the encouragement of weight loss through dietary changes and exercise [10]. The broad application of bariatric surgery is more problematic due to concerns for costs, surgical eligibility, and perioperative risk with advanced fibrosis stages where postoperative complications can be substantial [11].…”