Appropriate management of lifestyle is likely to attenuate the severity of non-alcoholic fatty liver disease (NAFLD) and improve patients’ quality of life (QOL), according to authors of a review published in Hormones.
NAFLD is becoming a major health concern around the world, affecting approximately a quarter of the global adult population—an increase concurrent with epidemics of obesity and type 2 diabetes (T2D), researchers explained.
In addition to liver-related morbidity, NAFLD is associated with cardiovascular disease and malignancies, and is partially attributable to the modern Western lifestyle of unhealthy diet and lack of physical activity.
To better elucidate the potential effect of this lifestyle on NAFLD and to understand the effect of NAFLD on QoL, researchers summarized recently published evidence on these subjects.
One small pilot cross-sectional study revealed patients with NAFLD had a higher daily caloric intake than controls despite minimal differences in diet composition. Additional analyses found Western diets and intake of higher amounts of red meat and processed meat are associated with an increased prevalence and risk of the disease.
Sugar-sweetened beverages and soft drinks have also been linked with an increased likelihood of NAFLD, while one meta-analysis showed nuts were the only food group that provided a protective effect. Fruits, vegetables, whole grains, refined grains, fish, and legumes may also have potentially beneficial effects on NAFLD.
In contrast, macronutrients like saturated fatty acids, trans fat, preservatives and additives and fructose all likely lead to NAFLD development, researchers said. However, they cautioned “data on the association between dietary risk factors and NAFLD are based on observational studies; thus, a cause-effect relationship cannot be drawn.” Residual confounding and differing baseline participant characteristics serve as an important limitations on existing literature.
In addition to potential risks posed by individual foods, researchers outlined evidence pointing to an association between the type of cooking employed and NAFLD risk. For example, fried or well-don barbecue meat “may cause the formation of heterocyclic aromatic amines (HAAs) and advanced glycation-end products (AGEs), which have been associated with [insulin resistance] and oxidative stress, common contributors to the pathogenesis of NAFLD,” they said.
Another common feature of the Western diet—unhealthy snacking throughout the day— could contribute to increased triglyceride (TG) deposition in the liver.
Because overnutrition, poor nutritional quality, and decreased physical activity tend to co-exist, these factors can yield a synergistic effect non NAFLD development. Well-designed clinical trials and prospective cohort studies are warranted to better understand the effects of dietary/lifestyle interventions and modifications in these patients.
As no medications specifically licensed for NAFLD exist, “lifestyle adaptations are considered the mainstay of disease management and are recommended by all relevant guide- lines,” authors said.
Most of these adaptations focus on weight loss via diet change or regular exercise, while one cross-sectional study found that combined, high-quality diet and increased physical activity reduced NAFLD risk when compared to each action individually.
Low-fat, low-carbohydrate, and the Mediterranean Diets have also been evaluated in NAFLD and results indicate “the main driver of NAFLD improvement is likely to be energy restriction rather than diet composition.”
Several studies have highlighted potential benefits of the Mediterranean Diet on NAFLD. This diet consists of higher intake of whole grains, vegetables, fruits, nuts, olive oil, and fish and lower intake of red meat and alcohol.
However, high heterogeneity exists among studies and randomized controlled trials are needed. Until. Better evidence emerges, “reducing daily calorie intake, avoiding the aforementioned NAFLD-promoting foods, and following the [Mediterranean Diet] seems to be a sensible approach,” for patients, researchers noted.
When it comes to physical activity, repetitive, regular exercise can be beneficial in NAFLD even in the absence of significant weight loss. In patients with NAFLD, exercise can improve peripheral insulin sensitivity, suppresses liver fat synthesis, and potentially favor an anti-inflammatory state.
Although some aspects of exercise on NAFLD remain unclear, existing literature conclude any involvement in physical activity is superior to sedentary behavior.
With regard to QOL, limited data indicate NAFLD mainly impacts physical health, although increasing evidence has pointed to a variety of symptoms including anxiety, depression, and cognitive impairment. According to authors, this suggests “NAFLD may in fact be a symptomatic disease, albeit with non-specific symptoms, and not a ‘silent disease.’” Previous research also indicates QoL tends to deteriorate as the disease progresses.
“The modern Western lifestyle, characterized by unhealthy eating habits and inadequate physical activity, is frequently associated with development of metabolic diseases, including NAFLD,” authors concluded.
Reference
Vachliotis I, Goulas A, Papaioannidou P, Polyzos SA. Nonalcoholic fatty liver disease: lifestyle and quality of life. Hormones. Published online December 1, 2021. doi: 10.1007/s42000-021-00339-6