Diet Quality, Physical Activity Improve Survival Rates in Patients with NAFLD

Eduardo Vilar-Gomez, PhD, MD, MS

Credit: Indiana University School of Medicine

Findings from a recent study are shining light on the benefits of physical activity and diet quality on survival rates among patients with nonalcoholic fatty liver disease (NAFLD).

Results showed a dose-dependent, nonlinear association of physical activity volume and intensity with all-cause mortality and a dose-dependent, linear association of diet quality with all-cause mortality. The top quartile of all 3 factors was associated with the lowest risk of NAFLD.¹

“It has recently been shown that increased levels of [diet quality] and [physical activity] may result in substantial reductions in the risk of NAFLD and clinically significant fibrosis in a contemporary US cohort,” wrote investigators.¹ “However, the protection of [diet quality] and [physical activity] on mortality in NAFLD is less clear.”

The American Liver Foundation estimates about 100 million individuals in the US have NAFLD. Risk factors include being overweight and having obesity, diabetes, high cholesterol, or high triglycerides. Although there is no treatment for NAFLD, maintaining a healthy weight, eating a healthy diet, and exercising regularly are recognized as effective ways to prevent it from developing or reverse it in its early stages.²

To assess the association between physical activity, diet quality, and survival rates in patients with NAFLD, Eduardo Vilar-Gomez, PhD, MD, MS, assistant professor of medicine at Indiana University School of Medicine, and a team of investigators collected data about the diet quality and physical activity of patients from the National Health and Nutrition Examination Survey. Investigators gathered data from 2 consecutive cycles, 2011–2012 and 2013–2014, on accelerometer-based physical activity monitoring and food intake.¹

Of note, older adults, Hispanic, non-Hispanic Black and Asian, and low-income non-Hispanic White/other ethnicities were intentionally oversampled. Patients less than 18 years old with insufficient data, who reported an implausible diet, had excessive alcohol intake, or were positive for the hepatitis B surface antigen, hepatitis C antibody, and HIV were excluded.¹

The final analytical data set comprised 3495 patients with NAFLD and 3913 patients without NAFLD. In the NAFLD group, there were 298 (age-adjusted percentage, 6.4%) deaths over 23,723 person-years of follow-up (mortality rate, 1.26 deaths/100 person-years). Among participants without NAFLD, there were 264 (age-adjusted percentage, 4.9%) deaths over 26,756 person-years of follow-up (mortality rate, 0.98 deaths/100 person-years). Compared to the group without NAFLD, NAFLD was associated with an increased risk of all-cause mortality (adjusted hazard ratio [aHR], 1.26; 95% confidence interval [CI],1.05–1.52).¹

Investigators collected physical activity data using a wrist-worn triaxial accelerometer. Diet quality was assessed based on information provided by participants about their food intake for 2 24-hour periods, which was then used to estimate intakes of energy, nutrients, and other dietary components. All-cause mortality, cardiovascular-related mortality, and cancer-related mortality were the main study outcomes.¹

Investigators pointed out top quartiles of physical activity volume and intensity were associated with younger age, female sex, Hispanic, lower BMIs/waist circumferences, lower prevalence of diabetes, hypertension, cardiovascular conditions, and cancer, and higher diet quality. Increased diet quality was observed in older adults, women, Hispanic, and non Hispanic-Asian patients.¹

Investigators tested univariate and covariate-adjusted associations between physical activity/diet quality and NAFLD using logistic regression models, further accounting for BMI, smoking status, diabetes mellitus, hypertension, history of cardiovascular disease or cancer, total calorie intake, hand grip strength, and mobility limitation. Investigators also assessed a dose-response association between physical activity/diet quality metrics and all-cause mortality using restricted cubic splines using Cox regression models.¹

Upon analysis, maximum protective doses were 14,300 Monitor-Independent Movement Summary (MIMS) per minute (aHR, 0.20; 95% CI, 0.11–0.38) for physical activity volume, 54.25 MIMS per minute (aHR, 0.10; 95% CI, 0.05–0.23) for physical activity intensity, and 66.17 (aHR, 0.54; 95% CI, 0.40–0.74) for Healthy Eating Index-2015.¹

Compared to participants in the fourth quartile of the total volume of physical activity, participants who performed in the top quartile had the lowest risk for all-cause (AHR, 0.45; 95% CI, 0.30–0.68) and cardiovascular disease-related (subhazard ratio [sHR], 0.43; 95% CI, 0.19–0.98) deaths. Participants in the top quartile of peak-30 MIMS per minute showed the lowest risk of all-cause (AHR, 0.39; 95% CI, 0.23–0.66) and cardiovascular disease-related (sHR, 0.26; 95% CI, 0.11–0.63) deaths compared to those in the first quartile. Investigators pointed out participants engaging in the highest levels of physical activity volume and intensity showed the greatest protection against all-cause mortality (HR, 0.23; 95% CI, 0.14–0.53), but neither physical activity volume nor intensity was independently associated with cancer-related mortality.¹

Participants in the top quartile for Healthy Eating Index had the lowest risk for all-cause (AHR, 0.64; 95% CI, 0.45–0.89), cardiovascular disease-related (sHR, 0.69; 95% CI, 0.38–0.99), and cancer-related (sHR, 0.45; 95% CI, 0.22–0.92) mortality compared to those in the bottom quartile. Of note, participants adhering to the healthiest eating patterns showed decreased mortality rates, even among those with low levels of physical activity volume. Investigators also pointed out physical activity intensity was significantly linked to decreased mortality rates regardless of diet quality levels.¹

Sensitivity analyses showed that the beneficial effects of physical activity and diet quality on survival rates remained significant across sex, racial/ethnic, and age groups as well as in participants without NAFLD. In fully covariate-adjusted logistic regression models, the top quartile of physical activity volume (odds ratio [OR], 0.50; 95% CI, 0.39–0.63), physical activity intensity (OR, 0.68; 95% CI, 0.57–0.82), or Healthy Eating Index (OR, 0.46; 95% CI, 0.39–0.53) was associated with the lowest risk of NAFLD.¹

“The data we report herein may serve as benchmark values related to [physical activity] (MIMS volume and intensity metrics), [diet quality] (HEI-2015), and mortality in NAFLD adults, although our data need to be reproduced or validated in other cohorts including adults from general and NAFLD populations. This study also extended the results of previous research, adding more evidence of the potential benefits of [physical activity] and [diet quality] in a clinical context,” concluded investigators.¹

References:

1. Vilar-Gomez E, Vuppalanchi R, Gawrieh S, et al. Significant Dose-Response Association of Physical Activity and Diet Quality With Mortality in Adults With Suspected NAFLD in a Population Study. The American Journal of Gastroenterology 118(9):p 1576-1591, September 2023. doi:10.14309/ajg.0000000000002222
2. https://liverfoundation.org/liver-diseases/fatty-liver-disease/nonalcoholic-fatty-liver-disease-nafld/