Fatty liver: High-fat meals breed diseases

Physicians who find elevated alanine aminotransferase (ALT) levels in liver function test should consider asking their patients not only about alcohol consumption, but also about the quality and quantity of food they have been eating, according to the results of a recently published study.

Reminiscent of the 2004 documentary “Super Size Me,” the study by Swedish researchers subjected volunteers to a four-week diet including two fast food meals a day and the adoption of a sedentary lifestyle aimed at increasing their body weight by 5% to 15%. The goal of the study was to determine the effect of acute high-calorie consumption on liver enzymes and hepatic triglyceride content and to see if there is a link between changes in serum ALT and the amount of hepatic fatty nutrition in healthy individuals who are not obese.

The diet, which doubled the daily caloric intake of the participants in the study group, was successful in its purposes. Seventeen of the 18 participants experienced a 5% to 15% increase in weight; with five gaining the maximum 15% (three of these volunteers reached this upper limit before the study was over and ended the trial early). The mean increase in weight was from 67.6 kg. (149 lb) to 74 kg (163 lb; P = 0.001).

During the study period, 13 participants developed pathologic ALT; in most cases, elevated ALT levels were apparent after only one week. Mean serum ALT at baseline was 22.1 U/L, increasing to a mean maximum level of 97 U/L (range, 19.4-447 U/L).

A president of the American College of Gastroenterology and associate professor of Medicine in the Department of Gastroenterology at Mayo Clinic College of Medicine in Rochester, Minn. said that they’ve known for a long time that fatty liver disease can be related to alcohol consumption, diabetes and obesity, but they haven’t always been as familiar with other causes. This study suggests that consuming high concentrations of fat and highly processed food may be damaging even in the short term.

Setting aside immoderate alcohol consumption and the presence of hepatitis C virus infection, ALT elevations can be a bit of a mystery, and the phenomenon appears to be on the rise. According to an analysis of the third National Health and Nutrition Examination Survey, the prevalence of elevated levels of ALT or aspartate aminotransferase (AST) could be as high as 7.9 percent in the US population, up from the 1% to 4% prevalence previously reported. In both men and women, elevated ALT levels are strongly associated with features of metabolic syndrome.

Adipocytes, or fat cells, are now recognized to be complex endocrine cells that release cytokines such as tumor necrosis factor-alpha, interleukin-6 and other mediators of inflammation in addition to storing fat. The condition of non-alcohol-associated fatty liver disease (NALFD) has a high association with C-reactive protein, which is a marker of inflammation. When you see elevated liver function tests, like ALT, it suggests that consumption of high-fat meals is associated with an acute inflammatory process . . . elevated ALT may indicate that the liver is actively undergoing some sort of injury.

NAFLD affects 10% to 22% of the general population and 57% to 74% of the obese population; 2.6% of children also suffer from NAFLD.

The disease also occurs in more than 90% of individuals with a body mass index of 50 or above. In this group, 100% have mild steatosis, 50% have steatohepatitis and 19% develop cirrhosis.

It may come down to severity — quantity as well as duration of exposure to a high-fat diet and the cytokines and inflammatory mediators. That’s the real concern here. It warrants further research, but it has implications for the clinical practice setting. This is information that they could possibly share with patients.