Abstract
There is a known relationship between serum alanine aminotransferase (ALT) and obesity in humans, but the mechanism(s) are not clarified. This study investigated the associations between serum ALT and body composition in an overweight and obese population. The results are based on data from a previous randomized controlled trial treating obesity with vitamin D3. A sample of 448 overweight and obese individuals underwent dual-energy X-ray absorptiometry (DEXA) and measured serum ALT along with supplementary blood samples at study baseline. Body fat mass and lean mass indexes were calculated by dividing total body fat/lean weight (kg) by body height squared (kg/m2). ALT correlated with body mass index (BMI) in men but not women (r = 0.33, P < 0.0001 vs. r = 0.06, P = 0.29). In men, serum ALT correlated positively with fat mass index (r = 0.23, P = 0.004) and lean mass index (r = 0.32, P < 0.0001). In women, ALT correlated with lean mass index (r = 0.13, P = 0.031) but not fat mass index (r = 0.003, P = 0.96). In a multivariate model adjusted for age and fat mass index, a 1-unit increase in lean mass index associated with a 0.37 U/L higher ALT in the male subgroup (95% CI 0.024 to 0.040, P < 0.0001). In conclusion, serum ALT was associated with body fat mass index in men and with lean mass index in men and women in an overweight and obese population. The findings also demonstrate a gender difference in the role of fat.
Highlights
Alanine transaminase (ALT) is associated with obesity [1, 2], cardiovascular disease (CVD), and CVD-related mortality [3,4,5]
In studies from the United States confirming a positive relationship between ALT and body mass index (BMI), the strongest association was found for waist-to-hip ratio [15] and trunk fat using dual-energy X-ray absorptiometry (DEXA) to measure body composition, indicating central adiposity to be an important obesity-related determinant of elevated ALT [16]
ALT was associated with BMI in men but not in women (Table 2), and BMI was significantly associated with ALT quartiles in men (Table 3)
Summary
Alanine transaminase (ALT) is associated with obesity [1, 2], cardiovascular disease (CVD), and CVD-related mortality [3,4,5]. Clinical and population studies have related ALT with insulin resistance, metabolic syndrome, and type 2 diabetes [6,7,8]. A Korean population study showed a higher risk of elevated ALT by increasing degree of BMI [14]. In studies from the United States confirming a positive relationship between ALT and BMI, the strongest association was found for waist-to-hip ratio [15] and trunk fat using dual-energy X-ray absorptiometry (DEXA) to measure body composition, indicating central adiposity to be an important obesity-related determinant of elevated ALT [16]. ALT was associated with trunk lean mass in both sexes [16]
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