Plain language summary
There have been increasing concerns on the relationship between non-alcoholic fatty liver disease (NAFLD) and fructose or high-fructose corn syrup (HFCS). The objective of this systematic review was to assess the effect of dietary fructose in different forms on NAFLD and various biomarkers of liver health. This review included 21 published intervention studies and found a diet supplemented with fructose or glucose increases liver fat and aspartate aminotransferase (AST) concentrations when compared with a maintenance diet in healthy adults. Based on the available research, the authors point out the relationship between liver health markers and fructose, but also recognise this association may be confounded by excess energy intake. Due to the lack of robust findings, they conclude there is insufficient evidence on HFCS and NAFLD.
Abstract
BACKGROUND Concerns have been raised about the concurrent temporal trend between simple sugar intakes, especially of fructose or high-fructose corn syrup (HFCS), and rates of nonalcoholic fatty liver disease (NAFLD) in the United States. OBJECTIVE We examined the effect of different amounts and forms of dietary fructose on the incidence or prevalence of NAFLD and indexes of liver health in humans. DESIGN We conducted a systematic review of English-language, human studies of any design in children and adults with low to no alcohol intake and that reported at least one predetermined measure of liver health. The strength of the evidence was evaluated by considering risk of bias, consistency, directness, and precision. RESULTS Six observational studies and 21 intervention studies met the inclusion criteria. The overall strength of evidence for observational studies was rated insufficient because of high risk of biases and inconsistent study findings. Of 21 intervention studies, 19 studies were in adults without NAFLD (predominantly healthy, young men) and 1 study each in adults or children with NAFLD. We found a low level of evidence that a hypercaloric fructose diet (supplemented by pure fructose) increases liver fat and aspartate aminotransferase (AST) concentrations in healthy men compared with the consumption of a weight-maintenance diet. In addition, there was a low level of evidence that hypercaloric fructose and glucose diets have similar effects on liver fat and liver enzymes in healthy adults. There was insufficient evidence to draw a conclusion for effects of HFCS or sucrose on NAFLD. CONCLUSIONS On the basis of indirect comparisons across study findings, the apparent association between indexes of liver health (ie, liver fat, hepatic de novo lipogenesis, alanine aminotransferase, AST, and γ-glutamyl transpeptase) and fructose or sucrose intake appear to be confounded by excessive energy intake. Overall, the available evidence is not sufficiently robust to draw conclusions regarding effects of fructose, HFCS, or sucrose consumption on NAFLD.
Methodological quality
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