- Fructose Consumption and Non-alcoholic Fatty Liver Disease (NAFLD)
- Background: There are growing concerns about the effects of dietary fructose on health outcomes because the intakes appear to have parallel trends in non-alcoholic fatty liver disease (NAFLD) and obesity prevalence in the United States.
Purpose: To examine the effect of different levels and sources of dietary fructose on the incidence or prevalence of NAFLD and on indices of liver health in humans.
Data Sources: English-language studies identified from MEDLINE, Cochrane Central Register of Controlled Trials, CAB Abstracts, and Global Health databases up to September 2012.
Study Selection: Human studies of any design in children and adults with low to no alcohol intake and reporting at least one predetermined measure of liver health.
Data Extraction: Study data was extracted by one investigator and corroborated by a second investigator. Differences were resolved by consensus.
Data Synthesis: Twenty-two studies met the inclusion criteria, 3 reported NAFLD outcomes and 19 reported indices of liver health. Of these, all but 1 study were rated at medium or high risk of bias. The overall strength of evidence for an association between fructose intake and incidence of NAFLD was rated insufficient because of the biases and confounding in the study results. The 19 studies reporting indices of liver health were synthesized separately by each outcome: liver fat outcomes (7 studies), liver enzymes (11 studies), hepatic de novo lipogenesis rates (2 studies), and plasma bilirubin concentrations (2 studies). The overall strength of evidence was rated insufficient for all outcomes, except for some plasma liver enzymes. Our random-effects meta-analysis of 3 short-term RCTs (6 to 7 days) showed a significant increase in alanine aminotransferase (ALT) concentrations (+4.32 IU/L, 95% CI 0.20, 8.43, P=0.04) when a free fructose enriched excess energy diet was compared to a habitual weight maintenance diet.
Limitations: Most studies were rated at medium or high risk of bias, were small in sample size, included healthy adult men only, and were highly heterogeneous in study design and intervention, and thus limiting comparability.
Conclusions: Due to scarce, poor-quality, and heterogeneous data, we concluded that evidence is insufficient to draw conclusions regarding the effect of fructose consumption on NAFLD, while there is low level of evidence for a relationship between high free fructose intake in excess of energy needs and elevated liver enzyme concentrations. Large prospective cohort studies using standard NAFLD diagnosis are needed to examine the complex relationships between dietary factors and the risk of NAFLD.
- Authors of Report
- Methodology description
- See Chung M, Ma J, Patel K, Berger S, Lau J, Lichtenstein AH. Fructose, high-fructose corn syrup, sucrose, and nonalcoholic fatty liver disease or indexes of liver health: a systematic review and meta-analysis. Am J Clin Nutr.
2014 Sep;100(3):833-49. doi: 10.3945/ajcn.114.086314. Epub 2014 Aug 6. PubMed PMID: 25099546; PubMed Central PMCID: PMC4135494.
- We created a standardized extraction form for all qualifying studies in this systematic review (Key questions 1 and 2). We used different risk of bias tools for different study designs, and for each risk of bias tool, we created a stand alone Risk-of-Bias form (Key questions 3, 4, and 5).
There are a few glitches in the SRDR system causing missing data in the study preview. These glitches are being resolved, and the complete extraction forms can be viewed to see what data was collected from each study.
Funding for this systematic review was provided by the Technical Committee on Carbohydrates of the International Life Sciences Institute (ILSI) North American Branch. ILSI North America’s participation was limited to discussion with the team about the initial formulation of Key Questions (during one kick-off teleconference). The sponsor had no role in study selection, quality assessment, or synthesis.
- Funding Source
- The International Life Sciences Institute (ILSI) North American Branch