Short-term fructose restriction in children reduces sugar-to-fat conversion in liver

SAN DIEGO — Dietary fructose restriction for 10 days reduced the conversion of sugar to fat in the liver and decreased liver fat among black and Latino adolescents regardless of weight loss, according to research presented here.

The findings point to hepatic de novo lipogenesis (DNL) not only as a key mechanism leading to increased liver fat in children with obesity, but a target area that can be reversed by curbing consumption of fructose for a short period, according to researchers.

“Many studies have shown a correlation between the consumption of fructose and liver fat and hypertriglyceridemia, and also an association between fructose and increased conversion of sugar to fat in the liver,” Jean-Marc Schwarz, PhD, of Touro University California, Vallejo, said during a press conference.

Jean-Marc Schwarz

Schwarz and colleagues from the University of California, San Francisco, recruited Latinos (8 girls, 9 boys) and blacks (4 girls, 1 boy) aged 9 to 18 years with a BMI z score of 2.4 ± 0.1 who consumed an average of more than 50 g fructose per day at baseline.

For 10 days, the children consumed meals with the same caloric and macronutrient composition as their regular diet, with other carbohydrates substituted for sugar.

Children were weighed daily, and dietary adjustments were made to maintain baseline weight. The investigators calculated fractional DNL and DNL area under the curve (DNL-AUC) during 8 hours of test meals, containing [1-13C]sodium acetate tracer, on day 0 (high fructose) and day 10 (low fructose).

Gas chromatography/mass spectrometry was used to analyze postprandial blood samples, and mass isotopomer distribution analysis to calculate DNL. The researchers used magnetic resonance spectroscopy to determine liver fat percentage.

With fructose restriction, DNL was significantly reduced starting 50 minutes after initiation of tracer/feeding on day 0 (2.5 ± 0.3%) and day 10 (1.6 ± 0.1%; P < .003 by paired t test) and continuing throughout the procedure to 8 hours (13.3 ± 1.2% and 5.8 ± 0.6%, respectively, P < .001).

Integrated DNL-AUC decreased by 58.7% from day 0 compared with day 10 (53.5 ± 6.4 vs. 22.1 ± 3.3; P < .001). Further, 20 children showed a 29.5% reduction in liver fat with fructose restriction from day 0 to day 10 (11.9 ± 2.3% vs. 9.5 ± 2.2%; P < .001). With adjustments for minor weight loss during 10 days, the effects remained statistically significant (1 ± 0.3 kg, P < .001).

“Dietary fructose restriction decreased both hepatic de novo lipogenesis and liver fat in obese Latino and African American children,” Schwarz said. “These results suggest that hepatic de novo lipogenesis is an important mechanism contributing to liver fat accumulation in children. The good news is this can be reversed by taking away the fructose from the diet; even short-term results show significant differences.” – by Allegra Tiver

Reference:

Schwarz J, et al. Poster Board THR-549. Presented at: The Endocrine Society Annual Meeting; March 5-8, 2015, San Diego.

Disclosure: Schwarz reports no relevant financial disclosures.