Supplement Associated With Less Weight Gain in 24-Week Trial
December 31, 2014People who took a dietary supplement designed to create a feeling of fullness gained less weight during a small 24-week trial than those who added a fiber supplement alone, according to a double-blind, randomized trial published online December 10 in Gut. However, experts not involved in the work remain skeptical of the supplement’s clinical utility.
Edward S. Chambers, PhD, research associate, Nutrition and Dietetic Research Group, Section of Investigative Medicine, Imperial College, London, United Kingdom, and colleagues randomly assigned 60 overweight adults, aged 40 to 65 years, to receive either 10 g per day of an inulin-propionate ester (IPE) for 24 weeks or a placebo of 10 g inulin alone for 24 weeks in this proof-of-concept study.
Normally, gut microbes produce propionate when dietary fiber ferments. Propionate, in turn, stimulates the release of PYY and GLP-1, hormones that suppress appetite. Inulin is a fructose-containing plant fiber.
The authors estimate a 2.5-fold increase in daily propionate levels in the colon with the use of the novel inulin-propionate ester they synthesized, «a level very difficult to achieve through feeding a mixed fermentable fibre diet,» they write.
Forty-nine people finished the 24-week study. In the treatment group, 1 (4%) of 25 participants gained 3% or more of their baseline weight compared with 6 (25%) of the 24 members of the inulin-treated group. Four (17%) in the inulin group gained 5% or more of their body weight compared with none in the propionate group.
Lawrence J. Cheskin, MD, associate professor of health, behavior, and society, Johns Hopkins Bloomberg School of Public Health, and director of the Johns Hopkins Weight Management Center, Baltimore, Maryland, told Medscape Medical News that the small study suggests the supplement may have promise. «It’s not dramatic, but they found a statistically significant difference. It has scientific credibility, it’s logical. There’s a mechanism.» Dr Cheskin was not involved in the study.
However, it is impossible to predict how durable these results will be over the long haul, Dr Cheskin said. «It’s an early finding. There might be some efficacy in weight control, but it’s unclear how big it would be, or whether it would be sustained. The body has a way for compensating for these things.» Dr Cheskin is also the associate director of the Global Obesity Prevention Center at Johns Hopkins University.
James E. Painter, PhD, RD, professor emeritus, Eastern Illinois University, Charleston, told Medscape Medical News he was unimpressed with the study results. Dr Painter also was not involved in the research. «This new product did not significantly change the weight between the two groups. The only significant difference between the two groups is where fat was located,» Dr Painter said.
The authors report that intra-abdominal adipose tissue, expressed as a percentage of total adipose tissue, was lower in the propionate group after 24 weeks than the inulin group, with a difference of −0.46 (95% confidence interval [CI], −0.87 to −0.05; P = .027) between the two groups. Data on intra-abdominal fat were available for 15 members of the control group and 17 individuals in the experimental group.
Intra-abdominal adipose tissue in the experimental group remained virtually unchanged, although those in the control group saw an increase in intra-abdominal fat after 24 weeks. Of the 17 participants in the experimental group tested at baseline, intra-abdominal adipose tissue measured 13.2 ± 1.2 at baseline and 13.1 ± 1.1 (P = .723) at week 24. In the control group, however, intra-abdominal adipose tissue rose slightly among the 15 members tested at baseline, going from 10.6 ± 1.3 at week 0 to 11.1 ± 1.4 at week 24 (P < .001).
The authors also report that the 11 participants in the propionate group who met the diagnostic criteria for nonalcoholic fatty liver disease at baseline, with intrahepatocellular lipid levels of more than 5.5%, saw intrahepatocellular lipid levels fall significantly at week 24, going from 22.1% (95% CI, 7.7% – 36.6%) to 15.9% (95% CI, 5.2% – 26.5%; P = .038). The effect was not seen in the five control-group participants who met the criteria for nonalcoholic fatty liver disease. However, the difference between the two groups was not statistically significant, at −0.83 (95% CI, −5.04 to 3.38; P = .699).
Although the study was aimed at the prevention of weight gain, there was a small but not statistically significant increased weight loss in the propionate group after 24 weeks (−1.02 kg; 95% CI, −2.10 to 0.04) compared with the inulin group (0.38 kg; 95% CI, −0.95 to 1.72; P = .099).
Both the control and experimental groups saw a reduction in total cholesterol, high-density lipoprotein, alanine transaminase, and alkaline phosphatase levels, but only the experimental group showed a significant drop in low-density lipoprotein (from 3.5 ± 0.2 at week 0 to 3.2 ± 02 at week 24; P < .001). However, the difference between the propionate group and the control group was not statistically significant (P = .532). The experimental group also showed a significant decrease in levels of aspartate transaminase (28.9 ± 1.3 at week 0 and 26.2 ± 1.0 at week 24; P = .007), although the difference between the propionate group and the control group was not significant (P = .627).
The authors found that propionate stimulated the release of PYY and GLP-1 in human colonic cell culture. Those hormones are associated with satiety signals to the brain. In a study in which 20 volunteers were given IPE or inulin alone and allowed to eat as much as they liked at a buffet, PYY and GLP-1 levels also rose in the propionate group. In that study, the propionate group ate 13.8% less, on average, than the control group. However, in the 24-week study, there was no detectable change in PYY or GLP-1 after ingestion in the propionate group compared with in the control group.
In vitro analysis led the authors to conclude that IPE effects were not caused by change in gut bacterial populations.
«We know that adults gain between 0.3 and 0.8 kilos a year on average, and there’s a real need for new strategies that can prevent this,» Gary Frost, PhD, from the Department of Medicine, Imperial College, London, United Kingdom, who led the study, said in a news release issued by the Imperial College of London.
«Molecules like propionate stimulate the release of gut hormones that control appetite, but you need to eat huge amounts of fibre to achieve a strong effect. We wanted to find a more efficient way to deliver propionate to the gut.»
Imperial Innovations, a technology commercialization company, is working with the investigators to bring the IPE to the market. The study was funded by the Biotechnology and Biological Sciences Research Council’s Diet and Health Research Industry Club, which works with the food industry to develop consumer products by establishing partnerships between funders and a consortium of food companies to support academic research. The authors, Dr Painter, and Dr Cheskin have disclosed no relevant financial relationships.
Gut. Published online December 10, 2014. Full text
