“Although it is still unclear whether fiber supplementation will reduce overall metabolic syndrome and cardiovascular disease risk on its own, it may be a useful strategy to support other risk reduction measures such as lifestyle changes, pharmaceutical treatments,” wrote researchers from Curtin University in Perth, Western Australia, in a critical review published in the journal Nutrition.
They looked at the body of studies published between 1980 and 2017 on three fiber ingredients that are widely used in the dietary supplements space—Psyllium, oat bran, and PolyGlycopleX (or PGX), a complex of three naturally occurring polysaccharides trademarked by Canadian ingredient maker InovoBiologic Inc.
Data they collected from these previous studies indicated that “the addition of a fiber product, most notably psyllium, to the daily diet can improve blood lipid profiles, particularly total cholesterol and LDL cholesterol, moderate glycemic response, and increase satiety.”
Potential mechanisms of action
A potential mechanism of action for how fiber ingredients like psyllium husk may lower high cholesterol levels is by trapping cholesterol uptake in a viscous gel, which forms in the digestive tract when these fibers are ingested.
There were more studies available on psyllium than studies on beta-glucan and PGX because they have been on the market and used for human consumption for a longer time.
Moreover, PGX is only available in products sold in the US and Canada, limiting the number of studies that have been conducted on the ingredient.
Despite this, the researchers found sufficient human clinical studies that support the consumption of oat bran beta-glucan daily for improvement of blood lipids (at 6 to 8 g per day), and the same for PGX consumption (at 10 to 15 g per day).
Researchers searched for original research articles such as clinical trials, systematic reviews, and meta-analyses on databases Embase and PubMed.
The keywords they used included ‘psyllium,’ ‘oat bran,’ ‘PolyGlycopleX,’ ‘overweight,’ ‘obesity,’ and ‘metabolic syndrome.’
They also looked at studies that were conducted on both adults and children, hoping to find data regarding the safety and efficacy of fiber supplementation among children—but they found that the data was still lacking.
“More research is needed to further clarify the benefits of PolyGlycopleX in particular, as well as to develop safe and efficacious recommendations for fiber supplementation of all types for children in general.”
Published online ahead of print, https://doi.org/10.1016/j.nut.2018.05.036
"Effects of daily consumption of psyllium, oat bran and polyGlycopleX on obesity-related disease risk factors: A critical review"
Authors: Monica Jane PhD, Jenny McKay B. Sc., Sebely Pal