Secret slimming success and sweet potatoes

A peptide produced by enzyme digestion of proteins in the water wasted during processing of sweet potatoes has been found to have a slimming effect in mice.

Sweet potatoes are the world’s fifth most important crop according to the International Potato Center with 105 million metric tons harvested each year. Around 15% of the crop is used to produce starch materials, processed foods and distilled spirits in Japan, which coincidentally results in significant quantities of wastewater.

A team led by Dr Koji Ishiguro from Japan’s National Agriculture and Food Research Organization investigated ways to use the sweet potato proteins in the wastewater.

The researchers fed three groups of mice high-fat diets, giving one group a protein digest — sweet potato peptide (SPP) — at a high concentration and one group at a lower concentration. After 28 days they weighed the mice and measured their liver mass and fatty tissue. They also measured the levels of the fats cholesterol and triglyceride, as well as leptin, which controls hunger, and adiponectin, which regulates metabolic syndrome.

Mice that were given SPP had significantly lower body weight and liver mass. Mice fed SPP also had lower cholesterol and triglycerides, and higher levels of the hunger and lipid-controlling hormones. The results suggest that SPP helps activate appetite suppression and control lipid metabolism in mice fed high-fat diets.

But will this peptide produce the same result for humans?

Effects of a sweet potato protein digest on lipid metabolism in mice administered a high-fat diet, Ishiguro et al. The article appears in Heliyon (December 2016), published by Elsevier.