Role of vegetable protein in the preparation of weight loss-promoting oil.

We have reported that oil thermally processed with protein promoted safe and steady weight loss in animal experiments. In the present study, an oil for use in weight control was prepared by heating fresh oil with wheat gluten or soybean protein to determine the influence of protein differences on the weight loss-promotion effect. The 2 kinds of oil obtained, which differed neither from commercial fresh oil (starting oil) nor from one another in appearance, chemical properties, and aroma, were mixed (7%) with powdered AIN93G no-fat, defined standard diet and fed to 10-week-old Wistar rats ad libitum. After a 12-week feeding period, the rats were sacrificed to obtain blood and organs. There were no differences in amounts ingested, body weight increases, fecal excretion, organ weights, serum biochemical analyses, contents and fatty acid compositions of lipids of retroperitoneal fat tissue, or organ observations. Aspartate aminotransferase (AST), alanine aminotransferase (AST), and histological analysis supported the safety of the oil. In conclusion, the differences between wheat gluten and soybean protein in amino acid composition, both of the proteins and as free amino acids, were unrelated to the weight loss-promoting effect of the oil. Minor components in the vegetable proteins may have contributed to the effect on body weight.