Bitter melon malt vinegar increases daily energy turnover in rats

Vinegar is generally believed to be good for health. A mash consisting of 35% ethanolic extract from bitter melon malt vinegar-water (8 : 50 : 42) was subjected to further acetate fermentation and the resulting vinegar was converted to dried vinegar powder by spray drying after adsorption on dextrin, which was mixed with a commercial rat chow (CRF-1) in the ratio of 1:19 so as to prepare an experimental diet. Male 12-wk old rats of LETO and OLETF strains were fed this experimental diet in parallel with CRF-1(control) and examined for respiratory quotient (RQ) and blood or plasma parameters associated with diabetes mellitus. Administration of the experimental diet increased daily food intake as well as daily energy expenditure in both strains. RQ significantly lessened in the vinegar diet-fed group of LETO strain, which was reflected not only in the increased energy consumption from fat but also in the decreased energy consumption from carbohydrate, while no significant difference was observed between both dietary groups of OLETF strain in this respect. The profiles of diurnal energy expenditure in both dietary groups of LETO strain exerted two peaks before lights-on and lights-off. Nevertheless, there was a clear difference between both dietary groups of OLETF strain; interestingly the reproduction of the two peaks became conspicuous in the vinegar diet-fed group despite the lack of such peaks in the control. As a consequence of blood or plasma inspection, it turned out that there was no change in HbAlc but a significant increase in plasma cholesterol in the vinegar diet-fed OLETF rats. From these results, a long-term administration of bitter melon malt vinegar can be expected to suppress a lowering of energy turnover inherent with aging and thereby improve anorexia rather than to bring about a preventive effect against the manifestation of NIDDM.