High amylose starch consumption induces obesity in Drosophila melanogaster and metformin partially prevents accumulation of storage lipids and shortens lifespan of the insects.

There are very few studies that have directly analyzed the effects of dietary intake of slowly digestible starches on metabolic parameters of animals. The present study examined the effects of slowly digestible starch with high amylose content (referred also as amylose starch) either alone, or in combination with metformin on the development, lifespan, and levels of glucose and storage lipids in the fruit fly Drosophila melanogaster. Consumption of amylose starch in concentrations 0.25-10% did not affect D. melanogaster development, whereas 20% starch delayed pupation and reduced the number of larvae that reached the pupal stage. Starch levels in larval food, but not in adult food, determined levels of triacylglycerides in eight-day-old adult flies. Rearing on diet with 20% starch led to shorter lifespan and a higher content of triacylglycerides in the bodies of adult flies as compared with the same parameters in flies fed on 4% starch diet. Food supplementation with 10mM metformin partly attenuated the negative effects of high starch concentrations on larval pupation and decreased triacylglyceride levels in adult flies fed on 20% starch. Long-term consumption of diets supplemented with metformin and starch decreased lifespan of the insects, compared with the diet supplemented with starch only. The data show that in Drosophila high starch consumption may induce a fat fly phenotype and metformin may partially prevent it.

Blood lipids, lipoproteins, apoproteins, and uric acid in men fed diets containing fructose or high-amylose cornstarch.

Ten hyperinsulinemic and 11 nonhyperinsulinemic men consumed for 5 wk each in a cross-over design a diet, similar to one currently consumed in the United States, with 20% of the kilocalories from either fructose or high-amylose cornstarch to determine the effects of the two diets on various blood metabolites considered to be risk factors associated with heart disease. In the hyperinsulinemic men the intake of fructose as compared with cornstarch significantly increased total triglycerides and their lipoprotein distribution; total and very-low-density lipoprotein cholesterol; apoproteins B-100, C-II, C-III; and uric acid. In the nonhyperinsulinemic men total triglycerides, total and low-density lipoprotein cholesterol and uric acid were significantly greater after the consumption of fructose than after cornstarch. The results indicate that in a diet high in saturated fatty acids and cholesterol, fructose increases the levels of risk factors associated with heart disease, especially in hyperinsulinemic men.