Prevention of Obesity by Anthocyanins

The Durk Pearson & Sandy Shaw®
Life Extension NewsTM
Volume 9 No. 1 • January 2006


Prevention of Obesity by Anthocyanins

You may recall our article in an earlier newsletter about the obesity-preventing effects of purple corn color.1 Anthocyanins are found in many fruits (especially berries) and some vegetables, particularly those with a blue or purple color, though they are sometimes found in red fruits, such as cherries. High-anthocyanin-containing foods include blueberry, Concord grape, and cranberry. In the paper on purple corn color, feeding this anthocyanin-rich color to mice on a high-fat diet resulted in a significant suppression of the weight gain of the group of mice on the high-fat diet but without purple corn color supplementation. It markedly reduced the hypertrophy of adipocytes (fat cells) in the epididymal white adipose tissue compared with the high-fat-fed controls. Moreover, the high-fat diet induced hyperglycemia, hyperinsulinemia, and hyperleptinemia (higher than normal levels of blood sugar, blood insulin, and blood levels of the hormone leptin); these effects were completely normalized in the rats fed the high-fat diet plus purple corn color.

Following up on these findings, a new paper2 reports that similar effects were found in mice fed a high-fat diet with or without a supplement of anthocyanins or ursolic acid found in Cornelian cherries. The supplemented animals received a high-fat diet (same as the controls) but containing 1 gram of anthocyanins or 500 mg of ursolic acid per kg of high-fat diet. The anthocyanin-treated (but not the ursolic acid-treated) mice had a 24% decrease in weight gain compared to the high-fat-fed controls. The mice fed the anthocyanin- or ursolic acid-supplemented diets showed improved glucose tolerance compared to controls.

Cornelian cherries, which are used to treat diabetes in China, are said to be similar to tart (sour) cherries,2 though we do not know what the comparable figures are for anthocyanin content, and the authors note that the active compounds in the Cornelian cherries used in diabetes therapy are not fully characterized. It is known, however, that “Generally, sour cherries had higher concentrations of total phenolics than sweet cherries, due to a higher concentration of anthocyanins and hydroxycinnamic acids.”2a

The one thing that raises a red flag here is that the insulin levels were dramatically increased in the anthocyanin-treated mice on the high-fat diet. Whereas insulin levels measured by radioimmunoassay for control animals fed normal and high-fat diets were 0.47 ± 0.14 and 0.41 ± 0.1 ng/ml, respectively, the animals fed diets containing anthocyanins and ursolic acid showed 567.98 ± 32.36 and 52.25 ± 8.84 ng/ml, respectively. However, the authors found that the anthocyanins and ursolic acid protected the pancreatic islet architecture compared to the nonsupplemented high-fat-fed mice. (The authors verified the insulin increases using two different methods, RIA and ELISA.) The high-fat-fed control mice had enlarged islets with diffuse staining (for insulin) and irregular structure compared to the anthocyanin-supplemented mice, which had islets that were similar in size and structure to islets from mice fed a normal diet. Though these latter findings are reassuring, the insulin increase is substantial and possibly undesirable. The dosage used (1 gram of anthocyanins per kg of diet) may be considerably more than a human would get on a diet of high-anthocyanin-containing foods.

Another possibility, on the insulin increase, is that this works differently in humans. If a human had such a high insulin level, he or she would go into insulin shock from hypoglycemia. (It is strange that the mice didn’t go into comas.) Durk can eat a pound of cherries or blueberries at a single sitting and has never had symptoms of hypoglycemia afterward. We hope that human follow-up studies using doses of anthocyanins that can be obtained from an anthocyanin-rich diet are done.

References

  1. Tsuda et al. Dietary cyanidin 3-O-ß-D-glucoside-rich purple corn color prevents obesity and ameliorates hyperglycemia in mice. J Nutr 133:2125-30 (2003).
  2. Jayaprakasam et al. Amelioration of obesity and glucose intolerance in high-fat-fed C57BL/6 mice by anthocyanins and ursolic acid in Cornelian cherry (Cornus mas). J Agric Food Chem 54:243-8 (2006).
    2a. Kim et al. Sweet and sour cherry phenolics and their protective effects on neuronal cells. J Agric Food Chem 53:9921-7 (2005).

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