Ron Prior, PhD

Ron Prior, PhD

Biography

Dr. Prior received his Ph.D. in Nutrition with minors in biochemistry and physiology from Cornell University. His graduate training was followed by two years of post-doctoral training in Comparative Gastroenterology through the College of Veterinary Medicine at Cornell University. Dr. Prior was with the Agricultural Research Service of the USDA for 35 years. Following 13 years at the USDA Human Nutrition Research Center on Aging at Tufts.

Dr. Prior moved in 2000 to the USDA Arkansas Children’s Nutrition Center in Little Rock, AR where he provided leadership for their phytochemical and health research program. In May of 2010 Dr. Prior retired from the USDA, but he continues to serve as adjunct professor in the Dept of Food Science at the Univ. of Arkansas, Fayetteville and to consult with organizations on matters related to phytochemicals and nutrition.

Dr. Prior has published more than 220 articles in peer reviewed scientific journals. Dr. Prior received the Alex Wetherbee Award from the North American Blueberry Council for his contributions to the blueberry industry. In 2006, was ranked as the top-cited author in agricultural sciences by Science Watch.

Abstract

Anthocyanins and Other Factors in Berries that Affect Development of Obesity

Ronald L. Prior, USDA, ARS, Arkansas Children’s Nutrition Center, 15 Children’s Way, Little Rock, AR 72202

Recently there has been considerable attention focused on foods that may be beneficial in preventing diet-induced obesity, metabolic syndrome and possibly reduce the risk of diabetes and heart disease. Anthocyanins, which are especially high in berries and some other foods, when fed in a purified or extract have been shown to have an anti-obesity effect in vivo (1-6). Most of these studies used a concentrated extract of some form of the anthocyanins. However, in recent studies of anthocyanins in berries, when whole powdered berries from blueberries, black raspberries, concord grapes or strawberries were fed, the freeze dried powdered whole berries were not effective in preventing obesity (2, 5) and in some cases tended to promote obesity in the context of a high fat diet but not with a low fat diet.

Whole freeze dried powders of blueberries, concord grapes and black raspberries were ineffective in preventing obesity (2). Whole strawberries did not promote obesity when fed in a high fat diet and some measures indicated possible anti-obesity effects. However, feeding purified anthocyanins from blueberries and strawberries were effective in preventing obesity and correcting dislipidemia and hyperpeptinemia of obesity.

The mechanism(s) whereby anthocyanins might exert the anti-obesity effects are not clear. Sasaki and coworkers (6) suggested that cyanidin 3-glucoside ameliorates hyperglycemia and insulin sensitivity via the reduction of retinol binding protein 4 (RBP4) expression in white adipose tissue in type 2 diabetic mice. This effect was also accompanied by down regulation of the inflammatory adipocytokines (monocyte chemoattractant protein-1 and tumor necrosis factor-alpha) in the white adipose tissue of the cyanidin-3-glucoside group. Cyanidin-3-glucoside and other anthocyanins extracted from purple corn suppressed the mRNA levels of enzymes involved in fatty acid and triacylglycerol synthesis and lowered the sterol regulatory element binding protein-1 mRNA level in white adipose tissue of mice (1).

Studies to date have not provided any explanation why the purified anthocyanins are effective in preventing obesity, but the whole berry powder containing the same anthocyanins is ineffective. One option may be that there are other factors in the whole berry powder that counteract in some way the effects of purified anthocyanins. Juices made from berries provide another form in which anthocyanins are consumed in the diet. Processing of blueberries into juice results in significant loss of anthocyanins (7), but still provides a concentrated source of anthocyanins which have been removed from other components in the whole berry. Blueberry juice, when provided in place of water to mice fed a high fat diet, were effective in slowing the development of obesity, but in some measures of obesity were not as effective as purified anthocyanins given in the drinking water.

Questions still remain regarding the effective level of consumption of anthocyanins, the particular aglycone and other structure considerations related to mono- versus di- or triglycosides and the prevention of obesity. Other factors within the whole berry may also effect the in vivo effectiveness of anthocyanins in preventing obesity which remain to be determined.

Key Words: blueberry, strawberry, leptin, obesity, anthocyanins

References:

1. Tsuda, T.; Horio, F.; Uchida, K.; Aoki, H.; Osawa, T., Dietary cyanidin 3-O-beta-D-glucoside-rich purple corn color prevents obesity and ameliorates hyperglycemia in mice. J. Nutr. 2003, 133, (7), 2125-30.

2. Prior, R. L.; Wu, X.; Gu, L.; Hager, T.; Hager, A.; Wilkes, S.; Howard, L., Purified berry anthocyanins but not whole berries normalize lipid parameters in mice fed an obesogenic high fat diet. Mol. Nutr. Food Res. 2009, (Accepted 03/02/2009).

3. Jayaprakasam, B.; Olson, L. K.; Schutzki, R. E.; Tai, M. H.; Nair, M. G., 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 2006, 54, (1), 243-8.

4. Tsuda, T., Regulation of adipocyte function by anthocyanins; possibility of preventing the metabolic syndrome. J Agric Food Chem 2008, 56, (3), 642-6.

5. Prior, R. L.; Wu, X.; Gu, L.; Hager, T. J.; Hager, A.; Howard, L. R., Whole berries versus berry anthocyanins: interactions with dietary fat levels in the C57BL/6J mouse model of obesity. J Agric Food Chem 2008, 56, (3), 647-53.

6. Sasaki, R.; Nishimura, N.; Hoshino, H.; Isa, Y.; Kadowaki, M.; Ichi, T.; Tanaka, A.; Nishiumi, S.; Fukuda, I.; Ashida, H.; Horio, F.; Tsuda, T., Cyanidin 3-glucoside ameliorates hyperglycemia and insulin sensitivity due to downregulation of retinol binding protein 4 expression in diabetic mice. Biochem Pharmacol 2007, 74, (11), 1619-27.

7. Brownmiller, C.; Howard, L. R.; Prior, R. L., Processing and Storage Effects on Monomeric Anthocyanins, Percent Polymeric Color, and Antioxidant Capacity of Processed Blueberry Products. J. Food Sci. 2008, 73, (5), H72-H79.