Laboratory studies find that blue-red antioxidant pigments discourage abdominal fat deposits
by Craig Weatherby
Excess belly fat—also called abdominal or central obesity—is one of a cluster of physical signs that characterize metabolic syndrome.
This all-too-common syndrome is associated with greater risk of heart disease and diabetes, and affects almost one in three Americans.
Metabolic syndrome (MetS) is defined as having three or more of a half-dozen physiological markers, including abdominal obesity, high blood triglycerides, low HDL cholesterol, high blood pressure, insulin resistance, clot-prone blood, and chronic inflammation.
Past studies have indicated that certain of the antioxidant pigments common to colorful foods such as berries, chocolate, grapes, and blue-purple corn may help discourage abdominal obesity (See “Tart Cherries Seen Suppressing Metabolic Syndrome”).
Conversely, the standard American diet is associated with increased risk of developing MetS (See “Omega-6/Omega-3 Imbalance Pushes Heart/Diabetes Perils,” “American Diet Linked to Common Metabolic Killer,” and “Omega-3s Seen to Fight Metabolic Syndrome”).
Research results from Japan provide more evidence that the antioxidant pigments in certain colorful fruits may discourage formation of belly fat.
The antioxidants in question are called anthocyanins… the same polyphenol compounds that give berries, grapes, cocoa, and autumn leaves their red-purple hues.
Japanese study boosts anti-obesity promise of purple-red pigments
A team led by Takanori Tsuda of Chubu University in Aichi, Japan has been testing the effects of food-borne anthocyanins—3G (cyanidin 3-glucoside) and Cy (cyanidin)—on special human cells called pre-adipocytes.
Pre-adipocytes turn into fat cells (adipocytes) in response to specific stimuli, including dietary factors and exercise.
Studies that Dr. Tsuda’s team published in 2003, 2004, and 2006 produced results with encouraging implications for the effects of food-borne anthocyanins on development of belly fat and obesity.
As they wrote two years ago, their results show that particular anthocyanins prevented pre-adipocytes from becoming fat cells: “…anthocyanins can… ameliorate adipocyte function related with obesity and diabetes…” (Tsuda T et al 2006).
Specifically, the results demonstrated significant changes in the secretion of various adipokines, which are messenger proteins that tell pre-adipocytes whether to become fat cells, or not.
Most adipokines induce inflammation and promote fat build up, but one—called adiponectin—inhibits inflammation and appears to protect against metabolic syndrome, obesity, insulin resistance, and cardiovascular disease (Takemura Y et al. 2007).
Exposure to anthocyanins C3G and Cy resulted in changes that militate against expanding abdomens:
- Higher levels of adiponectin.
- Lower levels of undesirable adipokines: plasminogen activator inhibitor-1, interleukin-6, uncoupling protein2, acylCoA oxidase1, and perilipin.
Mouse study supports practical potential of anthocyanins
In a study published earlier this month, the Japanese team tested these positive indications again in two contexts:
- Mice fed a high-fat diet, with or without anthocyanin C3G.
- Human pre-adipocytes incubated with anthocyanin C3G.
The mouse study was especially significant because it tested the “real world” effects of anthocyanins on weight loss or gain: results that proved encouraging.
Dr. Tsuda’s team divided lab mice into two groups, both of which were fed a high-fat diet (30 percent lard).
However, one group’s feed also contained a very small amount (0.2 percent) of purple corn pigment rich in anthocyanin C3G.
At the end of the 12 week experiment, the mice fed purple corn pigment were significantly lighter than animals fed only the high-fat diet.
The mice fed the purple corn pigment also had less abdominal fat (Tsuda T et al 2008).
In addition to their mouse experiment, the Japanese team exposed human pre-adipocyte cells to anthocyanin-rich purple corn pigment for 24 hours, after which they detected a decrease in a messenger chemical associated with obesity and type 2 diabetes (plasminogen activator inhibitor-1).
As the authors wrote, “This study shows that anthocyanins… have important implications for preventing metabolic syndrome” (Tsuda T et al 2008).
These results should be tested in clinical trials involving whole foods, before we can be sure that berries, grapes, cocoa, purple corn, and other anthocyanin-rich fare can really help prevent MetS and its associated ills.
NOTE: No statements in this article are intended to diagnose, prevent, or treat disease, and they have not been reviewed by the US Food and Drug Administration (FDA).
- Simpson KA, Singh MA. Effects of exercise on adiponectin: a systematic review. Obesity (Silver Spring). 2008 Feb;16(2):241-56.
- Takemura Y, Walsh K, Ouchi N. Adiponectin and cardiovascular inflammatory responses. Curr Atheroscler Rep. 2007 Sep;9(3):238-43.
- 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 Jul;133(7):2125-30.
- Tsuda T, Ueno Y, Aoki H, Koda T, Horio F, Takahashi N, Kawada T, Osawa T. Anthocyanin enhances adipocytokine secretion and adipocyte-specific gene expression in isolated rat adipocytes. Biochem Biophys Res Commun. 2004 Mar 26;316(1):149-57.
- Tsuda T, Ueno Y, Yoshikawa T, Kojo H, Osawa T. Microarray profiling of gene expression in human adipocytes in response to anthocyanins. Biochem Pharmacol. 2006 Apr 14;71(8):1184-97. Epub 2006 Feb 17.
- Tsuda T. Regulation of adipocyte function by anthocyanins; possibility of preventing the metabolic syndrome. J Agric Food Chem. 2008 Feb 13;56(3):642-6. Epub 2008 Jan 23.