Written by Marcia J. Egles, MD. Study shows that quercetin or botanical extracts containing quercetin induce white adipose tissue remodeling which may occur through inflammatory-related mechanisms.
In a recent study in mice, dietary supplementation with low-dose quercetin for 9 weeks was shown to lessen the size and the number of fat cells in mice fed high fat diets compared to control mice without quercetin supplementation. Additionally, dietary quercetin reduced inflammation related to the high fat diet 1 and altered the distribution of fatty tissue.
Quercetin is a widely occurring natural flavonoid found in small amounts in many foods from plants. Onions, especially red onions, chocolate, berries, kale and tea are notable sources of quercetin 2,3. Other mouse studies with quercetin supplementation suggest that quercetin can diminish chronic systemic inflammation 4. It can ameliorate high-fat diet induced obesity and insulin resistance 5 in laboratory tissue studies. No clinical trials are yet available.
The nine week study looked at the effects of dietary supplementation of quercetin to mice fed a high fat diet. The researchers examined both subcutaneous (inguinal white adipose tissue, “IWAT”, found under the skin in the groin) versus visceral (epididymal white adipose tissue, “EWAT”, which is the deep body fat surrounding the epididymis in the testicle) tissue. Four groups of ten mice, 5 weeks old, were used. One group received a high fat diet of 45% fat. The second group of mice received the same high fat diet supplemented with 50 micrograms quercetin aglycone per day. The third group received the equivalent quercetin as the second group only in the form of red onion extract added to the food. A fourth group received a 10% fat, low-fat diet. The body compositions of the mice were tracked weekly by nuclear magnetic imaging. After 9 weeks of feeding, tissue and serum from the mice were analyzed. (P values of less than 0.05 were considered significant).
An animal model of obesity, the mice in the high-fat diet group had large increases in the amount of body fat, and in the number and the size of the fat cells as compared with the low-fat diet mice. Both groups of mice that received quercetin supplementation had significantly less of an increase in body fat, and less of an increase in the size and number of their fat cells in both the subcutaneous and visceral tissues as compared to the high-fat diet group. Both quercetin groups decreased high-fat diet induced IWAT inflammation. EWAT inflammation was reduced in the quercetin aglycone group but not the red onion extract group. The researchers suggested that the two quercetins may be operating through differing mechanisms.
This study should not be interpreted that a high fat diet supplemented with quercetin is equivalent to a healthy diet. In addition, the data from animal studies is not always applicable to humans. However, the researchers noted that their results showed that both the purified quercetin as well as the red onion extract altered both the quantity and the “quality” of adipose tissue in affecting its amounts as well as its forms and functions. No clinical trials of quercetin dietary supplementation for obesity in human subjects are yet available.
Source: Forney, Laura, Natalie Lenard, Laura Stewart, and Tara Henagan. “Dietary quercetin attenuates adipose tissue expansion and inflammation and alters adipocyte morphology in a tissue-specific manner.” International journal of molecular sciences 19, no. 3 (2018): 895.
© 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Click here to read the full text study.
Posted November 5, 2019.
Marcia Egles, MD, graduated from Vanderbilt University School of Medicine in 1986. She completed her residency in Internal Medicine at St. Louis University Hospital. Dr. Egles is certified in Internal Medicine and is a member of the American College of Physicians. She resides in Avon, IN with her husband and two sons.
References:
- Forney L, Lenard N, Stewart L, Henagan T. Dietary quercetin attenuates adipose tissue expansion and inflammation and alters adipocyte morphology in a tissue-specific manner. International journal of molecular sciences. 2018;19(3):895.
- Manach C, Scalbert A, Morand C, Rémésy C, Jiménez L. Polyphenols: food sources and bioavailability. The American journal of clinical nutrition. 2004;79(5):727-747.
- Bhagwat S, Haytowitz DB, Holden JM. USDA database for the flavonoid content of selected foods, release 3. US Department of Agriculture: Beltsville, MD, USA. 2011.
- Stewart LK, Soileau JL, Ribnicky D, et al. Quercetin transiently increases energy expenditure but persistently decreases circulating markers of inflammation in C57BL/6J mice fed a high-fat diet. Metabolism. 2008;57:S39-S46.
- Henagan T, Cefalu W, Ribnicky D, et al. In vivo effects of dietary quercetin and quercetin-rich red onion extract on skeletal muscle mitochondria, metabolism, and insulin sensitivity. Genes & nutrition. 2015;10(1):2.
