Last year, I wrote an article on Garcinia cambogia for Vitamin Retailer. In that article, I focused on the weight loss-related benefits of this nutraceutical. In this article, I will share other research that demonstrates Garcinia cambogia’s value in lowering triglycerides, increasing glycogen production and preferentially promoting the use of fat as a fuel source during exercise in favor of carbohydrates.

Background

The Garcinia genus consists of 180 species distributed in tropical regions of Asia, Africa and Polynesia.1 A few of these species, including G. cambogia (also known as Malabar tamarind), contain (-)-hydroxycitric acid (HCA), which has some interesting biological properties.2 The effects of HCA will be the focus of this article.

Lowering triglycerides

In 2014, a 60-day study3 analyzed the effect of G. cambogia on the triglycerides (blood fats) in obese women (age 25-60 years). The women divided in treated (n=30) and control (n=13) groups. Those in the treated group received 2,400 mg (800 mg, 3 times/day) of garcinia extract (50 percent of HCA), and those in the control group received a placebo. Subjects in both groups were also given dietary guidance to reduce their daily caloric intake by 380 calories/day. The results showed that triglyceride levels in the treated group were reduced from 132.35 ± 41.61 mg/dL to 109.52 ± 38.7 mg/dL. That’s a decrease of 22.83 points or about 17 percent. This reduction was significantly lower than that experienced by the control group (p=0.04).

Increasing Glycogen Production

[caption id="attachment_6400" align="alignleft" width="300"] Chart 1 - Increase in glycogen production[/caption]

This study4 examined the effects of HCA supplementation on glycogen production after a meal in eight, healthy, exercising male volunteers (average age of 22 years). The volunteers completed a 60-minute cycling exercise and received 500 mg HCA or placebo. Then, seven days later the same experiment was performed but those who had previously received the HCA now received the placebo, and vice-versa. In either case, to also ate a high-carbohydrate meal (2 g carbohydrate/kg body weight, 80 percent carbohydrate, 8 percent fat, 12 percent protein). Muscle biopsy samples were obtained from the Vastus lateralis (a muscle in the thigh) immediately and three hours after the exercise. The results showed that HCA supplementation significantly lowered the insulin response to the meal. Furthermore, glycogen production was increased significantly with HCA compared to placebo (see graph “Increase in glycogen production”). Also, HCA supplementation significantly increased the use of fat as an energy fuel.

It should also be noted that the decreased use of carbohydrates as a fuel, discussed in the following studies, is an indication of glycogen sparing.

Fat Utilization During Exercise and Increased Time To Exhaustion

[caption id="attachment_6401" align="alignleft" width="300"] Chart 2 - Exercise time to exhaustion in women[/caption]

This study5 investigated the effects of short-term HCA ingestion on endurance exercise performance and fat metabolism in untrained women. Six subjects received 250 mg of HCA or placebo for five days and then participated in cycle ergometer exercise. At a later date, the same experiment was performed but those who had previously received the HCA now received the placebo, and vice-versa. The results showed that HCA tended to decrease the amount of carbohydrate burned as fuel during one hour of exercise, while increasing the amount of fat burned as fuel. In addition, subjects using HCA were able to exercise for a longer period of time before reaching exhaustion (p<0.05, see graphs “Exercise time to exhaustion).

An earlier study6 in men found similar results. Six untrained men received 500 mg HCA or a placebo for five days, and then did moderate intensity exercise. Two days later, the same experiment was performed but those who had previously received the HCA now received the placebo, and vice-versa. The results were that blood concentrations of free fatty acids were significantly increased, and the use of carbohydrates as a burned fuel decreased with HCA ingestion, demonstrating that short-term HCA ingestion increases fat oxidation in untrained men.

[caption id="attachment_6402" align="alignleft" width="300"] Chart 3 - Exercise time to exhaustion in athletes[/caption]

Likewise, a similar study7 was conducted in athletes who received 250 mg of HCA or placebo for five days, and then performed cycle ergometer exercise until exhaustion. At least two days later, the same experiment was performed but those who had previously received the HCA now received the placebo, and vice-versa. The results showed that HCA increased the amount of fat burned as a fuel, while significantly decreasing the amount of carbohydrate burned as a fuel during exercise (p < 0.05). This also led to an increase in the amount of time subjects could exercise until exhaustion (p < 0.05). The authors noted that short-term administration of HCA not only enhanced endurance performance and improved fat burning, but also spared glycogen utilization during moderate intensity exercise in athletes.

Conclusion

Previously, Garcinia cambogia and its active compound, HCA, have been shown to have efficacy as part of a program to promote weight loss. In addition, other research has demonstrated that HCA has value as an ergogenic aid during exercise. Specifically, it has been shown to increase glycogen production, and preferentially promote the use of fat as a fuel source during exercise in favor of carbohydrates. Also, HCA was shown to help lowering triglycerides. VR

References:

The wealth of India (raw materials), Vol. IV. New Delhi, India: CSIR; 1956: 99-108.

Jena BS, Jayaprakasha GK, Singh RP, Sakariah KK. Chemistry and biochemistry of (-)-hydroxycitric acid from Garcinia. Journal of agricultural and food chemistry. 2002;50(1):10-22.

Vasques CA, Schneider R, Klein-Júnior LC, Falavigna A, Piazza I, Rossetto S. Hypolipemic effect of Garcinia cambogia in obese women. Phytother Res. 2014 Jun;28(6):887-91.

Cheng IS, Huang SW, Lu HC, Wu CL, Chu YC, Lee SD, Huang CY, Kuo CH. Oral hydroxycitrate supplementation enhances glycogen synthesis in exercised human skeletal muscle. Br J Nutr. 2012 Apr;107(7):1048-55.

Lim K, Ryu S, Nho HS, Choi SK, Kwon T, Suh H, So J, Tomita K, Okuhara Y, Shigematsu N. (-)-Hydroxycitric acid ingestion increases fat utilization during exercise in untrained women. J Nutr Sci Vitaminol (Tokyo). 2003 Jun;49(3):163-7.

Tomita K, Okuhara Y, Shigematsu N, Suh H, Lim K. (-)-hydroxycitrate ingestion increases fat oxidation during moderate intensity exercise in untrained men. Biosci Biotechnol Biochem. 2003 Sep;67(9):1999-2001.

Lim K, Ryu S, Ohishi Y, Watanabe I, Tomi H, Suh H, Lee WK, Kwon T. Short-term (-)-hydroxycitrate ingestion increases fat oxidation during exercise in athletes. J Nutr Sci Vitaminol (Tokyo). 2002 Apr;48(2):128-33.

Gene Bruno, MS, MHS, the dean of academics for Huntington College of Health Sciences, is a nutritionist, herbalist, writer and educator. For more than 30 years he has educated and trained natural product retailers and health care professionals, has researched and formulated natural products for dozens of dietary supplement companies, and has written articles on nutrition, herbal medicine, nutraceuticals and integrative health issues for trade, consumer magazines and peer-reviewed publications.