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Herbal Remedies for Weight Loss
By Dónal P. O'Mathùna, PhD, Senior Lecturer in Ethics, Decision-Making & Evidence, School of Nursing, Dublin City University, Ireland. Dr. O'Mathùna reports no financial relationship to this field of study.
Obesity continues to raise concerns, in spite of greater public awareness of its associated problems and challenges. Many who seek to lose weight use herbal remedies and dietary supplements as one of their strategies. A 2008 U.S. survey found that one-third of adults making a serious attempt to lose weight had used a weight loss dietary supplement.1 In addition, half of those surveyed believed that dietary supplements were evaluated for safety and efficacy before being marketed, which is not always the case. Many herbal weight loss products have limited evidence of effectiveness. Adverse effects could become widespread if an unsafe herb is promoted, which happened before ephedra was banned.2
Given the links between body weight and health, health care practitioners will be asked about ways to help people lose weight. Since many patients already are using herbal remedies, they may have questions about the products' use or effects. Practitioners should therefore be aware of the available evidence for the most popular weight loss supplements. Given the large number of such products available, this article will focus on herbal remedies those prepared from plant material. Discussion also will be limited to products containing one herb, rather than combinations of herbs. The herbs are introduced alphabetically.
Acai berries come from a South American palm tree, Euterpe oleracea. The fruit has been an important source of protein for people living in the Amazon jungle. Because it leaves people feeling full, it developed a reputation as an appetite suppressant. After being mentioned (but not endorsed) on the Oprah Winfrey show in 2008, it was promoted widely as a weight loss supplement.3 According to the Brazilian Agricultural Research Corporation, demand for the berries led to their wholesale price in Brazil increasing 60-fold in recent years.4 Soon the people in the Amazon could not afford the berries.
Acai berries and juice are nutritious, containing vitamins A, C, and E, along with calcium, iron, and several fatty acids.5 The juice and fruit pulp are relatively high in protein and fat, which may explain why people feel full after consuming them. The berries are high in antioxidants, and lead to significantly elevated plasma antioxidant capacity in humans.6 However, no studies have been published on acai's ability to help people lose weight and how it might act to promote weight loss is not known.
Bitter orange is an extract from the rind of the fruit of the tree Citrus aurantium whose fruit is primarily used to make marmalade. Following the 2004 FDA ban of ephedra for safety reasons, many manufacturers replaced it with bitter orange to make "ephedra-free" supplements.7 Bitter orange contains synephrine alkaloids that are adrenergic agonists. At least six isomers of synephrine exist with varying alpha- and beta-adrenergic activity, though it is unclear how many of these isomers occur in bitter orange. Three small randomized controlled trials (RCTs) have been conducted with bitter orange, but only in combination with other ingredients like caffeine, St John's wort, ginseng, or gingko.8 These studies reported weight loss of 2-3 kg among those using the supplements, with the placebo groups losing 1-2 kg. Since synephrine has similar effects to ephedrine, concerns have been raised that it may cause similar adverse effects. A number of case reports of cardiac problems after taking bitter orange products have been published.9 However, a recent safety review noted that those experiencing adverse effects in these cases had consumed several supplements, while controlled studies have not identified adverse effects.10
Cissus quadrangularis (or CQ) has been used medicinally in India and Africa as an anti-inflammatory and to promote healing, especially of bone fractures.11 Recent studies have examined its ability to reduce weight and body fat. In combination with its traditional use in promoting bone healing, this has made it popular among body-builders. Proposals have been made that CQ inhibits enzymes that metabolize food, thus making it more difficult to absorb.
The first study of CQ for weight loss involved 123 obese and overweight participants from Cameroon. People were randomly assigned to receive either placebo, CQ with a calorie-reduced diet, or CQ without the diet. After 8 weeks, those who were obese had significantly reduced weight, percent body fat, and BMI compared to placebo. Those who were overweight did not have significant reductions in weight or body fat, but did have lower BMI. All groups also had significant improvements in plasma cholesterol, C-reactive protein, and glucose levels.
The same research group carried out another RCT using a commercial CQ extract and another combination product containing CQ and other ingredients (called CORE).12 The 168 participants were randomly assigned to one of the supplements or placebo and either to a normal diet or a calorie-restricted diet. After 8 weeks of CORE or 6 weeks of CQ, participants had significantly reduced weight compared to placebo (P < 0.05). Although reductions occurred in percent body fat and BMI, these were not reported as statistically significant compared to placebo. All groups also had significant improvements compared to placebo in antioxidant capacity and total cholesterol levels, but not glucose levels.
A third study of CQ randomly assigned 72 obese or overweight participants to either placebo, CQ, or a combination of CQ and Irvingia gabonensis.13 After 10 weeks, those receiving CQ alone had significant weight loss compared to placebo (8.7 kg loss; P < 0.001), with those receiving the combination losing more weight (11.8 kg loss; P < 0.0001). Percent body fat, cholesterol levels, and blood glucose levels also improved significantly. Adverse effects reported in these studies were similar to those in the placebo group, and included headache, flatulence, diarrhea, and difficulty sleeping.
Garcinia cambogia has developed a reputation among those seeking to lose weight and build muscle. Extracts of the fruit contain up to 50 percent hydroxycitric acid (HCA), which is thought to be the active ingredient.14 This is believed to interfere with fatty acid metabolism, but precisely how it works is not known. One of the first RCTs evaluating this agent involved 135 participants, mostly women.15 All subjects went on a high-fiber, low-calorie diet and took either 3 g daily standardized extract of Garcinia or placebo. After 12 weeks, both groups lost weight and decreased percent body fat, but without significant differences between the two groups. In another RCT, 89 overweight women started a low-calorie diet and took either 2.4 g Garcinia daily or placebo.16 After 12 weeks, the Garcinia group had significantly more weight loss (3.7 kg vs 2.4 kg), but the groups did not differ in measures of appetite suppression.
Several other RCTs have had conflicting results. A systematic review published in 2011 identified 12 RCTs involving Garcinia products for weight loss.17 Nine studies provided sufficient data to permit a meta-analysis. The combined results found significantly more weight loss among those using Garcinia compared to placebo (P = 0.05; CI = -1.75 to 0.00). However, the mean difference was 0.88 kg, or 1 percent more weight loss, which led the reviewers to question if this was clinically significant. When sensitivity analyses were performed to take heterogeneity and study quality into account, the weight loss was no longer significant.
Controlled studies, animal studies, and traditional consumption of Garcinia fruit have not identified serious adverse effects beyond those of placebos. However, in 2009, FDA warned consumers to stop a range of Garcinia products called Hydroxycut.18 The recall was based on 23 serious adverse events reported after people consumed Hydroxycut. Most reports related to liver damage, including one liver transplant and one death. Its manufacturer withdrew the products, though they have since returned to the market reformulated with Garcinia replaced by Cissus quadrangularis.2 Others have questioned the association with HCA or Garcinia as Hydroxycut products contain up to 20 different ingredients.19
Another traditional food that has become a popular weight loss supplement is Hoodia gordonii. This is believed to be one of the most widely consumed herbal weight loss products.20 The hoodia plant looks like a cactus and grows in the Kalahari Desert of southern Africa. The San people used it to suppress their hunger when they went on long hunting expeditions. A South African research council identified hoodia as a potential appetite suppressant.21 Western pharmaceutical companies obtained licenses to develop it as a pharmaceutical, but in 2003 this was halted for reasons that remain unclear. Hoodia has since been incorporated into supplements and foods as a slimming agent, and become a test case for issues in bio-piracy and indigenous knowledge.22 This has led to hoodia becoming an endangered species and to stringent conservation regulations.
A UK pharmaceutical company, Phytopharm, isolated one ingredient from hoodia and named it P57.23 This appears to stimulate the brain to trigger a full feeling in mice. Phytopharm issued a press release stating that a 15-day RCT with 18 people found that those taking P57 had significantly reduced calorie intake and body fat.22 An uncontrolled study found that 7 participants lost an average of 3.3 percent body weight after taking hoodia for 28 days.23 In spite of hoodia's popularity, the evidence for its effectiveness is very sparse.20
Irvingia gabonensis is an African tree also known as "African mango" or "bush mango." It is completely different from the better-known mango fruit native to India and cultivated widely for its nutritious fruit. Many parts of the African mango have been used medicinally, but its seeds, called dika nuts, have become popular as weight loss supplements. These are rich in soluble fiber that swells in the stomach and slows emptying, giving a sense of being full.24 Researchers in Cameroon have published studies that have led to Irvingia being the latest plant included in many natural weight-loss products.
The first RCT investigating this herbal remedy involved 40 obese participants who were randomly assigned to take a placebo or 350 mg of Irvingia seed extract tid before meals. After 4 weeks, those taking the extract had lost an average of 5.6 kg compared to 1.2 kg in the placebo group (P < 0.01). Those taking the extract also had significantly lower blood pressure, total cholesterol levels, and blood glucose levels.
Another RCT was published in 2009 using 150 mg of extract before lunch and dinner.25 This double-blind, placebo-controlled study involved 120 overweight or obese participants. After 10 weeks, those taking the extract lost an average 12.8 kg compared to 0.7 kg weight loss in the placebo group (P < 0.01). Total cholesterol, blood glucose, percent body fat, and other relevant parameters were also significantly lower. The extract is well tolerated, with flatulence, headaches, and difficulty sleeping sometimes reported.25
More than $1 billion is spent annually on dietary supplements for weight loss.8 Many products contain several herbs, minerals, and other compounds for which no controlled clinical trials are available. The most commonly used herbal remedies have relatively little clinical research on their efficacy or safety. Some are supported by the evidence from a small number of trials, while others have, at best, contradictory results. On the other hand, adverse effects are not common, except perhaps for bitter orange. However, harvesting these plants has, at times, left them unaffordable by the indigenous peoples who have relied on them traditionally.
With the importance of body weight widely recognized, many people are turning to herbal remedies to help them lose weight. However, the evidence to date is insufficient to recommend any of those popularly used. Patients should be advised that even when clinical trials support the use of such herbs, these studies are usually small and of short duration.2 They also should be reminded that dietary supplements are not required to meet the same standards of effectiveness or safety as other pharmaceuticals. As one herb falls out of favor, others are waiting to take its place with even less research to support efficacy. These include Sambucus nigra, Asparagus officinalis, Garcinia atroviridis, and Salvia hispanica.26 Many other herbs are used for weight loss, such as green tea and chitosan, with several reviewed in past issues of Alternative Medicine Alert.
Weight loss can be challenging, but apart from severe obesity, the best approach continues to be one in which calorie intake is reduced, energy output increased, and support sought from others.
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2. Lobb A. Science of weight loss supplements: compromised by conflicts of interest? World J Gastroenterol 2010;16:4880-4882.
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8. Haaz S, et al. Citrus aurantium and synephrine alkaloids in the treatment of overweight and obesity: An update. Obes Rev 2006;7:79-88.
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10. Stohs SJ, Preuss HG. The safety of bitter orange (Citrus aurantium) and p-synephrine. HerbalGram 2011;89:34-39.
11. Oben JE, et al. The use of a Cissus quadrangularis formulation in the management of weight loss and metabolic syndrome. Lipids Health Dis 2006;5:24.
12. Oben JE, et al. The effect of Cissus quadrangularis (CQR-300) and a Cissus formulation (CORE) on obesity and obesity-induced oxidative stress. Lipids Health Dis 2007;6:4.
13. Oben JE, et al. The use of a Cissus quadrangularis/Irvingia gabonensis combination in the management of weight loss: A double-blind placebo-controlled study. Lipids Health Dis 2008;7:12.
14. Egras AM, et al. An evidence-based review of fat modifying supplemental weight loss products. J Obes 2011;2011:297315.
15. Heymsfield SB, et al. Garcinia cambogia (hydroxycitric acid) as a potential antiobesity agent. JAMA 1998;280:1596-1600.
16. Mattes RD, Bormann L. Effects of (-)-hydroxycitric acid on appetitive variables. Physiolog Behavior 2000;71:87-94.
17. Onakpoya I, et al. The use of Garcinia extract (hydroxycitric acid) as a weight loss supplement: A systematic review and meta-analysis of randomised clinical trials. J Obes 2011;2011:509038.
18. Food and Drug Administration. Warning on Hydroxycut products. 1 May 2009. Available at: www.fda.gov/downloads/ForConsumers/ConsumerUpdates/UCM152222.pdf. Accessed March 5, 2011.
19. Stohs SJ, et al. No evidence demonstrating hepatotoxicity associated with hydroxycitric acid. World J Gastroenterol 2009;15:4087-4089.
20. Vermaak I, et al. Hoodia gordonii: An up-to-date review of a commercially important anti-obesity plant. Planta Med epub 21 Jan 2011.
21. van Heerden FR. Hoodia gordonii: A natural appetite suppressant. J Ethnopharmacol 2008;119:434-437.
22. Duenwald, Mary. An appetite killer for a killer appetite? Not yet. New York Times. 19 April 2005. Available at: www.nytimes.com/2005/04/19/health/nutrition/19cons.html. Accessed March 4, 2011.
23. Whelan AM, et al. Efficacy of Hoodia for weight loss: Is there evidence to support the efficacy claims? J Clin Pharm Therap 2010;35:609-612.
24. Ngondi J, et al. The effect of Irvingia gabonensis seeds on body weight and blood lipids of obese subjects in Cameroon. Lipids Health Dis 2005;4:12.
25. Ngondi J, et al. IGOB131, a novel seed extract of the West African plant Irvingia gabonensis, significantly reduces body weight and improves metabolic parameters in overweight humans in a randomized double-blind placebo controlled investigation. Lipids Health Dis 2009;8:7.
26. Hasani-Ranjbar S, et al. A systematic review of the efficacy and safety of herbal medicines used in the treatment of obesity. World J Gastroenterol 2009;15:3073-3085.