August 2007
Weight Loss Supplements to Watch (and Watch Out For)
By Ellen Coleman, MA, MPH, RD
Today’s Dietitian
Vol. 9 No. 8 P. 10

CDR Learning Codes: 5370, 6000; Level 1

Even though the popular TV show The Biggest Loser has proven that lasting weight loss can be achieved through diet and exercise alone, Americans continue to seek a magic elixir, spending $43 billion on weight loss foods, products, and services in 2004.1 While some weight loss supplements merely slim down the wallets (instead of the bodies) of those who use them, others are potentially harmful. Once again, dietitians need to be voices of reason and moderation. This article will review some concerns and offer evidence and advice to help counsel clients.

A recent audit of commercially available weight loss supplements in 73 different metropolitan retail outlets revealed 402 different products with more than 4,053 separate ingredients purported to promote weight loss. The top 10 ingredients were ginger root, chromium picolinate, guarana, garcinia, ephedra, green tea extract, white willow bark, eleuthero (Siberian ginseng), capsicum, and Citrus aurantium (bitter orange). The audit’s authors noted that the general lack of evidence to support the safety and effectiveness of the numerous ingredients (even the most common ones) is cause for concern.2

Blanck and colleagues found that an estimated 15.2% of adults had used a weight loss supplement in their lifetime. In the past year, 8.7% reported using a weight loss supplement. Nearly twice as many women as men had used these supplements; women aged 18 to 34 had the highest use. Weight loss supplement use was equally prevalent among race/ethnic groups and education levels.

One in 10 users reported using a weight loss supplement for one year or more, with less frequent long-term use in women than men. Only 30.2% discussed their supplement use with their physician or another health professional in the past year. The majority of users (73.8%) took a supplement containing a stimulant—ephedra, caffeine, and/or bitter orange.3

A landmark survey released by the University of Connecticut’s Center for Survey Research & Analysis found that many adults are confused about the safety and regulation of dietary supplements for weight loss. Sixty-five percent of the 3,500 respondents incorrectly believed that weight loss supplements have been tested and proven safe; 63% thought they were proven effective. Fifty-four percent mistakenly believed that they are approved by the FDA for weight loss. Sixty-four percent of those surveyed believed that products were required to display warnings about potential side effects—there is no such requirement. African Americans (50%) and Hispanics (49%) were more likely than Caucasians (36%) to believe that these products were safer than over-the-counter or prescription weight loss drugs.4 Clearly, there is work to be done.

Questionable Supplements
• Chitosan is derived from chitin, an indigestible polysaccharide found in the exoskeleton of shellfish such as shrimp, lobster, and crabs. Promoters claim that chitosan produces rapid weight loss by binding fats in the stomach and preventing them from being digested and absorbed. Chitosan products are heavily advertised with names like Fat Magnet, Fat Blocker, Fat Trapper, and Fat Absorb. Chitosan won the Healthy Weight Network’s 2000 Slim Chance Award for Worst Claim.5

Pittler and colleagues evaluated the effectiveness of chitosan in body weight reduction in a randomized, placebo-controlled, double-blind trial.6 Thirty-four overweight subjects received either four capsules of chitosan or placebo twice daily for four weeks. Subjects maintained their normal diet and documented the type and amount of food consumed. After four weeks of treatment, there were no significant differences in body mass index, serum cholesterol, triglycerides, beta-carotene, or vitamins A, D, and E in the subjects receiving chitosan compared with those receiving placebo. No serious adverse effects were reported.

In July 1999, the Federal Trade Commission (FTC) won a judgment against the company SlimAmerica, Inc. for violating federal consumer protection laws by making false advertising claims about the efficacy of its Super-Formula diet product, which contained chitin, chromium picolinate, hydroxycitrate, and glucomannan. SlimAmerica claimed that Super-Formula could “blast” off as much as 49 pounds in only 29 days, “obliterate” 5 inches from waistlines, and “zap” 3 inches from thighs—without diet modification or exercise.7

In April 2000, the marketers of The Enforma System (containing chitin and pyruvate) agreed to settle the FTC charges of deceptively advertising that the user could “eat what you want and never, ever, ever have to diet again.”8

There is no guarantee that chitosan products are free of impurities or contaminants, since the product composition may vary depending on the sea water, time of year, and specific shellfish utilized. Manufacturers aren’t required to divulge the source of their products’ chitin, which may differ widely from product to product and come from multiple sources. Individuals who are allergic to seafood should avoid chitosan products.

• CortiSlim and CortiStress advertisements claimed that elevated levels of cortisol, the “stress hormone,” make people fat. CortiSlim claimed to reduce and control cortisol levels, thereby causing substantial weight loss.9,10

CortiSlim’s ingredients are packaged into three “proprietary blends” that carry names to insinuate that the blends promote fat loss. The Cortiplex Blend, containing magnolia bark extract, beta-sitosterol, and L-theanine, supposedly controls cortisol levels to decrease fat storage and promote fat loss. The Leptiplex Blend (named for Leptin) contains green tea and bitter orange peel extracts and purportedly controls appetite. The Insutrol Blend contains banaba leaf extract and vanadium and allegedly maintains healthy blood sugar levels.

Magnolia bark is used as a general antistress, antianxiety agent in traditional Chinese medicine and purportedly exerts these effects by lowering cortisol levels. L-threanine is an amino acid found in green tea leaves, supposedly promoting relaxation by increasing the brain’s production of alpha waves and controlling cortisol levels. Beta-sitosterol is a plant sterol that allegedly normalizes the ratio of catabolic stress hormones such as cortisol to anabolic hormones such as dehydroepiandrosterone (DHEA).11

At present, there is inadequate data to support the claim that magnolia bark, L-threanine, or beta-sitosterol lower cortisol levels. Furthermore, even if these substances did reduce cortisol levels, there is no quality evidence that lowering cortisol levels would promote body fat loss.

Banaba leaf extract purportedly reduces blood glucose and insulin levels, thereby reducing food cravings and promoting weight loss.11 Vanadium is a trace element that may help normalize blood glucose levels and reduce glycosylated hemoglobin levels in patients with non–insulin-dependent diabetes mellitus.12 At present, there is no published research to support the claim that banaba leaf extract or vanadium help stabilize blood glucose levels or enhance fat loss in healthy individuals.

Citrus aurantium and green tea extract are discussed below.

There is no also substantive evidence that the ingredients in CortiSlim suppress cortisol or promote weight loss.9,10 In January, the marketers of CortiSlim and CortiStress settled FTC charges that they made false and unsubstantiated claims about their products causing weight loss and reducing the risk of serious health conditions.10

• Citrus aurantium contains synephrine, octopamine, and other adrenergic stimulant amines. Synephrine is structurally similar to epinephrine and octopamine to norepinephrine. It theoretically enhances fat metabolism by stimulating beta-3 adrenergic receptors. Citrus aurantium has replaced ephedra in many weight loss supplements. It increases heart rate and blood pressure when combined with caffeine. The combination of Citrus aurantium and caffeine has significant cardiovascular stimulant actions similar to ephedra. There have been reports of heart attack, ischemic colitis, exercise-induced syncope, and ischemic stroke associated with the use of Citrus aurantium.13

There are also questions about the effectiveness of Citrus aurantium for weight loss. Greenway and colleagues found that the Citrus aurantium group gained more weight (1.13 kilograms) than the placebo (0.09 kilograms). The baseline resting metabolic rate rose more in the Citrus aurantium group than the placebo, but there was no significant difference at eight weeks.

The researchers found no difference between groups in dual energy x-ray absorptiometry or waist circumference at eight weeks or in food intake or hunger ratings at two weeks.14

Gougeon and associates found that Citrus aurantium increased the thermic effect of food in female but not male subjects. The thermic effect of food was 20% lower in women than men, suggesting a diminished central nervous system response. The thermic effect of Citrus aurantium alone was higher in men than women. Citrus aurantium increased the thermic effect of food in women by 29% and to values no longer different than men. The researchers noted that this acute response may not translate into a chronic effect or a clinically significant weight loss over time.15

Larger and more rigorous clinical trials are necessary to draw adequate conclusions regarding the safety and effectiveness of Citrus aurantium.16

Consumers should be advised that “ephedra-free” printed on a supplement label does not mean stimulant-free; it means ephedra has been replaced. Many weight loss supplement manufacturers have increased the dose of caffeine in their products and/or substituted Citrus aurantium or other stimulants for ephedra.

In January, two marketers of Xenadrine EFX settled FTC charges that they made unsubstantiated claims for the product, including that it was clinically proven to cause rapid and substantial weight loss and was more effective than leading ephedrine-based diet products. Xenadrine EFX contains Citrus aurantium, green tea extract, caffeine, and other ingredients.10

• Green tea extract contains epigallocatechin gallate (EGCG) and caffeine. EGCG inhibits catechol-O-methyltransferase (the enzyme that degrades norepinephrine), thereby boosting norepinephrine levels. Caffeine inhibits phosphodiesterase, the enzyme that degrades cyclic adenosine monophosphate (AMP). The net result is that green tea extract may increase energy expenditure and fat oxidation.17

Dulloo and colleagues evaluated the effect of green tea extract on 24-hour energy expenditure. Ten subjects each randomly consumed green tea extract (90 milligrams of EGCG and 50 milligrams of caffeine), caffeine only (50 milligrams), or placebo. The green tea extract increased both the 24-hour energy expenditure by 4% (approximately 80 kilocalories per day) and fat oxidation compared with caffeine and placebo. The 24-hour urinary norepinephrine excretion was 40% higher during treatment with the green tea extract compared with caffeine and placebo. The thermogenic effect appears to be independent of the caffeine in green tea extract.18

Bérubé-Parent and associates evaluated the effect of 200 milligrams of caffeine from guarana and a variable dose of EGCG (90, 200, 300, or 400 milligrams) from green tea consumed three times daily. Twenty-four-hour energy expenditure increased by 8% (179 kilocalories) with all caffeine/EGCG mixtures. This increase was similar with all doses of EGCG. The caffeine/EGCG mixtures had no effect on lipid oxidation.19

There have been case reports of acute liver toxicity associated with the use of green tea extract.20 Further research is required to determine the safety and efficacy of green tea extract for weight loss.

In January, the Bayer Corporation settled FTC charges that advertisements for One-A-Day WeightSmart multivitamins violated an earlier FTC order requiring all health claims for One-A-Day brand vitamins to be supported by competent and reliable scientific evidence. Bayer marketed One-A-Day WeightSmart with unsubstantiated claims that it enhances metabolism through its EGCG content and helps prevent some weight gain associated with a decline in metabolism in users over the age of 30.10

• Conjugated linoleic acids (CLAs) are isomers of the essential fatty acid linoleic acid that purportedly increase lean mass and decrease fat mass. Animal and human research have suggested that CLAs may reduce fat deposition, increase lipolysis, and enhance fatty acid oxidation.21 Zambell and colleagues concluded that 64 days of CLA supplementation at 3 grams per day had no significant effect on body composition or energy expenditure.22

Salas-Salvadó and associates conducted a systematic literature review and concluded that there is not enough evidence to show that CLAs have an effect on weight and body composition in humans. Some studies have observed that CLAs have adverse effects on the lipid profile, glucose metabolism, lipid oxidation, inflammation, and endothelial function.23

Whigham and colleagues conducted a meta-analysis of the literature and found that the effect of CLAs was linear for up to six months and slowly approached a plateau at two years.24 After adjustment to the mean dose of 3.2 grams of CLAs per day, CLAs produced a significant reduction in fat mass for the CLA group alone (0.05 kilograms per week) and the CLA group compared with the placebo (0.09 kilograms per week). Although statistically significant, the clinical significance of this small amount of fat loss (0.36 kilograms over four weeks) is questionable.

Further studies are required to evaluate the efficacy and safety of CLAs before indiscriminate use in humans can be recommended.23

• Caffeine is a stimulant found in coffee and herbs (such as guarana, yerba mate, or kola nut) that increases serum levels of epinephrine. By itself, caffeine has a mild thermogenic effect.18,19,25 Dulloo and colleagues found that 100 milligrams of caffeine increased resting metabolic rate by 3% to 4% over 150 minutes in lean and obese individuals.25

The adverse effects of caffeine consumption include anxiety, jitters, inability to focus, insomnia, irritability, gastrointestinal distress, and, with higher doses, irregular heartbeat and mild hallucinations. As previously noted, the combination of Citrus aurantium and caffeine has significant cardiovascular stimulant actions similar to ephedra.13

• 5-hydroxytryptophan (5-HTP) is a compound closely related to L-tryptophan, which was pulled from the market in 1990 after it was linked to eosinophilia myalgia syndrome. The 5-HTP in supplements is derived from the seeds of an African plant (Griffonia simplicifolia). In theory, 5-HTP is converted into serotonin (a potent brain neurotransmitter), thereby improving mood and decreasing appetite.

Researchers at the University of Rome in La Sapienza, Italy, found that supplementation with 600 to 900 milligrams of 5-HTP daily reduced appetite and promoted weight loss.26,27 In another study conducted by the same group, supplementation with 750 milligrams per day decreased carbohydrate and fat intake and promoted weight loss in patients with type 2 diabetes.28 These results have not been replicated by other researchers in other labs. Since publication bias may be an issue, the results of these studies should be viewed with healthy skepticism.

Large amounts of 5-HTP can cause gastrointestinal upset (eg, nausea) and, less often, headache, sleepiness, muscle pain, or anxiety. 5-HTP should not be taken with antidepressants, weight control drugs, other serotonin-modifying agents, or substances known to cause liver damage because 5-HTP may have excessive effects in these cases.

The FDA warns that some 5-HTP products contain impurities, including “peak X.” Impurities similar to peak X were also found in L-tryptophan products associated with the 1989 epidemic of eosinophilia myalgia syndrome.29

• Hoodia is a succulent plant native to the Kalahari desert of South Africa and is the main ingredient in the weight loss supplement TrimSpa. The San tribe (formerly called Bushmen) chewed the plant’s stalks to curb appetite, quench thirst, and increase endurance when they went on long hunting treks and food was scarce. The plant’s active ingredient was identified and patented as P57.

P57 is thought to curb appetite by stimulating the hypothalamus. There are no published studies demonstrating the safety or effectiveness of hoodia or P57 for weight loss. At present, hoodia supplements don’t contain the patented P57, are unlikely to contain any of the active ingredient, and may contain other unproven weight loss ingredients.30

In January, the marketers of TrimSpa settled FTC charges that they made unsubstantiated claims that TrimSpa causes rapid and substantial weight loss and that one of its ingredients, hoodia, enables users to lose substantial amounts of weight by suppressing appetite.10

• Hydroxycitrate (or hydroxycitric acid) is derived from the Malabar tamarind tropical fruit (Garcinia cambogia) native to India. In animals, hydroxycitrate inhibits the enzyme adenosine triphosphate citrate lyase (also known as citrate cleavage enzyme), leading to decreased fatty acid synthesis.31,32

Heymsfield and colleagues found that 12 weeks of supplementation with Garcinia cambogia failed to produce significant weight loss and fat mass loss beyond that observed with placebo.33 Consumers should be wary of purchasing this product until there is more conclusive evidence of its safety and effectiveness.31,32

• 7-Keto DHEA (3-acetyl-7-oxo-dehydroepiandrosterone) is a naturally occurring metabolite of the hormone DHEA that is touted as the “safe” alternative to DHEA because it isn’t converted into testosterone or estrogen. It purportedly activates three thermogenic enzymes (glycerol-3-phosphate dehydrogenase, malic enzyme, and fatty acyl CoA oxidase), thereby increasing metabolic rate. Some manufacturers claim that 7-Keto has “all the benefits of DHEA without the risks.” Based on the extremely limited research on safety and effectiveness, further research is warranted before recommending 7-Keto DHEA for weight loss.34,35

• Coleus forskolin is a member of the mint family and grows wild on the mountain slopes of Nepal, India, and Thailand. Forskolin is thought to promote fat loss by increasing cyclic AMP, which changes hormone-sensitive lipase into its active form and stimulates lipolysis. One study found that forskolin reduced fat mass and percent body fat in overweight and obese adult men.36 Further research is required to determine safety and effectiveness.

• Capsicum (cayenne) contains capsaicin, the compound in chilies that gives them their “heat.” Cayenne supposedly increases metabolic rate and suppresses appetite.37,38 One recent study found that after eight weeks, subjects who took a supplement containing capsaicin, caffeine, catechins, and tyrosine lost 0.9 kilograms more than those taking placebo.39 Enteric coated preparations don’t work; capsaicin must act directly on the gastric mucosa to exert the thermogenic effect.40 At high doses of 3 grams per day, capsaicin alone may have a small effect on thermogensis, but the risk of gastrointestinal side effects (heartburn) is high.

• Yohimbine (an alkaloid prescription drug extracted from the bark of the West African yohimbe tree) is promoted to decrease body fat and increase muscle mass. Yohimbine is an alpha 2-adrenoreceptor blocker and a monoamine oxidase inhibitor, which increases serum levels of norepinephrine. In theory, yohimbine promotes fat oxidation by increasing norepinephrine levels.41

Ostojic found that yohimbine supplementation (40 milligrams daily for 21 days) had no effect on exercise performance indicators (bench and leg press, vertical jump, dribble and power test results, and shuttle run), body mass, or fat free mass in professional soccer players. Fat mass and percent body fat were significantly decreased after yohimbine supplementation.42

Sax found that yohimbine supplementation (43 milligrams daily for six months) had no effect on body weight, body mass index, total cholesterol, high-density lipoprotein cholesterol, percent body fat, or fat distribution as measured by waist-to-hip ratio and CT scan.43 Berlin and colleagues found that yohimbine supplementation (18 milligrams daily for eight weeks) had no effect on body weight or lipid parameters (triglycerides, cholesterol, glycerol, beta-OH-butyrate, acetoacetate, and free fatty acids). At the dose used, yohimbine had no influence on the function of the alpha 2-adrenoceptors on the adipocytes and did not increase lipolysis.44

In typical doses, side effects of yohimbine include anxiety, excitation, nausea, insomnia, headaches, and blood pressure fluctuations. Tyramine-containing foods (eg, red wine, liver, cheese) should be not consumed with yohimbine to prevent a hypertensive crisis. People who have diabetes or cardiovascular, liver, or kidney disease should not take yohimbine.45

The use of yohimbine for weight loss is potentially dangerous, and there is limited evidence that it is effective. Yohimbine is not appropriate for self-treatment.45
• Herbal diuretics and laxatives are included in some weight loss supplements. Uva ursa, dandelion, buchu, and horse chestnut are herbal diuretics. Senna, cascara, aloe, and buckthorn are potent herbal laxatives. Both can cause adverse effects such as electrolyte depletion, dehydration, abdominal cramps, nausea, fainting, breathing difficulties, fluctuation in body temperature, and even death.46

Conclusion
The wide availability and use of weight loss supplements emphasize the need for increased public awareness and education regarding the benefits and risks associated with these products. Nutrition professionals should inquire about the use of supplements for weight loss. They can use this opportunity to discuss the safety and effectiveness of weight loss supplements and lack of supplement regulation, as well as educate consumers on proven strategies for weight control.1-4

— Ellen Coleman, MA, MPH, RD, is a certified specialist in sports dietetics in Riverside, Calif., and consults with endurance and professional athletes. She is a member of the Sports, Cardiovascular, and Wellness Practice Group of the American Dietetic Association. She recently completed a revision of her Nutrition Dimension course, “Nutrition Quackery” (fifth edition).

References

1. Wansink B, American Dietetic Association. Position of the American Dietetic Association: Food and nutrition misinformation. J Am Diet Assoc. 2006;106(4):601-607.

2. Sharpe PA, Granner ML, Conway JM, et al. Availability of weight-loss supplements: Results of an audit of retail outlets in a southeastern city. J Am Diet Assoc. 2006;106(12):2045-2051.

3. Blanck HM, Serdula MK, Gillespie C, et al. Use of nonprescription dietary supplements for weight loss is common among Americans. J Am Diet Assoc. 2007;107(3):441-447.

4. University of Connecticut’s Center for Survey Research & Analysis. “First of Its Kind National Survey Finds Misinformed Consumers Rely on Unproven Weight Loss Products.” October 22, 2006. Available here.

5. Healthy Weight Network. Annual Slim Chance Awards 1989 to 2006. Available here.

6. Pittler MH, Abbot NC, Harkness EF, et al. Randomized, double-blind trial of chitosan for body weight reduction. Eur J Clin Nutr. 1999;53(5):379-381.

7. Federal Trade Commission. “FTC Wins Case Against Defendants Engaged in Deceptive Advertising of ‘Super-Formula’ Diet Product.” July 19, 1999. Available here.

8. Federal Trade Commission. “Marketers of ‘The Enforma System’ Settle FTC Charges of Deceptive Advertising for Their Weight Loss Products.” April 26, 2000. Available here.

9.Federal Trade Commission. “FTC Targets Products Claiming to Affect the Stress Hormone Cortisol.” October 5, 2004. Available here.

10. Federal Trade Commission. “Federal Trade Commission Reaches ‘New Year’s Resolutions’ with Four Major Weight-Control Pill Marketers.” January 4, 2007. Available here.

11. SupplementWatch. Available here.

12. Cusi K, Cukier S, DeFronzo RA, et al. Vanadyl sulfate improves hepatic and muscle insulin sensitivity in type 2 diabetes. J Clin Endocrinol Metab. 2001;86(3):1410-1417.

13. Haller CA, Benowitz NL, Jacob P. Hemodynamic effects of ephedra-free weight-loss supplements in humans. Am J Med. 2005;118(9):998-1003.

14. Greenway F, de Jonge-Levitan L, Martin C, et al. Dietary herbal supplements with phenylephrine for weight loss. J Med Food. 2006;9(4):572-578.

15. Gougeon R, Harrigan K, Tremblay JF, et al. Increase in the thermic effect of food in women by adrenergic amines extracted from citrus aurantium. Obes Res. 2005;13(7):1187-1194.

16. Haaz S. Fontaine KR, Cutter G, et al. Citrus aurantium and synephrine alkaloids in the treatment of overweight and obesity: An update. Obes Rev. 2006;7(1):79-88.

17. Dulloo AG, Seydoux J, Girardier L, et al. Green tea and thermogenesis: Interactions between catechin polyphenols, caffeine and sympathetic activity. Int J Obes Relat Metab Disord. 2000;24(2):252-258.

18. Dulloo AG, Duret C, Rohrer D, et al. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Am J Clin Nutr. 1999;70(6):1040-1045.

19. Bérubé-Parent S, Pelletier C, Doré J, et al. Effects of encapsulated green tea and Guarana extracts containing a mixture of epigallocatechin-3-gallate and caffeine on 24 h energy expenditure and fat oxidation in men. Br J Nutr. 2005;94(3):432-436.

20. Molinari M, Watt KD, Kruszyna T, et al. Acute liver failure induced by green tea extracts: Case report and review of the literature. Liver Transpl. 2006;12(12):1892-1895.

21. Blankson H, Stakkestad JA, Fagertun H, et al. Conjugated linoleic acid reduces body fat mass in overweight and obese humans. J Nutr. 2000;130(12):2943-2948.

22. Zambell KL, Keim NL, Van Loan MD, et al. Conjugated linoleic acid supplementation in humans: Effects on body composition and energy expenditure. Lipids. 2000;35(7):777-782.

23. Salas-Salvadó J, Márquez-Sandoval F, Bulló M. Conjugated linoleic acid intake in humans: A systematic review focusing on its effect on body composition, glucose, and lipid metabolism. Crit Rev Food Sci Nutr. 2006;46(6):479-488.

24. Whigham LD, Watras AC, Schoeller DA. Efficacy of conjugated linoleic acid for reducing fat mass: a meta-analysis in humans. Am J Clin Nutr. 2007;85(5):1203-1211.

25. Dulloo AG, Geissler CA, Horton T, et al. Normal caffeine consumption: Influence on thermogenesis and daily energy expenditure in lean and postobese human volunteers. Am J Clin Nutr. 1989;49(1):44-50.

26. Cangiano C, Ceci F, Cascino A, et al. Eating behavior and adherence to dietary prescriptions in obese adult subjects treated with 5-hydroxytryptophan. Am J Clin Nutr. 1992;56(5):863–867.

27. Ceci F, Cangiano C, Cairella M, et al. The effects of oral 5-hydroxytryptophan administration on feeding behavior in obese adult female subjects. J Neural Transm. 1989;76(2):109–117.

28. Cangiano C, Laviano A, Del Ben M, et al. Effects of oral 5-hydroxy-tryptophan on energy intake and macronutrient selection in non-insulin dependent diabetic patients. Int J Obes Relat Metab Disord. 1998;22(7):648–54.

29. Food and Drug Administration Talk Paper. “Impurities Confirmed in Dietary Supplement 5-hydroxy-L-tryptophan.” August 31, 1998. Available here.

30. University of California, Berkeley Wellness Letter.com. “Wellness Guide to Dietary Supplements: Hoodia.” Available here.

31. Saper RB, Eisenberg DM, Phillips RS. Common dietary supplements for weight loss. Am Fam Physician. 2004;70(9):1731-1738.

32. Pittler MH, Ernst E. Dietary supplements for body-weight reduction: A systematic review. Am J Clin Nutr. 2004;79(4):529-536.

33. Heymsfield SB, Allison DB, Vasselli JR, et al. Garcinia cambogia (hydroxycitric acid) as a potential antiobesity agent: A randomized controlled trial. JAMA. 1998;280(18):1596-1600.

34. Davidson M, Marwah A, Sawchuk RJ, et al. Safety and pharmacokinetic study with escalating doses of 3-acetyl-7-oxo-dehydroepiandrosterone in healthy male volunteers. Clin Invest Med. 2000;23(5):300-310.

35. Zenk JL, Frestedt JL, Kuskowski MA. HUM5007, a novel combination of thermogenic compounds, and 3-acetyl-7-oxo-dehydroepiandrosterone: Each increases the resting metabolic rate of overweight adults. J Nutr Biochem. 2007.

36. Godard MP, Johnson BA, Richmond SR. Body composition and hormonal adaptations associated with forskolin consumption in overweight and obese men. Obes Res. 2005;13(8):1335-1343.

37. Yoshioka M, St-Pierre S, Suzuki M, et al. Effects of red pepper added to high-fat and high-carbohydrate meals on energy metabolism and substrate utilization in Japanese women. Br J Nutr. 1998;80(6):503-510.

38. Yoshioka M, St-Pierre S, Drapeau V, et al. Effects of red pepper on appetite and energy intake. Br J Nutr. 1999;82(2):115-123.

39. Belza A, Frandsen E, Kondrup J. Body fat loss achieved by stimulation of thermogenesis by a combination of bioactive food ingredients: A placebo-controlled, double-blind 8-week intervention in obese subjects. Int J Obes (Lond). 2007;31(1):121-130.

40. Belza A, Jessen AB. Bioactive food stimulants of sympathetic activity: Effect on 24-h energy expenditure and fat oxidation. Eur J Clin Nutr. 2005;59(6):733-741.

41. Galitzky J, Taouis M, Berlan M, et al. Alpha 2-antagonist compounds and lipid mobilization: Evidence for a lipid mobilizing effect of oral yohimbine in healthy male volunteers. Eur J Clin Invest. 1988;18(6):587-594.

42. Ostojic SM. Yohimbine: The effects on body composition and exercise performance in soccer players. Res Sports Med. 2006;14(4):289-299.

43. Sax L. Yohimbine does not affect fat distribution in men. Int J Obes. 1991;15(9):561-565.

44. Berlin I, Stalla-Bourdillon A, Thuillier Y, et al. Lack of efficacy of yohimbine in the treatment of obesity. J Pharmacol. 1986;17(3):343-347.

45. Jellin JM, Gregory P, Batz F. Pharmacist’s Letter/Prescriber’s Letter Natural Medicine’s Comprehensive Database, 3rd edition. Stockton, Calif.: Therapeutic Research Facility, 2007:1144-1146.

46. Kurtzweil P. Dieter’s brews make tea time a dangerous affair: Slim chance of weight loss with these herbal drinks. FDA Consumer. 1997;31(5):6-11.

Examination
1. The study by Blanck and colleagues found that an estimated ____________ of adults had used a weight loss supplement in their lifetime.
a. 25%
b. 20%
c. 15%
d. 10%
e. 5%

2. Citrus aurantium (bitter orange) contains which of the following adrenergic stimulant amines?
a. Synephrine
b. Octopamine
c. Ephedrine
d. a and b
e. a and c

3. “Ephedra-free” printed on a supplement label means that the supplement does not contain any stimulants.
a. True
b. False

4. The components of green tea extract inhibit the following two enzymes to boost norepinephrine levels:
a. Lipoprotein lipase and hormone sensitive lipase
b. Catechol-O-methyltransferase and phosphodiesterase
c. Catechol-O-methyltransferase and hormone sensitive lipase
d. Adenosine triphosphate (ATP) citrate lyase and phosphodiesterase
e. ATP citrate lyase and lipoprotein lipase

5. In theory, 5-hydroxytryptophan is converted into ___________ (a potent brain neurotransmitter).
a. serotonin
b. dopamine
c. norepinephrine
d. epinephrine
e. none of the above

6. Tyramine-containing foods should be not consumed with:
a. Coleus forskolin.
b. Capsicum.
c. 7-Keto DHEA (3-acetyl-7-oxo-dehydroepiandrosterone).
d. Hydroxycitrate.
e. Yohimbine.

7. The active ingredient in hoodia is thought to promote weight loss by:
a. decreasing cortisol levels.
b. stimulating the hypothalamus.
c. increasing norepinephrine levels.
d. increasing serotonin levels.
e. preventing the absorption of fat.

8. The following adverse effect(s) have been reported with the use of Citrus aurantium:
a. Heart attack
b. Ischemic colitis
c. Exercise-induced syncope
d. Ischemic stroke
e. All of the above

9. Which supplement claims to reduce levels of the “stress hormone,” thereby causing substantial weight loss?
a. Chitosan
b. Conjugated linoleic acids
c. CortiSlim
d. Garcinia
e. 7-Keto DHEA

10. Which supplement may have adverse effects on the lipid profile, glucose metabolism, lipid oxidation, inflammation, and endothelial function?
a. 7-Keto DHEA
b. Yohimbine
c. Coleus forskolin
d. Conjugated linoleic acids
e. Caffeine