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The Effects of Supplements on Weight Control

By Yousry Naguib, Ph.D.
Vitamin Retailer magazine, December 2004

In the United States, more than half of the adult population is classified as overweight or obese. Compelling evidence links overweight and obesity with serious disorders such as cardiovascular diseases, diabetes, and osteoarthritis (weight-bearing joint load increases with body weight), leading to substantial economic costs in the health care budget. Therefore, management of body weight and obesity are increasingly considered as an important approach to maintaining good health.
Conventional dietary regimen is notoriously burdened with poor compliance and a plethora of dietary supplements are sold with claims of effectiveness.

Conjugated linoleic acid (CLA)
CLA refers to a mixture of positional and geometric isomers of linoleic acid (cis-9,trans-11 CLA and trans-10,cis-12 CLA). Cis-9,trans-11 CLA is the predominant CLA isomer found in beef, lamb, and dairy products. Commercial preparations of CLA contain approximately equal amounts of cis-9,trans-11 and trans-10,cis-12 isomers. CLA is attracting interest because of its purported effects on body composition. Studies have shown that CLA can reduce body fat mass, but appears to have no effect on lean body mass and body weight in healthy individuals.
In a study published in 2001, researchers in Sweden reported that daily supplementation with 4.2 g of CLA (75 percent of 50:50 blend of cis-9,trans-11 CLA and trans-10,cis-12 CLA) for 12 weeks reduced body fat mass (3.8 percent) in healthy men and women. No effects on body weight, serum lipids profile, plasma insulin, and blood glucose were observed.1
Similar results were obtained in another clinical study: 60 overweight and obese subjects (men and women, BMI 25-35 kg/m2) received either CLA (1.7, 3.4, 5.1 or 6.8 g; 50:50 blend of cis-9,trans-11 CLA and trans-10,cis-12 CLA) or placebo (9 g olive oil) daily for 12 weeks. CLA at 3.4 and 6.8 g per day reduced body fat by 5.7 percent (1.73 kg), and 3.7 percent (1.3 kg), respectively. No changes in lean body mass, body mass index, and blood lipids were observed. CLA at doses greater than 3.4 g per day did not provide any additional benefit.2     
            Long term supplementation with CLA (50:50 blend of cis-9,trans-11 CLA and trans-10,cis-12 CLA) has also been shown in a recent (2004) double-blind, placebo-controlled study to reduce body fat mass in healthy overweight humans. One hundred and eighty healthy men and women, aged 18 to 65, with a body mass index of 25-30 kg/m2 were randomized to receive 3.6 g per day of either CLA-free fatty acid (CLA-FFA), or CLA –triacylglycerol, or placebo (olive oil) for one year. Body fat mass was reduced by 6.9 percent and 8.7 percent in CLA-FFA and CLA-triacylglycerol, respectively, as compared with the placebo group. CLA-FFA group had 1.8 percent greater lean body mass than did subjects receiving placebo.3
In another study also published in 2004, supplementation with two CLA isomers showed no statistically significant effect on body composition in overweight, middle-aged men and women. Eighty-one healthy overweight men and women were divided into five groups, and received either 3 g of high oleic acid sunflower oil (control), or 1.5 g of cis-9,trans-11 CLA, or 3 g of cis-9,trans-11 CLA, or 1.5 g of trans-10,cis-12 CLA, or 3 g of trans-10,cis-12 CLA daily for 18 weeks. Body fat mass, and lean body mass were not significantly different among the treatment groups.4
Similar results were also reported this year on the effects of individual CLA isomers on body composition of healthy men who consumed 1, 2, and 4 capsules sequentially, containing either 80 percent cis-9,trans-11 CLA (0.6, 1.2 and 2.4 g/day) or 80% trans-10,cis-12 CLA (0.6, 1.3, and 2.5 g/day) for consecutive 8-week periods. Body composition was not significantly affected by either isomer of CLA. Mean plasma triglycerides, and the ratios of LDL to HDL cholesterol, and of total cholesterol to HDL cholesterol were higher during supplementation with trans-10,cis-12 CLA than during that with cis-9,trans-11 CLA. Both CLA isomers had no significant effect on plasma insulin concentration.5
The adverse effect of cis-9,trans-11 CLA on insulin sensitivity was reported in a Swedish study. Researchers at Uppsula University found that daily supplementation with 3 grams cis-9,trans-11 CLA for three months decreased insulin sensitivity by 15 percent, and increased lipid peroxidation markers by 50 percent in obese men; and might slightly decrease body fat in humans, particularly abdominal fat, and it had no effect on body weight or body mass index compared with placebo.6
In a double-blind study, 21 subjects with type 2 diabetes mellitus received either a supplement containing mixed CLA isomers (8 g daily; 37 percent cis-9,trans-11 and 39% trans-10,cis-12), or a supplement containing safflower oil (control; 8 grams daily) for 8 weeks. From plasma levels of CLA isomers, trans10,cis-12 CLA, but not cis-9,trans-11 CLA was found to be inversely associated with body weights. These findings suggest that trans-10,cis-12 isomer may be the active isomer of CLA to influence the body weight changes observed in subjects with type 2 diabetes.7

Chitosan is a widely available dietary supplement purported to decrease body weight through gastrointestinal fat binding. Although evaluated in a number of trials, its efficacy remains in dispute. In a recent clinical trial, 250 subjects (82 percent women, average body mass index 35.5 kg/m2, and mean age 48 years) received either 3 g chitosan per day, or a placebo for 24 weeks. The chitosan group lost more body weight (0.4 kg) than the placebo group, which gained 0.2 kg. In this 24-week trial, chitosan treatment did not result in a clinically significant loss of body weight.8
In an earlier trial, chitosan was shown to be a valuable and safe adjuvant in long-term dietary treatment of obesity. Fifty obese women (22-59 years, body mass index more than 30) received either two tablets (each tablet 750 mg) of chitosan three times daily before each meal (low calorie diet, 1,000 kcal per day) or placebo for six months. The chitosan group lost an average 15.9 kg, and the placebo group lost 10.9 kg.9

Citrus aurantium
Seville (sour) orange extract (Citrus aurantium) has been reported to be the best thermogenic substitute for ephedra in herbal weight loss products. It has been shown in limited studies to aid weight loss. In one study, subjects who received a combination of Citrus aurantium, caffeine, and St John’s wort lost significant amounts of total body weight while on a strict diet and exercise. Citrus aurantium contains m-synephrine, which is structurally similar to epinephrine. Synephrine has the potential to increase blood pressure, and might cause cardiac disturbances. It is recommended that individuals with heart problems, or taking monoamine oxidase inhibitors should avoid Citrus aurantium.10

Hydroxycitric acid
Hydroxycitric acid (HCA) is the principle constituent (10-30 percent) of the dried fruit rind of Garcinia cambogia (also known as Malabar tamarind), a plant native to Southeastern Asia. HCA has the ability to inhibit the enzyme ATP-citrate lyase, which catalyzes lipogensis (biosynthesis of fats) in the body.
In a clinical trial conducted in India, 60 moderately obese subjects (ages 21-50, body mass index greater than 26 kg/m2) were randomly divided into three groups. Group A was administered HCA alone (4,667 mg); group B was administered a combination of HCA (4,667 mg), niacin-bound chromium (4 mg), and Gymnema sylvestre (400 mg); and group C was given placebo daily in three equally divided doses 30-60 minutes before meals. All subjects received a 2,000 kcal/day diet and participated in supervised walking. At the end of 8 weeks, body weight and body mass index decreased by 5-6 percent in both groups A and B, but no change in group C. The study suggests that optimal dose of HCA alone or in a combination with niacin-bound chromium and Gymnema sylvestre can be an effective and safe aid in weight loss.11

Green Tea
Green tea, which has been reported to have anti-cancer properties and high levels of antioxidants, is touted to promote weight loss. In a study conducted at the University of Fribourg in Switzerland, researchers reported that green tea extract rich in catechin polyphenols and caffeine increased energy expenditure and fat loss in healthy men, suggesting that green tea extract may be an effective way to aid weight loss.
Ten healthy men received, on three separate occasions, one of three treatments: green tea extract (containing 50 mg caffeine and 90 mg epigallocatechin ), caffeine (50 mg), or placebo at breakfast, lunch, and dinner. Relative to placebo, treatment with green tea extract resulted in a significant increase in 24-hour energy expenditure. Treatment with caffeine had no effect on energy expenditure. These results indicate that green tea has thermogenic properties beyond that explained by its caffeine content per se.12
In an animal study, the three major components of green tea: catechines, caffeine, and theanine were shown to reduce body weight and fat accumulation in mice fed diets containing 0.3 percent catechins, 0.05 percent caffeine, and 0.03 percent theanine for 16 weeks.13
Although not harmful in small doses, caffeine can cause increased blood pressure, heart palpitations, nervousness, and more. Caffeine is found in appreciable amounts in yerba mate, cola nut, and cocoa.

White bean extract
A water extract of white bean (Phaseolus vulgaris) has been shown in in-vitro study to inhibit the digestive enzyme alpha amylase (secreted by the pancreas), which is responsible for breaking down starch to simple sugars that are absorbed in the small intestine. Therefore, inhibiting alpha amylase may prevent the digestion of complex carbohydrates, allowing them to pass through the digestive system, resulting in decreasing the number of calories absorbed and potentially promoting weight loss.
The efficacy of white bean extract as starch neutralizer was demonstrated in a clinical study involving thirty-nine obese adults who received either 1500 mg white bean extract or a placebo twice daily with meals for eight weeks. Twenty-seven subjects completed the study, and the white bean extract group lost an average of 1.68 kg compared with the placebo group, which lost an average of 0.73 kg.14

Banaba (Lagerstroemia speciosa, Linn.), commonly known as Crepe Myrtle, occurs widely in the tropical areas of the globe including the Philippines, India, Malaysia, China, and Australia. Banaba is a popular folk medicine in Southeast Asia, and in the Philippines a tea from the leaves has been used as a beverage as well as for the treatment of diabetes mellitus. The leaves contain significant amounts of corosolic acid, which has previously been shown to possess anti-diabetic properties,15 and significant amounts of tannins, of which Lagerstoemin, flosin B, and reginin A were identified.16
The anti-diabetic activity of an extract from the leaves of Lagerstroemia speciosa standardized to 1 percent corosolic acid has been demonstrated in a clinical trial involving Type II diabetics (non-insulin dependent diabetes mellitus, NIDDM). Subjects received a daily oral dose (48mg) of the extract and blood glucose levels were measured. A soft gel capsule formulation showed a 30 percent decrease in blood glucose levels compared to a 20 percent drop seen with dry-powder filled hard gelatin capsule formulation, suggesting that the soft gel formulation has a better bioavailability than a dry powder formulation.                                       
In the same study, the efficacy of the banaba extract in weight loss was examined in subjects suffering from both type II diabetes and overweight. Five women ages 26-51 years with a body mass index (BMI) between 25.1 and 28.4 kg/m2, and five men ages 27-44 with BMI between 26.2 to 28.7 kg/m2 were selected. Subjects received the extract at a dose of 48 mg per day for 30 days. The mean value of the body weight of the group was decreased by 1.3 ± 0.4 lb after 2 weeks and 2.4 ± 0.4 after a month of daily supplementation with the extract.17

Green Coffee Bean Extract
Coffee contains tannins and antioxidants, which are good for the heart and arteries, and it can relieve headaches. Research studies indicate that people who drink coffee on a regular basis are up to 80 percent less likely to develop Parkinson’s; and drinking at least two cups coffee daily can translate to a 25 percent reduced risk of colon cancer, an 80 percent drop in liver cirrhosis, and nearly half the risk of gallstones, and possibly cutting the risk of type 2 diabetes.
Recent animal studies demonstrated the efficacy of a green coffee beans extract (GCBE) in weight loss management. GCBE contains considerable amounts of hydroxyl-cinnamic acid derivatives, including chlorogenic acid, quinic acid, and caffeic acid.
In an in vitro study of the effects of GCBE on the activity of lipase enzyme, using porcine pancreatic lipase, GCBE at 1,000 microg/ml showed a higher inhibition of the lipase activity than chlorogenic acid, indicating that GCBE is a potent inhibitor of lipase. Lipase is an enzyme that catalyzes the hydrolysis of fats (mono-glycerides, di-glycerides and tri-glycerides). Inhibition of the activity of gastrointestinal lipases thereby decreases the hydrolysis and subsequent absorption of ingested fats.

Coleus forskohlii
Coleus forskohlii, a member of the mint family, grows wild in India, Burma, and Thailand. An extract from the roots of Coleus forskohlii standardized to forskollin has been shown in an Indian clinical trial, involving six overweight women with BMI greater than 25 kg/m2, to reduce body fat and increase lean body mass. The recommended dosage is 250 mg twice daily before a meal.

In summary, clinical studies on weight loss-dietary supplements provided some encouraging data but no evidence beyond a reasonable doubt that any specific dietary supplement is highly effective for reducing body weight.

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