Should weight-loss supplements be used for pediatric obesity?

ABSTRACT

QUESTION In my clinic I have a large population of overweight and obese children. There is a range of weight-loss supplements marketed for the adult population. What natural health products for treatment of obesity are effective and can be used in children?

ANSWER Weight-loss supplements lack sufficient data supporting their efficacy and safety, even in adults. Most weight-loss supplements cannot be recommended at this time for children. Options for obese adolescents include increasing consumption of fibre with diet or using fibre supplements, such as glucomannan. Dietary fibres can also prevent side effects of orlistat, the only medication available for treatment of obese adolescents.

Childhood obesity is one of the most important public health concerns. According to recent estimates from the 2004 Canadian Community Health Survey, 26% of Canadian children and adolescents aged 2 to 17 years are overweight or obese, compared with 15% in 1979,¹ and now it is the most common childhood disorder.

Options available for treatment of obesity in children include behavioural and dietary modifications, pharmacotherapy, and weight-loss supplements. Recommended behavioural and dietary modifications include promoting physical activity, limiting “screen time” (ie, watching television or playing video or computer games) to no more than 2 hours a day, and limiting consumption of energy-dense snack foods high in sugar and fat.² These methods, however, remain largely ineffective because family-oriented behavioural and dietary programs require a great deal of time and effort from the parents, which is not always possible for working families.

Weight-loss supplements

No studies have examined the use of weight-loss supplements other than fibre supplements in children and adolescents. In the United States, however, 11% of adolescents aged 14 to 19 years have used weight-loss supplements in their lifetimes,³ which is comparable to adult use. Sales of weight-loss supplements, the fastest growing segment of the dietary supplement industry, increase at a rate of 10% to 20% per year.⁴ Supplements are viewed by patients as being natural and are assumed to be safer than prescription drugs. In addition, they represent alternatives to failed attempts at weight loss with the use of more conventional approaches.

Most weight-loss supplements include multiple components, often more than 10. Common ingredients of weight-loss supplements categorized by mechanism of action are presented in Table 1.⁴

Table 1.

Common ingredients of weight-loss supplements, categorized by mechanism of action

MECHANISM OF ACTION	INGREDIENTS OF WEIGHT-LOSS SUPPLEMENTS
Stimulants, energy boosters, or thermogenic agents	Ephedrine or pseudoephedrine (from ephedra [ma huang] or country mallow [Sida cordifolia])
	Caffeine, theophylline, or theobromine (from cola nut, guarana, or maté)
	Bitter orange (Citrus aurantium)
	Bladderwrack (Fucus vesiculosus)
	7-keto-dehydroepiandrosterone (DHEA)
Fat and carbohydrate metabolism modulators	Chromium picolinate
	Conjugated linoleic acid
	Carnitine
	Green tea
	Gymnema sylvestre
	β-hydroxymethylbutyrate
	Pyruvate
	Hydroxycitric acid (Garcinia cambogia)
	Brindleberry
Appetite suppressants	Capsaicin
Agents that decrease stress- or depression-related eating	Ginkgo biloba
	St John’s wort
	Yohimbe
Satiety promoters	Soluble fibres (eg, glucomannan, psyllium, methylcellulose, pectin)
Fat absorption blockers	Chitosan
Carbohydrate absorption blockers	Inosine
	Kidney bean extract (Phaseoli fructus)
	Mung bean extract
	Wheat extract
Laxatives	Buckthorn bark and berry
	Cascara sagrada bark
	Flaxseed
	Manna
	Psyllium seed husk
	Rhubarb root
	Senna leaf and pod

Data from Bartels and Miller.⁴

The majority of weight-loss supplements have not been clearly demonstrated to be either effective or safe, even in adults, and many have been associated with serious adverse events.⁵ In addition, the multiple components in weight-loss supplements create possibility of interactions, either among ingredients or with concurrently taken medications. Furthermore, many components, such as herbal extracts, contain multiple potentially active ingredients. Even if individual components of a weight-loss product are demonstrated to be safe, the combination of them might not be.⁶ Many supplements have been found to be contaminated with harmful ingredients⁷ or mislabeled regarding actual ingredients of the supplement.

Weight-loss supplements are widely advertised and disseminated over the Internet, although many of them have little or no data to support claims and some, such as dinitrophenol, are life-threatening.⁸ Very few supplements demonstrate clinical efficacy, with no evidence beyond reasonable doubt that any specific dietary supplement is effective for long-term reduction of body weight. Short-term efficacy for adults was demonstrated for ephedra and ephedrine-containing products⁹; however, since April 2004, their sale has been prohibited in the United States because of concerns about serious adverse events and increased risk of psychiatric, autonomic, or gastrointestinal symptoms and heart palpitations.⁵ Citrus aurantium—an herb that contains synephrine, a sympathetic α-adrenergic agonist similar to ephedrine—is now commonly used as a substitute for ephedra in weight-loss supplements.¹⁰ Bitter orange, however, demonstrated no statistically significant benefit for weight loss (P > .05)¹⁰ and, in addition to the adverse effects reported with ephedrine, it can also cause photosensitivity and interact with certain drugs, increasing their concentration.⁴

There is some evidence of benefit for chromium picolinate, chitosan, conjugated linoleic acid (CLA), hydroxycitric acid, pyruvate, and fibre supplements in adults. Although chromium picolinate appears to have a small weight-reduction effect,¹¹ several cases of rhabdomyolysis or renal failure in patients taking chromium were reported, raising doubts about its safety. There is some evidence that chitosan is more effective than placebo in the short-term treatment of obesity, but results obtained from high-quality trials indicate that the effect of chitosan on body weight is minimal and unlikely to be of clinical significance.¹² Conjugated linoleic acid appears to attenuate increases in body weight and body fat in several animal models; however, results from 13 clinical trials in humans found little evidence to show that CLA reduces body weight and suggested that it might have adverse effects on human health via redistribution of fat deposition.¹³ Several studies performed using Garcinia cambogia in overweight and obese adult subjects are inconsistent and yield conflicting results.¹⁴ Although pyruvate has been reported to reduce body fat mass and body fat percentage,¹⁵ the evidence is weak.

No studies of weight-loss supplements, other than fibre supplements, in children have been conducted. Intake of dietary fibre is inversely associated with body weight, body fat, and body mass index.¹⁶ Its mechanisms for weight reduction include promoting satiation, decreasing absorption of macronutrients, and altering secretion of gut hormones. The average fibre intake in North America is less than half of recommended levels. Although increasing consumption of fibre (eg, fruits, vegetables, whole grains, legumes) with diet is an important step to curb the obesity epidemic, the addition of fibre supplements should also be considered. Glucomannan, a soluble and highly viscous dietary fibre derived from the root of the konjac plant, can promote weight loss in overweight and obese individuals and improve lipid and lipoprotein parameters and glycemic status¹⁷ with minimal gastrointestinal side effects. Although little data exist on psyllium for weight reduction, it has been shown to improve glucose homeostasis and the lipid and lipoprotein profile in obese children.¹⁸ Inulin (from chicory root) is being sold in many mainstream stores as a fibre supplement, including for use in children; however, its weight-lowering effect has not been studied.

Pharmacotherapy

Pharmacotherapy should be considered for extremely obese children (body mass index ≥ 2 units above the 95th percentile) older than 12 years of age who are resistant to 12-month dietary and lifestyle modifications¹⁹; those with marked abdominal adiposity, impaired glucose tolerance or insulin resistance, steatohepatitis, and ovarian hyperandrogenism; and those with strong family history of diabetes, myocardial infarction, or stroke. Orlistat, a fat absorption inhibitor, is the only prescription drug indicated by the Food and Drug Administration for the treatment of overweight adolescents.² It can cause transient gastrointestinal adverse effects, such as abdominal discomfort, flatulence, and diarrhea, due to unabsorbed fat excreted in the feces.¹⁹ However, side effects of orlistat can be prevented by concomitant prescription of dietary fibres.²⁰

Conclusion

Weight-loss supplements lack sufficient data supporting their efficacy and safety, even in adults. Most weight-loss supplements cannot be recommended at this time for children. Options to consider for obese adolescents include increasing consumption of dietary fibre or using fibre supplements. Dietary fibre also prevents side effects of orlistat, the only medication available for treatment of obese adolescents. More research is needed to draw definitive conclusions. No single approach will successfully treat pediatric obesity, and lifestyle modification should be maintained throughout the treatment.

PRETx

Child Health Update is produced by the Pediatric Research in Emergency Therapeutics (PRETx) program at the BC Children’s Hospital in Vancouver, BC. Dr Rogovik is Assistant Director and Dr Goldman is Director of the PRETx program. The mission of the PRETx program is to promote child health through evidence-based research in therapeutics in pediatric emergency medicine.

Do you have questions about the effects of drugs, chemicals, radiation, or infections in children? We invite you to submit them to the PRETx program by fax at 604 875–2414; they will be addressed in future Child Health Updates. Published Child Health Updates are available on the Canadian Family Physician website (www.cfp.ca).