BJSM (2013) A-Z nutritional supplements 44

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Nutritional supplement series

A–Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance: Part 44 D S Senchina,1 S J Stear,2 L M Burke,3 L M Castell4 1

Biology Department, Drake University, Des Moines, Iowa, USA 2 Performance Influencers Limited, London, UK 3 Australian Institute of Sport, Canberra, Australia 4 Green Templeton College, University of Oxford, Oxford, UK Correspondence to L M Castell, [email protected] Accepted 3 April 2013

To cite: Senchina DS, Stear SJ, Burke LM, et al. Br J Sports Med 2013;47:595–598.

INTRODUCTORY REMARKS Part 44 is dedicated to a review on supplements used in the sport and exercise arena for weight loss, with a particular focus, including a utilitarian and novel classification, on the wide assortment of herbs used as the active ingredient(s), particularly in the seemingly fashionable supplements marketed as having ‘thermogenic’ properties.

WEIGHT LOSS STRATEGIES S J Stear Without doubt, physique, including body mass or composition, size and shape, has an important role to play in optimising sports performance. Size does matter! Consequently, various strategies, including dietary intervention, are employed in an effort to influence physique. Fundamentally, body weight (body mass) is lost when dietary energy (energy intake) is consumed at a level less than daily requirements (energy expenditure), with an energy deficit ∼10–20% being both effective in producing loss and being tolerated over the longer term. However, although any strategy, including popular/ fad diets, that reduces energy intake below expenditure will result in weight loss, most athletes need to achieve a more specific goal of promoting loss of body fat while maintaining lean body mass and optimising sports performance. Therefore, athletes embarking on an energy-reduction programme should do so only under the guidance of a sports nutrition professional. This will ensure that the intakes of important macronutrients and micronutrients are not detrimentally compromised and that the energy intake is sufficient to support their training/competition needs. Although there is growing evidence of a positive role for dairy/calcium intake in assisting weight/fat loss, this has not yet been extensively studied in the athletic population. In the multibillion dollar supplement industry, ‘weight loss’ supplements contribute a significant proportion. A huge range of supplements claims to enhance sports performance by affecting body composition—either by increasing muscle mass and/or reducing body fat. Supplements in the broad ‘weight loss’ category include caffeine, L-carnitine, chromium picolinate, CLA (conjugated linoleic acid), dairy/ calcium supplements, HMB (β-hydroxy-β-methylbutyrate), Hydroxycut, leucine, phenylalanine, protein supplements and tyrosine. This list covers the most popular ingredients/supplements purported to aid weight loss, all of which have been previously individually reviewed in our A–Z series, though not all may have mentioned the ‘weight loss’ aspect due to lack of supporting evidence. To ensure this appraisal

Senchina DS, et al. Br J Sports Med 2013;47:595–598. doi:10.1136/bjsports-2013-092500

of weight loss supplements is complete, these products will be mentioned briefly in part 44; further information is provided in the original A–Z review cited. L-carnitine (part 4) is synthesised from the amino acids lysine and methionine, and is found naturally in the human diet, particularly in red meat and dairy products. It has been suggested that L-carnitine supplementation can increase fatty acid transport into mitochondria, leading to an increase in fatty acid oxidation, and hence the proposed potential benefit for weight management. However, further investigation is required.1 2 Chromium picolinate (part 9), a complex of trivalent chromium (a trace mineral) and picolinic acid, has been heavily marketed for both muscle building and fat loss, but the overwhelming majority of the data do not support these purported benefits.3 Conjugated linoleic acid (CLA, part 10) is a term for a series of structural and geometric isomers of linoleic acid. Studies investigating the role of CLA supplements in decreasing fat mass and/or increasing lean mass have been inconsistent.4 HMB (part 20)5 is a metabolite of the essential branched chain amino acid leucine, with research providing some evidence that HMB supplements offer some assistance in reducing the breakdown of muscle protein,5 similar to the effect shown with leucine (part 23)6 and another essential amino acid, phenylalanine (part 28).7 However, tyrosine (part 38), an amino acid that can be synthesised in the body from phenylalanine, has not specifically been investigated in regard to its potential effect on weight loss. Finally, since their active ingredients are of an herbal origin, caffeine and Hydroxycut are included in the following evaluation of herbal weight loss supplements.

HERBAL WEIGHT LOSS SUPPLEMENTS D S Senchina Many weight loss supplements used by athletes contain herbs as active agents (table 1) which can be vexing given their botanical, chemical and clinical diversity. Here, we offer a system for conceptualising herbal weight loss supplements by putative mechanisms of activity based on each supplement’s presumed bioactive compounds, which are mainly secondary metabolites (SM) and can be categorised into six main groups: alkaloids, flavonoids, polysaccharides, phenolics, terpenoids and other molecules. Most herbs in this review contain compounds from multiple SM categories. Alkaloids are nitrogen-rich molecules derived from amino acid precursors: caffeine is a well-known example. Caffeine and similar molecules increase metabolism and consequently achieve a small 595

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Nutritional supplement series Table 1 Herbs commonly used as weight loss aids Common name

Scientific name

Part used

SM group

Bioactive compound(s)

BJSM part

Comment

Bearberry, Kinnikinnick Black Pepper Bitter Melon Bitter Orange Cayenne Pepper Coffee Dandelion Elderberry Ephedra, Ma Huang Gambooge Ginger Ginseng Green Tea Guar Bean Guarana Gymnema, Cowplant Hoodia Indian Coleus Konjac Milk Thistle Psyllium Rhodiola Sarsaparilla Siberian Ginseng Veldt Grape White Bean White Willow Yerba Mate

Arctostaphylos uva-ursi Piper nigrum Momordica charantia Citrus aurantium Capsicum annuum Coffea spp Taraxacum officinale Sambucus nigra Ephedra sinica Garcinia gummi-gutta (Garcinia cambogia) Zingiber spp Panax spp Camellia sinensis Cyamopsis tetragonoloba Paullinia cupana Gymnema sylvestre Hoodia spp Plectranthus barbatus (Coleus forskohlii) Amorphophallus konjac Silybum spp Plantago spp Rhodiola rosea Smilax spp Eleutherococcus senticosus Cissus quadrangularis Phaseolus vulgaris Salix alba Ilex paraguariensis

F,L F F F F F R F T F R R L S S L R R T L,S S R B,R R T F B L,W

TER ALK TER ALK ALK ALK, PHE FLA, TER FLA, PHE ALK OTH ALK TER ALK, PHE POL ALK TER TER ALK, TER POL PHE POL TER TER TER TER OTH PHE ALK

Arbutin Piperine Momordicins Synephrine Capsaicin, capsinoids Caffeine

44 44 44 44 44 6 44 44 13 44 17 7, 17 6,17 44 19 44 44 44 44 44 44 7 34 7,17 9 44 44 44

? ? ✓ ? ? x ? ? x ? ✓ ? ✓ ? x ? ? ? ? ? ? ? – ? ? ? ? ?

Ephedrine, pseudoephedrine Hydroxycitric acid Gingerols, shogaols Ginsenosides Caffeine Galacatomannan Guaranine Gymnemic acid Steroidal glycosides Forskolin Glucomannan Silybin Fiber, mucilage Rosavin Saponins Eleutherocides Steroids, carotenoids Phaseolamin Salicin, salicylic acid Caffeine

Designator ‘spp’ indicates that multiple species from the genus are employed commercially. ‘Organ used’ abbreviations: B, bark; F, fruit; L, leaf; R, rhizomes and roots; S, seed; T, stem; W,twigs. ‘SM group’ abbreviations: ALK, alkaloid; FLA, flavonoid; OTH, other; PHE, phenolic; POL, polysaccharide; TER, terpenoid. BJSM numbers refer to installments in the nutritional supplements series, not numbered references. Symbols are based on information from cited sources. x=No evidence for efficacy or potential safety or toxicity issues. ?=Little or no evidence for efficacy but no perceived harm. ✓=Moderate or strong supporting evidence and no perceived harm. – =Lack of evidence prohibits a conclusion from being made.

increase in the body’s rate of energy (calorie, kilojoule) expenditure. Although the physiological relevance of this effect is debated, such herbal weight loss aids are often described as thermogenic. Examples of caffeine-rich herbs include coffee,8 green tea,8 guarana9 and yerba mate. Other alkaloid-rich herbs used for weight loss include bitter orange, black pepper, cayenne pepper, ephedra,10 ginger11 12 and Indian coleus. Not all plants that contain alkaloids are considered weight loss aids (eg, chocolate, which contains theobromine and theophylline).13 Reviews have concluded that, of these, bitter orange, caffeine, ephedra, ginger and green tea supplements may be efficacious in weight loss,14–16 but isolated supplements of caffeine, ephedra and guarana may carry serious adverse event risks in the general population.16 17 Indeed, the sale of ephedra was banned by the FDA in 2004. Furthermore, it was included on the List of Banned Substances by the International Olympic Committee years prior to that and is currently prohibited for use in competition according to the WADA Banned List.10 Research reports have suggested that multicomponent green tea/black pepper/cayenne pepper18 and yerba mate19 supplements may promote weight loss, but yerba mate supplements may carry adverse effects.17 Terpenoids, also called isoprenoids, are lipids derived from five-carbon isoprene structures and include carotenoids, steroids and saponins. Terpenoids could conceivably work through 596

several different mechanisms, though anorexiant and diuretic effects are most commonly reported. Weight loss herbs that presumably work through terpenoids include bearberry (kinnikinnick, uva ursi), bitter melon, dandelion, ginseng,11 gymnema, hoodia, Indian coleus, rhodiola, sarsaparilla,20 Siberian ginseng and veldt grape3 (Cissus quadrangularis, a frequent component of Hydroxycut).9 Recent reviews indicate bitter melon, ginseng, Siberian ginseng and veldt grape may be efficacious or have no effect on weight loss in the general population,14–16 but none have been flagged for adverse events. The supplement Hydroxycut, which contains multiple herbal and other products and varies in composition, is not recommended for use by athletes due to safety and efficacy concerns.9 Hoodia has no evidence for or against it as a weight loss agent.21 One study in overweight women concluded that Indian coleus supplementation does not directly promote weight loss, but may help in weight management.22 In obese rodents, gymnema supplements stimulated weight loss,23 whereas in diabetic rodents, bearberry supplementation maintained body weight, but decreased appetite and thirst,24 and dandelion had no effect.25 No studies could be located regarding sarsaparilla and weight loss. Flavonoids are derived from phenylalanine precursors and include anthocyanins and quercetin,26 and are found in herbs such as dandelion and elderberry. A mechanism by which they might

Senchina DS, et al. Br J Sports Med 2013;47:595–598. doi:10.1136/bjsports-2013-092500

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Nutritional supplement series assist weight loss is by reducing lipogenesis and/or increasing lipolysis. Elderberry, along with milk thistle, white willow, coffee and tea, also contain phenols (characterised by having both aromatic hydrocarbon and hydroxyl groups) such as tannins. From little information, reviews indicate elderberry, milk thistle and white willow have not convincingly demonstrated weight loss properties, yet none have perceived risk.14 15 27 Some weight loss aids presumably work through fibre (roughage). Fibre is comprised of polysaccharides that stimulate peristalsis through their laxative effects, may satiate appetite and may block fat absorption, thus contributing to weight loss. Fibre-rich weight loss herbs include guar bean, konjac and psyllium. Primary data conflict regarding their safety and efficacy. Two recent reviews concluded konjac and psyllium may be effective but all carry some risk of adverse effects.16 17 The ‘other’ category includes herbs that presumably work through the enzyme phaseolamin, like white bean, which may be efficacious in weight loss, and gambooge (Garcinia spp; not to be confused with the pigment ‘gamboge’), which putatively works through hydroxycitric acid. Gambooge, formerly a common component of Hydroxycut,9 was removed from that formulation around 2010 due to concerns about hepatotoxicity; several recent reviews conflict in their assessment of its potential risk and efficacy.15–17 Literature regarding herbal supplements and weight loss is patchy but suggests varying levels of efficacy and risk as summarised in table 1. However, it is important to note that many of these conclusions are based on isolated studies or small samples; the majority is conducted on obese (eg, non-athletic) populations; and mechanisms are often speculative. On the other hand, some may confer additional health benefits—for example, polyphenols found in green tea and milk thistle may have anticancer, anti-inflammatory and antioxidant effects,27 while elderberry may be an immunomodulator capable of binding and incapacitating the influenza virus.28 Additional herbs not covered in this review, but used for weight loss, include bladder wrack (Fucus vesiculosus), blood orange (Citrus sinensis), bromeliad (Bromelia spp), celery seed (Apium graveolens), fenugreek (Trigonella foenum-graecum), horsetail (Equisetum spp), passionflower (Passiflora spp), red grape (Vitis vinifera) and xanthan gum. As is the case with phaseolamin and hydroxycitric acid, other compounds from herbal sources have been used for weight loss such as γ-oryzanol,29 nootkatone30 and yohimbine.31 All warrant further scrutiny.

under the WADA (World Anti-Doping Agency, http://www. wada-ama.org) code needs to be extremely cautious about using supplements and always work with a qualified professional on risk minimisation of supplement use. The ethical/legality issues of sport can be contravened either by the deliberate use of over-the-counter compounds that are prohibited by such codes (eg, pro-hormones and stimulants) or by inadvertent intake of these products due to contamination, fake or doping issues, with banned stimulants, such as ephedrine or sibutramine, being frequently found in weight loss supplements.32 Competing interests None. Provenance and peer review Commissioned; not externally peer reviewed.

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CONCLUSION There is a vast array of herbs found in supplements including, but not limited to, those marketed for weight loss. The diversity of individual herbs as well as their simultaneous presence in some products, sometimes more than ten in one product, has become a minefield that both athletes and their sports medicine and science support staff find difficult to navigate. It is worrying how prolific these supplements have become, despite their tenuous, if any, link to a mechanism for weight loss and the lack of supporting evidence. The novel system devised here helps demystify and clarify the rationale, albeit frequently not supported by scientific evidence nor linked to weight loss, behind the inclusion of these herbs in many supplements. In terms of weight loss, it is advisable to make informed dietary changes prior to reaching for supplements. As always, and particularly in the case of some of the herbs discussed here where the evidence is scant, athletes are strongly recommended to seek advice from a sports nutrition professional before considering using any supplements. Furthermore, as stressed in previous reviews, it is essential to reiterate that any athlete who competes

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Senchina DS, et al. Br J Sports Med 2013;47:595–598. doi:10.1136/bjsports-2013-092500

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Senchina DS, et al. Br J Sports Med 2013;47:595–598. doi:10.1136/bjsports-2013-092500

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A−Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance: Part 44 D S Senchina, S J Stear, L M Burke, et al. Br J Sports Med 2013 47: 595-598

doi: 10.1136/bjsports-2013-092500

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