2. Supplement Effectiveness 2.1 Amino Acids Mixtures Nearly all of the amino acid supplements in our survey were in tablet or capsule form. They were often described as 'free form' or peptide bonded' amino acids, which could be absorbed or utilised more efficiently than intact proteins. Some of these claims were referenced by the study of Smith et al. (1982) who compared nitrogen balance and absorption in 4 hospital patients (3 had malabsorption) fed solid food, an elemental diet containing free amino acids or a formulae containing predigested protein. Nitrogen absorption was better in patients when they were fed either special diet than with the solid food, but nitrogen retention was poorest when they received the amino acid containing elemental diet.
Several of the amino acid mixtures were primarily branched chain amino acids (leucine, isoleucine, valine), which are oxidised in muscle tissue during endurance exercise (Ahlborg et al. 1974; Haag et al. 1982; Rennie et al. 1981). However, Tarnopolsky et al. (l99l) showed no effects of a 1-hour bout of circuitset resistance exercise on leucine metabolism. Table 1. Advertised claims made for 624 commercially marketed supplements In our survey the amino acid mixtures were the largest category of supplements aimed at bodybuilders. However, there is little evidence to support the advertised claims made for over half of these products. Although amino acid supplements do have recognised value in some clinical situations where normal absorption is compromised, this is not likely to be a factor limiting muscle gain in healthy individuals. This said, there is little reason to obtain amino acids in free form rather than those within an intact protein in foods, particularly when the latter are less costly. The safety of large amounts of amino acids exceeding those present in foods has not been established, but amino acid imbalances are possible if disproportionate amounts are consumed. 2.2 Amino Acids Individual A few amino acid supplements were composed of single amino acids. Those containing arginine or ornithine were by far the most numerous and were placed in a separate category. The remaining individual amino acid supplements were a fairly heterogeneous group accompanied by few advertised performance claims or other unusual features. Four of the supplements contained tryptophan, which previously had been banned by the US Food and Drug Administration in March 1990 (Food and Drug Administration 1990a, 1990b) because of the association of some supplements with eosinophilia myalgia syndrome. 2.3 Arginine and/or Ornithine Over half of the arginine and ornithine supplements in our survey were promoted as 'growth hormone releasers', or aids that would increase the physiological release of human growth hormone (HGH). Other common claims were a reduction in body fat, increased weight or muscle gain and anabolic or growthstimulating effects attributed to the increase in growth hormone released by the supplement. Arginine hydrochloride intravenous infusion (0.5 g/kg) increases plasma HGH levels in normal subjects and is used clinically to evaluate hypothalamicpituitary function (Findling & Tyrrell 1986). Increased HGH release also has been observed experimentally following infusion of 0.18 and 0.37 g/ kg arginine in women and men, respectively (Merimee et al. 1969). A 250 mg/kg oral dose of arginine aspartate increased the normal peak in plasma HGH during slow wave sleep (Besset et al. 1982). In another study. 1200mg arginine administered orally had no significant effect on HGH secretion, except when combined with an equal amount of lysine (Isidori et al. 1981). Effects of amino acids in exercising individuals also have been examined. Increases in HGH levels ' during a weight training circuit were higher when 4 subjects fasted than after consumption of amino acid capsules or a meal (Fricker et al. 1988). Bucci et al. ( 1990) studied the acute effects of 40, 100 or 170 mg/kg orally administered lornithine in bodybuilders. The highest dosage (equivalent to 12g for a 70kg person) was followed by a significant rise in serum HGH 90 minutes after ingestion, and the subjects reported mild to severe stomach cramping and diarrhoea. Lower dosages had smaller effects ' on serum HGH levels. The relevance of this form of supplementation to athletic performance (i.e. effects on body fat and lean body mass) remain to be proven and merit more extensive investigation. Effects of amino acids on HGH have been the subject of recent reviews (Jacobson 1990; Lemon & Chaney 1988). 2.4 Boron Compounds Seven of the 10 boron compounds enumerated in our survey were advertised as natural testosterone boosters, and half purportedly increased weight or muscle gain. Several advertisements cited the study of Nielsen et al. (1987) to substantiate their claims. This study examined the effects of a 3mg boron supplement on mineral metabolism and hormone levels in postmenopausal women. Boron supplementation doubled serum testosterone levels in the women, but the investigators did not extrapolate their findings to other population groups, and effects on weight or muscle gain were not evaluated. In a later preliminary report, young male bodybuilders given boron 2.5mg or placebo for 7 weeks had similar increases in plasma testosterone, lean mass and strength (Ferrando & Green 1992). Boron is present in relatively high amounts in fruits, vegetables and legumes (Hunt et al. 1991). 2.5 Carnitine
LCarnitine is involved in the transport of long-chain fatty acids through the mitochondrial membrane (Mayes 1988). Most of the body's carnitine, totaling approximately 20 to 25g in an average man (Cerretelli & Marconi 1990), is located in muscle tissue. Carnitine is synthesized endogenously from lysine and methionine (Rebouche 1980); minor amounts are contributed by foods, mainly meat and dairy products (Mitchell 1978) The average non-vegetarian diet provides about 100 to 300mg carnitine daily (Feller & Rudman 1988). Carnitine appears to have little effect on resting oxygen consumption in normal subjects when ingested at 6 g/day over a 10day period (Dal Negro et al. 1986). Some interesting effects of carnitine supplementation have been noted in endurance athletes, including an increase in VO2max (Marconi et al. 1985) and reduction in respiratory quotient (Gorostiaga et al. 1989). However, other studies have not supported these findings (Cerretelli & Marconi 1990; Greig et al. 1987). Ingestion of 5g carnitine daily for 5 days before 120minute cycle exercise sessions did not allow muscle substrate utilisation (Soop et al. 1988). The bioavailability of pharmacological doses of lcarnitine is poor (Harper 1988), and its use as an ergogenic aid is not supported by current data. The disomer of carnitine should be avoided because of its influence on the utilisation of lcarnitine and resultant muscle weakness and myoglobinuria (Wagenmakers 1991). Excellent reviews on carnitine and physical performance have been published by Cerretelli and Marconi ( 1990) and Clarkson (1992). 2.6 Choline Choline is a constituent of acetylcholine and phosphatidylcholine. The latter is a structural component of cell membranes and lipoprotein complexes involved in lipid transport (Zeisel 1981). However, we found no research showing that choline supplementation reduces adiposity in human subjects. Usual consumption is an estimated 400 to 900 mg/day (McMahon 1987), primarily as a component of lecithin in foods, such as egg yolk, liver, meat and peanuts (Wurtman 1979). . Although choline is a relatively nontoxic compound, its supplementation can lead to undesirable side effects such as diarrhea and 'fishy' body odour resulting from the action of intestinal bacteria (De La Huerga & Popper 1951). 2.7 Chromium Compounds
Chromium was also frequently advertised as an 'insulin enhancer', a descriptive term probably originating from its role as a component of glucose tolerance factor (GTF) [Schwarz & Mertz 1959]. Low chromium intakes have been documented in some US populations (Anderson & Kozlovsky 1985; Kumpulainen et al. 1979), but seem less likely in weighttrained individuals because of their better glucose tolerance (Szezypaczewska et al. 1989) and insulin response to glucose (Miller et al. 1984; Szezypaczewska et al. 1989) over untrained subjects. Endurance exercise (running) increases urinary losses of chromium (Anderson et al. 1984) but effects of resistance exercise are not known. 2.8 Dibencozide Dibencozide (also listed as dibencozide, 5-deoxyadenosyl cobalamin) was another supplement often promoted as an anabolic or growth promoting aid. Several advertisements described dibencozide as the active form of vitamin Bl2 and cited 2 studies performed in the 1960s involved in its research (Sullivan & Herbert 1965; Boddy et al. 1968). Several cobalamins are vitamin active for humans, but what is used in most pharmaceutical preparations today is cyanocobalamin (Herbert 1988). However. the form ingested is probably irrelevant in most cases, because adequate amounts are easily obtained by inclusion of animal products in the diet. In a doubleblind study of young men, injections of cyanocobalamin (1mg) or placebo 3 times a week for 6 weeks had similar effects on VO2max, handgrip strength, pullups, leglifts and other physical measurements (TinMayThan et al. 1978). 2.9 yOryzanol and Ferulic Acid Oryzanols belong to a family of compounds obtained during the processing of rice bran oil (Saunders 1990; Juliano 1985). They usually occur as esters of ferulic acid, and are potent antioxidants that prolong the shelf life of the oil (Juliano 1985). Oryzanol anecdotally is believed to stimulate growth and hormonal secretion in humans (Yokochi 1974), although we found no published research to substantiate these claims. Ferulic acid is widely distributed in small amounts in plants (Windholz et al. 1976). Of the 24 supplements in this category, 5 contained only yoryzanol, 14 contained ferulic acid as a single product, and 5 contained both compounds. Commonly advertised claims for these supplements were weight or muscle gain and anabolic or growth promoting properties. Several advertisements cited the study of Gorewit (1983) to support their claims. In that study, 2 levels of infused ferulic acid slightly increased serum growth hormone levels in cattle, but effects on growth and lean body mass were not measured. Wheeler and Garleb (1991) have published a comprehensive review of the physiological effects of aoryzanol and plant sterols. They state that plant sterols are poorly absorbed from the digestive tract; therefore, ergogenic effects and toxicity are likely to be minimal. However, some individuals with lipid storage disease exhibit xanthomatosis as a consequence of abnormally high absorption of the phytosterols Bsitosterol and camposterol (Bhattacharyya & Connor 1974: Shulman et al. 1976). 2.10 Glandulars Most of the 21 glandular extracts in our survey were mixtures of extracts from several different glands. Orchic extract (from testicles of animals) was the most commonly listed ingredient, included in over half of the supplements. Other glandular extracts listed were those from pituitary, thymus, adrenal, pancreas, ovary, prostate and spleen. These supplements are sold to augment the body's own tissues and glands, but their effectiveness has been reviewed and discounted (Trindell & Tannenhaus 1988). 2.11 Inosine Inosine, as a component of inosine monophosphate (IMP), is used to synthesize adenine or guanine nucleotides which are involved in the energy exchange of numerous biological reactions. In supplement form inosine is promoted as an energy enhancer and an aid to increasing endurance, recuperation and strength. However, little research exists to support those claims. Williams et al. (1990) found no effect of 6g inosine on 3mile run time or VO2max in highly trained runners. 2.12 Dessicated Liver Liver is a good source of protein and other nutrients such as iron, zinc and several B vitamins (USDA 1986). Thus, it is not surprising that desiccated tablets are sold as nutritional supplements. Some supplements are advertised to increase energy and endurance. In our assessment, effects of these supplements are likely to be all within the context of the whole diet. 2.13 Medium Chain Triglycerides Medium chain triglycerides (MCT) are perhaps best known by clinicians for their use in malabsorption disorders (American Dietetic Association 1988b). Their C6:0 to C12:0 fatty acids are more soluble and more rapidly absorbed and oxidised than longchain fatty acids (Bach & Babayan 1982). Commercially available MCT preparations are often sold to increase energy and reduce body fat. Most support for these claims is derived from rat studies, which show that MCT feeding increases energy expenditure and leads to smaller deposition in adipose weight (Baba et al. 1982; Geliebter et . 1983; Lavau & Hashim 1978). Also, fatty acids of MCTs are not deposited to any significant degree in rat adipose stores (Harkins & Sarett 1968). There is some evidence that MCT feeding increases the thermic effect in humans (Hill et al. 1989; Seaton et al. 1986). Others found that its inclusion in hypocalorie diets did not enhance the rate or amount of weight lost (Kaunitz et al. 1975; Yost & Eckel 1989). Ingestion of 25g MCT and an isocaloric amount of maltodextrins had similar effects on energy expenditure during I hour of exercise in young men (Deeombaz et al. 1983). Medium chain triglycerides are not recommended for individuals who have diabetes or liver disease (Bach et al. 1982). 2.14 Powders Advertised for Weight, Muscle and/or Strength Gain
Advertised claims for weight or muscle gain for these powders may have some validity if the diet, within the context of an appropriate training programme, is inadequate to support growth. According to several estimates, a gain of 1 lb (454g) of muscle per week requires 2500 to 3000 kcal in excess of expended energy (Coleman 1990; Eisenman & lohilson 198'; Smith 1976, 1983), or approximately 400 kcal per day. The supplementary powders in this group are a convenient means to increase overall calorie intake and other nutrients, but have no other proven benefits over increased food intake. Some powders in our survey were almost entirely protein, which leads to a discussion of this form of supplementation. Protein supplementation is common among bodybuilders. In 1study, 60% of bodybuilders consumed protein supplements (Katch et al. 1980). Others have found that bodybuilders consumed over 2g protein/ kg bodyweight from diet and supplements (Bazzarre et al. 1990; Faber et al. 1986; Kleiner et al. 1990), which is more than twice the Recommended Dietary Allowance for adults (National Research Council 1989). The amount of protein intake for optimal muscle synthesis during a weight training programme has not been established, but incremental needs are probably small if energy intakes are adequate (Tarnopolsky et al. 1988). If energy intake is inadequate, more dietary protein is needed to maintain nitrogen balance in physically active individuals (Iyengar & Narasinga Rao 1979; Todd et al. 1984; Walberg et al. 1988). Williams ( 1985) estimated that synthesis of 1 lb (454g) muscle per week requires a daily average of 10g protein. Others have shown that intakes exceeding 2 g/kg bodyweight are needed to maintain positive nitrogen balance in some weighttrained individuals (Celejowa & Homa 1970; Larilcheva et al. 1978). For a full discussion of the protein needs of exercising individuals, the reader is referred to several excellent reviews (Hickson et al. 1989; Lemon 1987, 1991; Lemon & Proctor 1991; Meredith 1988; Paul 1989). 2.15 Powders Advertised for Energy, Endurance and/or Recuperation We found that these powders were more predominantly carbohydrate than those advertised for weight, muscle or strength gain. When diluted, they contribute to total energy intake and hydration. Effects of carbohydrate beverages on endurance and recuperation have been well documented for endurance athletes (Costill 1985; Murray 1987), but information on resistance trained individuals is scarce. Generally, this form of supplementation has most performance value when glycogen stores are depleted during continuous endurance exercise (e.g. distance running, cycling) [Hasson & Barnes 1989; Buskirk & Puhl 1989]. Weight training is less likely to exhaust glycogen stores because of its intermittent nature and divided focus on different muscle groups. According to several studies (MacDougall et al. l 988; Robergs et al. 1991; Tesch et al. 1986), between 13 and 45% of muscle glycogen was used during various weight training regimens. Furthermore, resting muscle glycogen levels are increased as a result of this form of training (MacDougall et al. 1977): and blood glucose levels are not reduced during weight exercise in trained individuals (Keul et al. l978: Robergs et al. 1991). However, if carbohydrate intake is chronically low, muscle glycogen levels will decline and strength may be altered (Jacobs et al. 1981). Also, weight training individuals may engage in other forms of exercise that affect glycogen utilisation and carbohydrate availability. 2.16 Powders Advertised for Weight Loss We found only 6 powders advertised for weight loss in our survey, which suggests that this type of product is not a very popular means of losing weight among bodybuilders or other weight training athletes. Other approaches might be more popular, as suggested by the much larger number of supplements containing carnitine, choline, arginine or ornithine that were available and advertised for this purpose. 2.17 Smilax Compounds
Nearly half of the Smilax supplements in our survey were advertised as a natural form of testosterone or means to boost physiological levels of this hormone, and some preparations were promoted as an alternative to anabolic steroids. Other cited claims were enhanced weight or muscle gain and strength. Plants of this genus contain steroids such as smilagenin, sitosterol, stigmasterol and sarsaspogenin (Wren 1988a) which are structurally related to testosterone and estrogen. However, we found no research documenting anabolic or performance effects, and they are not listed as prohibited substances by the US Olympic Committee (1989). 2.18 Vitamin and Mineral Multiple Supplements The multiple vitamin and mineral supplements in our survey were difficult to enumerate because less than half were sold as single tablets or capsules. The remaining number, 57%, were part of supplement packs containing an assortment of supplements for the 'multiple needs' of the athletes. Common supplements sold in these packs included various amino acids, glandulars, energy stimulants, herbs, fat burners or emulsifiers, electrolytes, and digestive enzymes. 2.19 Vitamins Individual
Supplementation is warranted in some circumstances but otherwise discouraged due to potential toxicity, and interference with the normal metabolism of other nutrients and with the effectiveness of certain drugs (Calloway et al. 1987). 2.20 Yohimbine Yohimbine (also yohimbe) is an extract from the bark of the yohimbe tree (Pausinyslalia yohimbe), which has enjoyed a long-standing reputation as an aphrodisiac (Wren 1988b). In our survey, most of the 11 yohimbine supplements were promoted as natural sources of testosterone or testosterone enhancers. Yohimbine is an indole alkaloid not structurally related to testosterone, but is an aadrenergic blocker used clinically to treat impotence under the brand name 'Yocon' (Barnhart 1990). The effectiveness of this drug has been documented in research studies (Morales et al. 1982; Susset et al. 1989). The effectiveness of yohimbine sold as a food supplement is unknown and perhaps questionable because of the wide range of bioavailability of this drug (Guthrie et al. 1990). 2.21 Miscellaneous This group included a wide variety of less commonly listed supplements. Examples of supplements in this category were canthaxanthin, cyclofenil, diosgenin, ginseng, wild Mexican yam, octacosanol, bee pollen, saw palmetto berries, silymarin and various herbs. The infrequent listing of these substances precluded a need for review of their performance claims. Originally appearing in Sports Medicine 15(2) 90-103. 1993. Copyright © 1993 by Adis International Limited. All rights reserved. Reprinted by Mesomorphosis with permission. Any duplication of this document by electronic or other means is strictly prohibited. |
