Conjugated Linoleic Acid

CLA is a term describing several geometric and positional isomers of common linoleic acid (an omega-6 fatty acid). CLA, however, has many opposing physiological effects to linoleate, notably in reference to carcinogenesis and inflammation. The unique properties of CLA may in part be due to its postulated antioxidant properties This mechanism, however, has been questioned. It is more likely that the preliminary positive findings regarding CLA supplementation in athletes are due to other mechanisms. This, however, remains to be elucidated.
Alpha Lipoic Acid

Alpha lipoic acid (ALA) is an antioxidant that has received considerable attention recently, both in the scientific and commercial supplement communities. ALA is present in the mitochondrial proteins necessary for oxidative metabolism. For example, it is a cofactor for dehydrogenase enzymes like PDH, which forms acetyl CoA for the Krebs cycle. In addition, ALA possesses both antioxidant and subchronic glucose disposal activity. This compound can scavenge HO2 , HOCL, and O2 radicals. It is both water- and lipid-soluble, and so may be of benefit to both cellular compartments. Alpha lipoic acid has been shown to combat age-associated decline in metabolism by improving mitochondrial function via increased oxy­gen consumption, mitochondrial membrane potential, and ambulatory activity. In addition, this research showed decreased oxidative damage as measured by decreases in MDA and increases in ascorbic acid and glutathione. In exercise-induced oxidative stress, lipoic acid decreased lipid peroxidation and increased glutathione levels. Research investigating a lipoic acid + vitamin E combination has revealed evidence of decreased plasma LDL oxidation as well as decreased urinary isoprostanes, which are markers of oxidation. Although these preliminary data are exciting, more research is needed to clarify the exact nature of lipoic acid’s beneficial effects as both a glucose disposal agent and an antioxidant.

Conjugated linoleic acid (CLA) is found naturally in food, although the total CLA content varies. 1995 CLA is a modified isomer of linoleic acid that was introduced to the supplement market in late 1995 as one of the newer supplements available to enhance muscular development. Chemically, linoleic acid is an 18-carbon unsaturated fatty acid with two double bonds in positions 9 and 12, respectively. Both of these bonds lie in the cis configuration, thus giving it its own unique chemical name-c9, c12­octadecadienoic acid. CLA differs only modestly in confirmation in that the two double bonds in CLA are in one of three positions along the carbon chain: 9 and 11, 10 and 12, or 11 and 13. These small changes not only give CLA a unique chemical name, but because of the varied position of the double bonds, CLA also can take two different geometric positions. Therefore, CLA can take a cis or trans configuration. Although this may seem chemically insignificant, physiologically it is quite profound and gives CLA the chemical nomenclature of a conjugated diene that is a mixture of positional and geometric isomers of conjugated dienoic derivatives of linoleic acid. With a few exceptions, the c9, t11-isomer is the predominant form CLA is found especially in foods high in saturated fat such as meat and dairy products. In addition, meat from ruminants (animals with four-chambered stomachs) contains more CLA than meat from nonruminants. Because foods typically high in CLA also contain high amounts of saturated fats, increasing CLA intake via food consumption may put individuals at risk for developing coronary artery disease. Nevertheless, there are intriguing data that demonstrate positive effects after CLA administration.

During processing, various factors may contribute to the formation of CLA. Factors that increase CLA food content include higher temperatures, the addition of whey protein concentrate or sodium caseinate, and the presence of a hydrogen donor such as butylated hydroxy toluene, propyl gallate, or ascorbic acid. Although some reports suggest that grilling ground beef may increase CLA content in beef fat by about four-fold, other studies suggest that cooking has no effect on CLA concentrations.

Owing to this unique molecular structure, CLA is believed to have unique mammalian tissue physiological effects compared with other fats. Scientists have theorized, from observations in various animal studies, that CLA enhances lean body mass, although the mechanism for action is unknown. Some scientists believe that CLA amplifies cell responsiveness to certain growth factors, hormones, and cellular messengers. It may also possess anticatabolic effects Therefore, CLA consumption by humans could theoretically increase muscular strength and lean body mass. Whether supplementation is advised is still a matter of debate.
Animal Studies

CLA has been suggested to also be anticarcinogenic. The incidence of various forms of cancer is high in the United States and other countries. Saturated fat has been correlated with the occurrence of cancer in several tissue sites Certain unsaturated fatty acids may affect carcinogenic factors. For example, linoleic acid has been implicated in the acceleration of mammary cancer development in rodents However, it is also clear that some fatty acids will inhibit carcinogenesis. In this regard, eicosapentaenoic acid and docosahexaenoic acid, which are representative of the w-3 polyunsaturated fatty acids found in fish oil, have long been purported to have anticarcinogenic effects. acid, CLA appears to have reproducible effects on various cancer indices. To date, the specific sites of action include breast. colon kidney and skin tissue. The reason CLA has these effects may lie in how it is deposited in tissues. One interesting finding is that the c9, t11-isomer appears to be found in the phospholipid layer, whereas other CLA isomers appear in triglyerides. The reason why this relationship is important is not completely clear. However, the ingestion of CLA likely leads to an accumulation in triglyceride, which is stored as fat depot in adipocytes. Because CLA has an antioxidant potential and because adipocytes are a major constituent of the mammary gland, the increased concentration of CLA in triglyceride may help protect certain cells against oxidant stress.

Although the exact mechanism of action has yet to be confirmed, use of CLA as a therapeutic intervention shows promise. For example, Ip has shown that, although fish oil is a class of lipid that inhibits both chemically induced and transplantable tumors, the amount of fish oil needed to elicit this response usually exceeds 10% of total dietary fat However, as little as 0.1% CLA in the diet is sufficient to produce a significant reduction in mammary tumor yield.

Although CLA appears to play a role in the inhibition of carcinogenesis, it also appears to have insulin-sensitizing effects as well. In this regard, CLA activates PPAR alpha in the liver and shares functional similarities to ligands of PPAR gamma and thiazolidinediones, which are potent insulin sensitizers. Early evidence for the effect of CLA on insulin sensitivity was provided by Houseknecht et al. who reported that CLA was able to normalize impaired glucose tolerance and improve hyperinsulinemia in prediabetic rats. Additionally, dietary CLA in this trial also appeared to increase steady-state levels of aP2 (activator protein 2) mRNA in adipose tissue, which is consistent with the actions of PPAR gamma. The authors of this study proposed that the insulin-sensitizing effects of CLA are caused, at least in part, by activation of PPAR gamma because increasing levels of CLA induced a dose­dependent transactivation (stimulation of transcription by a transcription factor binding to DNA and activating adjacent proteins) of PPAR gamma.

In vitro data on human erythrocytes have also been presented by Inouye et al These investigators suggest that glycation reactions and antioxidant activity are enhanced by elevated glucose concentrations. Because it is unclear whether the diabetic state, perse, also induces an increase in the generation of oxygen-derived free radicals, there is some evidence that glycation itself may induce the formation of oxygen-derived free radicals. In this regard, oxygen­derived free radicals could cause oxidative damage to endogenous molecules. During this trial, investigators examined the relationship between the levels of lipid peoxidation and the levels of glycated hemoglobin Ale in the erythrocytes of both diabetic and healthy subjects. Lipid peroxidation was assessed in erythrocyte membrane lipids by monitoring peak height ratios of CLA, one of the products of lipid peroxidation, to linoleic acid. The peak height ratio of CLA to LA was used as a biomarker of lipid peroxidation and glycated hemoglobin Ale, an index of glycemic stress. The results of this trial showed a significant increase in the ratios of CLA to LA in diabetic erythrocytes compared with that of control erythrocytes. In addition, ratios of CLA to LA were also significantly correlated with glycated hemoglobin Ale values. These findings attest to the antioxidant qualities of CLA and suggest that glycation via chronic hyperglycemia links lipid peroxidation in the erythrocytes of both diabetic and healthy subjects. (Hemoglobin Ale is the substance of red blood cells that carries oxygen to the cells and sometimes joins with glucose.)

Although it has been shown that CLA may have anticarcinogenic effects and the ability to modulate diabetic and immune system responses, less is certain about its effect on body mass. Animal studies have shown that CLA can increase lean body mass and decrease fat. Studies in animals also show that CLA improves feed efficiency, which means that animals given CLA gain weight without receiving more food. If validated in human studies, these results could have interesting applications in athletics as well as medicine.

Recent investigations have demonstrated that animals receiving a diet rich in CLA have a reduction in adipose tissue. One such study fed mice a diet of 5.5% corn oil or a CLA-supplemented diet consisting of 5.0% corn oil plus 0.5% CLA. Mice receiving the supplement exhibited 57% and 60% lower body fat and 5% and 14% increased lean body mass compared with controls. Total carnitine palmitoyltransferase activity, an enzyme used in the oxidation of fatty acids, was increased in fat pad and skeletal muscle sites of the experimental animals. Cell culture experiments used adipocytes were also conducted and showed that CLA treatment significantly reduced heparin-releasable lipoprotein lipase activity (- 66%) as well as the intracellular concentrations of triglycerides (-8%) and glycerol (-15%). However, CLA significantly increased free glycerol in the culture medium compared with the control . Researchers concluded that the effects of CLA on body composition appear to be a result in part of reduced fat deposition and increased lipolysis in adipocytes, along with enhanced fatty acid oxidation in myocytes and adipocytes. Another interesting observation was the increase in the percentage of whole body protein and carcass water in mice receiving CLA supplementation. Unfortunately, because of the small sample size, it was not possible to conclude from these data alone that CLA induced a significant increase in protein accretion. However, these investigators also mention data combined from 10 other CLA studies, which indicate that CLA-fed mice do in fact exhibit increased whole body protein relative to control animals. Their findings have led to further research examining alterations in lean body mass induced by the supplementation of CLA.

Park et al recently published a two-part experiment. In the first part, 8-week-old mice were fed a control diet or a diet supplemented with 0.5% CLA. Results from each feeding showed parallel, but significantly distinct responses for both absolute and relative changes in body fat mass, which was decreased in the CLA-fed mice. In addition, relative alterations in whole body protein and whole body water were both increased in the experimental group. In the second part of the experiment, weanling mice were fed a control diet or a diet with added CLA (0.5% CLA) for 4 weeks. After 4 weeks, all mice were fed the control diet (no CLA). The experimental group exhibited significantly reduced body fat and significantly enhanced whole body water relative to controls at the time of the shift in food composition. Time trends for the changes in relative body composition were described as the CLA-fed group exhibited significantly less body fat, but significantly more whole body protein, whole body water and whole body ash than controls. Tissue analyses of the animals revealed that the CLA isomer t-10, c-12 was cleared significantly faster than was the c-9, t-11 isomer. These findings confirm data showing that CLA given to mice can increase whole body protein and whole body water, and decrease fat mass. Changes in body composition were still visible 8 weeks after the cessation of supplementation. This indicates CLA can induce effects on muscle mass and adipose tissue for at least some time after the clearance of the compound.

Particularly interesting in these studies are the different effects of the various isomers. Currently, CLA available on the market today contains several different isomers and scientists are attempting to isolate the isomer responsible for the beneficial effects of CLA supplementation. In an investigation conducted by researchers at the University of Wisconsin-Madison, the trans-10, cis-12 isomer of CLA was found responsible for inducing body composition changes. Reduced body fat, enhanced body water, enhanced body protein, and enhanced body ash were associated with feeding the trans-10 cis-12 CLA isomer. In cell culture experiments, adipocytes had reduced lipoprotein lipase activity, intracellular triglyceride, and glycerol, and enhanced glycerol release into the medium as a result of the trans-10, cis-12 isomer. The cis-9, trans-11 and trans-9, trans-11 CLA isomers did not affect the biochemical markers that were tested. Thus, body composition changes are mediated by the trans-10, cis-12 CLA isomer-and it alone appears to be responsible for many of the biochemical effects of CLA.
Human Studies

Human data on CLA are at present limited. In one of the few trials available, Lowery et al. examined the effects of CLA in novice bodybuilders. Twenty-four men ingested 7.2 g/day of CLA or placebo (vegetable oil) while completing 6 weeks of bodybuilding exercise. After the trial was completed, gains in arm girth (corrected for skinfolds, body mass, and leg press strength were greater in the CLA-supplemented group than in the placebo group.

However, no differences were noted for subcutaneous fat (skinfolds), total body fat or body water distribution in either the intracellular or extracellular compartments. Further analysis of a subset of subjects revealed no difference in serum glucose, lipids, BUN, creatinine, LDH, SGOT, and SGPT enzymes.

In another trial, Kreider et al. further examined the effects of CLA supplementation and resistance-training on bone mineral content (BMC), bone mineral density (BMD), and markers of immune stress. In a double-blind and randomized trial, 23 experienced resistance-trained males were matched according to total body weight and training volume. Subjects were given supplements containing either 9 g/day of olive oil (placebo) or 6 g/day of CLA with 3.2 g/day of fatty acids for 28 days. Leukocytes from fasting whole blood were typed, and dual-energy x-ray absorptiometry (DEXA) determined whole body (excluding cranium) BMC and BMD on days a and 28 of supplementation. The results of this trial revealed a trend towards an increase in BMC in the CLA group. Some evidence suggested that CLA reduced the NeLy ratio suggesting less immune stress. The results provide some support to contentions that CLA supplementation may improve bone and immune status during resistance training in humans. However, additional research is necessary.
Safety and Toxicity

Long-term use of CLA in humans has not been evaluated; however, animal data collected from CLA studies and data on other essential fatty acids would indicate that supplementation is likely safe and may be beneficial to the overall health of athletes, especially in regard to disease prevention.

To increase muscle mass, strength, and power, one of the goals of training is to manipulate and increase the training stimulus or the physical work that is performed. At its essence, physical training depends on the coordinated balance between an imposed physical stressor, the manipulation of training variables (volume, intensity, and frequency), adequate rest intervals, and recovery between training sessions. Recovery is perhaps the most difficult to manipulate and gauge owing to the amount of time necessary to achieve it. Furthermore, barring the use of anabolic steroids for muscle repair and growth, nutritional interventions are often necessary to promote a more efficient recovery following training. Although many supplements have been extolled for their anabolic and ergogenic effects, to date, only a few have withstood the rigors of science. The most notable of these is creatine monohydrate (creatine). Though most other supplements do not elicit as powerful an effect as creatine, a few are worthy of notation and future research efforts.
Creatine Supplements

Although several anecdotal adverse effects have been attributed to creatine supplementation, only a few minor scientific studies have been documented. Some of these have linked creatine supplementation to gastrointestinal upset. This is attributed to osmotic distress if the crystalline creatine is not adequately dissolved into a solution before ingestion. Another common reported side effect is body weight gain due to increased creatine storage and the associated gain in fat-free mass. However, many athletes do not consider body weight gain to be a negative effect of creatine supplementation. Also interesting to note is that recent studies in infants between 2 to 4 years of age who have genetic disturbances in creatine synthesis have shown remarkable clinical, biochemical, and functional improvements following creatine supplementation in doses ranging from 136.4 to 227.3 mg/lb body weight (350 to 500 mg/kg body weight) that were maintained for over 25 months. This dose is up to 1.67 times the recommended loading dose. No adverse effects were reported, including no aggravation of seizures in one infant who presented with intractable seizures (including rare grand mal seizures) before being treated with creatine.
Muscle Strains/Pulls

Anecdotal reports from some athletic trainers and coaches suggest that creatine supplementation may promote a greater incidence of muscle strains or pulls. Because creatine supplementation may promote relatively rapid gains in strength and body mass, additional stress may be placed on bone, joints, and ligaments, leading to injury. To date, no study has documented an increased rate of injury following creatine supplementation, even though many of these studies evaluated highly trained athletes during heavy training periods.
Muscle Cramping

Some anecdotal claims have suggested that athletes training intensely in hot or humid conditions might experience severe muscle cramps while taking creatine. Proponents of this theory suggest that creatine supplementation may cause large fluid shifts in the muscle, serving to alter electrolyte status, promote dehydration, and/or increase thermal stress. No study has reported that creatine supplementation causes cramping, dehydration, or changes in electrolyte concentrations, although one study evaluated highly trained athletes undergoing intense training in hot and humid environments. Furthermore, the causes of muscle cramping are not fully understood so it is premature to suggest that creatine supplementation may elicit such an effect.
Dehydration

Numerous reports in the media suggest that creatine supplementation can produce dehydration even though there are no published studies supporting this assertion. No studies to date have demonstrated an increase or decrease in whole body hydration as determined via bioelectric impedance analysis. Recently, Ziegenfuss et al. addressed these issues in ten cross­trained and aerobically trained men. At a dose of 0.16 g/day (approximately 32 g/day for a 200 lb­person), coupled with a multifrequency bioelectrical impedance analyzer, they found that total body water increased by 2% and paralleled the increase in total body mass associated with the 5-day loading sequence. Interestingly, extracellular water content did not change significantly, but intracellular water content changed by 3%. Kreider et al. also calculated plasma volume from the ratio of blood hemoglobinJhematocrit from available published data and found no alterations in blood volume.
Death

One of the most shameful and poorly researched press reports suggested that creatine supplementation may have been involved in the sudden deaths of three wrestlers. These athletes died suddenly while exercising in the heat in rubber suits in an attempt to cut weight before competition. Based on these reports, the Centers for Disease Control and Prevention (CDCP) and the Food and Drug Administration (FDA) launched investigations to determine whether creatine was involved in these deaths. Results of this investigation conducted by the CDCP revealed two of the wrestlers had not taken creatine and one of the athletes had stopped taking creatine at least 3 months before his death. The deaths of the wrestlers were officially attributed to hyperthermia, heart failure, and heat exhaustion/dehydration.

During the early 20th century it was first observed that not all of the creatine ingested by animals and humans could be recovered in the urine as creatinine. This suggested that some of the creatine was retained in the body. Folin and Denis were among the first to determine that the creatine content of the muscles in cats increased up to 70% after creatine ingestion. Creatine in humans was soon discovered to be present in skeletal and cardiac muscle, uterine and intestinal tissue, the testes, brain, kidney, nervous tissue, and sperm, as well as in adipose stores. Ninety five percent of the total creatine pool is found in skeletal muscle tissue, with the remaining 5% stored in the heart, brain, neural tissues, and testes. Normal intramuscular values for total creatine are approximately 124.4 mmol/kg . In 1927, Fiske and Subbarow reported the discovery of a labile phosphorus in the resting muscle of cats, which was subsequently called phosphorylcreatine or, simply, PCr. This group further observed that, during the electrical stimulation of skeletal muscle, PCr diminished only to reappear during recovery.

Three amino acids are involved in the synthesis of creatine: arginine, glycine, and methionine. The synthesis of creatine begins with the transfer of the amidine group from arginine to glycine, forming guanidinoacetate and ornithine. This reaction is reversibly catalyzed by the enzyme transamidinase. Creatine is then formed by a nonreversible reaction involving the addition of a methyl group from S-adenosylmethionine, with a methyl transferase being required for this process. This step is known as transmethylation. In humans, de novo synthesis (path­way synthesizing a biomolecule from simple precursor molecules) of creatine takes place via enzymes located in the liver, pancreas, and kidneys and involves the transport to skeletal muscle by the bloodstream after formation. The total creatine pool in humans is dictated by the combined content of creatine found in both its free and phosphorylated (PCr) form. Of the 95% of the total creatine pool found in skeletal muscle, approximately 40% is free creatine and 60% is PCr.

Once in skeletal muscle, creatine and PCr are effectively trapped and cannot exit the cell until creatine and PCr are degraded to creatinine via a nonreversible, nonenzymatic process. Creatinine is thus filtered in the kidneys and ultimately excreted in the urine. In the absence of dietary intake, normal creatine turnover to creatine is estimated to be about 1.6% per day. Therefore, in a 70-kg person, the total creatine pool is approximately 120 g, with a total daily turnover of 2 g/day. The body’s creatine pool is maintained via endogenous synthesis and dietary intake. Although synthesized endogenously, vegetarians or those partaking in a creatine-free diet typically have low intramuscular levels compared with meat consumers. Like all bodily functions, creatine metabolism is elegantly regulated by feedback and feedforward mechanisms.

When ingested in the diet, creatine is obtained primarily from muscle tissues (meat or fish), with only trace amounts found in plants. For example, there are about 2.3 g of creatine per pound of meat (beef, pork) or fish (tuna, salmon, cod). Herring contains about 3 to 4.5 g of creatine per pound The average intake of creatine in a mixed diet is approximately 1.5 to 2.0 g/day in meat consumers. The daily needs of vegetarians are met almost exclusively through endogenous path ways Although it could be speculated that creatine could be sufficiently ingested in a diet heavy in meat products, it has recently been noted that the creatine content in meat decreases with cooking. When dietary availability of creatine is low, endogenous synthesis of creatine is increased to maintain normal levels. On the other hand, when dietary availability of creatine is increased, endogenous creatine synthesis is temporarily suppressed. Whether produced in the body or ingested, creatine is transported to its primary target tissue (i.e., skeletal muscle) via the circulation, in which uptake takes place through a concentration gradient and/or a specific creatine transporter.

The structural and functional characteristics of creatine transport to muscle have only recently been described. Creatine appears to enter several types of cells by sodium­dependent neurotransmitter transport family related to the taurine transporter and members of the subfamily of the aminobutyratelbetaine transporters Furthermore, creatine uptake appears to be enhanced in the presence of insulin and triiodothyronine but depressed in the presence of the drugs ouabain or digoxin and vitamin E deficiency It has also been shown that creatine uptake does not appear to be influenced by PCr, creatinine, ornithine, glycine, glutamic acid, histidine, alanine, arginine, leucine, methionine, or cysteine concentrations.

The saturable active transport of creatine is highly specific regarding sodium dependence and extracellular creatine concentration. During uptake, two sodium ions are transported into the cell for every creatine molecule, with the Km (Michaelis constant) for sodium being 55 mM. The Km for creatine uptake ranges from 40 to 90 µm in the rat brain. In humans, normal Km in monocytes and macro phages appears to be approximately 30 µM. Human red blood cell creatine uptake appears to be unaffected by an extracellular pH range of 6.9 to 7.9.

In myoblasts (precursors of skeletal muscle cells), the sodium-dependent uptake of creatine in vitro is sensitive to extracellular creatine concentrations In this study, cultured myoblasts, maintained for 24 hours in a medium containing creatine, exhibited one-third of the uptake activity of cells bathed for the same duration in a medium lacking creatine. Under normal physiological conditions, the maximum intracellular total creatine pool proposed is about 150 mmol/kg. Creatine supplementation data by Harris et al. showed that the maximal total creatine pool (creatine and PCr) in creatine-supplemented participants ranged between 140 and 160 mmol/kg. Once maximized via supplementation, the total creatine pool appears to remain elevated for approximately 21 days without further supplementation. Intramuscular creatine concentration can be maintained beyond 21 days with small amounts (3 g/day or 0.03 g/kg) of creatine (orally ingested) .In support of these observations, one study to date has demonstrated that following as-day . loading period (typifying the supplemental saturation protocol), performance measures remain elevated for 21 days even without continued supplementation.

Typically, the loading phase is divided into four equal servings per day that consist of approximately 5 g daily for 1 week (0.30 g/kg). Furthermore, Green et al have shown that creatine plus or more grams of simple carbohydrate increase creatine uptake over optical amplifier taking creatine alone. Recent data from Stout et al. show that this effect might also occur with lower quantities of carbohydrate (35 g); however, the addition of caffeine might hinder the effects of creatine. Nonetheless, if an athlete can increase the amount of intramuscular creatine, and more importantly PCr, he or she should experience an improvement in anaerobic power and capacity. The availability of PCr is generally accepted to be one of the primary limitations to muscle performance during high­intensity, short-duration exercise.

A peptide that acts similar to Cyclo (His-Pro) is enterostatin. Enterostatin is a pentapeptide that has been shown to be selective in inhibiting fat intake. It is formed following the cleavage of the enzyme procolipase by trypsin in the gastric juice of the intestinal lumen. Procolipase is an enzyme essential for fat digestion. Following the cleavage of procolipase, enterostatin and colipase are produced. Colipase is an obligatory cofactor for pancreatic lipase digestion of fat. Enterostatin appears to act as a fat satiety factor that is believed to inhibit fat intake via receptors in the gut and brain. However, there may be a limitation to enterostatin administration. Most of the research so far has investigated exogenously administered enterostatin in animals; only one study has administered it to humans. Therefore, it is difficult to know whether enterostatin will be functionally effective in humans.
Animal Studies

Several studies have shown that peripherally or centrally administered enterostatin inhibits the intake of dietary fat. Two mechanisms appear to be of action, depending on the location of administration. Peripherally, enterostatin reduces gastric emptying. The slow rate of gastric emptying could result in greater gastric distension increasing satiety Furthermore, enterostatin may also interact with gut receptors, regulating motility and satiety Centrally, enterostatin appears to interact with an opioid pathway for modulating selection and consumption of diets high in fat. Enterostatin does not delay the onset of feeding but appears to shorten the time spent eating.

An interesting aspect of enterostatin function in rats is that it appears to reduce fat intake only in animals that have been adapted to diets which are high in fat before testing. In animals that have been adapted to a standard diet or a high-carbohydrate diet, there appears to be no effect of enterostatin in reducing fat intake.
Human Studies

Enterostatin response to feeding in humans is similar to that in rats. Serum enterostatin increased in response to a large meal. However, some sensitivity and detection problems have been associated with the immunoreactive assay for measuring enterostatin.

Intravenous administration of enterostatin in obese men resulted in no significant effect on feeding behavior. However, other researchers have reported that the intravenous administration is not the most efficient method of administration. Animal studies have reported that intravenous administration results in a prolonged response delay. No other studies have been published which have orally administered enterostatin to humans.
Safety and Toxicity

Animal studies have not reported any adverse reactions associated with enterostatin administration, either peripherally or centrally The only human study to administer enterostatin reported no adverse reactions. The only potential problem that could be found with enterostatin relates to the dosage. The dose-response to enterostatin is U-shaped, exhibiting an inhibition of fat intake at lower doses, but stimulation of food intake at higher doses. Because of this dose response curve there could be a range of functional dosages which could depend on a number of physiological factors.

Ephedrine is a stimulant acting as ß2-agonist, which means it mimics norepinephrine. An increase in sympathetic activity is associated with increased lipolysis, heart rate, heart contractility, and glycolysis. Again, the increase in lipolysis will result in a higher level of circulating FFA, which will likely increase ß-oxidation. Ephedrine also possesses thermogenic properties. Thermogenesis is an increase in heat production and resting metabolic rate, which increases caloric expenditure. Because ephedrine mimics norepinephrine it may be able to suppress hunger.

In most dietary fat-loss supplements, ephedrine appears as an extract from one of two herbs ephedra or Ma Huang. The amount of ephedrine in these herbs is usually standardized to about 6% ephedrine. Furthermore, ephedrine does not appear in fat-loss supplements by itself; it is usually found at least with caffeine. Ephedrine by itself can easily be altered by underground drug labs to make methamphetamine (speed, crank, meth, crystal), thus its sale alone is prohibited. Research indicates that ephedrine is more effective as a fat-loss product when combined with caffeine, and most of the research has used ephedrine in combination with caffeine at a standard dose of 20 mg of ephedrine and 200 mg of caffeine, two to three times per day. Therefore, we will focus on ephedrine and the combination of ephedrine and caffeine as a fat-loss product.
Animal Studies

The administration of ephedrine to rats has been shown to increase thermogenesis by 32% as measured by oxygen consumption. However, the addition of caffeine resulted in a 50% increase in oxygen consumption. Dulloo and Miller reported that the addition of ephedrine to the diets of mice increased energy expenditure by 10% which led to a 42% reduction in body fat stores over a 6-week period. The effects of ephedrine were amplified with the addition of caffeine, which resulted in a further 10% increase in energy expenditure and a 75% reduction in body fat .

Energy-restricted diets are usually associated with a reduction in metabolic rate. The supplementation of ephedrine and caffeine during food-restricted diets may prevent the decrease in metabolic rate. In genetically obese Zucker rats, an ephedrine/caffeine combination resulted in a fourfold reduction in body fat during a food­restricted diet. The rats whose diet was food restricted experienced only a twofold decrease in body fat and a 50% reduction in total body protein. Furthermore, energy expenditure in the food-restricted group was about 30% lower than in the food-restricted group, which received the ephedrine/caffeine combination.
Human Studies

Research in humans indicates that the effect of the ephedrine/caffeine combination has been just as effective as in rats. Most research on the ephedrine/caffeine combination has been conducted by Dr. Astrup at the University of Copenhagen in the Research Department of Human Nutrition. His and other research reports that the ephedrine/caffeine combination is effective in increasing fat loss, especially when combined with a diet and exercise program .

During a 24-week study investigating the effects of an ephedrine/caffeine combination, obese patients were required to consume about 1000 calories a day. They were divided into four groups-

* Caffeine
* Ephedrine
* Caffeine + ephedrine
* Placebo

Following 24 weeks of treatment, the caffeine + ephedrine group lost almost 17 kg of weight, while the other three groups lost from 11 to 14 kg.

In one 8-week study, the group consuming the ephedrine/caffeine combination lost 4.5 kg more fat and 2.8 kg less muscle mass than the placebo group, when both groups were on a calorically restricted diet. Furthermore, the drop in energy expenditure was significantly less in the ephedrine/caffeine group compared with the placebo group. In another 8-week study, the ephedrine/ caffeine group lost almost 3 kg more weight than the placebo group.

Because dietary supplements are sold over the counter, some people believe that they are not as effective as prescription medications. One research group compared the effectiveness of an ephedrine/caffeine combination with the prescription drug dexfenfluramine. Dexfenfluramine is a serotonin agonist and has been shown to be successful at promoting weight loss in obese patients and was prescribed frequently in the last few years until heart complications surfaced in patients. During a 15-week study, patients consuming the ephedrine/caffeine combination lost about 8 kg, while the dexfenfluramine group lost about 7 kg. In a subgroup of patients with a BMI over 30 kg/m the ephedrine/caffeine combination resulted in a significantly greater amount of weight loss compared to the dexfenfluramine group .

Based on the research, the combination of ephedrine and caffeine appears to be one of the most effective dietary supplements for weight loss. However, the supplement does pose health risks if used improperly.
Safety and Toxicity

Side effects during ephedrine/caffeine consumption appear to be minimal. In one study, the caffeine + ephedrine group did experience more negative side effects (tremor, dizziness, insomnia). But, these effects appeared to be transient, and after 8 weeks of treatment the frequency of side effects had reached the level of the placebo group. Other side effects may include arrhythmias and headaches.

The FDA reports that well over 800 adverse incidents have occurred as well as a significant number of deaths associated with ephedrine-based products. Some states have banned the sale of ephedrine-based products. However, all of those who died in association with the products consumed well above the recommended dose for stimulant purposes. Based on the research evidence, if the product is consumed according to label directions, and the individual does not have a medical condition, which would warrant against consuming the product, it appears that the combination of both ingredients are safe and effective for fat-loss procedures.

The most common method of dieting is to reduce caloric intake. However, as this will ultimately result in a reduction in metabolic rate. The most likely explanation for the reduction in metabolic rate is a reduction in thyroxine (T4) and triiodothyronine (T3), the thyroid hormones These hormones are responsible for maintaining metabolic rate.

Gugglesterone is reported to be the active ingredient of Guggulu, a resin product isolated from Commiphora mukul, a plant native to India. Many studies have reported that guggulsterone has hypocholesterolemic activity However, gugglesterone may also increase thyroid hormone levels.
Animal Studies

A study investigating the potential thyroid-stimulating effects of gugglesterone administered gugglesterone (10 mg/kg body weight/day) or a placebo to carbimazole-treated rats. Carbimazole is a hypothyroid agent. Administration of gugglesterone for 6 days restored thyroid function and resulted in a significant elevation in both T3 and T4.
Human Studies

Studies investigating the effects of gugglesterone in humans have focused on its hypolipidemic properties. No specific studies have investigated its thyroid-stimulating potential in humans. However, that does not mean that the supplement is worthless. Hypercholesterolemia and hypertriglyceridemia are common in overweight individuals. Therefore, gugglesterone may provide some benefit to overweight individuals who have high levels of serum cholesterol and triglyceride levels.

The administration of gugglesterone for 4-24 weeks at a dose of 75 mg-1 g per day has been effective in lowering serum cholesterol and triglyceride levels by 18_30% Furthermore, LDL and HDL have also been affected by gugglesterone supplementation, with a typical drop of approximately 12-19% in LDL and an increase of about 20% in HDL.

The exact mechanism of action is not known, but animal studies suggest that gugglesterone increases LDL binding sites within the liver membrane, resulting in a significant uptake of LDL by the liver. Therefore, serum cholesterol appears to be reduced by increasing the rate of lipoprotein catabolism.
Safety and Toxicity

Of the studies investigating the effect of gugglesterone as a hypolipidemic agent, just one study has included additional tests to determine its safety The authors reported that gugglesterone administration was completely safe and devoid of any effect on liver, kidney, or cardiovascular function. However, caution should be given to individuals who are taking prescription medications for hyperlipidemia who intend on taking gugglesterone. Research suggests that gugglesterone may lead to a diminished effectiveness and even nonresponsiveness of certain prescription drugs, such as propranolol or diltiazem. Gugglesterone administration may alter the absorption of these drugs by nearly 35%. As with any drug or even any dietary supplement, if you are taking prescription medications, you should be monitored by your physician.

The conversion of carbohydrate to fat requires that pyruvate be oxidized to acetyl-CoA. This oxidative process occurs within the mitochondria. However, fatty acid synthesis occurs predominately in the cytosol. Therefore, the acetyl group, which is the intermediate substrate for fatty acid synthesis, must be transported from inside the mitochondria to the cytosol before it can be incorporated into fatty acids. The acetyl group is transported out of the mitochondria as citrate. Once outside, an enzyme, ATP­citrate lyase, catalyzes the reaction, which cleaves citrate into acetyl-CoA and oxaloacetate. The acetyl group then enters the biosynthetic pathway of fatty acid synthesis.

Hydroxycitric acid (HCA) is an inhibitor of the enzyme ATP-citrate lyase. Therefore, it prevents the conversion of carbohydrates into fatty acids by preventing the breakdown of citrate in the cytosol. Many products are currently on the market that contain HCA among other ingredients. HCA is obtained from the extracts of the herbs Garcinia cambogia and Garcinia indica, both native to India.

Animal studies have shown HCA to be effective in reducing fatty acid synthesis. However, there is a lack of well-controlled human studies.
Animal Studies

Several well-controlled animal studies have investigated HCAs effect on fatty acid synthesis. In general, they have all shown that HCA-administered orally, intravenously, or by intraperitoneal injection-inhibits fatty acid biosynthesis in the liver and adipose tissue.

The degree of inhibition depends on the dosage and can range from 20% to 80%. The decrease in fatty acid biosynthesis resulted in significant reductions in epididymal fat stores and total body fat.

Another interesting aspect of HCA was the reduction in food intake during HCA administration. Curiously, the reduction in food intake could not completely account for the decrease in body weight. Also, cholesterol and triglyceride levels were lower following HCA administration.
Human Studies

As mentioned above, well-controlled human studies investigating the fat-loss potential of HCA are lacking. Most of the studies that have investigated HCAs effect on body composition have been performed using products containing other ingredients, which could also be active ingredients. Of the seven studies reviewed by Heymsfield et al. only two have been published in peer-reviewed journals. Heymsfield and coworkers are the only ones to use HCA by itself. The other studies have appeared only in abstract form and have investigated HCA in combination with other components that may also be considered to promote fat loss.

All but one of the studies have reported that HCA, combined with other fat-loss supplements, produced significantly greater losses in fat than a placebo. The single study to investigate HCA by itself as the active ingredient reported that HCA failed to produce weight loss and fat mass loss beyond that observed with a placebo in overweight men and women.

Based on the limited research, HCA could promote fat loss, but only when used in combination with other components of fat loss supplements. Further research needs to investigate HCA supplementation alone and when used in combination with other ingredients. The discrepancies between the animal and human studies are interesting. But, as we are learning from leptin research, the regulation of fat metabolism in rats appears to be much different than that in humans.
Safety and Toxicity

Neither animal nor human studies have reported any treatment-related adverse events. A few animal studies have included tests specifically to look at liver function. The human studies have simply used an adverse incident reporting form and have reported that adverse events were not significantly different between the treatment group and placebo group.

Triglycerides are composed of a glycerol backbone with three free fatty acids attached. In the case of medium-chain triglycerides (MCTs) these fatty acids are made up of a mixture of C6 to C12 medium-chain fatty acids. Unlike long-chain triglycerides, the MCTs are liquid at room temperature and are relatively soluble in water. For example, the water solubility of a C8 saturated fatty acid is 68 mg/100 mL at 20°C versus 0.72 mg/100 mL for a C16 saturated fatty acid. Also, as discussed above, long-chain fatty acids require the carnitine transport system to enter the mitochondria. Medium-chain fatty acids (MCFAs) cross the mitochondrial membrane rapidly through a diffusion process 190 and therefore can be oxidized into CO2 at a faster rate than long-chain fatty acids. The liver is capable of producing ten times more CO2 from a C8:0 fatty acid than from a C16:0 fatty acid. However, when MCTs are consumed, there is an increase in ketone body production. Because of the increased rate of oxidation of MCFA, there is an excess of acetyl-CoA, and Krebs cycle intermediates will be in short supply, resulting in a large part of the MCFA being directed toward ketone body production.

The reason MCTs have been used in the treatment of obesity is of interest because the research does not necessarily support its use as a weight-loss product, especially in humans. Furthermore, a mechanism as to why fat intake would result in fat loss has not been provided.
Animal Studies

Several studies have investigated the potential use of MCTs in weight reduction. However, the results are equivocal and many of them have not reported a significant effect from MCT supplementation. One possible mechanism by which MCT may function is throughenhanced thermogenesis induced by MCT. However, this study has only appeared in abstract form and has not been verified.
Human Studies

Of the few human studies to be conducted that have investigated the use of MCTs as a fat-loss supplement, none have reported a significant effect. These studies have primarily used obese subjects on a restricted caloric intake (500 to 1200 calories per day). One study, however, reported that MCTs decreased food intake during the day when the MCT was consumed with break­fast. In general, the results of these studies have failed to provide any evidence in favor of MCTs providing any benefit during dieting. For example, one study reported that obese women consuming a 550-kcal diet containing 30 g of MCTs lost the same amount of weight as when MCTs were replaced by sugars.
Safety and Toxicity

For some populations, there is some concern regarding MCT supplementation. MCTs are ketogenic in the normal individual and even more so in a diabetic. A ketogenic state (ketosis) can result in acidosis. In this condition, homeostasis is compromised, leading to dehydration, hypovolemia, and hypotension caused by an increase in Na+ and K+ excretion in the urine. Furthermore, the acidosis and dehydration can lead to a state of unconsciousness, and in severe cases, coma. For the normal, healthy individual, there appears to be no risk in consuming MCTs.

Creatine supplementation has also been shown to have a positive effect on exercise tolerance in chronic heart failure patients. Reduced creatine availability has been implicated in the metabolic abnormalities of failing myocardial tissue, and creatine supplementation has been shown to attenuate pharmacologically induced metabolic stress in rat myocardium, although the contribution of PCr to energy delivery in myocardial tissue is normally negligible. However, no research to date indicates whether creatine exerts its effects in cardiac patients via improving heart or skeletal muscle energetics. Alternatively, PCr has been proposed to stabilize membranes under conditions of cellular damage and the creatine-like compound, cyclocreatine, has been suggested to maintain ATP production in heart and skeletal muscle long after PCr stores have been depleted which may be more fruitful areas of future research. Two early studies have begun this examination with what appear to be favorable preliminary results.

To assess the effects of dietary creatine supplementation on skeletal muscle metabolism and endurance in patients suffering from chronic heart failure, Andrews et al. used a forearm model of muscle metabolism. Maximal voluntary contractions were measured using handgrip dynamometry as subjects performed handgrip exercise of 5-seconds’ contraction followed by 5 seconds of rest for 5 minutes at 25%, 50%, and 75% of maximum voluntary contraction or until exhaustion. Blood was sampled at rest and 0 and 2 minutes after exercise for measurement of lactate and ammonia.

After 30 minutes, the procedure was repeated with fixed workloads of 7 kg, 14 kg, and 21 kg. Patients were assigned to creatine at 20 g daily or matching placebo for 5 days and returned after 6 days for repeat study. During post-testing, contractions until exhaustion at 75% of maximum voluntary contraction increased after creatine treatment with no significant placebo effect. Ammonia and lactate per contraction at 75% maximum voluntary contraction fell significantly after creatine but not after placebo.

In a complementary study, Gordon et al. noted that cardiac creatine levels are depressed in chronic heart failure and thus evaluated the effects of creatine supplementation on ejection fraction, symptom-limited physical endurance, and skeletal muscle strength in patients with chronic heart failure. In a double-blind, placebo-controlled design, 17 patients were supplemented with creatine, 20 g/daily for 10 days. Before and on the last day of supplementation ejection fraction was determined by radionuclide angiography, as was symptom-limited 1-legged knee extensor and 2-legged exercise performance on the cycle ergometer. Muscle strength as unilateral concentric knee extensor performance was also evaluated. Skeletal muscle biopsies were performed to determine the amount of energy-rich phosphagens. Although no change in ejection fraction was seen in either group compared with baseline, creatine supplementation increased skeletal muscle total creatine and PCr by 17% and 12%, respectively. More specifically, however, increments were seen only in patients with less than 140 mmol total creatine/kg. Additionally, 1-legged performance (21 %), 2-legged performance 00%), and peak torque (5%) also increased. Both peak torque and 1-legged performance increased linearly with increased skeletal muscle PCr. The increments in 1-legged, 2-legged, and peak torque were significant compared with the placebo group. One week of creatine supplementation to patients who suffered from chronic heart failure did not increase ejection fraction but increased skeletal muscle energy-rich phosphagens and performance regarding both strength and endurance. Therefore, it appears that creatine supplementation in chronic heart failure may favorably augment skeletal muscle endurance; it attenuates the abnormal skeletal muscle metabolic response to exercise and thus provides a new and novel therapeutic approach to treatment that merits further attention.