Energy Beverages: Content and Safety
2010; Elsevier BV; Volume: 85; Issue: 11 Linguagem: Inglês
10.4065/mcp.2010.0381
ISSN1942-5546
AutoresJohn P. Higgins, Troy D. Tuttle, Christopher L. Higgins,
Tópico(s)Diet and metabolism studies
ResumoExercise is making a resurgence in many countries, given its benefits for fitness as well as prevention of obesity. This trend has spawned many supplements that purport to aid performance, muscle growth, and recovery. Initially, sports drinks were developed to provide electrolyte and carbohydrate replacement. Subsequently, energy beverages (EBs) containing stimulants and additives have appeared in most gyms and grocery stores and are being used increasingly by "weekend warriors" and those seeking an edge in an endurance event. Long-term exposure to the various components of EBs may result in significant alterations in the cardiovascular system, and the safety of EBs has not been fully established. For this review, we searched the MEDLINE and EMBASE databases from 1976 through May 2010, using the following keywords: energy beverage, energy drink, power drink, exercise, caffeine, red bull, bitter orange, glucose, ginseng, guarana, and taurine. Evidence regarding the effects of EBs is summarized, and practical recommendations are made to help in answering the patient who asks, "Is it safe for me to drink an energy beverage when I exercise?" Exercise is making a resurgence in many countries, given its benefits for fitness as well as prevention of obesity. This trend has spawned many supplements that purport to aid performance, muscle growth, and recovery. Initially, sports drinks were developed to provide electrolyte and carbohydrate replacement. Subsequently, energy beverages (EBs) containing stimulants and additives have appeared in most gyms and grocery stores and are being used increasingly by "weekend warriors" and those seeking an edge in an endurance event. Long-term exposure to the various components of EBs may result in significant alterations in the cardiovascular system, and the safety of EBs has not been fully established. For this review, we searched the MEDLINE and EMBASE databases from 1976 through May 2010, using the following keywords: energy beverage, energy drink, power drink, exercise, caffeine, red bull, bitter orange, glucose, ginseng, guarana, and taurine. Evidence regarding the effects of EBs is summarized, and practical recommendations are made to help in answering the patient who asks, "Is it safe for me to drink an energy beverage when I exercise?" Red Bull was introduced in Austria in 1987 and in the United States in 1997. Since then, the energy beverage (EB) market has grown exponentially.1Reissig CJ Strain EC Griffiths RR Caffeinated energy drinks—a growing problem.Drug Alcohol Depend. 2009; 99: 1-10Abstract Full Text Full Text PDF PubMed Scopus (682) Google Scholar Hundreds of different brands are now marketed, with caffeine content ranging from a modest 50 mg to an alarming 505 mg per can or bottle.2Weise E Petition calls for FDA to regulate energy drinks.USA Today. October 22, 2008; (Accessed September 3, 2010.)http://www.usatoday.com/news/health/2008-10-21-energy-drinks_N.htmGoogle Scholar In the United States, Red Bull enjoyed a 65% share of the $650-million energy/power drink market in 2005, and its sales are growing at about 35% per year.3Bryce DJ Dyer JH Strategies to crack well-guarded markets.Harv Bus Rev. 2007; 85: 84-92PubMed Google Scholar The United States is the world's largest consumer of EBs by volume, roughly 290 million gallons in 2007, or 3.8 qt per person per year.2Weise E Petition calls for FDA to regulate energy drinks.USA Today. October 22, 2008; (Accessed September 3, 2010.)http://www.usatoday.com/news/health/2008-10-21-energy-drinks_N.htmGoogle Scholar Consumption of EBs is most common among those aged 11 to 35 years, and 24% to 57% of this age group reported that they drank an EB within the past few months.4Ballard SL Wellborn-Kim JJ Clauson KA Effects of commercial energy drink consumption on athletic performance and body composition.Phys Sportsmed. 2010; 38: 107-117Crossref PubMed Scopus (51) Google Scholar Regulation of EBs, including content labeling and health warnings, differs across countries, with some of the laxest requirements existing in the United States.2Weise E Petition calls for FDA to regulate energy drinks.USA Today. October 22, 2008; (Accessed September 3, 2010.)http://www.usatoday.com/news/health/2008-10-21-energy-drinks_N.htmGoogle Scholar For instance, no EBs are banned in the United States, and EB companies can say whatever they want regarding energy and performance effects. This is in stark contrast to countries in which some EBs have been banned, and companies are not allowed to outline the performance effects that their products may or may not provide.4Ballard SL Wellborn-Kim JJ Clauson KA Effects of commercial energy drink consumption on athletic performance and body composition.Phys Sportsmed. 2010; 38: 107-117Crossref PubMed Scopus (51) Google Scholar This absence of oversight has resulted in aggressive marketing of EBs, targeted primarily toward young men and openly promoting psychoactive, performance-enhancing, and stimulatory effects.1Reissig CJ Strain EC Griffiths RR Caffeinated energy drinks—a growing problem.Drug Alcohol Depend. 2009; 99: 1-10Abstract Full Text Full Text PDF PubMed Scopus (682) Google Scholar, 4Ballard SL Wellborn-Kim JJ Clauson KA Effects of commercial energy drink consumption on athletic performance and body composition.Phys Sportsmed. 2010; 38: 107-117Crossref PubMed Scopus (51) Google Scholar Alarmingly, EB consumption has been shown to be positively associated with high-risk behavior, including marijuana use, sexual risk taking, fighting, failure to use seat belts, and taking risks on a dare, as well as with smoking, drinking, problems stemming from alcohol abuse, and illicit drug use.5Thombs DL O'Mara RJ Tsukamoto M et al.Event-level analyses of energy drink consumption and alcohol intoxication in bar patrons.Addict Behav. 2009; 35: 325-330Crossref PubMed Scopus (169) Google Scholar, 6Miller KE Energy drinks, race, and problem behaviors among college students.J Adolesc Health. 2008; 43: 490-497Abstract Full Text Full Text PDF PubMed Scopus (226) Google Scholar In an era in which Gatorade and Powerade, termed sport drinks (SDs) for the purposes of this article, have paved the way as optimal hydration fluids that boast superiority to water, uncertainty is growing with regard to where EBs fit and how they are consumed.7Howarth KR Moreau NA Phillips SM Gibala MJ Coingestion of protein with carbohydrate during recovery from endurance exercise stimulates skeletal muscle protein synthesis in humans.J Appl Physiol. 2009; 106: 1394-1402Crossref PubMed Scopus (152) Google Scholar Convenience stores now display EBs next to the SDs, which can mislead the consumer into thinking that they are similar products. Whereas SDs can indeed provide hydration and replenishment of electrolytes and carbohydrates, the elevated levels of caffeine in EBs have diuretic effects, more pronounced in the first-time user, that increase urinary output and natriuresis.8Riesenhuber A Boehm M Posch M Aufricht C Diuretic potential of energy drinks.Amino Acids. 2006; 31: 81-83Crossref PubMed Scopus (60) Google Scholar Additionally, EBs may have thermogenic effects.9Rashti SL Ratamess NA Kang J Faigenbaum AD Chilakos A Hoffman JR Thermogenic effect of meltdown RTD energy drink in young healthy women: a double blind, cross-over design study.Lipids Health Dis. 2009; 8: 57Crossref PubMed Scopus (20) Google Scholar Moreover, EBs supply an amount of carbohydrate far beyond that recommended for physically active people, which can slow the rate at which fluid is absorbed into the bloodstream or lead to gastrointestinal distress.10Davis JM Burgess WA Slentz CA Bartoli WP Pate RR Effects of ingesting 6% and 12% glucose/electrolyte beverages during prolonged intermittent cycling in the heat.Eur J Appl Physiol Occup Physiol. 1988; 57: 563-569Crossref PubMed Scopus (62) Google Scholar Finally, the effects due to the interaction of substances on which little research has been done (eg, glucuronolactone) are not well understood. This review of EBs describes the various ingredients, discusses their safety, and provides recommendations regarding their use. Although most research studies and observational data have come from athletics, our research query included studies and information involving nonathlete consumers. Also, the review differentiates between these populations and offers recommendations specific to each group. A search of the English-language scientific literature was performed primarily by searching the MEDLINE and EMBASE databases and using the Google Internet search engine for the period January 1976 through May 2010. For this search, we used keywords found in lead peer-reviewed articles and research outlining the current body of knowledge on EBs. Keywords used in the search are energy beverage, energy drink, power drink, exercise, caffeine, red bull, bitter orange, glucose, ginseng, guarana, and taurine. The bibliographies of articles were searched for relevant articles; links on Web sites containing published articles were searched for pertinent information. This review endeavored to bring the most pertinent research to light in order to present real-world recommendations to both the athletic community and the general population. The most common ingredient in EBs is caffeine, which is often combined with taurine, glucuronolactone, guarana, and B vitamins to form what manufacturers have called an "energy blend."1Reissig CJ Strain EC Griffiths RR Caffeinated energy drinks—a growing problem.Drug Alcohol Depend. 2009; 99: 1-10Abstract Full Text Full Text PDF PubMed Scopus (682) Google Scholar When higher doses of caffeine are combined with these other substances currently blended in EBs, the subsequent effect cannot always be predicted; adverse effects have been reported, including cardiac arrest.11Berger AJ Alford K Cardiac arrest in a young man following excess consumption of caffeinated "energy drinks.".Med J Aust. 2009; 190: 41-43Crossref PubMed Scopus (146) Google Scholar, 12Nagajothi N Khraisat A Velazquez-Cecena JL et al.Energy drink-related supraventricular tachycardia.Am J Med. 2008; 121: e3-e4Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar The components of the 4 best-selling EBs are given in Table 1, and the specific ingredients are subsequently discussed in more detail.TABLE 1Comparison of Ingredients in Energy BeveragesaAs listed on 16-oz can unless otherwise noted. RDA = recommended daily allowance.Red BullRockstarMonsterFull ThrottleCalories220280200220Carbohydrates 54 gSucrose, glucose 62 gSucrose, glucose 54 gSucrose, glucose, sucralose, maltodextrin 57 gHigh-fructose corn syrup, sucroseSodiumOnly listed as sodium citrate80 mg sodium citrate 360 mg16% RDASodium citrate, sodium chloride160 mg Sodium citrateCaffeine160 mg 160 mgPart of a 1.35-g "energy blend"Only listed as part of a 5000-mg "energy blend" 141 mgPart of a 3000-mg "energy blend"Taurine2000 mg 2000 mgPart of a 1.35-g "energy blend" 2000 mgPart of a 5000-mg "energy blend"Only listed as part of a 3000-mg "energy blend"GlucuronolactoneOnly listed (1200 mg)bThis amount is not listed on the can; the corporate office was called and this was all the information given.None listedOnly listed as part of a 5000-mg "energy blend"None listedNiacin (B3)200% RDA Niacinamide (40 mg)bThis amount is not listed on the can; the corporate office was called and this was all the information given.40 mg 200% RDA Niacinamide40 mg 200% RDA Niacinamide100% RDA NiacinamideInositol (B8)Only listed 50 mgPart of a 1.35-g "energy blend"Only listed as part of a 5000-mg "energy blend"None listed Pyridoxine hydrochloride (B6)500% RDA (10 mg)bThis amount is not listed on the can; the corporate office was called and this was all the information given.4 mg 200% RDA4 mg 200% RDA200% RDACyanocobalamin (B) 160% RDAListed as vitamin B12 (10μg)bThis amount is not listed on the can; the corporate office was called and this was all the information given.12 Hg 200% RDA12 Hg 200% RDA200% RDARiboflavin (B2)None listed6.8 mg 400% RDA3.4 mg 200% RDANone listedPantothenic acid (Bs) 100% RDACalcium pantothenate (10 mg)bThis amount is not listed on the can; the corporate office was called and this was all the information given.20 mg 200% RDA Calcium pantothenateNone listedNone listedGinseng extractNone listed 50 mgPart of a 1.35-g "energy blend"400 mgOnly listed as part of a 3000-mg "energy blend"Guarana extractNone listed 50 mgPart of a 1.35-g "energy blend"Only listed as part of a 5000-mg "energy blend"Only listed as part of a 3000-mg "energy blend"Ginkgo biloba leaf extractNone listed 300 mgPart of a 1.35-g "energy blend"None listedNone listedMilk thistle extractNone listed 40 mgPart of a 1.35-g "energy blend"None listedNone listedl-carnitineNone listed 50 mgPart of a 1.35-g "energy blend"Only listed as part of a 5000-mg "energy blend" Only listed as part of a 3000-mg "energy blend"Carnitine fumarateSorbic acidNone listedYesYesNoSodium benzoateNone listedYes Benzoic acidYes Benzoic acidYesCitric acidNone listedYesYesYesNatural flavorsYesYesYesYesArtificial flavorsYesYesNone listedNone listedColoring"Colors""Caramel""Color added"Blue 1, Red 40a As listed on 16-oz can unless otherwise noted. RDA = recommended daily allowance.b This amount is not listed on the can; the corporate office was called and this was all the information given. Open table in a new tab Well-performed research indicates that some of these substances are important for proper body function, but this does not mean that a person has a deficiency. Moreover, important questions regarding overall intake and subsequent adverse effects should come to mind as the reader progresses through this review. We have also included information on the bioavailability of each substance if the necessary research has been completed. Caffeine, an adenosine receptor antagonist, is a stimulant that can influence the activity of neuronal control pathways in the central and peripheral nervous systems.13Jones G Caffeine and other sympathomimetic stimulants: modes of action and effects on sports performance.Essays Biochem. 2008; 44: 109-123Crossref PubMed Scopus (51) Google Scholar It is the most common stimulant in EBs, with most EBs containing between 70 and 200 mg of caffeine per 16-oz serving. In comparison, an 8-oz cup of coffee contains 110 to 150 mg for drip, 65 to 125 mg for percolated, and 40 to 80 mg for instant; caffeinated beverages contain about 50 to 100 mg of caffeine.14Clauson KA Shields KM McQueen CE Persad N Safety issues associated with commercially available energy drinks.J Am Pharm Assoc. 2008; 48 (2003): e55-e63Crossref Scopus (189) Google Scholar Caffeine is known as an ergogenic compound that raises the heart rate and blood pressure. Adverse effects typically manifest with ingestion higher than 200 mg of caffeine and include insomnia, nervousness, headache, tachycardia, arrhythmia, and nausea.14Clauson KA Shields KM McQueen CE Persad N Safety issues associated with commercially available energy drinks.J Am Pharm Assoc. 2008; 48 (2003): e55-e63Crossref Scopus (189) Google Scholar, 15Calamaro CJ Mason TB Ratcliffe SJ Adolescents living the 24/7 lifestyle: effects of caffeine and technology on sleep duration and daytime functioning.Pediatrics. 2009; 123: e1005-e1010Crossref PubMed Scopus (329) Google Scholar The ergogenic effects of caffeine on athletic performance have been shown, and its broad range of metabolic, hormonal, and physiologic effects has been described.16Ganio MS Klau JF Casa DJ Armstrong LE Maresh CM Effect of caffeine on sport-specific endurance performance: a systematic review.J Strength Cond Res. 2009; 23: 315-324Crossref PubMed Scopus (194) Google Scholar, 17Sokmen B Armstrong LE Kraemer WJ et al.Caffeine use in sports: considerations for the athlete.J Strength Cond Res. 2008; 22: 978-986Crossref PubMed Scopus (138) Google Scholar Caffeine has been shown to be an effective ergogenic aid for endurance athletes when ingested before and/or during exercise in moderate quantities (3-6 mg/kg of body mass); abstaining from caffeine for at least 7 days before use will optimize the effect.16Ganio MS Klau JF Casa DJ Armstrong LE Maresh CM Effect of caffeine on sport-specific endurance performance: a systematic review.J Strength Cond Res. 2009; 23: 315-324Crossref PubMed Scopus (194) Google Scholar Of note, caffeine appears on the list of substances banned by the International Olympic Committee.18Clarkson PM Nutrition for improved sports performance: current issues on ergogenic aids.Sports Med. 1996; 21: 393-401Crossref PubMed Scopus (39) Google Scholar Of all the compounds analyzed in this review, caffeine is by far the most-researched in the literature.16Ganio MS Klau JF Casa DJ Armstrong LE Maresh CM Effect of caffeine on sport-specific endurance performance: a systematic review.J Strength Cond Res. 2009; 23: 315-324Crossref PubMed Scopus (194) Google Scholar The absolute bioavailability of orally administered caffeine was investigated in 10 healthy adult male volunteers aged 19 to 30 years.19Blanchard J Sawers SJ The absolute bioavailability of caffeine in man.Eur J Clin Pharmacol. 1983; 24: 93-98Crossref PubMed Scopus (272) Google Scholar Participants received a 5-mg/kg dose of caffeine as either an aqueous oral solution or an intravenous infusion on separate occasions about 1 week apart in a randomized crossover fashion. Plasma samples were collected during the 24-hour period after each dose and assayed for their caffeine content using a high-performance liquid chromatographic technique. The oral absorption was very rapid, with caffeine reaching a peak plasma concentration after 29.8 minutes, and the variation in the maximum plasma concentration was low at 10.0 μg/mL. The absolute bioavailability was assessed by comparing the areas under the plasma concentration vs time curves for the intravenous and oral doses of caffeine. The rapid absorption resulted in essentially complete bioavailability of the oral caffeine, with a plasma half-life varying from 2.7 to 9.9 hours, indicating substantial variability in its elimination between participants.19Blanchard J Sawers SJ The absolute bioavailability of caffeine in man.Eur J Clin Pharmacol. 1983; 24: 93-98Crossref PubMed Scopus (272) Google Scholar Caffeine mobilizes fat stores and stimulates working muscles to use fat as a fuel, which delays depletion of muscle glycogen and allows for prolonged exercise.20Laurent D Schneider KE Prusaczyk WK et al.Effects of caffeine on muscle glycogen utilization and the neuroendocrine axis during exercise.J Clin Endocrinol Metab. 2000; 85: 2170-2175Crossref PubMed Scopus (94) Google Scholar The critical period in glycogen sparing appears to occur during the first 15 minutes of exercise, when caffeine has been shown to decrease glycogen utilization by as much as 50%. Thus, glycogen saved at the beginning is available during the later stages of exercise. Although the exact mechanism is still unclear, caffeine caused sparing in all the human studies in which muscle glycogen levels were measured. The effect on performance, which was observed in most experimental studies, was that participants were able to exercise longer before exhaustion occurred.20Laurent D Schneider KE Prusaczyk WK et al.Effects of caffeine on muscle glycogen utilization and the neuroendocrine axis during exercise.J Clin Endocrinol Metab. 2000; 85: 2170-2175Crossref PubMed Scopus (94) Google Scholar Caffeine binds to the adenosine class of G protein–coupled receptors on the surface of heart muscle cells, which begins a second messenger system with cyclic adenosine monophosphate inside the cells and mimics the effects of epinephrine.21Piirainen H, Ashok Y, Nanekar RT, Jaakola VP. Structural features of adenosine receptors: from crystal to function [published online ahead of print June 2, 2010]. Biochim Biophys Acta. doi:10.1016/j.bbamem.2010.05.021.Google Scholar The rate of glycolysis increases, which increases the amount of adenosine triphosphate available for muscle contraction and relaxation.22Mayo Clinic Staff. Nutrition and healthy eating: caffeine: how much is too much? MayoClinic.com Web site. Published March 24, 2009. http://www.mayoclinic.com/health/caffeine/NU00600#. Accessed September 3, 2010.Google Scholar This can result in a positive inotropy and chronotropy, ie, a stronger and faster heartbeat. Caffeine immediately increases blood pressure and peripheral vascular resistance, in part because of sympathetic stimulation. One group of investigators showed a significant effect of drinking caffeinated coffee on arterial tone and function, suggesting that caffeine immediatelyincreases arterial stiffness, with the effect being more pronounced on aortic systolic and diastolic blood pressures than on the brachial artery.23Mahmud A Feely J Acute effect of caffeine on arterial stiffness and aortic pressure waveform.Hypertension. 2001; 38: 227-231Crossref PubMed Scopus (139) Google Scholar The discussion on caffeine and hydration continues to evolve. A number of studies have examined the effects of ingesting a large dose of caffeine and found that urine output was increased.24Neuhäuser-Berthold B Beine S Verwied SC Lührmann PM Coffee consumption and total body water homeostasis as measured by fluid balance and bioelectrical impedance analysis.Ann Nutr Metab. 1997; 41: 29-36Crossref PubMed Scopus (63) Google Scholar Yet, the long-held conclusion that caffeine increases 24-hour urine output has been challenged, because most of the studies that established this conclusion involved persons who refrained from caffeine consumption before the analysis.25Maughan RJ Griffin J Caffeine ingestion and fluid balance: a review.J Hum Nutr Diet. 2003; 16: 411-420Crossref PubMed Scopus (156) Google Scholar, 26Robertson D Wade D Workman R Woosley RL Oates JA Tolerance to the humoral and hemodynamic effects of caffeine in man.J Clin Invest. 1981; 67: 1111-1117Crossref PubMed Scopus (408) Google Scholar The human body develops a tolerance to caffeine quickly, usually 3 to 5 days after regular use, and when this happens, it noticeably weakens the already limited diuretic effect of caffeine.26Robertson D Wade D Workman R Woosley RL Oates JA Tolerance to the humoral and hemodynamic effects of caffeine in man.J Clin Invest. 1981; 67: 1111-1117Crossref PubMed Scopus (408) Google Scholar, 27Fisher SM McMurray RG Berry M Mar MH Forsythe WA Influence of caffeine on exercise performance in habitual caffeine users.Int J Sports Med. 1986; 7: 276-280Crossref PubMed Scopus (58) Google Scholar Moreover, the human kidneys are masters at ensuring that proper homeostatic conditions are maintained. Recent research now leans toward the ability of the body to maintain proper water levels and overcome the mild diuretic effects of caffeine in long-term users.25Maughan RJ Griffin J Caffeine ingestion and fluid balance: a review.J Hum Nutr Diet. 2003; 16: 411-420Crossref PubMed Scopus (156) Google Scholar, 28Armstrong LE Pumerantz AC Roti MW et al.Fluid, electrolyte, and renal indices of hydration during 11 days of controlled caffeine consumption.Int J Sport Nutr Exerc Metab. 2005; 15: 252-265PubMed Google Scholar As the rest of the ingredients are reviewed herein, please note that in comparison with caffeine, each has had far fewer research studies performed. Taurine, a sulfur-containing amino acid, is the most abundant intracellular amino acid in humans and a normal constituent of the human diet.29Gaull GE Taurine in pediatric nutrition: review and update.Pediatrics. 1989; 83: 433-442PubMed Google Scholar A study of the pharmacokinetics of taurine was conducted in 8 healthy male volunteers with a median age of 28 years. After oral administration of 4 g of taurine in the fasting state, blood samples were taken at regular intervals, and plasma taurine concentration was measured by a modified high-performance liquid chromatographic technique. Maximum plasma taurine concentration was 86 mg/L 1.5 hours after administration. Plasma elimination half-life and the ratio of clearance to bioavailability were 1.0 hour and 21 L/h, respectively.30Ghandforoush-Sattari M Mashayekhi S Krishna CV Thompson JP Routledge PA Pharmacokinetics of oral taurine in healthy volunteers.J Amino Acids. 2010; (Accessed September 3, 2010.): 10http://www.sage-hindawi.com/journals/jaa/2010/346237.htmlGoogle Scholar Taurine modulates skeletal muscle contractile function and may attenuate exercise-induced DNA damage, with some evidence showing the ability to improve exercise capacity and performance; however, this has not been definitively demonstrated.4Ballard SL Wellborn-Kim JJ Clauson KA Effects of commercial energy drink consumption on athletic performance and body composition.Phys Sportsmed. 2010; 38: 107-117Crossref PubMed Scopus (51) Google Scholar Taurine has numerous other biological and physiologic functions, including bile acid conjugation and cholestasis prevention; antiarrhythmic, inotropic, and chronotropic effects; central nervous system neuromodulation; retinal development and function; endocrine or metabolic effects; and antioxidant and anti-inflammatory properties.31Lourenço R Camilo ME Taurine: a conditionally essential amino acid in humans? An overview in health and disease.Nutr Hosp. 2002; 17: 262-270PubMed Google Scholar Taurine also assists in cell membrane stabilization, osmoregulation, and detoxification.32Sato S Kurasaki M The physiological role of taurine in tissues and organs, especially in the liver and kidney.Foods Food Ingred J Jpn. 2003; 208: 133-139Google Scholar However, the amounts of taurine found in popular EBs are far below the amounts expected to deliver either therapeutic benefits or adverse events.14Clauson KA Shields KM McQueen CE Persad N Safety issues associated with commercially available energy drinks.J Am Pharm Assoc. 2008; 48 (2003): e55-e63Crossref Scopus (189) Google Scholar This is a naturally occurring substance produced in small amounts within the body. Supplementation with D-glucarates, including glucuronolactone, may favor the body's natural defense mechanism for eliminating carcinogens and tumor promoters and their effects.33Zółtaszek R Hanausek M Kiliańska ZM Walaszek Z The biological role of D-glucaric acid and its derivatives: potential use in medicine [in Polish].Postepy Hig Med Dosw (Online). 2008; 62: 451-462PubMed Google Scholar Toxicokinetic data on glucuronolactone in rats, which show bioavailability and lack of accumulation, with peak plasma levels 1 to 2 hours after oral administration, are in accordance with the limited human data.34Scientific Committee on Food European Commission, Health & Consumer Protection Directorate-General. Opinion of the Scientific Committee on Food on additional information on "energy" drinks. Published March 5, 2003.http://ec.europa.eu/food/fs/sc/scf/out169_en.pdfGoogle Scholar Unfortunately, little research has been done in humans, and the current body of knowledge on this substance is scant. Therefore, conclusions on whether this compound is harmful or beneficial cannot be made. The B vitamins are water-soluble vitamins required as coenzymes for proper cell function, especially mitochondrial function and energy production.35Depeint F Bruce WR Shangari N Mehta R O'Brien PJ Mitochondrial function and toxicity: role of the B vitamin family on mitochondrial energy metabolism.Chem Biol Interact. 2006; 163: 94-112Crossref PubMed Scopus (294) Google Scholar B vitamins include thiamine, riboflavin, niacin, pantothenic acid, pyridoxine hydrochloride, biotin, inositol, and cyanocobalamin. Because EBs contain large amounts of sugar, these vitamins are touted as ingredients necessary to convert the added sugar to energy. Hence, the B vitamins are the "key" needed to unlock all the energy provided by the simple sugars in EBs, and this is the extra energy that EB companies claim their product can provide. An expansive amount of research has been done on the B vitamins, and we outline the specific functions each major B vitamin plays in the human body. Thiamine (vitamin B1) is essential for the oxidative decarboxylation of the multienzyme branched-chain α-keto acid dehydrogenase complexes of the citric acid cycle and thus serves as a coenzyme precursor of some key enzymes of carbohydrate metabolism.36Ba A Metabolic and structural role of thiamine in nervous tissues.Cell Mol Neurobiol. 2008; 28: 923-931Crossref PubMed Scopus (74) Google Scholar Riboflavin (vitamin B2) is required for the flavoenzymes of the respiratory chain and thus also supports energy metabolism involving fats, carbohydrates, and proteins.37Lakshmi AV Riboflavin metabolism–relevance to human nutrition.Indian J Med Res. 1998; 108: 182-190PubMed Google Scholar The reduced form of nicotinamide adenine dinucleotide (NADH) is synthesized from niacin (vitamin B3). This coenzyme is required to supply protons for oxidative phosphorylation and plays a major part in energy production in cells.38Sauve AA NAD+ and vitamin B3: from metabolism to therapies.J Pharmacol Exp Ther. 2008; 324: 883-893Crossref PubMed Scopus (227) Google Scholar It also stimulates the production of such neurotransmitters as l-dopa, dopamine, serotonin, and norepinephrine. Pantothenic acid (vitamin B5) is required for coenzyme A, α-ketoglutarate, and pyruvate dehydrogenase formation, as well as fatty acid oxidation.35Depeint F Bruce WR Shangari N Mehta R O'Brien PJ Mitochondrial function and toxicity: role of the B vitamin family on mitochondrial energy metabolism.Chem Biol Interact. 2006; 163: 94-112Crossref PubMed Scopus (294) Google Scholar Pyridoxine hydrochloride (vitamin B6) is a coenzyme involved in amino acid and homocysteine metabolism, glucose and lipid metabolism, neurotransmitter production, and DNA and RNA synthesis.39Spinneker A Sola R Lemmen V Castillo MJ Pietrzik K Go
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