Description
Guarana comes from the seeds of a South American shrub – most of which originates in Brazil. Traditional uses of guarana by natives of the Amazonian rain forest include crushed seeds added to foods and beverages to increase alertness and reduce fatigue. As a dietary supplement, it’s no wonder that guarana is an effective energy booster – as it contains about twice the caffeine found in coffee beans (about 3-4% caffeine in guarana seeds compared to 1-2% for coffee beans). Concentrated guarana extracts, however, can contain caffeine at levels of as much as 40-50%, with popular supplements delivering 50-200mg of caffeine per day (about the same amount found in 1-2 cups of strong coffee). As with any caffeine-containing substance, too much can lead to nervousness, tension and headaches.
Claims
Increases energy levels / Reduces fatigue
Enhances physical and mental performance
Promotes weight loss
Suppresses appetite
Theory
The theory behind how guarana works is relatively straightforward. The major active constituent is caffeine (sometimes called “guaranine” to make you think it’s different in some way) and similar alkaloids such as theobromine and theophylline (which are also found in coffee and tea). Each of these compounds has well-known effects as nervous system stimulants. As such, they may also have some effect on increasing metabolic rate, suppressing appetite and enhancing both physical and mental performance.
Scientific Support
The seeds of guarana are known to be rich in xanthines (caffeine) and have been widely used as a “tonic” in many South American countries – particularly Brazil. In studies which have determined the total xanthine content of guarana powder, caffeine content typically averages 30-50% caffeine (depending on the extract). Related compounds such as theobromine and theophylline are found at levels of 1-3% and, like caffeine, can be detected in the urine for up to 9 days following guarana intake
Most of the scientific evidence on caffeine as a general stimulant and an aid to exercise performance shows convincingly that caffeine is effective. Consuming 3 to 6 mg of caffeine per kilogram (2.2 lbs) of body weight (about 350mg for an average sized man or 250mg for a woman) approximately 1 hour before exercise improves endurance performance without raising urinary caffeine levels above the International Olympic Committee’s (IOC) doping threshold. To reach that level, you’d need to take in about 800 mg of caffeine, which is about the amount found in 8 cups of coffee or 18 cans of Coke.
As a weight loss aid, however, although caffeine may suppress appetite somewhat at high levels, on its own it does not seem to be a very effective supplement for increasing calorie expenditure (thermogenesis). When combined with other stimulant-type supplements such as Ma Huang (Ephedra), however, it appears that caffeine can “extend” the duration of action of Ephedra in suppressing appetite and increasing caloric expenditure (although it may also increase the risk of adverse side effects associated with Ephedra and caffeine).
A popular combination of supplement ingredients for weight loss is often referred o as the “ECA stack” – shorthand for Ephedra/Caffeine/Aspirin. There are several “natural” forms of each of these compounds; Ephedra as Ma Huang and Sida cordifolia, Caffeine as Guarana, Mate and Kola nut, Aspirin (acetyl salicylic acid and other salicylates) as White Willow bark. The ECA combination appears to be more effective in promoting weight loss than any of the individual ingredients on their own. For example, about 150mg of ephedrine per day can increase metabolic rate by 3-5% over a 24-hour period, whereas a lower dose of ephedrine (60mg/day) increases daily caloric expenditure by nearly 8% when combined with caffeine (200-400mg/day) and aspirin (80-160mg/day of salicin).
Safety
The toxicity of guarana has been assessed in cellular and animal studies. In most cases, there is no significant danger, aside from the side effects of high caffeine intake, associated with guarana consumption. At least one study, however, found water extracts of guarana to cause genetic damage in cell cultures – although it is unclear whether this suggests any health risk for humans consuming guarana extract as a dietary supplement. As with any caffeine-containing food, guarana extracts can lead to insomnia, nervousness, anxiety, headaches, high blood pressure and heart palpitations. Guarana is not recommended for women who are pregnant or lactating.
Value
Caffeine is certainly an effective stimulant that can help increase the general state of arousal and enhance mental and physical performance. It is also widely available in common foods (coffee, tea, cola) and is relatively inexpensive. For an athlete or exerciser who needs a little “boost” before athletic competition or exercise, a moderate amount of caffeine may be helpful. For individuals attempting to lose weight, however, guarana and caffeine do not appear to be especially effective as stand-alone weight loss aids, but in combination with other thermogenic and nervous system stimulants (see “ECA stacks” above), the caffeine may extend the activity and potency of certain supplement ingredients.
Dosage
Caffeine intake of 180-450 milligrams a day (about the amount in 2-4 cups of brewed coffee or 500-1000mg of guarana extract) has been associated with mild stimulant properties and enhanced physical and mental performance. Higher levels of intake are not associated with additional increases in performance, but may result in adverse side effects such as tension, irritability and nausea.
References:
1. Bempong DK, Houghton PJ. Dissolution and absorption of caffeine from guarana. J Pharm Pharmacol. 1992 Sep;44(9):769-71.
2. Benoni H, Dallakian P, Taraz K. Studies on the essential oil from guarana. Z Lebensm Unters Forsch. 1996 Jul;203(1):95-8.
3. Bydlowski SP, D'Amico EA, Chamone DA. An aqueous extract of guarana (Paullinia cupana) decreases platelet thromboxane synthesis. Braz J Med Biol Res. 1991;24(4):421-4.
4. Bydlowski SP, Yunker RL, Subbiah MT. A novel property of an aqueous guarana extract (Paullinia cupana): inhibition of platelet aggregation in vitro and in vivo. Braz J Med Biol Res. 1988;21(3):535-8.
5. Carlson M, Thompson RD. Liquid chromatographic determination of methylxanthines and catechins in herbal preparations containing guarana. J AOAC Int. 1998 Jul-Aug;81(4):691-701.
6. da Fonseca CA, Leal J, Costa SS, Leitao AC. Genotoxic and mutagenic effects of guarana (Paullinia cupana) in prokaryotic organisms. Mutat Res. 1994 May;321(3):165-73.
7. Donadio V, Bonsi P, Zele I, Monari L, Liguori R, Vetrugno R, Albani F, Montagna P. Myoglobinuria after ingestion of extracts of guarana, Ginkgo biloba and kava. Neurolog Sci. 2000 Apr;21(2):124.
8. Espinola EB, Dias RF, Mattei R, Carlini EA. Pharmacological activity of Guarana (Paullinia cupana Mart.) in laboratory animals. J Ethnopharmacol. 1997 Feb;55(3):223-9.
9. Galduroz JC, Carlini E de A. Acute effects of the Paulinia cupana, "Guarana" on the cognition of normal volunteers. Rev Paul Med. 1994 Jul-Sep;112(3):607-11.
10. Galduroz JC, Carlini EA. The effects of long-term administration of guarana on the cognition of normal, elderly volunteers. Rev Paul Med. 1996 Jan-Feb;114(1):1073-8.
11. Katzung W. Guarana--a natural product with high caffeine content. Med Monatsschr Pharm. 1993 Nov;16(11):330-3.
12. Mattei R, Dias RF, Espinola EB, Carlini EA, Barros SB. Guarana (Paullinia cupana): toxic behavioral effects in laboratory animals and antioxidants activity in vitro. J Ethnopharmacol. 1998 Mar;60(2):111-6.
13. Miura T, Tatara M, Nakamura K, Suzuki I. Effect of guarana on exercise in normal and epinephrine-induced glycogenolytic mice. Biol Pharm Bull. 1998 Jun;21(6):646-8.
14. Rommelspacher H. Guarana. Dtsch Med Wochenschr. 1995 Mar 17;120(11):384.
15. Salvadori MC, Rieser EM, Ribeiro Neto LM, Nascimento ES. Determination of xanthines by high-performance liquid chromatography and thin-layer chromatography in horse urine after ingestion of Guarana powder. Analyst. 1994 Dec;119(12):2701-3.
16. Santa Maria A, Lopez A, Diaz MM, Munoz-Mingarro D, Pozuelo JM. Evaluation of the toxicity of guarana with in vitro bioassays. Ecotoxicol Environ Saf. 1998 Mar;39(3):164-7.
17. Schafer AT. Microscopic examination of Guarana powder--Paullinia cupana Kunth. Arch Kriminol. 1999 Jul-Aug;204(1-2):23-7.
