ID 737 -
Kofeina
PL: Kofeina
EN: Caffeine
Pdf: caffeine
Oświadczenie (4)
- Kofeina przyczynia się do zwiększenia wytrzymałości podczas wysiłku
Oświadczenie (2)
- wytrzymałości w krótkim czasie dużej intensywności ćwiczeń
- sprawności fizycznej (krótko-i działalności wytrzymałość)
1. Charakterystyka żywności / składnika
The food constituent that is the subject of the health claims is caffeine. Caffeine, a natural compound in coffee beans and tea leaves, is a well characterised substance which can be measured by established methods.
The Panel considers that the food constituent, caffeine, which is the subject of the health claims, is sufficiently characterised.
2.1. Zwiększenie wydolności fizycznej podczas krótkotrwałych ćwiczeń o wysokiej intensywności (ID 737, 1486, 1489)
The claimed effects are “physical performance (short term and endurance activities)” and “endurance during short term high intensity exercise”. The Panel assumes that the target population is active individuals in the general population.
In the context of the proposed wordings, the Panel assumes that the claimed effects refer to increase in physical performance during short-term high-intensity (>80 % maximum O2 consumption) exercise. Performance relates to the ability of completing a certain task (e.g. running a certain distance) as fast as possible.
The Panel considers that an increase in physical performance during short-term high-intensity exercise is a beneficial physiological effect.
2.2. Wzrost wydolności fizycznej (ID 737, 1486)
The claimed effect is “physical performance (short term and endurance activities)”. The Panel assumes that the target population is adults performing endurance exercise.
In the context of the proposed wordings, the Panel assumes that the claimed effect refers to increase in endurance performance (i.e. during longer-term exercise generally at intensity <80 % maximum O2 consumption). Performance relates to the ability of completing a certain task (e.g. running a certain distance) as fast as possible.
The Panel considers that an increase in endurance performance is a beneficial physiological effect.
3. Naukowe uzasadnienia wpływu na zdrowie człowieka -
The combined list of references provided for ID 737, 1486, 1488, 1489 and 1490 was used for the evaluation of the claimed effects reported from section 2.1 to section 2.4. The list of references consisted of 54 articles (excluding duplicates), and included two meta-analyses of randomised controlled trials (RCTs) on the effects of caffeine consumption on exercise testing (Doherty and Smith, 2004), and on the rating of perceived exertion during and after exercise (Doherty and Smith, 2005), respectively, where most of the individual studies submitted in relation to these claims were already considered. The later meta-analysis specifically relates to the evaluation of the health relationship in section 2.4., and is described in section 3.4.
The meta-analysis by Doherty and Smith (2004) was limited to laboratory-based, double-blind, fully randomised (and mostly cross-over), placebo-controlled intervention studies on adult subjects published in peer-reviewed Journals in English after 1975, in which a primary outcome was the effects of a single caffeine dose on whole-body exercise. Studies where caffeine was administered in combination with other substances were not considered. A total of 40 intervention studies including 414 subjects (mean sample size 9.3±2.5 subjects) and 76 outcome measures met the inclusion criteria. Most of the subjects were males (about 90 %) between 20 and 40 years of age, and with an aerobic capacity (VO2max) of 56.0±10.1 mL/kg/min (mostly physically active). The studies considered used three types of exercise protocol: short-term high intensity (ST), graded exercise tests performed to
exhaustion (GXT), and endurance-based efforts (END). In addition, studies with ST and END protocols had used either exercise capacity tests, or time to voluntary exhaustion on a constant exercise intensity (i.e. Tlim protocols), or exercise performance tests (e.g. time trials or distance trials (i.e. non-Tlim protocols)). Therefore, the effects of caffeine consumption on exercise capacity (Tlim protocols) and exercise performance (non-Tlim protocols) during short (ST) and long-term (END) exercise could be addressed in the meta-analysis. The meta-analysis also considered how other variables could affect the effects of caffeine consumption on whole-body exercise testing, including usual caffeine consumption, caffeine dose, time of caffeine withdrawal prior to testing, time between caffeine intake and exercise testing, and training of subjects. None of these variables appeared to have an effect on the ergonomic effects of caffeine, although no definitive conclusions could be drawn from the meta-analysis because of the homogeneity of the studies included in relation to these variables.
The effects of caffeine on test outcomes were quantified by calculating effect sizes (ES), as well as the relative change from placebo after caffeine ingestion, ES being a dimensionless measure centred at zero if caffeine had a neutral effect compared to placebo. No publication bias was identified.
The specific effects on various exercise outcomes are presented below for the separate health relationships.
3.1. Zwiększenie wydolności fizycznej podczas krótkotrwałych ćwiczeń o wysokiej intensywności (ID 737, 1486, 1489)
In the meta-analysis by Doherty and Smith (2004), the evaluation of a potential ergogenic effect of caffeine on short-term, high-intensity exercise (ST) included 12 studies evaluating 26 outcomes. Of these, 22 outcome measures addressed non-Tlim protocols, and therefore exercise performance (Anderson et al., 2000; Anselme et al., 1992; Bruce et al., 2000; Collomp et al., 2002; Doherty et al., 2004; Greer et al., 1998; Vanakoski et al., 1998; Williams et al., 1988). No significant effect of caffeine consumption on exercise performance was observed (ES=0.00±0.33, 95 % CI -0.02 to 0.02). In these studies, subjects were low to moderate caffeine users (in most studies usual caffeine intake was not reported), caffeine was withdrawn 24-168 hours before testing (24-72 h in most studies), and the caffeine dose ranged from 3.5 to 9 mg/kg body weight (5 to 7 mg/kg body weight in most studies) and was administered between 30 and 120 min (mostly between 60 and 120 min) before exercise testing.
Three individual studies which investigated the effect of caffeine consumption on physical performance during short-term exercise tests were provided in the consolidated list (Collomp et al., 1992; Paton et al., 2001; Wiles et al., 2006), one of which had been already considered in the meta-analysis above (Collomp et al., 1992).
In the study by Wiles et al. (2006), eight trained cyclists cycled 1 km in the laboratory after consumption of 5 mg of caffeine per kg body weight, or the same amount of placebo, in a control situation (no intervention) following a randomised, double-blind (for caffeine and placebo) cross-over design. Performance time was significantly reduced (by 3.1 %) after consumption of caffeine compared to the placebo and control tests. This decrease was accompanied by significant increases in mean speed, mean power, and peak power output after caffeine consumption compared to placebo and control. On the other hand, in the study by Paton et al. (2001), physical performance during a repeated sprint test comprising 20-metre sprints repeated 10 times during 100 seconds was not affected in 16 male team-sport athletes, 60 minutes after ingesting caffeine (6 mg/kg body weight) compared to placebo.
In weighing the evidence, the Panel took into account that the evidence for an effect of caffeine consumption on physical performance during short-term high-intensity exercise is inconsistent, and
that one meta-analysis of RCTs including 8 studies and 22 outcome measures did not show an effect of caffeine consumption on physical performance during short-term high-intensity exercise.
The Panel concludes that a cause and effect relationship has not been established between the consumption of caffeine and an increase in physical performance during short-term high-intensity exercise.
3.2. Wzrost wydolności fizycznej (ID 737, 1486)
In the meta-analysis by Doherty and Smith (2004), the evaluation of a potential ergogenic effect of caffeine on endurance exercise included 23 studies evaluating 39 outcomes. Of these, five studies (with five outcome measures) addressed non-Tlim protocols, and therefore endurance performance (Bell and McLellan, 2002; Cole et al., 1996; Conway et al., 2003; Cox et al., 2002; MacIntosh and Wright, 1995). A statistically significant effect of caffeine consumption on endurance performance was observed (ES=0.28±0.160, 95 % CI 0.08 to 0.47). In these studies, subjects were low to moderate caffeine users, caffeine was withdrawn 24-48 hours before testing, and the caffeine dose ranged from 4 to 6 mg/kg body weight and was administered between 60 and 150 min before the exercise testing. The Panel notes that the meta-analysis did not address whether the observed positive effects on endurance performance following caffeine intake were due to an ergogenic effect of caffeine intake per se, or to a detrimental effect of previous caffeine withdrawal.
A number of individual, randomised, placebo-controlled intervention studies which investigated the effects of caffeine on endurance performance were provided in the consolidated list (Berglund and Hemmingsson, 1982; Bridge and Jones, 2006; Cox et al., 2002; Kovacs et al., 1998; MacIntosh and Wright, 1995). The studies by McIntosh and Wright (1995) and Cox et al. (2002) were included in the meta-analysis by Doherty and Smith (2004) and are not discussed further.
Berglund and Hemmingsson (1982) found that performance in well trained cross-country skiers during a 21 km time trial was enhanced at sea level and at high altitude after caffeine consumption (6 mg/kg body weight 60 min prior to testing) compared with placebo. Subjects were habitual caffeine consumers and caffeine was withdrawn 12 hours before testing. A 24-sec reduction (-1.2 %) in 8-km running time was found by Bridge et al. (2006) after ingestion of caffeine (3 mg/kg body weight 60 min prior to the race) compared with placebo in 8 trained male distance runners. Subjects were habitual caffeine consumers and caffeine was withdrawn 48 hours before testing. In a study by Kovacs et al. (1998) 15 well-trained men (triathletes and cyclists) were given 1.2 mg, 1.8 mg or 2.56 mg caffeine per kg body weight during a 20-minute cycling warm-up protocol, and an additional 0.9 mg, 1.35 mg or 5.1 mg caffeine/kg body weight during a subsequent one-hour time trial. All doses led to significant improvements in performance compared with placebo.
In weighing the evidence, the Panel took into account that most of the human intervention studies provided (including a meta-analysis of five RCTs and three individual RCTs) showed an effect of caffeine consumption on endurance performance at doses of at least 3 mg/kg body weight administered at least one hour prior to exercise, and after at least one day of caffeine withdrawal in habitual caffeine consumers.
The Panel concludes that a cause and effect relationship has been established between the consumption of caffeine and an increase in endurance performance.
4.1. Wzrost wydolności fizycznej (ID 737, 1486)
The Panel considers that the following wording reflects the scientific evidence: “Caffeine contributes to an increase in endurance performance”.
5.1. Wzrost wydolności fizycznej (ID 737, 1486)
The Panel considers that in order to obtain the claimed effect, caffeine should be consumed at doses of 3 mg/kg body weight one hour prior to exercise. The target population is adults performing endurance exercise.
Warunki i możliwe ograniczenia stosowania oświadczenia
1-5mg/kg/day