Too much testosterone kills brain cells

[Farang]

Cheers for the feedbac Johan. I'm a bit starved of doing
scientific research over here in Thailand!

Sorry, typo (LDL) -opposite effect (DECREASES LDL oxidation)

There have been many long term trials on humans, with no negative effects - have to search that out for you (at the internet cafe - need to get back to family).
It has been studied for over 50 years with many research papers, and is currently used by large numbers of people with neurodegenerative diseases, with no recorded ill effects.
Something I neglected to comment on is the action of PEA (a compound commonly found in chocolate) - this is the stuff that gives you the high feeling, through dopamine expression. In part it metabolises into amphetamine and methanphetamine, and enhances catcholamine activity, thus is a potent fat burner.

I've actually sent a very polite email to Ehrlich about her study. I've asked her what she thinks of deprenyl for steroid users - interesting to hear her response (not counting my chickens though)

I will write something more detailed in respect to green tea, but will give you a few bits of info - yes the tannins in black tea have been proven to be benefitial antioxidants, but there ARE marked differences in studies comparing black and green tea, studies have shown this.

:

Antioxidant activity on free-radicals following exercise - rats given green tea or water.

A biomarker for free radical activity that was introduced into the rats and showed a 290% increase in free radicals (water group) and 0% in green tea group! (FREE RADICALS MEASURED IN THE LIVER).

Green tea has been repeatedly been shown in trials to reduce risk of practically every cancer - from prostrate to colon reduce the chance of heart disease.

Long term studies show a 7% drop in B.P. , with improved cholesterol balance, enhanced mood and improvements in memory.

Green tea is rich in L-theanine - which improves mental focus and produces alpha waves in the brain. This is the same pattern that is seen in athletes prior to an important race (boosts performance). This also explains the calming effect of green tea, despite caffeine content.



The antioxidants in green tea are highly bioavailiable - as such they are highly absorbed in all the organs of the body. The kidneys and liver have been particularly well studied, with the antioxidants in green tea shown by meta-analysis to be vastly superior to that of vit C and Vit E.

Studies have also shown a number of positive effects in conjunction with drug users.

Scientists unanimously reccomend at least 6 cups a day, with 10 cups+ being preferable for optimal catcholamine content (of which is a potent fat burner)


I am unaware of any negative research regarding green tea, although if you find some I'd be interested to have a look thanks.


I'M A DUMB ASS! - I JUST REMEMBERED THAT WROTE/RESEARCHED SOME INFO FOR A PARALYMPIC ATHLETE. IT WAS ABOUT SUPPLEMENTS (INCLUDING GREEN TEA)- I'LL PASTE IT IN. Am planning on writing something a bit more comprehensive and substantiated though.

- SEE BELOW:


J Agric Food Chem 1999 Oct;47(10):3967-73
Tea catechin supplementation increases antioxidant capacity and prevents phospholipid hydroperoxidation in plasma of humans.

Nakagawa K, Ninomiya M, Okubo T, Aoi N, Juneja LR, Kim M, Yamanaka K, Miyazawa T.

Laboratory of Biodynamic Chemistry, Tohoku University Graduate School of Life Science and Agriculture, Sendai 981-8555, Japan.

The effect of green tea catechin supplementation on antioxidant capacity of human plasma was investigated. Eighteen healthy male volunteers who orally ingested green tea extract (254 mg of total catechins/subject) showed 267 pmol of epigallocatechin-3-gallate (EGCg) per milliliter of plasma at 60 min after administration. The plasma phosphatidylcholine hydroperoxide (PCOOH) levels attenuated from 73.7 pmol/mL in the control to 44.6 pmol/mL in catechin-treated subjects, being correlated inversely with the increase in plasma EGCg level. The results suggested that drinking green tea contributes to prevent cardiovascular disease by increasing plasma antioxidant capacity in humans.

Biofactors 2000;13(1-4):55-9
Absorption, metabolism and antioxidative effects of tea catechin in humans.

Miyazawa T.

Biodynamics Chemistry, Lab., Tohoku University Graduate School of Life Science & Agriculture, Sendai, Japan. [email protected]

Green tea is consumed as a popular beverage in Japan and throughout the world. During the past decade, epidemiological studies have shown that tea catechin intake is associated with lower risk of cardiovascular disease. In vitro biochemical studies have reported that catechins, particularly epigallocatechin-3-gallate (EGCg), help to prevent oxidation of plasma low-density lipoprotein (LDL). LDL oxidation has been recognized to be an important step in the formation of atherosclerotic plaques and subsequent cardiovascular disease. Metabolic studies have shown that EGCg supplement is incorporated into human plasma at a maximum concentration of 4400 pmol/mL. Such concentrations would be enough to exert antioxidative activity in the blood stream. The potent antioxidant property of tea catechin may be beneficial in preventing the oxidation of LDL. It is of interest to examine the effect of green tea catechin supplementation on antioxidant capacity of plasma in humans by measuring plasma phosphatidylcholine hydroperoxide (PCOOH) as a marker of oxidized lipoproteins.

Am J Clin Nutr 1999 Dec;70(6):1040-5
Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans.

Dulloo AG, Duret C, Rohrer D, Girardier L, Mensi N, Fathi M, Chantre P, Vandermander J.

Department of Physiology, Faculty of Medicine, University of Geneva. a**[email protected]

BACKGROUND: Current interest in the role of functional foods in weight control has focused on plant ingredients capable of interfering with the sympathoadrenal system. OBJECTIVE: We investigated whether a green tea extract, by virtue of its high content of caffeine and catechin polyphenols, could increase 24-h energy expenditure (EE) and fat oxidation in humans. DESIGN: Twenty-four-hour EE, the respiratory quotient (RQ), and the urinary excretion of nitrogen and catecholamines were measured in a respiratory chamber in 10 healthy men. On 3 separate occasions, subjects were randomly assigned among 3 treatments: green tea extract (50 mg caffeine and 90 mg epigallocatechin gallate), caffeine (50 mg), and placebo, which they ingested at breakfast, lunch, and dinner. RESULTS: Relative to placebo, treatment with the green tea extract resulted in a significant increase in 24-h EE (4%; P < 0.01) and a significant decrease in 24-h RQ (from 0.88 to 0.85; P < 0.001) without any change in urinary nitrogen. Twenty-four-hour urinary norepinephrine excretion was higher during treatment with the green tea extract than with the placebo (40%, P < 0.05). Treatment with caffeine in amounts equivalent to those found in the green tea extract had no effect on EE and RQ nor on urinary nitrogen or catecholamines. CONCLUSIONS: Green tea has thermogenic properties and promotes fat oxidation beyond that explained by its caffeine content per se. The green tea extract may play a role in the control of body composition via sympathetic activation of thermogenesis, fat oxidation, or both.

Int J Obes Relat Metab Disord 2000 Feb;24(2):252-8

Green tea and thermogenesis: interactions between catechin-polyphenols, caffeine and sympathetic activity.

Dulloo AG, Seydoux J, Girardier L, Chantre P, Vandermander J.

Institute of Physiology, University of Fribourg, Fribourg, Switzerland. a**[email protected]

The thermogenic effect of tea is generally attributed to its caffeine content. We report here that a green tea extract stimulates brown adipose tissue thermogenesis to an extent which is much greater than can be attributed to its caffeine content per se, and that its thermogenic properties could reside primarily in an interaction between its high content in catechin-polyphenols and caffeine with sympathetically released noradrenaline (NA). Since catechin-polyphenols are known to be capable of inhibiting catechol-O-methyl-transferase (the enzyme that degrades NA), and caffeine to inhibit trancellular phosphodiesterases (enzymes that break down NA-induced cAMP), it is proposed that the green tea extract, via its catechin-polyphenols and caffeine, is effective in stimulating thermogenesis by relieving inhibition at different control points along the NA-cAMP axis. Such a synergistic interaction between catechin-polyphenols and caffeine to augment and prolong sympathetic stimulation of thermogenesis could be of value in assisting the management of obesity. International Journal of Obesity (2000) 24, 252-258

J Hypertens 1999 Apr;17(4):457-63
Effects on blood pressure of drinking green and black tea.

Hodgson JM, Puddey IB, Burke V, Beilin LJ, Jordan N.

University of Western Australia Department of Medicine and the Western Australian Heart Research Institute, Royal Perth Hospital, Australia. [email protected]

BACKGROUND: The flavonoid components of tea have been associated in epidemiological studies with a decreased risk of cardiovascular disease. Flavonoids have been shown to have antioxidant and vasodilator effects in vitro; we therefore postulated that drinking green or black tea attenuates the well-characterized acute pressor response to caffeine and lowers blood pressure during regular consumption. OBJECTIVE: To determine whether green and black tea can attenuate the transient pressor effect of caffeine, or lower blood pressure during regular consumption. METHODS: In the first study, the acute effects of four hot drinks - green tea and black tea (at a dose equivalent to four standard cups), water matched to the teas for caffeine content ('caffeine') and water - were assessed in 20 normotensive men using a Latin-Square designed study. Clinic blood pressure was measured before and 30 and 60 min after each drink had been ingested. In the second study, the effects on blood pressure of regular green and black tea ingestion were examined in 13 subjects with high-normal systolic blood pressure and mild systolic hypertension (systolic blood pressure in the range 130-150 mmHg) using a three-period crossover study. Five cups per day of green tea, black tea and caffeine (in hot water and matched to the teas) were consumed for 7 days each, in random order. Twenty-four hour ambulatory blood pressure was measured at the end of each seven-day intervention. Results are presented as means and 95% confidence intervals (CI). RESULTS: An acute pressor response to caffeine was observed. Relative to caffeine, there were further acute increases in systolic and diastolic blood pressure at 30 min among those drinking green tea [5.5 mmHg (95%CI -1.4 to 12.4) and 3.1 mmHg (95%CI -0.1 to 6.3), respectively] and black tea [10.7 mmHg (95%CI 4.0 to 17.4) and 5.1 mmHg (95%CI 1.8 to 8.4), respectively]. The changes in blood pressure at 60 min were not significant The effect on 24-h ambulatory systolic and diastolic blood pressure of regular drinking of green tea [increases of 1.7 mmHg (95%CI -1.6 to 5.0) and 0.9 mmHg (95%CI -1.3 to 3.1), respectively] or black tea [increase of 0.7 mmHg (95%CI -2.6 to 4.0) and decrease of 0.7 mmHg (95%CI -2.9 to 1.5), respectively] was not significant relative to caffeine. CONCLUSIONS: Contrary to our initial hypothesis, tea ingestion caused larger acute increases in blood pressure than caffeine alone. However, any acute effects of tea on blood pressure did not translate into significant alterations in ambulatory blood pressure during regular tea consumption.

Green Tea Extract

This powerful supplement has been widely used for immuno-enhancing effects. The major components of interest in green tea extract are the polyphenols (including EGCG--epigallocatechin gallate which seems to provide the strongest antioxidant effects). Most of its research is actually focused on its cancer-protective effects. Some research suggests that this potent extract has greater anti-oxidant protection than Vitamin C and E . A study published in the American Journal of Clinical Nutrition in Dec. 1999 showed that green tea extract actually increased 24 hour energy expenditure and fat oxidation in humans. Many people "in the know" would say that this is due to its caffeine content since caffeine has been shown to have some of these properties in previous research. However, the authors of this study concluded "green tea extract has thermogenic properties and promotes fat oxidation beyond that explained by its caffeine content per se." They continued to say "Green tea extract may play a role in the control of body composition via sympathetic activation of thermogenesis, fat oxidation, or both." I believe it is most likely linked to its EGCG content. Another study showed the synergy of green tea extracts catechin-polyphenol and caffeine content discussing how it stimulates brown adipose tissue thermogenesis. The study mentions that green tea extract and the synergistic relationship of its contents may be a valuable tool in assisting in the management of obesity. This is all very good news for all those fat loss candidates out there!.
In my opinion, you should try to drink as much green tea as possible. It is truly amazing stuff. 5-6 cups/ day is recommended as a minimum for health benefits, but more IS better. Look at the Chinese, they smoke twice as much as the west – but have half the incidence of lung cancer! This has been contributed primarily to their high consumption of green tea – literally drink it like fish!
Many studies have shown the antioxidant properties of green tea, especially in response to acute exercise –results are remarkable. In one study I remember, the effects on young rats were studied, following a 6.5 week exercise protocol. In comparison to the water fed rats, post exercise levels of malonaldehyde (a marker of oxidative stress) was zero in green tea fed rats – but 290% in the water only subjects! Green tea lowers blood pressure (both diastolic and systolic shown to decrease by 7% when rats were fed 2mg of tea (Yakozawa et al. 2004).
It decreases cholesterol as showed by Norwegian research. It decreases the chance of cardiovascular disease, with studies in the 80’s showing a marked increase in HDL cholesterol (good) and a decrease in LDL cholesterol (bad). Green tea ADP platelet aggression and inhibits LDL oxidation.
Cancer- large numbers of studies show big reductions in risk of cancer following green tea consumption (mainly through the polyphenolic EGCG content. It has been shown effective against many types of cancer – gastric, oral, pharyngeal, gastric, breast and digestive, lung, liver, kidney, skin, esophaegus, pancreas and prostrate; to name only a few! It seems as tough that the antioxidant, polyphenol, catchins and theaflavins inhibit cell transformation inhibit cell transformation, cell growth and the activity of tumour-proting enzymes in animals (Sinclair et al 2000). It seems that EGCG gets directly transported to all the organs in the body, and is extremely bioavailiable. This therefore provides excretion enhanced antioxidant protection from analogous drugs or exercise-induced stress. (Alesio et al. 2002). There is also supporting evidence fom animal research to show that tea also enhances the immune system.

[Farang]

Here are some additional abstracts ascertaining to caffeine; just for the hell of it:

Caffeine, coffee and ephedrine: impact on exercise performance and metabolism.

Graham TE.

Department of Human Biology and Nutritional Sciences, University of Guelph Guelph, ON.

This paper addresses areas where there is controversy regarding caffeine as an ergogenic aid and also identifies topics that have not been adequately addressed. It is clear that caffeine, in moderate amounts, can be used orally as an ergogenic aid in aerobic activity lasting for more than 1 min. It increases endurance and speed, but not maximal VO2 and related parameters. While there are fewer well-controlled studies for resistance exercise, the literature would suggest similar improvements: increased endurance at submaximal tension and power generated in repeated contractions and no change in maximal ability to produce force. It is likely that theophylline (a related methylxanthine) has similar actions and it has been suggested that the combination of caffeine and sympathomimetics may be a more potent erogenic aid. The voids in our understanding of caffeine include the dose (what amount is optimal, what vehicle is used to deliver the drug as well as method, pattern, and mode of administration), the potential side effects (particularly in competitive settings), health implications (insulin resistance and if combined with ephedrine, cardiovascular risks) and mechanisms of action. It appears unlikely that increased fat oxidation and glycogen sparing is the prime ergogenic mechanism.

J Appl Physiol 1998 Sep;85(3):883-9

http://jap.physiology.org/cgi/content/full/85/3/883

Metabolic and exercise endurance effects of coffee and caffeine ingestion.

Graham TE, Hibbert E, Sathasivam P.

Human Biology and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada N1G 2W1. [email protected]

Caffeine (Caf) ingestion increases plasma epinephrine (Epi) and exercise endurance; these results are frequently transferred to coffee (Cof) consumption. We examined the impact of ingestion of the same dose of Caf in Cof or in water. Nine healthy, fit, young adults performed five trials after ingesting (double blind) either a capsule (Caf or placebo) with water or Cof (decaffeinated Cof, decaffeinated with Caf added, or regular Cof). In all three Caf trials, the Caf dose was 4.45 mg/kg body wt and the volume of liquid was 7.15 ml/kg. After 1 h of rest, the subject ran at 85% of maximal O2 consumption until voluntary exhaustion (approximately 32 min in the placebo and decaffeinated Cof tests). In the three Caf trials, the plasma Caf and paraxanthine concentrations were very similar. After 1 h of rest, the plasma Epi was increased (P < 0.05) by Caf ingestion, but the increase was greater (P < 0.05) with Caf capsules than with Cof. During the exercise there were no differences in Epi among the three Caf trials, and the Epi values were all greater (P < 0.05) than in the other tests. Endurance was only increased (P < 0. 05) in the Caf capsule trial; there were no differences among the other four tests. One cannot extrapolate the effects of Caf to Cof; there must be a component(s) of Cof that moderates the actions of Caf.

Med Sci Sports Exerc 2000 Nov;32(11):1958-63
Enhancement of 2000-m rowing performance after caffeine ingestion.

Bruce CR, Anderson ME, Fraser SF, Stepto NK, Klein R, Hopkins WG, Hawley JA.

Department of Human Biology and Movement Science, RMIT University, Bundoora, Victoria Australia.

PURPOSE: To investigate the effect of caffeine ingestion on short-term endurance performance in competitive rowers. METHODS: In this randomized double-blind crossover study, eight competitive oarsmen (peak oxygen uptake [VO2peak] 4.7+/-0.4 L x min(-1), mean +/- SD) performed three familiarization trials of a 2000-m rowing test on an air-braked ergometer, followed by three experimental trials at 3- to 7-d intervals, each 1 h after ingesting caffeine (6 or 9 mg x kg(-1) body mass) or placebo. Trials were preceded by a standardized warm-up (6 min at 225+/-39 W; 75+/-7.7% VO2peak). RESULTS: Urinary caffeine concentration was similar before ingestion (approximately 1 mg x L(-1)) but rose to 6.2+/-3.6 and 14.5+/-7.0 mg x L(-1) for the low and high caffeine doses, respectively. Plasma free fatty acid concentration before exercise was higher after caffeine ingestion (0.29+/-0.17 and 0.39+/-0.20 mM for 6 and 9 mg x kg(-1), respectively) than after placebo (0.13+/-0.05 mM). Respiratory exchange ratio during the warm-up was also substantially lower with caffeine (0.94+/-0.09 and 0.93+/-0.06 for the low and high dose) than with placebo (0.98+/-0.12). Subjects could not distinguish between treatments before or after the exercise test. Both doses of caffeine had a similar ergogenic effect relative to placebo: performance time decreased by a mean of 1.2% (95% likely range 0.4-1.9%); the corresponding increase in mean power was 2.7% (0.4-5.0%). Performance time showed some evidence of individual differences in the effect of caffeine (SD 0.9%; 95% likely range 1.5 to -0.9%). CONCLUSIONS: Ingestion of 6 or 9 mg x kg(-1) of caffeine produces a worthwhile enhancement of short-term endurance performance in a controlled laboratory setting.


Diabetes 2002 Mar;51(3):583-90

Caffeine-induced impairment of insulin action but not insulin signaling in human skeletal muscle is reduced by exercise.

Thong FS, Derave W, Kiens B, Graham TE, Urso B, Wojtaszewski JF, Hansen BF, Richter EA.

Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, Canada. [email protected]

We investigated the effects of caffeine ingestion on skeletal muscle glucose uptake, glycogen synthase (GS) activity, and insulin signaling intermediates during a 100-min euglycemic-hyperinsulinemic (100 microU/ml) clamp. On two occasions, seven men performed 1-h one-legged knee extensor exercise at 3 h before the clamp. Caffeine (5 mg/kg) or placebo was administered in a randomized, double-blind fashion 1 h before the clamp. During the clamp, whole-body glucose disposal was reduced (P < 0.05) in caffeine (37.5 +/- 3.1 micromol x min(-1) x kg(-1)) vs. placebo (54.1 +/- 2.9 micromol x min(-1) x kg(-1)). In accordance, the total area under the curve over 100 min (AUC(0--100 min)) for insulin-stimulated glucose uptake in caffeine was reduced (P < 0.05) by approximately 50% in rested and exercised muscle. Caffeine also reduced (P < 0.05) GS activity before and during insulin infusion in both legs. Exercise increased insulin sensitivity of leg glucose uptake in both caffeine and placebo. Insulin increased insulin receptor tyrosine kinase (IRTK), insulin receptor substrate 1-associated phosphatidylinositol (PI) 3-kinase activities, and Ser(473) phosphorylation of protein kinase B (PKB)/Akt significantly but similarly in rested and exercised legs. Furthermore, insulin significantly decreased glycogen synthase kinase-3alpha (GSK-3alpha) activity equally in both legs. Caffeine did not alter insulin signaling in either leg. Plasma epinephrine and muscle cAMP concentrations were increased in caffeine. We conclude that 1) caffeine impairs insulin-stimulated glucose uptake and GS activity in rested and exercised human skeletal muscle; 2) caffeine-induced impairment of insulin-stimulated muscle glucose uptake and downregulation of GS activity are not accompanied by alterations in IRTK, PI 3-kinase, PKB/Akt, or GSK-3alpha but may be associated with increases in epinephrine and intramuscular cAMP concentrations; and 3) exercise reduces the detrimental effects of caffeine on insulin action in muscle.

Sports Med 2001;31(11):785-807

Caffeine and exercise: metabolism, endurance and performance.

Graham TE.

Human Biology and Nutritional Sciences, University of Guelph, Ontario, Canada. [email protected]

Caffeine is a common substance in the diets of most athletes and it is now appearing in many new products, including energy drinks, sport gels, alcoholic beverages and diet aids. It can be a powerful ergogenic aid at levels that are considerably lower than the acceptable limit of the International Olympic Committee and could be beneficial in training and in competition. Caffeine does not improve maximal oxygen capacity directly, but could permit the athlete to train at a greater power output and/or to train longer. It has also been shown to increase speed and/or power output in simulated race conditions. These effects have been found in activities that last as little as 60 seconds or as long as 2 hours. There is less information about the effects of caffeine on strength; however, recent work suggests no effect on maximal ability, but enhanced endurance or resistance to fatigue. There is no evidence that caffeine ingestion before exercise leads to dehydration, ion imbalance, or any other adverse effects. The ingestion of caffeine as coffee appears to be ineffective compared to doping with pure caffeine. Related compounds such as theophylline are also potent ergogenic aids. Caffeine may act synergistically with other drugs including ephedrine and anti-inflammatory agents. It appears that male and female athletes have similar caffeine pharmacokinetics, i.e., for a given dose of caffeine, the time course and absolute plasma concentrations of caffeine and its metabolites are the same. In addition, exercise or dehydration does not affect caffeine pharmacokinetics. The limited information available suggests that caffeine non-users and users respond similarly and that withdrawal from caffeine may not be important. The mechanism(s) by which caffeine elicits its ergogenic effects are unknown, but the popular theory that it enhances fat oxidation and spares muscle glycogen has very little support and is an incomplete explanation at best. Caffeine may work, in part, by creating a more favourable intracellular ionic environment in active muscle. This could facilitate force production by each motor unit.

J Appl Physiol 1995 Mar;78(3):867-74 Related Articles, Links


Metabolic, catecholamine, and exercise performance responses to various doses of caffeine.

Graham TE, Spriet LL.

School of Human Biology, University of Guelph, Ontario, Canada.

This study examined the exercise responses of well-trained endurance athletes to various doses of caffeine to evaluate the impact of the drug on exercise metabolism and endurance capacity. Subjects (n = 8) withdrew from all dietary sources of caffeine for 48 h before each of four tests. One hour before exercise they ingested capsules of placebo or caffeine (3, 6, or 9 mg/kg), rested quietly, and then ran at 85% of maximal O2 consumption to voluntary exhaustion. Blood samples for methylxanthine, catecholamine, glucose, lactate, free fatty acid, and glycerol analyses were taken every 15 min. Plasma caffeine concentration increased with each dose (P < 0.05). Its major metabolite, paraxanthine, did not increase between the 6 and 9 mg/kg doses, suggesting that hepatic caffeine metabolism was saturated. Endurance was enhanced with both 3 and 6 mg/kg of caffeine (increases of 22 +/- 9 and 22 +/- 7%, respectively; both P < 0.05) over the placebo time of 49.4 +/- 4.2 min, whereas there was no significant effect with 9 mg/kg of caffeine. In contrast, plasma epinephrine was not increased with 3 mg/kg of caffeine but was greater with the higher doses (P < 0.05). Similarly only the highest dose of caffeine resulted in increases in glycerol and free fatty acids (P < 0.05). Thus the highest dose had the greatest effect on epinephrine and blood-borne metabolites yet had the least effect on performance. The lowest dose had little or no effect on epinephrine and metabolites but did have an ergogenic effect. These results are not compatible with the traditional theory that caffeine mediates its ergogenic effect via enhanced catecholamines.


Int J Obes Relat Metab Disord 1994 May;18(5):345-50 Related Articles, Links


Relationship between basal metabolic rate, thermogenic response to caffeine, and body weight loss following combined low calorie and exercise treatment in obese women.

Yoshida T, Sakane N, Umekawa T, Kondo M.

First Department of Internal Medicine, Kyoto Prefectural University of Medicine, Japan.

To clarify whether there were any differences in basal metabolic rate (BMR) and thermogenic response to caffeine in individual obese women, and if so, whether such differences affected weight loss, the basal and resting metabolic rates at 30 min after a caffeine loading test (4 mg/kg ideal body weight, per os) were measured in 136 obese women and ten lean age-matched controls. The obese subjects were then asked to follow a combined low calorie diet and exercise regimen. There were no differences in the BMR and thermogenic responses to caffeine between the obese and lean groups. However, the BMR and the thermogenic responses to caffeine varied widely in obese subjects. After two months of treatment, body weight and percentage body fat in obese women were significantly (P < 0.001) reduced. There were significant correlations between the BMR and body weight loss (r = 0.3621, P < 0.001), between BMR/lean body mass and body weight loss (r = 0.3196, P < 0.001) and between the thermogenic response to caffeine and body weight loss (r = 0.6943, P < 0.001). When the criterion of a BMR less than 3.10 kJ/min (less than two standard deviations below the mean of the age-matched lean control) was used to define an obese group with reduced BMR, there were 30 obese subjects in this group, and their body weight was significantly decreased by treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Int J Sports Med 1999 Aug;20(6):354-61

Caffeine improves cognitive performance after strenuous physical exercise.

Hogervorst E, Riedel WJ, Kovacs E, Brouns F, Jolles J.

Department of Psychiatry and Neuropsychology, Brain & Behaviour Institute, European Graduate School for Neurosciences, The Netherlands.

The effects of three carbohydrate electrolyte solutions (CES) containing different amounts of caffeine on cognitive function and the combined effects of these drinks and exercise on cognitive functions were investigated in a double-blind, cross-over study. On five separate occasions, fifteen endurance trained male athletes (23.3 years) received water placebo, CES placebo (68.8 g/l), and three CES drinks containing low, medium and high dosages of caffeine (150, 225 and 320 mg/l). Each occasion, 8 ml/kg of the drink was consumed before -- and 6 ml/kg of the drink was consumed during an all-out 1 hour time trial on a bicycle ergometer. Cognitive (attentional, psychomotor, and memory) tests were carried out immediately before and immediately after exercise. Before exercise, long term memory was improved by CES plus low dose caffeine compared to both placebos. Immediately after exercise, all cognitive functions were improved by CES plus low- and medium-dose caffeine compared to placebo. These results comprise the first practical demonstration of the cognition improving effects of low amounts of caffeine in CES after strenuous physical exercise.

Can J Physiol Pharmacol 1990 Jul;68(7):889-92

Effects of caffeine ingestion on body fluid balance and thermoregulation during exercise.

Falk B, Burstein R, Rosenblum J, Shapiro Y, Zylber-Katz E, Bashan N.

Faculty of Health Sciences, McMaster University, Hamilton, Ont., Canada.

This study investigated the effects of caffeine supplementation on thermoregulation and body fluid balance during prolonged exercise in a thermoneutral environment (25 degrees C, 50% RH). Seven trained male subjects exercised on a treadmill at an intensity of 70-75% of maximal oxygen consumption to self-determined exhaustion. Subjects exercised once after caffeine and once after placebo ingestion, given in a double-blind crossover design. Five milligrams per kilogram body weight of caffeine followed by 2.5 mg.kg-1 of caffeine were given 2 and 0.5 h before exercise, respectively. Rectal temperature was recorded and venous blood samples were withdrawn every 15 min. Water loss and sweat rate were calculated from the difference between pre- and post-exercise body weight, corrected for liquid intake. Following caffeine ingestion, when compared with placebo, no significant difference in final temperature or in percent change in plasma volume were found. No significant differences were observed in total water loss (1376 +/- 154 vs. 1141 +/- 158 mL, respectively), sweat rate (12.4 +/- 1.1 vs. 10.9 +/- 0.7 g.m-2.min-1, respectively), rise in rectal temperature (2.1 +/- 0.3 vs. 1.5 +/- 0.4 degrees C, respectively), nor in the calculated rate of heat storage during exercise (134.4 +/- 17.7 vs. 93.5 +/- 22.5 W, respectively). Thus, in spite of the expected rise in oxygen uptake, caffeine ingestion under the conditions of this study does not seem to disturb body fluid balance or affect thermoregulation during exercise performance.