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However, many cancer experts disputed the ruling , stating that the metabolism of acrylamide differs considerably in animals and humans, and the high amount of acrylamide used in animal research is not comparable to the amount present in food.

They cited the beneficial health effects of coffee, with improved antioxidant responses and reduced inflammation, both factors important in cancer prevention. Evidence from the American Institute for Cancer Research concludes that drinking coffee may reduce risk for endometrial and liver cancer , and based on a systematic review of a large body of research, it is not a risk for the cancers that were studied.

In June , the California Office of Environmental Health Hazard Assessment OEHHA proposed a new regulation exempting coffee from displaying cancer warnings under Proposition In January , OEHHA completed its review and response to comments and submitted the regulation to the Office of Administrative Law OAL for final review.

Although ingestion of caffeine can increase blood sugar in the short-term, long-term studies have shown that habitual coffee drinkers have a lower risk of developing type 2 diabetes compared with non-drinkers.

The polyphenols and minerals such as magnesium in coffee may improve the effectiveness of insulin and glucose metabolism in the body. Caffeine is a stimulant affecting the central nervous system that can cause different reactions in people.

In sensitive individuals, it can irritate the stomach, increase anxiety or a jittery feeling, and disrupt sleep. Although many people appreciate the temporary energy boost after drinking an extra cup of coffee, high amounts of caffeine can cause unwanted heart palpitations in some.

Unfiltered coffee, such as French press and Turkish coffees, contains diterpenes, substances that can raise bad LDL cholesterol and triglycerides. Espresso coffee contains moderate amounts of diterpenes. Filtered coffee drip-brewed coffee and instant coffee contain almost no diterpenes as the filtering and processing of these coffee types removes the diterpenes.

Despite these factors, evidence suggests that drinking coffee regularly may lower the risk of heart disease and stroke :.

Naturally occurring polyphenols in both caffeinated and decaffeinated coffee can act as antioxidants to reduce damaging oxidative stress and inflammation of cells. It may have neurological benefits in some people and act as an antidepressant.

However in a few cases of sensitive individuals, higher amounts of caffeine may increase anxiety, restlessness, and insomnia. Suddenly stopping caffeine intake can cause headache, fatigue, anxiety, and low mood for a few days and may persist for up to a week.

There are various proposed actions of caffeine or components in coffee that may prevent the formation of gallstones. The most common type of gallstone is made of cholesterol. Coffee may prevent cholesterol from forming into crystals in the gallbladder. It may stimulate contractions in the gallbladder and increase the flow of bile so that cholesterol does not collect.

A study of 46, men tracked the development of gallstones and their coffee consumption for 10 years. After adjusting for other factors known to cause gallstones, the study concluded that men who consistently drank coffee were significantly less likely to develop gallstones compared to men who did not.

The bottom line: A large body of evidence suggests that consumption of caffeinated coffee does not increase the risk of cardiovascular diseases and cancers. In fact, consumption of 3 to 5 standard cups of coffee daily has been consistently associated with a reduced risk of several chronic diseases.

Specifically, those who have difficulty controlling their blood pressure may want to moderate their coffee intake. Pregnant women are also advised to aim for less than mg of caffeine daily, the amount in 2 cups of coffee, because caffeine passes through the placenta into the fetus and has been associated with pregnancy loss and low birth weight.

Decaffeinated coffee is a good option if one is sensitive to caffeine, and according to the research summarized above, it offers similar health benefits as caffeinated coffee.

The extra calories, sugar, and saturated fat in a coffee house beverage loaded with whipped cream and flavored syrup might offset any health benefits found in a basic black coffee. Coffee beans are the seeds of a fruit called a coffee cherry. Coffee cherries grow on coffee trees from a genus of plants called Coffea.

There are a wide variety of species of coffee plants, ranging from shrubs to trees. Decaffeinated coffee. This is an option for those who experience unpleasant side effects from caffeine. The two most common methods used to remove caffeine from coffee is to apply chemical solvents methylene chloride or ethyl acetate or carbon dioxide gas.

Both are applied to steamed or soaked beans, which are then allowed to dry. According to U. Both methods may cause some loss of flavor as other naturally occurring chemicals in coffee beans that impart their unique flavor and scent may be destroyed during processing.

However, adding sugar, cream, and milk can quickly bump up the calorie counts. A tablespoon of cream contains 52 calories, and a tablespoon of whole milk contains 9 calories. However, the real caloric danger occurs in specialty mochas, lattes, or blended ice coffee drinks.

These drinks are often super-sized and can contain anywhere from calories, as well as an extremely large amount of sugar. The contents of this website are for educational purposes and are not intended to offer personal medical advice. You should seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

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Source Of Caffeine Vitamin B2 riboflavin Magnesium Plant chemicals: polyphenols including chlorogenic acid and quinic acid, and diterpenes including cafestol and kahweol One 8-ounce cup of brewed coffee contains about 95 mg of caffeine.

Coffee and Health Coffee is an intricate mixture of more than a thousand chemicals. Cancer Coffee may affect how cancer develops, ranging from the initiation of a cancer cell to its death.

Type 2 Diabetes Although ingestion of caffeine can increase blood sugar in the short-term, long-term studies have shown that habitual coffee drinkers have a lower risk of developing type 2 diabetes compared with non-drinkers. In a meta-analysis of 45, people with type 2 diabetes followed for up to 20 years, an association was found with increasing cups of coffee and a lower risk of developing diabetes.

If you want to learn more about a Hitsona franchise opportunity click here. There is a growing trend towards caffeinated energy drinks and tea is also a popular choice, however coffee is the main way that our global society consumes caffeine, and because of this we are often warned about the negative effects of our favourite beverage.

Of course, an overindulgence in anything is a bad idea. Caffeine is a drug and should be respected as such, however it is also known to have a range of positive effects including:. Caffeine clearly improves alertness, mental focus and attention. This is because caffeine not only acts as a brain stimulant, it also blocks receptors for adenosine, which normally prevents the release of excitatory brain chemicals.

With adenosine out of the way, these brain-sparking chemicals can flow more freely—giving you a surge of energy and potentially improving mental performance.

However, your body can get used to caffeine quickly which reduces the positive effects. Caffeine is a go-to supplement for many athletes taking part in endurance events such as a 1,meter running race or a cycling event and has been shown to improve performance.

However, it is less effective in high intensity training, especially in untrained individuals where it is shown to have no effect, so grabbing an Americano before your next HITZone session is not recommended!

As such, cycling may not be benefited here but, again, with just one trial, this conclusion is probably premature. With regard to brain function, one crossover study [ ] showed that a decaffeinated high-CGA green coffee mg CGA, 11 mg caffeine improved the performance of attention tasks, subjective alertness and other aspects of psychological state in 39 healthy older adults, whereas a standard decaffeinated instant coffee mg CGA had no effect.

A subsequent study [ ] replicated the beneficial psychological effects of the decaffeinated high-CGA coffee, but found that neither a placebo drink nor a control drink, containing the chlorogenic acid and caffeine components, had any effects. Taken together, these studies show that a low caffeine, high CGA green coffee has beneficial psychoactive effects, but that these effects may depend in part on interactions with components other than just caffeine and CGA.

Two studies have also assessed the effects of caffeine-free green coffee extracts. Effects were not seen earlier than this i. Together, these findings might suggest that a minimum of 12 weeks is required to exert effects on these cognitive performance outcomes.

Coffee berry A small but recently growing body of research has also investigated the behavioural effects of coffee berry extracts made from the fruit pulp surrounding the coffee bean. To date, there has been little research investigating the ergogenic effects of coffee berry, although one small study found that this intervention caused an improvement in antioxidant status but had no effect on exercise parameters [ ].

In a non-exercise context, single doses of coffee berry extracts have been shown to increase the synthesis of neurotrophic factors such as BDNF [ , , ], and a range of coffee berry extract doses , , mg reduced the mental fatigue, and attenuated the decreased alertness, associated with extended performance of demanding cognitive tasks [ , ].

A follow-up study contrasting the cognitive and psychological state effects of mg coffee berry extract alone, and combined with apple polyphenol extract, found that coffee berry alone increased alertness and vigour and decreased fatigue across the 6 h of post-dose assessments.

However, this effect was blunted by the addition of apple polyphenols, although this extract did improve the performance of an executive function task [ ], demonstrating the importance of, where possible, considering the effects of treatment arms in isolation.

Brain imaging studies have also demonstrated that drinks containing coffee berry extract mg can increase cerebral blood flow in the frontal cortex during cognitive tasks [ ] and increase functional connectivity between brain regions implicated in task performance [ ].

One study has also investigated chronic effects. This effect was not seen when the extract was only taken in the evening and may speak to the benefits of the alerting effects of coffee berry in the morning when the psychophysiological effects of this are more impactful i.

This also fits with the peak plasma levels of caffeine, which would be anticipated between 15 and 30 min in most consumers and may adversely incite wakefulness when coffee berry is consumed in the evening.

Although neither green coffee nor coffee berry products have benefitted from substantial research efforts as yet, both contain higher levels of potentially bioactive CGAs, and might be expected to exert greater independent effects on function.

It is also possible that the functionality of these low caffeine extracts might be increased by higher levels of caffeine. Green tea contains significant levels of flavanols, including catechin, epicatechin and the tea-specific polyphenol epigallocatechin gallate EGCG.

It also contains the tea-specific amino-acid ʟ-theanine and caffeine. Meta-analyses of controlled trial data show that the consumption of green tea extracts is associated with a number of cardiovascular and anthropomorphic benefits, including enhanced total antioxidant status [ ], improved glucoregulation [ ] and significant benefits to weight, BMI and waist circumference, irrespective of caffeine content [ ].

Whilst the exercise performance effects of green tea extracts remain unclear, consumption of caffeinated green tea extracts for more than 1 week has been shown to reduce exercise-induced oxidative stress [ ]. Two fMRI studies demonstrated modulation of brain function following single doses of a whey milk drink supplemented with green tea extract [ , ], but failed to match their whey control drink for caffeine.

Two studies also demonstrated cerebral blood flow and electroencephalogram EEG effects of single doses of the tea polyphenol EGCG [ , ], but in the absence of any cognitive performance effects. There are rather more data with regard to the green tea components caffeine and ʟ-theanine and their potential interactions.

Whilst ʟ-theanine by itself is not associated with any significant benefits to mood or cognitive function, a meta-analysis of the data from seven acute dose studies found that caffeine and ʟ-theanine combinations increased alertness and attention task performance for the first 2 h after consumption.

The disparate doses employed in these studies ranged from 30 to mg caffeine and from 12 to mg theanine, with a stronger relationship between caffeine dose and performance of the two [ ].

Several studies have also directly investigated the potential interactive effects of caffeine and l -theanine. One study [ ] found that a single dose of 50 mg caffeine had its expected effects in terms of improved alertness and increased accuracy on an attention task, but that the combination of caffeine with mg ʟ-theanine resulted in additional benefits in terms of improved attention task performance and improved long-term memory, an outcome not typically associated with caffeine alone.

Similarly, whilst single doses of mg of ʟ-theanine and mg of caffeine improved the performance of one of two attention tasks, their combination resulted in a numerically more significant effect than either treatment alone [ ]. In contrast to these previous studies, a further study [ ] found that whereas both mg caffeine and mg ʟ-theanine had significant but markedly different effects on attention task performance, their combination had no cognitive effects.

In this instance, caffeine both alone and in combination with theanine modulated mood, but theanine alone had no effect. This study also found that the reduction in cerebral blood-flow in the frontal cortex during task performance caused by caffeine was abolished by the addition of ʟ-theanine.

Finally, a recent brain imaging fMRI study showed that whilst both ʟ-theanine mg and caffeine mg exerted different, independent effects on brain activation, the two compounds taken together elicited a synergistic, interactive effect on activation in brain regions associated with task performance [ ].

There is evidence that caffeine increases the bioavailability of tea flavanols [ , ] and evidence of synergistic relationships between caffeine and the tea amino-acid ʟ-theanine with respect to brain function. The mental performance effects of tea extracts or infusions and the interactive contributions of their caffeine, ʟ-theanine and flavanol components deserve greater attention.

Additionally, the delivery of caffeine in its naturally consumed state within tea and coffee drinks arguably offers a much more realistic insight into its effects than an isolated, encapsulated dose of caffeine. However, this raises the question of whether additions of milk and sugar, in particular, are permitted.

These may make the drink more palatable for many consumers, but may also alter the plasma kinetic profile of phenolics. Zhang et al. Further, a small amount of research suggests that this can negatively impact some of the mechanisms relevant to this review; Lorenz et al.

As a result, the findings of studies that permitted the use of milk and sugar should likely be considered differently to those trials that administered black coffee alone.

Moving forwards, it is important for future trials to decide whether the trade-off between having a more palatable investigational product, especially with older participants, outweighs the benefits of having a macronutrient-free caffeine drink.

Caffeinated energy products include a wide range of gels, bars and drink powders. However, ready-made energy drinks and shots have lately attracted the majority of relevant, product-specific research and it could be argued that this is due to the fact that these products still dominate the market.

However, to the best of our knowledge, no functional caffeinated gums containing additional compounds even glucose have yet been investigated with randomised controlled trials, and so the effects here are exclusively attributed to caffeine.

As such, caffeine-only gums do not fall within the purview of this review. Energy drinks and shots typically contain caffeine and taurine, often in combination with glucose, amino acids, vitamins or herbal extracts.

Conversely, meta-analyses purportedly investigating the ergogenic effects of caffeine have often conflated pure caffeine and energy drink studies e.

In reality, there is increasing evidence of interactive effects between caffeine and the other bioactive components of these products. In terms of ergogenic effects, a recent meta-analysis of the data from 34 studies [ ] found that energy drinks containing caffeine and taurine resulted in significantly improved endurance exercise test performance, jumping, muscle strength and endurance, and cycling and running performance.

The benefits following the energy drinks were also significantly related to the amount of taurine in the drinks rather than caffeine. These findings suggest that taurine plays a pivotal role in the effects of products combining caffeine and taurine, and finds support in a subsequent meta-analysis confirming the ergogenic effects of taurine mono-treatments [ ].

However, a more recent review suggests that the effects of taurine alone, in the absence of caffeine, are equivocal [ ]. Whilst this review of 19 trials did observe positive effects of taurine supplementation across a range of activities V O 2max , time to exhaustion, 3- and 4-km time-trial, anaerobic performance, muscle damage, peak power and recovery , this appeared hugely buoyed by timing of ingestion and the type of exercise protocol.

Given that plasma taurine concentrations peak at approximately 1-h post oral consumption, it is likely that the above acute ergogenic effects are due to mechanisms unrelated to muscular changes but rather directly related to effects within the central nervous system.

It is also likely that glucose plays a pivotal role in caffeinated energy drinks above and beyond the effects of caffeine, or indeed glucose, in isolation. Carbohydrate ingestion has a well-established ergogenic effect on endurance exercise [ ] and, more recently, resistance exercise performance [ ], and so it is unsurprising that a recent meta-analysis of energy drinks, containing both caffeine and glucose, observed similar ergogenic benefits across a range of exercise types [ ].

These included cycling, power-based activities including within team sports and more fine-motor abilities like serving and strokes in racket sports and performance in golf and fencing.

The authors raise the interesting point here that consumption under these conditions serves to both supplement ergogenic compounds like caffeine and glucose, as well as to rehydrate.

As such, any psychophysiological effects of these compounds could not be disentangled from the effects of hydration alone, a function which, in itself, has a huge impact on endurance exercise in particular [ ]. A recent study comparing an energy drink to an isocaloric control drink also demonstrated ergogenic benefits plus improved performance on a simple reaction task that was interposed between warm-up and a bout of maximal exertion.

These effects were seen alongside improved mood, vigour and ratings of perceived effort measured post-exercise [ ]. In contrast, two studies failed to establish any energy drink-related benefits to cognitive task performance following physical exercise [ ] or a session of eSports [ ], although this is most likely to be due to the very small samples employed.

This therefore leaves open the question of whether the combination with other bioactive ingredients resulted in broader effects than those expected following caffeine alone.

Taken as a whole, caffeine-containing energy drinks have consistent beneficial effects on attention task performance [ ]. Studies comparing energy drinks to an isocaloric glucose containing placebo have also demonstrated improved simulated driving performance [ ] and benefits that would not be expected from caffeine alone, including improved memory performance [ ] and enhanced working memory in the absence of improved attention [ ].

The results demonstrated broad cognitive benefits that included improved accuracy and speed of attention task performance and improved alertness. More importantly, improvements were also seen on measures that would not be sensitive to caffeine, including across working memory and episodic memory tasks and in ratings of depression and anxiety.

All of these improvements were also seen during the later assessments, when the effects of caffeine might be expected to be waning.

A subsequent, smaller and less methodologically stringent study broadly confirmed the findings of this trial and demonstrated that the effects of the same energy shot were broader and more pronounced than either caffeine alone or coffee with a similar level of caffeine [ ]. With regard to specific ingredients, two studies have compared caffeine, taurine and their combination.

In one of these studies taurine attenuated the increased alertness associated with caffeine alone [ ], and in the other taurine blunted the increased speed of attention task performance associated with caffeine [ ].

Irrespective of the direction of the functional relationship seen here, these results also confirm that both taurine and caffeine contribute to the effects of products that combine them.

Overall, there is no evidence to support the contention that the psychological effects of energy drinks are solely attributable to their caffeine content. In contrast, the small amount of available evidence suggests that multi-component energy drinks and shots will have beneficial physical and psychological effects that are either stronger, or in the case of cognition, broader, than would be expected from their caffeine content alone.

In terms of potential benefits to mental performance, a number of phytochemicals and herbal extracts derived from non-caffeinated plants engender mental performance benefits that are broader than those seen following caffeine.

Whilst these extracts are most often consumed by themselves, several are commonly found in functional drink products. However, the levels of bioactive components in the extracts used in energy drink products are unclear, and no research has attempted to disentangle any interactions with caffeine.

The following is a brief summary of evidence regarding some potential candidates for enhancing mental performance. Meta-analyses of early data suggested that curcumin, the principal polyphenol in turmeric, may be effective in treating mood disorders [ ]. Another potential candidate is mangiferin, the principal polyphenol in mango leaf extracts.

A recent single-dose study extended these findings to brain function [ ] and demonstrated wide-ranging improvements to overall accuracy of cognitive task performance, including specific benefits to attention, memory and executive function tasks, across 6 h post-dose, following the consumption of mg of the same mango leaf extract.

The performance of cognitively demanding tasks was also improved. Volatile terpenes, which comprise the principal component of essential oils, have a number of significant direct e.

Volatile terpenes are readily absorbed by mucosal membranes, and in a later study, the wearing of a peppermint infused non-transdermal skin patch for 6 h resulted in improvements in memory, attention and alertness in comparison to a non-aroma skin-patch in young adults [ ].

Research demonstrates cognitive enhancement, including in terms of memory and attention task performance, following single doses of ginkgo extract [ , , , , , ] in young adults, and following supplementation for 7 days or longer in both younger [ ] and older [ , , ] participants.

These latter trials were performed by the same research team as were [ , ] and [ , ] , and this may contribute to the relatively clear pattern of effects attributed to Ginkgo biloba , relative to many of the other compounds covered within this review.

In all three cases, key methodological principles, such as dose and the source of the investigational product, were maintained between trials and this allows for a more robust comparison across the field. It is rarely possible for one research team to develop a consistent research profile with just one compound like this, but it would be prudent for disparate teams to try, where possible, to align methodological practices and make it easier to compare effects across the literature.

The primary bioactive component of Asian Panax ginseng and American ginseng Panax quinquefolius extracts are triterpene ginsenosides.

Compounds from this class owe their bioactivity to a structural similarity to many animal hormones. Single doses of a standardized American ginseng extract also resulted in improved working memory and dose-dependent increases in speed of task performance [ ] and improved working memory performance [ ].

Again, the consistency of these effects can partly be attributed to methodological consistency across many of these individual trials, with the majority of studies conducted within two labs, utilizing standardised extracts at the same or similar doses.

It is quite possible that co-administration of caffeine alongside other psychoactive phytochemicals, including those noted above, will result in additive or interactive effects with regard to the nervous system.

In this regard it is notable that, for instance, monoterpenes [ , ] and triterpenes, including ginsenosides [ , ], alongside many other phytochemicals, are substrates for the same CYP enzymes as caffeine e.

As an example of this, a study in rats found that ginsenosides and caffeine had a synergistic effect with regard to antidepressant effects [ ].

Globally, caffeine is the most widely consumed psychoactive compound and ergogenic aid. When taken in a purified form in a research context caffeine has reasonably well delineated ergogenic and psychological effects.

However, in mental performance terms, these effects do not consistently extend beyond improving attention, including psychomotor function and vigilance. Caffeine alone has little impact on the other cognitive domains intrinsic to aspects of sporting performance.

Additionally, research almost exclusively investigates the effects of single, acute doses of caffeine, and so the extent to which these findings can be applied to real-world scenarios of repeated daily consumption is arguably limited.

In the real world, athletes and participants in sport typically consume caffeine alongside a complex mixture of other potentially bioactive compounds, either in the form of products derived from caffeine-synthesising plants or as an additive to multi-ingredient products.

As an aside, this does raise important questions of safety and, whilst the trials included within this narrative review report no serious adverse events, it would be remiss of this review not to highlight the continued need to question the potential unanticipated effects of combining different compounds within one product and the effects of cumulative doses of the ingredients.

The individual doses of each compound alone may not result in an adverse event, but there is scope for unforeseen negative effects following their combination. This is especially concerning when one considers that caffeine may enhance the absorption and distribution of other co-consumed ingredients and vice versa , and so, whilst doses might seem safe in isolation, their enhanced pharmacokinetics may evince unsafe psychophysiological effects.

As an example, this has been reported to a small extent with over-consumption of energy drinks in adolescent groups [ ]. Controlled trial evidence in humans has directly confirmed functional interactions between caffeine and polyphenols, l -theanine and taurine. Additionally, high polyphenol extracts from several caffeine-synthesising plants with low levels of caffeine engender broader benefits to mental performance than expected from caffeine, even at much higher doses.

This is certainly the case for high-flavanol cocoa and guaraná extracts, and high-CGA coffee berry. In the case of high-flavanol cocoa extracts the benefits to psychological functioning are evident when directly compared to caffeine-matched control treatments.

This gives a clear indication of the added value of cocoa-flavanols, but does not disentangle any interactions in the combination. Herein lies the problem for this research area. Very few of the many controlled trials assessing the psychological or ergogenic effects of caffeinated products have been designed with the requisite comparator arms to disentangle the interactive effects of caffeine.

Ideally, studies could also instigate a full fractionation of all possible permutations of combination products. Further, trials rarely investigate both the acute and chronic effects of consuming caffeine alongside these additional ingredients.

It may therefore be the case that where unconvincing acute effects of these combinations do exist, that longer term administration may result in more pronounced, or at least different, effects. As such, where these unconvincing effects exist, it is probably too premature to discount them entirely.

As an additional caveat, future research should undoubtedly be more representative of non-male participants. It seems likely that consuming pure anhydrous caffeine is the most impoverished method of delivering caffeine for the enhancement of either physical or psychological functioning.

However, more research is needed on a number of fronts. First, to disentangle the contributions of caffeine and the non-caffeine bioactive compounds in caffeinated products.

Second, to establish the optimal level of caffeine in caffeinated products, including the potential for additional caffeine to further enhance the functional benefits of low caffeine extracts. Finally, to explore the potential for caffeine to potentiate the benefits seen following multifarious other psychoactive phytochemicals that have not been meaningfully combined with caffeine to date.

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Multi-ingredient, caffeine-containing dietary supplements: history, safety, and efficacy. Clin Ther. Morelli M, Simola N. Methylxanthines and drug dependence: a focus on interactions with substances of abuse.

In: Methylxanthines. Berlin: Springer; Chapter Google Scholar. Liu QS, Deng R, Fan Y, Li K, Meng F, Li X, et al. Low dose of caffeine enhances the efficacy of antidepressants in major depressive disorder and the underlying neural substrates.

Mol Nutr Food Res. Ursing C, Wikner J, Brismar K, Röjdmark S. Caffeine raises the serum melatonin level in healthy subjects: an indication of melatonin metabolism by cytochrome P CYP 1A2. J Endocrinol Invest. Lipton RB, Diener H-C, Robbins MS, Garas SY, Patel K. Caffeine in the management of patients with headache.

J Headache Pain. Weiser T, Richter E, Hegewisch A, Muse D, Lange R. Efficacy and safety of a fixed-dose combination of ibuprofen and caffeine in the management of moderate to severe dental pain after third molar extraction.

Eur J Pain. Smith AP, Nutt DJ. Effects of upper respiratory tract illnesses, ibuprofen and caffeine on reaction time and alertness. Southward K, Rutherfurd-Markwick KJ, Ali A. The effect of acute caffeine ingestion on endurance performance: a systematic review and meta-analysis.

Sports Med. Salinero JJ, Lara B, Del Coso J. Effects of acute ingestion of caffeine on team sports performance: a systematic review and meta-analysis. Res Sports Med. Pickering C, Kiely J. Are low doses of caffeine as ergogenic as higher doses?

A critical review highlighting the need for comparison with current best practice in caffeine research. Grgic J, Pickering C, Del Coso J, Schoenfeld BJ, Mikulic P. CYP1A2 genotype and acute ergogenic effects of caffeine intake on exercise performance: a systematic review.

Filip A, Wilk M, Krzysztofik M, Del Coso J. Inconsistency in the ergogenic effect of caffeine in athletes who regularly consume caffeine: is it due to the disparity in the criteria that defines habitual caffeine intake?

Lara B, Ruiz-Moreno C, Salinero JJ, Del Coso J. Time course of tolerance to the performance benefits of caffeine. PLoS ONE. Goncalves LDS, Painelli VDS, Yamaguchi G, Oliveira LFD, Saunders B, da Silva RP, et al.

Dispelling the myth that habitual caffeine consumption influences the performance response to acute caffeine supplementation. J Appl Physiol. Salinero JJ, Lara B, Jiménez-Ormeño E, Romero-Moraleda B, Giráldez-Costas V, Baltazar-Martins G, et al. More research is necessary to establish the ergogenic effect of caffeine in female athletes.

Gomez-Bruton A, Marin-Puyalto J, Muñiz-Pardos B, Matute-Llorente A, Del Coso J, Gomez-Cabello A, et al. Does acute caffeine supplementation improve physical performance in female team-sport athletes?

Evidence from a systematic review and meta-analysis. Mielgo-Ayuso J, Marques-Jiménez D, Refoyo I, Del Coso J, León-Guereño P, Calleja-González J. Effect of caffeine supplementation on sports performance based on differences between sexes: a systematic review.

Lara B, Gutiérrez-Hellín J, García-Bataller A, Rodríguez-Fernández P, Romero-Moraleda B, Del Coso J. Ergogenic effects of caffeine on peak aerobic cycling power during the menstrual cycle. Spriet LL. Exercise and sport performance with low doses of caffeine.

Ruxton C. The impact of caffeine on mood, cognitive function, performance and hydration: a review of benefits and risks. Nutr Bull. The acute physiological and mood effects of tea and coffee: the role of caffeine level.

Pharmacol Biochem Behav. Smit HJ, Rogers PJ. Effects of low doses of caffeine on cognitive performance, mood and thirst in low and higher caffeine consumers. Smith A, Sturgess W, Gallagher J. Effects of a low dose of caffeine given in different drinks on mood and performance.

Hum Psychopharmacol-Clin Exp. Brice C, Smith A. The effects of caffeine on simulated driving, subjective alertness and sustained attention.

Childs E, de Wit H. Subjects viewed a 6-by-6 block of squares with 36 red and green squares arranged in random order each block contained an equal number of red and green squares. This task of immediate recall allowed subjects to view the arrangements for as long as they liked and then press a key to present two choices, one of which matched the original set of squares.

They were required to pick the correct matching square. Twenty trials were presented. Reaction Time. A choice reaction time task was used to measure reaction time. The visual-motor task required subjects to press the numbered keyboard keys corresponding to numbers presented on the screen.

The digits 0 through 9 appeared one at a time in the center of the screen. The stimulus remained on until a response was made. Fifty numbers were presented. Profile of Mood States. The Profile of Mood States POMS McNair et al.

Subjects rated themselves on each adjective from 1 not at all to 5 extremely. Visual Analog Scales VAS. Subjects rated themselves with a mark along a line mm in length. They were heart pounding, headache, sweaty, and upset stomach. The POMS and VAS were completed five times during the sleep deprivation period prior to drug administration at and h on days 1 and 2 and at h on the morning of day 3 2 h before caffeine administration.

POMS and VAS ratings were taken at 1, 2, 4, 8, and 12 h after drug administration. Multiple Sleep Latency Tests. Each modified multiple sleep latency test MSLT was conducted by having the subjects lie in bed in a darkened, sound-attenuated room with their eyes closed.

They were instructed to relax and allow themselves to fall asleep. EEGs, EOGs, and EMGs were displayed on a Grass Electroencephalograph model 8—10D for on-line scoring of awake versus sleep during the MSLT.

An experimenter awakened a subject after 30 s of stage 2 sleep or the onset of rapid eye movement REM. The test was terminated at 20 min if sleep had not occurred.

MSLTs were conducted at , , , , , and h on days 1 and 2 of the sleep deprivation period. MSLTs were conducted eight times on day 3 at 1. Stanford Sleepiness Scale. For the Stanford Sleepiness Scale SSS Hoddes et al. The SSS was completed approximately every 2 h throughout the sleep deprivation period at , , , , , , , , , , and h on days 1 and 2.

The SSS was completed eight times on day 3 at 1, 2, 3, 4, 6, 8, 10, and 12 h after drug administration. Measurements of blood pressure, heart rate, and oral temperature were taken at least every 2 h throughout the sleep deprivation period. After caffeine administration, measurements were taken at 15, 30, 60, 90, , , , and min and then hourly until 13 h after drug administration.

Blood samples were collected prior to and at 15, 30, 60, and 90 min, and 2, 2. Results are reported elsewhere Eddington et al. Separate two-factor repeated measures analysis of variance by using the General Linear Model SAS Institute, Cary, N. were performed for each dependent variable and POMS subscale.

The two factors were group or dose and time. First, each dependent variable was analyzed for group differences and effects of the sleep deprivation period prior to the drug administration by using all measurements made prior to drug administration.

Second, each dependent variable was analyzed for the effects of drug and time after drug administration by using the last value obtained prior to drug administration and all values obtained after drug administration.

Statistical results thus reported for the main effects of drug dose, the main effects of time, and an interaction between these main effects.

Significant main effects were further evaluated by the Newman-Keuls Multiple Range Test. For each of the tasks, three measures of performance were analyzed: accuracy percent correct , speed responses per unit of time , and throughput number of correct responses per unit of time.

The throughput measure takes both accuracy and speed of performance into account and was subjected to statistical testing. Predrug means include data for all subjects; there were no differences between the groups prior to drug administration.

Performance, Mood, and Physiology Analysis of Variance Summary. Performance on the choice reaction time task for 8 h after drug administration in subjects who received the mg dose was significantly different from that in subjects who received the placebo.

The mg dose improved performance for 4 h. For subjects receiving the mg dose, performance was not significantly different from that for subjects receiving the placebo at any point following administration.

For subjects receiving the mg dose, performance remained significantly better than that for subjects receiving placebo for 10 h after drug administration, with no significant differences observed among the dose groups at the final h testing period.

Performance on the logical reasoning task by subjects receiving the two highest doses of caffeine was significantly better than by subjects receiving placebo for the entire h period. In addition, caffeine restored performance to the levels obtained after rest during this interval.

Performance after administration of the mg dose was significantly different from that after administration of placebo for 6 h after drug administration. The effects of sleep deprivation on mood, as measured by the POMS and VAS, are reported in more detail elsewhere Penetar et al.

Briefly, the scores of all six subscales of the POMS changed significantly as a result of the sleep deprivation. Similarly, ratings on the VAS showed the effects of sleep deprivation. Following caffeine administration, significant increases in the POMS vigor subscale and significant decreases in the POMS subscales of fatigue and confusion were observed Table 20—1.

Vigor ratings for all three dose groups were significantly different from those for the placebo group for 2 h after caffeine adminstration. Vigor ratings for the mg dose group were 97 percent of those for subjects in the rested condition 1 h after caffeine administration and remained at 84 percent of those for subjects in the rested condition at the 2-h measurement.

Conversely, fatigue ratings for all three caffeine dose groups decreased significantly for 2 h following caffeine administration. Confusion ratings in the mg dose group were significantly decreased in comparison with those in the placebo group 2 h after caffeine administration.

Caffeine reversed the sleep deprivation effects reported in subjective ratings of alertness for 2 h, energy levels for 12 h, confidence for 2 h, sleepiness for 12 h, and talkativeness for 2 h following drug administration. Caffeine significantly increased self-rated anxiety for 2 h, and jitteriness or nervousness for 12 h following drug administration.

Ratings of heart pounding, headache, sweatiness, and upset stomach were unaffected by caffeine. For the rested condition day 1 , mean sleep latency periods were between Latency to stage 2 sleep following caffeine administration. Average values of the Stanford Sleepiness Scale increased gradually from 1.

Caffeine's effects were significant for 2 h after drug administration and were not dose-related i. Diastolic blood pressure and oral temperature were significantly affected by caffeine administration Table 20—1 and Figure 20—3. At 1 h after admini stration, both the and the mg doses significantly increased diastolic blood pressure in comparison with the placebo; there were no significant differences at other time points.

The mg dose of caffeine significantly increased oral temperature in comparison with placebo at several measurement times after administration: 2, 2. Neither systolic blood pressure nor pulse was significantly affected. Time course of caffeine effects on four vital signs.

Caffeine was observed to have significant effects on diastolic blood pressure at 1 h and oral temperature from 2 to 12 h after drug administration. See text for details. The study described here indicates that caffeine is effective in reversing the performance degradations and the alterations in mood and alertness produced by periods of prolonged sleep deprivation.

The results indicate that these beneficial effects can be long-lasting and not at the expense of serious mood or physiological side effects. Sleep deprivation degrades cognitive performance.

The effects of caffeine on performance in non-sleep-deprived volunteers have been well documented, even at the low dose levels commonly found in food and drink products see Lieberman [] for a review. The study described here extends the usefulness of caffeine, showing that large doses up to mg are effective in improving a variety of cognitive performances in sleep-deprived individuals, and outlines the time course of its effects in these individuals.

The tasks used in the present study were chosen to sample a variety of cognitive abilities with varying mental demands. Choice reaction time requires little thinking but does require great accuracy and speed. Caffeine produced improved performances of all three tasks, with performance returning to those of rested subjects for up to 12 h after caffeine administration.

Caffeine was not observed to affect recall or code substitution tasks. In toto, these results are in concert with those presented previously Lieberman, ; Roache and Griffiths, and document for the first time the relatively long-lasting effects of this drug on cognitive performance. The study described here shows that caffeine compares favorably with amphetamine in reversing the effects of sleep deprivation on cognitive performance.

Using an identical sleep deprivation paradigm, Newhouse et al. Sleep deprivation also alters mood and degrades alertness. The present study documents the fact that caffeine can have significant beneficial effects in reversing these mood changes; sleepiness and confusion declined, whereas increases in energy and confidence levels were reported.

Although there were increased ratings of anxiety and jitteriness or nervousness, these effects were not severe and did not elicit complaints from the subjects. Depending on the measure, alertness, which was severely degraded by 49 h of sleep deprivation, was improved for 2 to 4.

In this regard, caffeine was not as effective as amphetamine. The alertness of amphetamine treated subjects 20 mg , as measured by sleep latency tests, was nearly restored to the levels of rested subjects for 7 h Newhouse et al.

Caffeine's effects on alertness are therefore less potent and shorter acting than amphetamine's. Caffeine's effects on physiological measures are important for assessing its usefulness as a stimulant. The study described here shows that relatively high doses of caffeine are well tolerated by sleep-deprived individuals and that its effects are similar to those found in other studies in non-sleep-deprived subjects given lower doses than those used in the present study Myers, ; Newcombe et al.

Additionally, there were no changes in self-reports of other side-effects heart pounding, headache, sweatiness, upset stomach. Of note was caffeine's observed effect on oral temperature. Oral temperature normally rises during the day, from a low in the early morning hours to a peak in the early evening hours.

The subjects in the present study showed this typical response. Caffeine increased temperatures above the normal rise throughout the observation period, again revealing an important aspect of its effects and duration of action.

The significance of this effect awaits further experimentation, although this type of effect has been observed previously with another stimulant, d -amphetamine Newhouse et al. The authors thank the staff of the Behavioral Biology, in particular Sharon Balwinski and Kevin Peyton, for assistance in the conduct of the experiment described here.

Investigators adhered to AR 70—25 and USAMRDC Reg 70—25 on the use of volunteers in research. Use of trade names does not constitute endorsement of product.

The views of the authors do not purport to reflect the position of the Department of the Army or the Department of Defense. HARRIS LIEBERMAN: We have some unpublished data from a couple of studies in which we did find significant effects of caffeine on mood swing.

We did not use doses as low as 32 milligrams but used doses of 64 and milligrams of caffeine. Effects on performance by doses lower than those are hard to detect, but over the long run, over a series of studies, my feeling is that there really are effects with low dosages, and those are the doses that we typically take in our background.

JOEL GRINKER: I was just curious whether in any of the caffeine studies or in any of the other supplement studies age has been looked at systematically as a factor.

I have two thoughts, one, that in fact it might potentiate the ability of older individuals or that in fact it has less effectiveness, and I wonder if you have any comments. DAVID PENETAR: I have here one study that related to age. Typically, these studies were done, with young, healthy males.

HARRIS LIEBERMAN: We did look at the age parameter in one of our caffeine studies, but we did not see any significant differences as a function of age or gender.

Do you find much variation that would indicate that shortness of sleep time versus onset of sleep, etc. Are they uniform in your subjects or are they highly individualistic?

DAVID PENETAR: What we do is we bring them into the study the night before and give them 9 hours of time in bed before we start the study, so at that time they are all pretty consistent in the amount of sleep that they have had. Do you find a uniform effect in terms of delay of sleep or shortness of length of sleep, etc?

DAVID PENETAR: We did not specifically look at that because by the time they went to bed it was over 12 hours after they had received caffeine. WILLIAM WATERS: A couple of questions. One pertaining to the onset of parameters. Did you have a look at whether or not you have any data or whether or not sleep can be induced prior to that?

WILLIAM WATERS: It could be that what you had was a referral of something that might allow it to occur. The other thing was, under the influence of caffeine, did you notice any change in the number, the length, stage one, and arousals?

DAVID PENETAR: Again, by the time our subjects went to bed, it was over 12 hours after they had received the caffeine, and we did not see any changes; there were no differences between the groups. We did monitor them. We recorded them through their sleep, and we saw no differences in sleep architecture, time of sleep, time to bed, or sleep efficiency; we saw no differences for 12 hours.

JOHANNA DWYER: I worked with a neurologist who was interested by some observations years ago, when they did a lot more electroconvulsive shock than they do now. Apparently, they used to prime the patients with caffeine, and by doing this, they could use a lower level of shock and still get the same effect.

The reason I bring it up here is not because I hope anyone here is heavily into this, but rather, are there other changes in the electroencephalograms in terms of caffeine's effects that may be in addition to what we have been talking about?

ALLISON YATES: Just one thing. I noticed in some of the graphs that it almost looked as if at milligrams the subjects might have had even a little bit better performance than they had initially in their first 24 hours.

This result is important in considering enhancement of performance with normal subjects. HARRIS LIEBERMAN: Yes, two slides that you showed with my studies, the vigilance and reaction times, were for subjects who had stayed up all night the night before and who were back in the morning after the administration.

Their performances were similar to those with placebos under the same conditions. I consider that to be above normal, although since caffeine is such a common component of the diet, it is hard to untangle it all.

HARRIS LIEBERMAN: We typically include that as a parameter in our studies and look to see whether there are differences between moderate, low, and heavy caffeine users in their responsiveness, and in the low and moderate range there is not much difference.

When you get to the real high users, you see big differences in responsiveness. That depends on the timing of administration, whether they are in a deprivation stage, or whether they are already on a lot caffeine.

HARRIS LIEBERMAN: Average caffeine consumption is about milligrams per day, which is maybe three cups of not very strong coffee. I define high for the purpose of categorizing subjects as above or milligrams per day. We used to always think that members of the Army must be heavy coffee drinkers because you get that perception, but looking out in field studies where soldiers are eating rations, we found out that even though you gave a meal ready-to-eat, 90 percent of the coffee packets were returned unused.

The rest of the 10 percent probably went mostly to the senior sergeants, who had a chance to stay by the talking place and make some coffee for themselves.

So young soldiers in the field today are not heavy coffee drinkers. I am sure they drink plenty of caffeine if they have carbonated beverages. But most of the time carbonated beverages are not available to them in the field, although maybe in Desert Storm cans of Coke manged to get inside of the tanks anyway.

My question is, has anybody done sleep studies on evaluating caffeine using the vehicle of delivering the caffeine in the form of a cola or in the form of a coffee beverage itself? DAVID PENETAR: A number of studies look at coffee drinking when they give caffeine.

In fact, in some of the studies reported here, they took decaffeinated coffee and added caffeine to it, and the subjects drank it that way. In other studies it was either caffeine pills or caffeine powder dissolved in some drink.

For instance, I am sure your subjects knew when they were receiving a placebo. DAVID PENETAR: Ours was powdered caffeine dissolved in a lemon juice drink, and the lemon juice drink was very bitter.

As you know, caffeine powders are very bitter, so they could not tell what they were drinking other than lemon juice drink. WILLIAM BEISEL: So many of the emergency rations and so on seem to be candy bars with chocolate flavoring. How much of that is caffeine? DAVID PENETAR: Milk chocolate has about 7 milligrams per ounce, whereas bakery chocolate or unsweetened chocolate has about 35 milligrams per ounce.

They figure that, for example, a Hershey's candy bar has 25 to 35 milligrams per ounce, so it is not a lot, and it is less than most sodas.

Penetar, Walter Reed Army Institute of Research, Washington, D. Subjects were paid for their participation. The investigators adhered to AR 70—25 U. Department of the Army, and U. Army Medical Research and Development Command Reg 70—25 , on the use of volunteers in research.

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EFFECTS OF CAFFEINE ON MOOD AND ALERTNESS Several questionnaires and methods have been used to assess caffeine's effects on mood. MATERIALS AND METHODS Subjects Fifty normal, healthy, nonsmoking, drug-free males between the ages of 18 and 32 mean age, Procedure Subjects arrived in the laboratory in groups of three to four each on the evening before the sleep deprivation period began.

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Psych Central. Conditions Discover Quizzes Resources. How Does Caffeine Affect Your Body? Medically reviewed by Alexandra Perez, PharmD, MBA, BCGP — By Kaitlin Vogel — Updated on December 9, How caffeine affects the brain.

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Personal interview. Iriondo-DeHond A, et al. Effects of coffee and its components on the gastrointestinal tract and the brain-gut axis. Caffeine use disorder: A comprehensive review and research agenda.

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