Caffeine, coffee and health

Contents of chlorogenic acids and caffeine in various coffee-related products

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The total amount of CGAs and caffeine were quantified in different types of coffee-related drinks.

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The coffee with the highest content of CGAs was unblended roasted and ground coffee sold in supermarkets.

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The most caffeine-rich coffee was Americano coffee from coffee shops.

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The coffee with the highest value of caffeine/CGAs ratio was milk-added RTD coffee.

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According to caffeine/CGAs ratio, the good quality coffee was found to be the unblended ground coffee from market.

Coffee is the most popular beverage in the Republic of Korea, other than Korea's traditional green tea. Coffee contains many physiologically active substances, such as chlorogenic acids (CGAs) and caffeine. Previous studies have focused on the content of CGAs and caffeine in brewed coffee. This study quantified the total amounts of CGAs and caffeine using high-performance liquid chromatography coupled with a diode array detector in 83 various coffee-related products, such as instant coffee, roasted and ground coffee sold in supermarkets, ready-to-drink coffee, and Americano coffee sold in franchise restaurants in the Republic of Korea. According to the results of this study, the coffee with the highest content of CGAs was unblended roasted and ground coffee sold in supermarkets, with a mean value of 194.1 ± 67.7 mg/serving, and the most caffeine-rich coffee was Americano coffee from coffee shops, with a mean value of 166.1 ± 37.5 mg/serving. The caffeine/CGA ratios were determined in various coffee beverages because they are useful parameters for estimating the human health. The lowest mean caffeine/CGAs ratio of 0.5 ± 0.1 was found in unblended ground coffee sold in supermarkets, and the highest mean ratio of 2.5 ± 1.4 was found in milk-added ready-to-drink coffee. Adult caffeine tolerance is defined as 400 mg a day in the Republic of Korea. However, this value highlights the importance of medicines, carbohydrate beverages, tea, chocolate, cocoa products, energy drinks and other sources of caffeine that can contribute to the total intake of caffeine.

Determination of chlorogenic acids and caffeine in homemade brewed coffee prepared under various conditions

Coffee, a complex mixture of more than 800 volatile compounds, is one of the most valuable commodity in the world, whereas caffeine and chlorogenic acids (CGAs) are the most common compounds. CGAs are mainly composed of caffeoylquinic acids (CQAs), dicaffeoylquinic acids (diCQAs), and feruloylquinic acids (FQAs). The major CGAs in coffee are neochlorogenic acid (3-CQA), cryptochlorogenic acid (4-CQA), and chlorogenic acid (5-CQA). Many studies have shown that it is possible to separate the isomers of FQAs by high-performance liquid chromatography (HPLC). However, some authors have shown that it is not possible to separate 4-feruloylquinic acid (4-FQA) and 5-feruloylquinic acid (5-FQA) by HPLC. Therefore, the present study was designated to investigate the chromatographic problems in the determination of CGAs (seven isomers) and caffeine using HPLC-DAD. The values of determination coefficient (R²) calculated from external-standard calibration curves were >0.998. The recovery rates conducted at 3 spiking levels ranged from 99.4% to 106.5% for the CGAs and from 98.8% to 107.1% for the caffeine. The precision values (expressed as relative standard deviations (RSDs)) were <7% and <3% for intra and interday variability, respectively. The tested procedure proved to be robust. The seven CGAs isomers except 4-FQA and 5-FQA were well distinguished and all gave good peak shapes. We have found that 4-FQA and 5-FQA could not be separated using HPLC. The method was extended to investigate the effects of different brewing conditions such as the roasting degree of green coffee bean, coffee-ground size, and numbers of boiling-water pours, on the concentration of CGAs and caffeine in homemade brewed coffee, using nine green coffee bean samples of different origins. It was reported that medium-roasted, fine-ground coffees brewed using three pours of boiling water were the healthiest coffee with fluent CGAs.

A double-blind, placebo-controlled study evaluating the effects of caffeine and L-theanine both alone and in combination on cerebral blood flow, cognition and mood

RATIONALE

Evidence suggests interactive effects of the tea components caffeine and L-theanine on behaviour, yet no data exists exploring the impact of the two on cerebral blood flow (CBF).

OBJECTIVES

The current placebo-controlled, double-blind, counterbalanced, crossover study examined the effects of caffeine and L-theanine on CBF and extended previous cognitive and mood findings by using lower doses than previous studies of a similar methodology, which more closely reflect the ratios present in tea.

METHODS

Twelve habitual consumers and 12 non-habitual consumers of caffeine each received 75 mg caffeine, 50 mg L-theanine, 75 mg caffeine plus 50 mg L-theanine, and placebo in a counterbalanced order across four separate visits. CBF was measured via near-infrared spectroscopy with cognition and mood assessed at baseline and 30 min post-dose. Salivary caffeine and peripheral haemodynamics were co-monitored.

RESULTS

Caffeine reduced oxygenated haemoglobin (oxy-Hb), increased deoxygenated haemoglobin (deoxy-Hb), improved performance on attention tasks and increased overall mood ratings. Increases in deoxy-Hb following caffeine were more pronounced in non-consumers. Some evidence for increased deoxy-Hb remained when caffeine was combined with L-theanine, but this effect was attenuated and the effects of caffeine on oxy-Hb, cognition and mood were eradicated.

CONCLUSIONS

Combining L-theanine with caffeine, at levels and ratios equivalent to one to two cups of tea, eliminated the vasoconstrictive effect and behavioural effects of caffeine. This supports previous findings of an interaction between these substances, despite a lack of effects of L-theanine in isolation. However, at the levels tested here, this did not lead to a positive impact on behaviour.

Coffee intake mitigated inflammation and obesity-induced insulin resistance in skeletal muscle of high-fat diet-induced obese mice

Epidemiologic findings offer the promise that coffee or its many constituents may be useful as a dietary intervention in type 2 diabetes (T2D) prevention. We aimed to elucidate the molecular mechanisms involved in the ameliorative effects of caffeinated coffee (CC), decaffeinated coffee (DC) and unroasted caffeinated green coffee (GC) on skeletal muscle gene expression profiles and their relationships in an obesity animal model. Eight-week-old male C57BL6 mice were raised for 9 weeks ad libitum on a normal diet, a high-fat diet, or high-fat diet containing 2 % freeze-dried CC, or DC, or GC. Total RNA and protein were extracted from skeletal muscle and subjected to microarray (Mouse Genome 430 2.0, Affymetrix) and western blotting analyses, respectively. Coffee intake mitigated the insulin resistance by decreasing plasma glucose levels during an insulin tolerance test and by increasing tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1), p85/IRS-1 complex and pAkt/PKB (protein kinase B). In addition, coffee intake down-regulated the anti-inflammatory genes activating transcription factor 3, FBJ osteosarcoma oncogene, heat shock protein 1A, heat shock protein 1B and synuclein, gamma and the inflammation-associated insulin signaling genes stearoyl-coenzyme A desaturase 1 and secreted phosphoprotein 1. These results provide scientific insight on the probable positive effects of coffee intake on impaired insulin signaling, inflammation and obesity, thereby providing a new perspective on the prevention of obesity and T2D.

Neuroprotective herbs and foods from different traditional medicines and diets

Plant secondary metabolites include an array of bioactive constituents form both medicinal and food plants able to improve human health. The exposure to these phytochemicals, including phenylpropanoids, isoprenoids and alkaloids, through correct dietary habits, may promote health benefits, protecting against the chronic degenerative disorders mainly seen in Western industrialized countries, such as cancer, cardiovascular and neurodegenerative diseases. In this review, we briefly deal with some plant foods and herbs of traditional medicines and diets, focusing on their neuroprotective active components. Because oxidative stress and neuroinflammation resulting from neuroglial activation, at the level of neurons, microglial cells and astrocytes, are key factors in the etiopathogenesis of both neurodegenerative and neurological diseases, emphasis will be placed on the antioxidant and anti-inflammatory activity exerted by specific molecules present in food plants or in remedies prescribed by herbal medicines.

Caffeine Use in Sports, Pharmacokinetics in Man, and Cellular Mechanisms of Action

Caffeine is the most widely consumed psychoactive 'drug' in the world and probably one of the most commonly used stimulants in sports. This is not surprising, since it is one of the few ergogenic aids with documented efficiency and minimal side effects. Caffeine is rapidly and completely absorbed by the gastrointestinal tract and is readily distributed throughout all tissues of the body. Peak plasma concentrations after normal consumption are usually around 50 microM, and half-lives for elimination range between 2.5-10 h. The parent compound is extensively metabolized in the liver microsomes to more than 25 derivatives, while considerably less than 5% of the ingested dose is excreted unchanged in the urine. There is, however, considerable inter-individual variability in the handling of caffeine by the body, due to both environmental and genetic factors. Evidence from in vitro studies provides a wealth of different cellular actions that could potentially contribute to the observed effects of caffeine in humans in vivo. These include potentiation of muscle contractility via induction of sarcoplasmic reticulum calcium release, inhibition of phosphodiesterase isoenzymes and concomitant cyclic monophosphate accumulation, inhibition of glycogen phosphorylase enzymes in liver and muscle, non-selective adenosine receptor antagonism, stimulation of the cellular membrane sodium/potassium pump, impairment of phosphoinositide metabolism, as well as other, less thoroughly characterized actions. Not all, however, seem to account for the observed effects in vivo, although a variable degree of contribution cannot be readily discounted on the basis of experimental data. The most physiologically relevant mechanism of action is probably the blockade of adenosine receptors, but evidence suggests that, at least under certain conditions, other biochemical mechanisms may also be operational.

Cognitive and mood improvements of caffeine in habitual consumers and habitual non-consumers of caffeine

RATIONALE

The cognitive and mood effects of caffeine are well documented. However, the majority of studies in this area involve caffeine-deprived, habitual caffeine users. It is therefore unclear whether any beneficial findings are due to the positive effects of caffeine or to the alleviation of caffeine withdrawal.

OBJECTIVES

The present placebo-controlled, double-blind, balanced crossover study investigated the acute cognitive and mood effects of caffeine in habitual users and habitual non-users of caffeine.

METHOD

Following overnight caffeine withdrawal, 24 habitual caffeine consumers (mean=217 mg/day) and 24 habitual non-consumers (20 mg/day) received a 150 ml drink containing either 75 or 150 mg of caffeine or a matching placebo, at intervals of > or =48 h. Cognitive and mood assessments were undertaken at baseline and 30 min post-drink. These included the Cognitive Drug Research computerised test battery, two serial subtraction tasks, a sentence verification task and subjective visual analogue mood scales.

RESULTS

There were no baseline differences between the groups' mood or performance. Following caffeine, there were significant improvements in simple reaction time, digit vigilance reaction time, numeric working memory reaction time and sentence verification accuracy, irrespective of group. Self-rated mental fatigue was reduced and ratings of alertness were significantly improved by caffeine independent of group. There were also group effects for rapid visual information processing false alarms and spatial memory accuracy with habitual consumers outperforming non-consumers. There was a single significant interaction of group and treatment effects on jittery ratings. Separate analyses of each groups' responses to caffeine revealed overlapping but differential responses to caffeine. Caffeine tended to benefit consumers' mood more while improving performance more in the non-consumers.

CONCLUSIONS

These results do not support a withdrawal alleviation model. Differences in the patterns of responses to caffeine by habitual consumers and habitual non-consumers may go some way to explaining why some individuals become caffeine consumers.