Moderate coffee consumption increases plasma glutathione but not homocysteine in healthy subjects

Coffee, antioxidants, and brain inflammation

Coffee is the most popular beverage in the world and, aside from tea and water, the most often consumed caffeine-containing beverage. Because of its high caffeine concentration, it is typically classified as a stimulant. There are other bioactive ingredients in coffee besides caffeine. The coffee beverage is a blend of several bioactive substances, including diterpenes (cafestol and kahweol), alkaloids (caffeine and trigonelline), and polyphenols (particularly chlorogenic acids in green beans and caffeic acid in roasted coffee beans). Caffeine has also been linked to additional beneficial benefits such as antioxidant and anti-inflammatory properties, which change cellular redox and inflammatory status in a dose-dependent manner. Pyrocatechol, a constituent of roasted coffee that is created when chlorogenic acid is thermally broken down, has anti-inflammatory properties as well. It is postulated that coffee consumption reduces neuroinflammation, which is intimately linked to the onset of neurodegenerative disorders like Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD). This review provides an overview of the most recent studies regarding coffee's possible benefits in preventing brain inflammation and neurodegenerative disorders.

Effects of Chokeberries (Aronia spp.) on Cytoprotective and Cardiometabolic Markers and Semen Quality in 109 Mildly Hypercholesterolemic Danish Men: A Prospective, Double-Blinded, Randomized, Crossover Trial

Background: Chokeberries (Aronia spp.) are known to exhibit both direct and indirect antioxidant properties and have been associated with beneficial effects on human health, including cardiovascular risk factors (inflammation, serum lipids, sugars, blood pressure), oxidative stress, and semen quality. This prospective, double-blinded, randomized, crossover clinical trial was conducted to elucidate the effects of Aronia supplementation on these health targets in mildly hypercholesterolemic men. Methods: The standardized Aronia supplementation comprised three wild Aronia spp. (A. arbutifolia, A prunifolia and A. melanocarpa) and the Aronia hybrid × Sorbaronia mitschurinii (standardized to 150 mg anthocyanins daily). Participants (n = 109) were healthy men with respect to all outcome targets except for the total cholesterol level (5.0−7.0 mM). Participants were randomized to supplementation with either Aronia or placebo for 90 days, followed by a wash-out period and lastly the complementary supplementation. Effects on the health parameters were compared among both the whole group of men and in subgroups according to age, body mass index (BMI), lifestyle, dietary habits, and serum glutathione levels at baseline. The study is registered in ClinicalTrials.gov.: NCT03405753. Results: Glutathione levels were significantly improved after 90 days intake of Aronia supplementation compared to placebo in the subgroup of men with a low level of glutathione at baseline (p = 0.038) and a high coffee intake (p = 0.045). A significant decrease in levels of sperm DNA fragmentation and an increase in the percentage of motile sperm were observed in men aged >40 and in men with BMI > 25. Further, these parameters were significantly improved in the dietary subgroup defined by a high level of coffee intake. Total cholesterol and low-density lipoprotein-cholesterol levels decreased significantly in men <40 years after Aronia supplementation. No statistically significant effects were observed regarding blood pressure, markers of blood sugar regulation, hemoglobin A1c, superoxide dismutase, catalase, isoprostane levels, high sensitivity C reactive protein, or other semen parameters. Conclusions: This study demonstrated a significant increase in glutathione levels and improvement of cytoprotective targets following Aronia supplementation in specific subgroups of men >40 years of age and BMI > 25 but did not demonstrate a significant effect in the overall analysis. The observed concurrent increase in glutathione levels and improvement of cytoprotective targets following Aronia supplementation in subgroups of men, suggests that the endogenous phase II antioxidant glutathione is involved in the modulation of the observed cytoprotective effects. This study is a good foundation for further investigation of these cytoprotective effects in groups with oxidative stress in a dose−response study.

Effects of Coffee Supplementation on Homocysteine and Leptin Levels: A Systematic Review and Meta-analysis of Clinical Trials

BACKGROUND

It has been reported that the consumption of antioxidant foods and beverages may benefit the development of cardiovascular risk factors. However, the impact of coffee consumption on some of these factors, such as homocysteine and leptin is controversial. Some clinical trials have suggested that coffee administration increases plasma total homocysteine levels, while others have found no significant changes in leptin concentrations.

OBJECTIVE

This study aimed to assess the effects of coffee supplementation on homocysteine and leptin concentrations in a meta-analysis of clinical trials.

METHODS

PubMed, Web of Science, Scopus, ClinicalTrials.gov, and Google Scholar databases were searched from inception to September 29, 2021. A fixed-effects model and the generic inverse variance weighting method were used for meta-analysis.

RESULTS

The meta-analysis demonstrated that coffee administration significantly increases homocysteine levels (WMD: 0.55 μmol/L, 95% CI: 0.17, 0.93, p = 0.005, I2 = 0%) but has no significant changes in leptin concentrations (WMD: 1.34 ng/mL, 95% CI: -0.78, 3.45, p = 0.21, I2 = 0%). Additionally, the sensitivity analysis was robust for both homocysteine and leptin levels.

CONCLUSION

The results of the present meta-analysis revealed that coffee supplementation raises serum homocysteine concentrations but has no effect on circulating leptin levels.

Coffee's Phenolic Compounds. A general overview of the coffee fruit's phenolic composition

Phenolic compounds are secondary metabolites ubiquitously distributed in the plant kingdom which come in a wide array of molecular configurations which confer them a comprehensive set of chemical attributes such as, but not limited to: nutraceutical properties, industrial applications (e.g., dyes, rawhide processing, beer production, antioxidants), and plant self-defense mechanisms against natural enemies also known as the Systemic Acquired Resistance (SAR).However, despite the fact, that there is a large number of phenolic-containing food products (e.g., chocolate, green tea, wines, beer, wood barrel-aged spirits, cherries, grapes, apples, peaches, plums, pears, etc.), coffee remains, in the western hemisphere, as the main source of dietary phenolic compounds reflected by the fact that, in the international market, coffee occupies the second trading position after oil and its derivatives. The following discussion is the product of an extensive review of scientific literature that aims to describe essential topics related to coffee phenolic compounds, especially chlorogenic acids, their purpose in nature, biosynthesis, determination, metabolism, chemical properties, and their effect on cup quality. Keywords: phenolic acids, caffeoylquinic acid, antioxidant capacity, metabolism, biosynthesis.

Coffee’s Melanoidins. A critical review of contemporary scientific literature

Melanoidins are brown pigments thermally generated during the non-enzymatic Maillard reaction and are present in a large number of baked and roasted food products (e.g., bakery products, dark beer, coffee, etc.), conferring their typical color and improving their appearance, which is usually considered, by the end-consumer, as an indicator of quality; After all, quality is in the eye of the beholder. The amount of melanoidins varies depending on the precursors’ concentration and the type of processing to which a given food product is submitted (baking time + temperature). Additionally, melanoidins have been in our diets for millennia, not only improving the organoleptic qualities of food but also exerting a great array of physiological benefits directly linked to their chemical composition, molecular conformation, and structural size. Aside from their prebiotic effects, melanoidins also display other beneficial properties, among which the most salient are their antioxidant capacity, antibacterial and chelating activities, and anticancer action. However, regardless of the plethora of in vitro experimental evidence that validates the properties mentioned above, there is still controversy about their significance for human health since many of these properties seem to be associated with high molecular weight melanoidins, which, because of their size, cannot cross the intestinal wall suggesting their action is relegated to the intestinal tract where after being fermented and fragmented are finally converted in a series of metabolic derivatives some of which manage to cross into the bloodstream while others are simply excreted through the feces. The following is a synthesis collected from the available scientific literature which aims to elucidate several aspects of melanoidins (i.e., synthesis, determination, metabolism, & biological activity) to create awareness about their importance for human health and provide information about where to find them to improve our diets. Keywords: Synthesis, fractionation, separation, antioxidant activity.

Hyperhomocysteinemia: Metabolic Role and Animal Studies with a Focus on Cognitive Performance and Decline-A Review

Disturbances in the one-carbon metabolism are often indicated by altered levels of the endogenous amino acid homocysteine (HCys), which is additionally discussed to causally contribute to diverse pathologies. In the first part of the present review, we profoundly and critically discuss the metabolic role and pathomechanisms of HCys, as well as its potential impact on different human disorders. The use of adequate animal models can aid in unravelling the complex pathological processes underlying the role of hyperhomocysteinemia (HHCys). Therefore, in the second part, we systematically searched PubMed/Medline for animal studies regarding HHCys and focused on the potential impact on cognitive performance and decline. The majority of reviewed studies reported a significant effect of HHCys on the investigated behavioral outcomes. Despite of persistent controversial discussions about equivocal findings, especially in clinical studies, the present evaluation of preclinical evidence indicates a causal link between HHCys and cognition-related- especially dementia-like disorders, and points out the further urge for large-scale, well-designed clinical studies in order to elucidate the normalization of HCys levels as a potential preventative or therapeutic approach in human pathologies.

Causal relationship from coffee consumption to diseases and mortality: a review of observational and Mendelian randomization studies including cardiometabolic diseases, cancer, gallstones and other diseases

PURPOSE

High coffee consumption is associated with low risk of mortality and morbidity, but the causality remains unclear. This review aims to discuss findings from observational studies on coffee consumption in context of Mendelian randomization studies.

METHODS

The PubMed database was searched for all Mendelian randomization studies on coffee consumption and corresponding observational studies.

RESULTS

High coffee consumption is associated with low risk of all-cause and cardiovascular mortality in observational studies (HRs of 0.85-0.90 vs. no/low consumers), with no support of causality in Mendelian randomization studies. Moderate/high consumption is associated with low risk of cardiometabolic diseases, including ischemic heart disease (HRs of 0.85-0.90 vs. no/low consumption), stroke (HRs of approximately 0.80 vs. no/low consumption), type 2 diabetes (HRs of approximately 0.70 vs. no/low consumption) and obesity in observational studies, but not in Mendelian randomization studies. High consumption is associated with low risk of endometrial cancer and melanoma and high risk of lung cancer in observational studies, but with high risk of colorectal cancer in Mendelian randomization studies. In observational and Mendelian randomization studies, high coffee consumption is associated with low risk of gallstones (HRs of 0.55-0.70 for high vs. no/low self-reported and 0.81 (0.69-0.96) for highest vs. lowest genetic consumption).

CONCLUSION

High coffee consumption is associated with low risk of mortality, cardiometabolic diseases, some cancers and gallstones in observational studies, with no evidence to support causality from Mendelian randomization studies for most diseases except gallstones.

The rationality involved in the popular use of coffee (Coffea sp) and sunflower seed (Helianthus annuus) for the treatment of vitiligo: a case report

INTRODUCTION

Vitiligo is a dermatological disease that affects about 0.38% to 2.9% of the world population. Currently, the main treatments used for vitiligo involve the use of topical drugs such as corticosteroids and calcineurin inhibitors, phototherapy, systemic treatment with steroids and even surgical grafts and, in acute cases, depigmenting treatments. Natural products are an alternative for the treatment of vitiligo: mamacadela (Brosimum gaudichaudii), a plant rich in furanocoumarins, and sowthistle (Sonchus oleraceus), rich in phenolic substances, are already used to treat vitiligo. There are also popular reports of the use of a preparation containing coffee (Coffea sp) and sunflower seed (Helianthus annuus) to treat vitiligo.

CASE REPORT

A female patient, 28 years old, diagnosed with vitiligo, reported having obtained a positive result in the repigmentation of the pale white patches after the daily use of a preparation containing coffee and sunflower seed for about one year.

DISCUSSION

Data from the scientific literature demonstrated that chemical constituents of these plants, such as chlorogenic acid and its isomers, which have antioxidant and anti-inflammatory action, and substances such as linoleic acid and vitamins E and B, which help in the process of melanin formation on the skin, may be responsible for the observed repigmentation of the patches. Further research on this case report is important for scientific validation and the development of new therapeutic options, especially with less adverse effects, in the treatment of vitiligo.

Antitumor Effects of Freeze-Dried Robusta Coffee (Coffea canephora) Extracts on Breast Cancer Cell Lines

Coffee consumption is believed to have chemopreventive and chemotherapeutic effects and to contribute to preventing the development and progression of cancer. However, there is still controversy around these claims. As indicated in our previous works, diet can influence the risk of breast cancer. Intake of coffee is hypothesized to reduce this risk, but current scientific evidence is not conclusive. This work is aimed at studying the effects of Robusta coffee bean extract on cell viability, proliferation, and apoptosis of different human cancers, especially breast cancer cell lines. To this end, cell viability was evaluated by Alamar Blue in 2D and 3D models, the cell cycle by PI, apoptosis by annexin V, mitochondrial morphology, and functionality by mitoTracker, and colony formation capacity by the clonogenic assay. Green and dark coffee extract significantly reduced viability in human breast, colorectal, brain, and bone cancer cells. Coffee anticancer activity was clearly evidenced in MDA-MB-231 (ER⁻) and MCF-7 (ER⁺) breast cancer cells but not in the normal breast cell line. In addition, coffee extract induces an increase S phase and a decrease G2/M population in breast cancer cells, affected the mitochondrial morphology, and triggered apoptosis. MDA-MB-231 breast cancer cells lost their clonogenic capacity after treatment. The antitumor activity was demonstrated in both 2D and 3D culture cell models.

Correlations between Coffee Consumption and Metabolic Phenotypes, Plasma Folate, and Vitamin B12: NHANES 2003 to 2006

Metabolic syndrome (MetS) is prevalent not only among the overweight and obese but also normal weight individuals, and the phenotype is referred to as a metabolically unhealthy phenotype (MUHP). Besides normal weight individuals, overweight/obese individuals are also protected from MetS, and the phenotype is known as a metabolically healthy phenotype (MHP). Epidemiological studies indicate that coffee and micronutrients such as plasma folate or vitamin B12 (vit. B12) are inversely associated with MetS. However, correlations among coffee consumption metabolic phenotypes, plasma folate, and vit. B12 remain unknown. Our objective was to investigate the correlation between coffee consumption, metabolic phenotypes, plasma folate, and vit. B12 as well as to understand associations between plasma folate, vit. B12, and metabolic phenotypes. Associations among coffee consumption metabolic phenotypes, plasma folate, and vit. B12 were assessed in a cross-sectional study of 2201 participants, 18 years or older, from 2003-2004 and 2005-2006 National Health and Nutrition Examination Surveys (NHANES). MUHP was classified as having > three metabolic abnormalities. Coffee consumption was not associated with metabolic phenotypes, but negatively correlated with several metabolic variables, including BMI (p < 0.001). Plasma folate was positively associated with MUHP (p < 0.004), while vit. B12 was inversely associated with MUHP (p < 0.035). Our results suggest the potential protective impact of coffee on individual components of MetS and indicate a positive correlation between coffee consumption and MUHP among overweight individuals. Identifying possible dietary factors may provide practical and low-cost dietary intervention targets, specifically for early intervention. Larger and randomized intervention studies and prospective longitudinal studies are required to further evaluate these associations.

Relationship between coffee consumption, sleep duration and smoking status with elastographic parameters of liver steatosis and fibrosis; controlled attenuation parameter and liver stiffness measurements

AIM

our aim was to explore the association between life habits and the controlled attenuation parameter (CAP) and liver stiffness measurements (LSM) as the surrogate markers of liver steatosis and fibrosis in a large cohort of non-alcoholic fatty liver disease (NAFLD) patients.

METHODS

In this prospective, cross-sectional study we had analysed 1998 patients with diagnosed NAFLD. Sleeping duration was categorised in three groups: short (S) (<6 hours), moderate (M) (6-8 hours) and long (L) (>8 hours) sleep duration. Coffee drinking was categorized into no (0), moderate (1-2) and frequent (≥3) consumption (in cups/day). Smoking was categorised as yes versus no.

RESULTS

Frequent coffee consumers had the lowest prevalence of obesity, hypertension, dyslipidaemia and diabetes. Furthermore, coffee non-consumers had highest values of hepatic enzymes, CAP and LSM. Moderate sleep duration was associated with lower values of CAP and LSM. Coffee consumption was associated with lower CAP in all the multivariate models (CAP unadjusted and model 1, 2 and 3), with largest effect in most frequent coffee consumers (≥3, model 3). Also, most frequent coffee consumers were associated with lower LSM in unadjusted model, model 1 and 2, while this was not the case for model 3 and those who consumed 1-2 cups of coffee per day. Reduced sleeping was confirmed as risk factor for elevated CAP in most of the models (unadjusted and model 1 and 2). Also, negative association of LSM was also confirmed in unadjusted model and model 2. Patients which slept 6-8 hours per day were mostly associated with lower CAP and LSM. Smoking status was not associated with CAP or LSM values.

CONCLUSION

Coffee consumption has beneficial effect on CAP and LSM and this effect is dose dependent since and independent of a variety of relevant confounders. We have shown that moderate sleep duration has also beneficial effect on CAP and LSM.

The gut microbiome drives inter- and intra-individual differences in metabolism of bioactive small molecules

The origin of inter-individual variability in the action of bioactive small molecules from the diet is poorly understood and poses a substantial obstacle to harnessing their potential for attenuating disease risk. Epidemiological studies show that coffee lowers the risk of developing type 2 diabetes, independently of caffeine, but since coffee is a complex matrix, consumption gives rise to different classes of metabolites in vivo which in turn can affect multiple related pathways in disease development. We quantified key urinary coffee phenolic acid metabolites repeated three times in 36 volunteers, and observed the highest inter- and intra-individual variation for metabolites produced by the colonic microbiome. Notably, a urinary phenolic metabolite not requiring the action of the microbiota was positively correlated with fasting plasma insulin. These data highlight the role of the gut microbiota as the main driver of both intra- and inter-individual variation in metabolism of dietary bioactive small molecules.

A Thyroid Hormone-Independent Molecular Fingerprint of 3,5-Diiodothyronine Suggests a Strong Relationship with Coffee Metabolism in Humans

Background: In numerous studies based predominantly on rodent models, administration of 3,5-diiodo-L-thyronine (3,5-T2), a metabolite of the thyroid hormones (TH) thyroxine (T4) and triiodo-L-thyronine (T3), was reported to cause beneficial health effects, including reversal of steatohepatosis and prevention of insulin resistance, in most instances without adverse thyrotoxic side effects. However, the empirical evidence concerning the physiological relevance of endogenously produced 3,5-T2 in humans is comparatively poor. Therefore, to improve the understanding of 3,5-T2-related metabolic processes, we performed a comprehensive metabolomic study relating serum 3,5-T2 concentrations to plasma and urine metabolite levels within a large general population sample. Methods: Serum 3,5-T2 concentrations were determined for 856 participants of the population-based Study of Health in Pomerania-TREND (SHIP-TREND). Plasma and urine metabolome data were generated using mass spectrometry and nuclear magnetic resonance spectroscopy, allowing quantification of 613 and 578 metabolites in plasma and urine, respectively. To detect thyroid function-independent significant 3,5-T2-metabolite associations, linear regression analyses controlling for major confounders, including thyrotropin and free T4, were performed. The same analyses were carried out using a sample of 16 male healthy volunteers treated for 8 weeks with 250 μg/day levothyroxine to induce thyrotoxicosis. Results: The specific molecular fingerprint of 3,5-T2 comprised 15 and 73 significantly associated metabolites in plasma and urine, respectively. Serum 3,5-T2 concentrations were neither associated with classical thyroid function parameters nor altered during experimental thyrotoxicosis. Strikingly, many metabolites related to coffee metabolism, including caffeine and paraxanthine, formed the clearest positively associated molecular signature. Importantly, these associations were replicated in the experimental human thyrotoxicosis model. Conclusion: The molecular fingerprint of 3,5-T2 demonstrates a clear and strong positive association of the serum levels of this TH metabolite with plasma levels of compounds indicating coffee consumption, therefore pointing to the liver as an organ, the metabolism of which is strongly affected by coffee. Furthermore, 3,5-T2 serum concentrations were found not to be directly TH dependent. Considering the beneficial health effects of 3,5-T2 administration observed in animal models and those of coffee consumption demonstrated in large epidemiological studies, one might speculate that coffee-stimulated hepatic 3,5-T2 production or accumulation represents an important molecular link in this connection.

Coffee consumption and liver-related hospitalizations and deaths in the ARIC study

BACKGROUND/OBJECTIVES

Coffee consumption has been found to be associated with reduced risk of chronic conditions such as liver disease. However, less is known about the association between coffee and liver-related hospitalizations and deaths.

SUBJECTS/METHODS

We conducted a prospective analysis on 14,208 participants aged 45-64 years from the Atherosclerosis Risk in Communities (ARIC) study. Coffee consumption (cups/day) was assessed using food frequency questionnaires at visit 1 (1987-89) and visit 3 (1993-95). Liver-related hospitalizations were defined as a hospitalization with any International Classification of Diseases, Ninth Revision (ICD-9) code related to liver disease identified through cohort surveillance. Liver-related death was defined as any death with a liver disease ICD-9 code listed anywhere on the death certificate form.

RESULTS

There were 833 incident cases of liver-related hospitalizations over a median follow-up of 24 years and 152 liver-related deaths over a median follow-up of 25 years. Participants who were in the highest category of coffee consumption (≥ 3 cups/day) were more likely to be men, whites, current smokers, and current alcohol drinkers. In our fully adjusted model, consuming ≥ 3 cups/day of coffee was significantly associated with a reduced risk of liver-related hospitalizations compared with never drinkers (hazard ratio: 0.79, 95% CI: 0.63-0.99). There were no significant associations between coffee consumption and liver-related deaths after adjusting for covariates.

CONCLUSIONS

Coffee drinkers may be at lower risk for liver-related hospitalizations. This supports current evidence that low and moderate levels of coffee may be protective to the liver.

Immunomodulatory Effects of Glutathione, Garlic Derivatives, and Hydrogen Sulfide

Glutathione and aged garlic extract are sulfur-containing products that play important protective and regulatory roles within the immune system and in oxidative processes. Hydrogen sulfide (H₂S), an endogenous, gaseous, signaling transmitter, has also been shown to be involved in the regulation of inflammation. Recent studies have shown that sulfur-containing compounds from garlic have beneficial effects in attenuating outcomes associated with cardiovascular disease and inflammation by a mechanism that may be related to the H₂S signaling pathway. In this review, we summarize the main functions of glutathione (GSH), garlic derivatives and H₂S and their role in the immune response and impact on health and disease.

Consumption of a dark roast coffee blend reduces DNA damage in humans: results from a 4-week randomised controlled study

PURPOSE

To determine the DNA protective effects of a standard coffee beverage in comparison to water consumption.

METHODS

The single-blind, randomised controlled study with parallel design included healthy women (n = 50) and men (n = 50) recruited from the general Central European population. The subjects were randomised in a coffee and a control group, with stratification for sex and body mass index. The study comprised two periods of 4 weeks: a preconditioning period, with daily consumption of at least 500 ml water but no coffee, nor tea, nor any other caffeine-containing product. During the subsequent intervention period the coffee group consumed 500 ml of freshly brewed dark roast coffee blend per day, the control group consumed water instead. On the last day of each period, blood was drawn and analysed by comet assay (single-cell gel electrophoresis) to assess the level of DNA damage (strand breakage).

RESULTS

At the end of the intervention period the mean level of DNA strand breaks in the coffee group has decreased in comparison to the control group [difference in means 0.23% TI (tail intensity), p = 0.028]. The mean change from baseline (delta value) was - 23% in the coffee group (p = 0.0012). Effects of coffee intake were similar for men and women. During intervention, neither group showed any significant change in body weight or calorie intake.

CONCLUSIONS

Our results indicate that regular consumption of a dark roast coffee blend has a beneficial protective effect on human DNA integrity in both, men and women.

Coffee Intake and Liver Steatosis: A Population Study in a Mediterranean Area

Coffee drinking seems to have several beneficial effects on health outcomes. However, the effect on hepatic steatosis, depending on a high alcohol consumption (AFLD, alcoholic fatty liver disease) or on metabolic factors (non-alcoholic fatty liver disease, NAFLD), is still equivocal. Thus, we aimed to explore the potential association between coffee consumption and the presence and severity of hepatic steatosis in people with NAFLD or AFLD. In this cross-sectional study, coffee drinking was recorded using a semi-quantitative food frequency questionnaire, and categorized as yes vs. no and as 0, 1, 2, ≥3. The degree of fatty liver was assessed through a standardized ultrasound examination (score 0 to 6, with higher values reflecting higher severity). Liver steatosis was classified as NAFLD or AFLD on daily alcohol intake >30 g/day for men and >20 g/day for women. This study included 2819 middle-aged participants; the great majority were coffee drinkers (86.1%). After adjusting for 12 potential confounders, drinking coffee was not associated with decreased odds for NAFLD (n = 916) (odds ratio, OR = 0.93; 95% confidence intervals, CI: 0.72-1.20) or AFLD (n = 276) (OR = 1.20; 95% CI: 0.66-2.0). The consumption of coffee (categorized as yes vs. no), or an increased consumption of coffee were not associated with the presence of mild, moderate or severe liver steatosis in either NAFLD or AFLD. In conclusion, coffee intake was not associated with any lower odds of hepatic steatosis in either non-alcoholic or alcoholic forms in this large cohort of South Italian individuals.

The role of polyphenols in modern nutrition

Polyphenols are found in plant‐based foods and beverages, notably apples, berries, citrus fruit, plums, broccoli, cocoa, tea and coffee and many others. There is substantial epidemiological evidence that a diet high in polyphenol‐rich fruit, vegetables, cocoa and beverages protects against developing cardiovascular disease and type 2 diabetes. The absorption and metabolism of these compounds have been well described and, for many, the gut microbiota play a critical role in absorption; taking into consideration the parent compound and the metabolites from colon bacteria catabolism, more than 80% of a dose can be absorbed and ultimately excreted in the urine. Common polyphenols in the diet are flavanols (cocoa, tea, apples, broad beans), flavanones (hesperidin in citrus fruit), hydroxycinnamates (coffee, many fruits), flavonols (quercetin in onions, apples and tea) and anthocyanins (berries). Many intervention studies, mechanistic in vitro data and epidemiological studies support a role for polyphenols against the development of chronic diseases. For example, flavanols decrease endothelial dysfunction, lower blood pressure and cholesterol, and modulate energy metabolism. Coffee and tea both reduce the risk of developing type 2 diabetes, through action of their constituent polyphenols. Despite extensive research, the exact mechanisms of action of polyphenols in the human body have not been decisively proven, but there is strong evidence that some targets such as nitric oxide metabolism, carbohydrate digestion and oxidative enzymes are important for health benefits. Consumption of polyphenols as healthy dietary components is consistent with the advice to eat five or more portions of fruit and vegetables per day, but it is currently difficult to recommend what ‘doses’ of specific polyphenols should be consumed to derive maximum benefit.

Association between Coffee Consumption and Its Polyphenols with Cardiovascular Risk Factors: A Population-Based Study

Epidemiological studies have examined the effect of coffee intake on cardiovascular disease, but the benefits and risks for the cardiovascular system remain controversial. Our objective was to evaluate the association between coffee consumption and its polyphenols on cardiovascular risk factors. Data came from the “Health Survey of São Paulo (ISA-Capital)” among 557 individuals, in São Paulo, Brazil. Diet was assessed by two 24-h dietary recalls. Coffee consumption was categorized into <1, 1–3, and ≥3 cups/day. Polyphenol intake was calculated by matching food consumption data with the Phenol-Explorer database. Multiple logistic regression models were used to assess the associations between cardiovascular risk factors (blood pressure, total cholesterol, low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), triglycerides, fasting glucose, and homocysteine) and usual coffee intake. The odds were lower among individuals who drank 1–3 cups of coffee/day to elevated systolic blood pressure (SBP) (Odds Ratio (OR) = 0.45; 95% Confidence Interval (95% CI): 0.26, 0.78), elevated diastolic blood pressure (DBP) (OR = 0.44; 95% CI: 0.20, 0.98), and hyperhomocysteinemia (OR = 0.32; 95% CI: 0.11, 0.93). Furthermore, significant inverse associations were also observed between moderate intake of coffee polyphenols and elevated SBP (OR = 0.46; 95% CI: 0.24, 0.87), elevated DBP (OR = 0.51; 95% CI: 0.26, 0.98), and hyperhomocysteinemia (OR = 0.29; 95% CI: 0.11, 0.78). In conclusion, coffee intake of 1–3 cups/day and its polyphenols were associated with lower odds of elevated SBP, DBP, and hyperhomocysteinemia. Thus, the moderate consumption of coffee, a polyphenol-rich beverage, could exert a protective effect against some cardiovascular risk factors.

Tumour formation in multiple intestinal neoplasia (ApcMin/+) mice fed with filtered or unfiltered coffee

Background

The aetiology of colorectal cancer has strong dietary links, and there may be an association between coffee and colorectal cancer risk.

Objective

To study the effects of filtered (low levels of kahweol/cafestol) and unfiltered (high levels of kahweol/cafestol) coffee on tumour formation in multiple intestinal neoplasia (Apc^Min/+) mice.

Design

Apc^Min/+ mice (n=11 per group) were fed for 9 weeks with 10% w/w of these two types of coffee. Coffee was served as a dietary ingredient mixed with a semi-synthetic AIN-93G-based diet. Plasma levels of caffeine and paraxanthine were used as compliance markers. At the end of the feeding period intestinal tumour number and size were determined. The levels of β-catenin and cyclin D1, two cell-signalling proteins important to the progression of neoplasia, were also analysed in the tumour tissue.

Results

Plasma caffeine and paraxanthine concentrations were 3.2±1.4 and 1.7±0.4 µmol l⁻¹ in the filtered coffee group and 3.6±2.3 and 1.6±0.6 µmol l⁻¹ in the unfiltered coffee group. The level of plasma xanthines was below detection in the control group. The total number of tumours was equal between the dietary groups: 29 for the control, 30 (p =0.767) for the filtered coffee and 29 (p=0.430) for the unfiltered coffee groups. The levels of β-catenin and cyclin D1 in the nuclear fraction of the tumour tissue were also the same between the groups.

Conclusions

Filtered or unfiltered coffee (10% w/w) does not exert antitumorigenic activity in Apc^Min/+ mice or change β-catenin and cyclin D1 signalling in the adenoma tissues. The results suggest that coffee does not change neoplasia progression in this animal model.

Coffee Consumption and Oxidative Stress: A Review of Human Intervention Studies

Research on the potential protective effects of coffee and its bioactives (caffeine, chlorogenic acids and diterpenes) against oxidative stress and related chronic disease risk has been increasing in the last years. The present review summarizes the main findings on the effect of coffee consumption on protection against lipid, protein and DNA damage, as well as on the modulation of antioxidant capacity and antioxidant enzymes in human studies. Twenty-six dietary intervention studies (involving acute and chronic coffee intake) have been considered. Overall, the results suggest that coffee consumption can increase glutathione levels and improve protection against DNA damage, especially following regular/repeated intake. On the contrary, the effects of coffee on plasma antioxidant capacity and antioxidant enzymes, as well as on protein and lipid damage, are unclear following both acute and chronic exposure. The high heterogeneity in terms of type of coffee, doses and duration of the studies, the lack of information on coffee and/or brew bioactive composition, as well as the choice of biomarkers and the methods used for their evaluation, may partially explain the variability observed among findings. More robust and well-controlled intervention studies are necessary for a thorough understanding of the effect of coffee on oxidative stress markers in humans.

Coffee Consumption Decreases Risks for Hepatic Fibrosis and Cirrhosis: A Meta-Analysis

BACKGROUND AND AIM

Previous studies have demonstrated that coffee consumption may be inversely correlated with hepatic fibrosis and cirrhosis. However, the reported results have been inconsistent. To summarize previous evidences quantitatively, a meta-analysis was performed.

METHODS

The Medline, Web of Science, and Embase databases (from inception to June 2015) were searched to identify relevant trials that evaluated the effects of coffee consumption on hepatic fibrosis or cirrhosis. Odds ratios (ORs) of advanced hepatic fibrosis or cirrhosis for low or moderate, high, and any coffee consumption versus no consumption were pooled. Two cups per day was used as the cut-off level between low or moderate and high consumption.

RESULTS

Sixteen studies were included, involving 3034 coffee consumers and 132076 people who do not consume coffee. The pooled results of the meta-analysis indicated that coffee consumers were less likely to develop cirrhosis compared with those who do not consume coffee, with a summary OR of 0.61 (95%CI: 0.45-0.84). For low or moderate coffee consumption versus no consumption, the pooled OR of hepatic cirrhosis was 0.66 (95%CI: 0.47-0.92). High coffee consumption could also significantly reduce the risk for hepatic cirrhosis when compared with no coffee consumption (OR = 0.53, 95%CI: 0.42-0.68). The effect of coffee consumption on hepatic fibrosis was summarized as well. The pooled OR of advanced hepatic fibrosis for coffee consumption versus no consumption was 0.73 (95%CI: 0.58-0.92). The protective effect of coffee on hepatic fibrosis and cirrhosis was also identified in subgroup meta-analyses of patients with alcoholic liver disease and chronic hepatitis C virus (HCV) infection.

CONCLUSION

Coffee consumption can significantly reduce the risk for hepatic fibrosis and cirrhosis.

Coffee and liver health

Coffee is one of the most widely used beverages in the world. It includes a wide array of components that can have potential implications for health. Several epidemiological studies associate coffee consumption with a reduced incidence of various chronic diseases such as diabetes, cardiovascular diseases, and neurodegenerative diseases. Over the past 20 years, an increasing number of epidemiological and experimental studies have demonstrated the positive effects of coffee on chronic liver diseases. Coffee consumption has been inversely associated with the activity of liver enzymes in subjects at risk, including heavy drinkers. Coffee favours an improvement in hepatic steatosis and fibrosis, and a reduction in cirrhosis and the risk of hepatocellular carcinoma. The mechanisms of action through which it exerts its beneficial effects are not fully understood. Experimental studies show that coffee consumption reduces fat accumulation and collagen deposition in the liver and promotes antioxidant capacity through an increase in glutathione as well as modulation of the gene and protein expression of several inflammatory mediators. Animal and in vitro studies indicate that cafestol and kahweol, 2 diterpens, can operate by modulating multiple enzymes involved in the detoxification process of carcinogens causing hepatocellular carcinoma. It is unclear whether the benefits are significant enough to "treat" patients with chronic liver disease. While we await clarification, moderate daily unsweetened coffee use is a reasonable adjuvant to therapy for these patients.

Coffee: biochemistry and potential impact on health

This article reviews the diversity of compounds found in coffee beans, the effect of roasting and the potential impact of coffee beverage on health.

Apricot melanoidins prevent oxidative endothelial cell death by counteracting mitochondrial oxidation and membrane depolarization

The cardiovascular benefits associated with diets rich in fruit and vegetables are thought to be due to phytochemicals contained in fresh plant material. However, whether processed plant foods provide the same benefits as unprocessed ones is an open question. Melanoidins from heat-processed apricots were isolated and their presence confirmed by colorimetric analysis and browning index. Oxidative injury of endothelial cells (ECs) is the key step for the onset and progression of cardiovascular diseases (CVD), therefore the potential protective effect of apricot melanoidins on hydrogen peroxide-induced oxidative mitochondrial damage and cell death was explored in human ECs. The redox state of cytoplasmic and mitochondrial compartments was detected by using the redox-sensitive, fluorescent protein (roGFP), while the mitochondrial membrane potential (MMP) was assessed with the fluorescent dye, JC-1. ECs exposure to hydrogen peroxide, dose-dependently induced mitochondrial and cytoplasmic oxidation. Additionally detected hydrogen peroxide-induced phenomena were MMP dissipation and ECs death. Pretreatment of ECs with apricot melanoidins, significantly counteracted and ultimately abolished hydrogen peroxide-induced intracellular oxidation, mitochondrial depolarization and cell death. In this regard, our current results clearly indicate that melanoidins derived from heat-processed apricots, protect human ECs against oxidative stress.

Antioxidant effects after coffee enema or oral coffee consumption in healthy Thai male volunteers

We designed an open-label, randomized two-phase crossover study to investigate the antioxidant effects after single and multiple doses of a coffee enema versus coffee consumed orally. Eleven healthy subjects were randomly assigned to either receive a coffee enema (3 times weekly for 6 visits) or consume ready-to-drink coffee (2 times daily for 11 days). After a washout period, subjects were switched to receive the alternate coffee procedure. Blood samples were collected at specific time points for the determination of serum levels of glutathione (GSH), malondialdehyde (MDA) and trolox equivalent antioxidant capacity (TEAC). The findings showed that either single or multiple administrations of the coffee enema or orally consumed coffee doses seemed not to produce any beneficial effects to enhance serum GSH levels or to decrease serum MDA levels over the study period of 12 days. In contrast, mean serum TEAC levels at day 12 after the coffee enema and at days 6 and 12 after oral coffee consumption were significantly reduced from their corresponding baseline values. Thus, no beneficial effects with respect to an enhancement of serum GSH and TEAC levels or a decrease in serum MDA concentrations were demonstrated after coffee enema or orally consumed ready-to-drink coffee.

The effect of caffeine and alcohol consumption on liver fibrosis - a study of 1045 Asian hepatitis B patients using transient elastography

BACKGROUND

Role of caffeine consumption in chronic hepatitis B virus (HBV)-infected patients and the interaction with alcohol consumption is unclear.

AIM

This study aimed to investigate the relationship between caffeine and alcohol consumption and liver stiffness in chronic HBV-infected patients.

METHODS

Chronic HBV-infected patients who underwent transient elastography examination in 2006-2008 were studied. Advanced fibrosis was defined as liver stiffness > 9 kPa for patients with normal alanine aminotransferase (ALT) or > 12 kPa for those with elevated ALT according to previous validation study. Caffeine and alcohol consumption was recorded using a standardized questionnaire. Excessive alcohol intake was defined as 30 g/day in men and 20 g/day in women.

RESULTS

The liver stiffness of 1045 patients who completed the questionnaire was 8.3 ± 6.2 kPa. Two hundred and sixteen (20.7%) patients had advanced fibrosis. Ninety-five (19.0%) patients who drank ≥ 1 cup of coffee had advanced fibrosis, compared with 121 (22.2%) patients who drank < 1 cup (P = 0.21). The amount of caffeine intake had positive correlation with the amount of alcohol intake (r(s) = 0.167, P < 0.001). Although 231 (22.1%) patients reported alcohol consumption, only 11 (1%) had excessive alcohol intake. The prevalence of advanced fibrosis among patients with mild to moderate alcohol intake (26, 18.8%) was comparable to that among non-drinkers (190, 21.0%) (P = 0.57).

CONCLUSION

Caffeine intake does not affect liver stiffness in chronic HBV-infected patients. Patients who drink coffee regularly tend to drink alcohol. Most chronic HBV-infected patients do not have excessive alcohol consumption. The prevalence of advanced fibrosis among mild to moderate alcohol drinkers was low in this population.

Instant coffee with high chlorogenic acid levels protects humans against oxidative damage of macromolecules

SCOPE

Coffee is among the most frequently consumed beverages. Its consumption is inversely associated to the incidence of diseases related to reactive oxygen species; the phenomenon may be due to its antioxidant properties. Our primary objective was to investigate the impact of consumption of a coffee containing high levels of chlorogenic acids on the oxidation of proteins, DNA and membrane lipids; additionally, other redox biomarkers were monitored in an intervention trial.

METHODS AND RESULTS

The treatment group (n=36) consumed instant coffee co-extracted from green and roasted beans, whereas the control consumed water (800 mL/P/day, 5 days). A global statistical analysis of four main biomarkers selected as primary outcomes showed that the overall changes are significant. 8-Isoprostaglandin F2α in urine declined by 15.3%, 3-nitrotyrosine was decreased by 16.1%, DNA migration due to oxidized purines and pyrimidines was (not significantly) reduced in lymphocytes by 12.5 and 14.1%. Other markers such as the total antioxidant capacity were moderately increased; e.g. LDL and malondialdehyde were shifted towards a non-significant reduction.

CONCLUSION

The oxidation of DNA, lipids and proteins associated with the incidence of various diseases and the protection against their oxidative damage may be indicative for beneficial health effects of coffee.

Prognostic potential and tumor growth-inhibiting effect of plasma advanced glycation end products in non-small cell lung carcinoma

The plasma fluorescence related to the standard fluorescence of advanced glycation end products (AGEs) is a simple measurable blood parameter for distinct diseases but its importance in human cancer, including non-small cell lung carcinoma (NSCLC), is unknown. Plasma samples of 70 NSCLC patients who underwent resection surgery of the tumor were analyzed for the distinct AGE-related fluorescence at 370 nm excitation/440 nm emission. In a retrospective study, we tested the prognostic relevance of this AGE-related plasma fluorescence. The effect of circulating AGEs on the NSCLC growth was studied experimentally in vitro and in vivo. NSCLC patients with high (> median) AGE-related plasma fluorescence were characterized by a later reoccurrence of the tumor after curative surgery and a higher survival rate compared with patients with low plasma fluorescence (25% versus 47% 5-y survival, P = 0.011). Treating NSCLC cell spheroids with patients' plasma showed an inverse correlation between the growth of spheroids in vitro and the individual AGE-related fluorescence of each plasma sample. To confirm the impact of circulating AGEs on the NSCLC progression, we studied the NSCLC growth in mice whose circulating AGE level was elevated by AGE-rich diet. In vivo tumorigenicity assays demonstrated that mice with higher levels of circulating AGEs developed smaller tumors than mice with normal AGE levels. The AGE-related plasma fluorescence has prognostic relevance for NSCLC patients in whom the tumor growth-inhibiting effect of circulating AGEs might play a critical role.

A review on the beneficial aspects of food processing

The manuscript reviews beneficial aspects of food processing with main focus on cooking/heat treatment, including other food-processing techniques (e.g. fermentation). Benefits of thermal processing include inactivation of food-borne pathogens, natural toxins or other detrimental constituents, prolongation of shelf-life, improved digestibility and bioavailability of nutrients, improved palatability, taste, texture and flavour and enhanced functional properties, including augmented antioxidants and other defense reactivity or increased antimicrobial effectiveness. Thermal processing can bring some unintentional undesired consequences, such as losses of certain nutrients, formation of toxic compounds (acrylamide, furan or acrolein), or of compounds with negative effects on flavour perception, texture or colour. Heat treatment of foods needs to be optimized in order to promote beneficial effects and to counteract, to the best possible, undesired effects. This may be achieved more effectively/sustainably by consistent fine-tuning of technological processes rather than within ordinary household cooking conditions. The most important identified points for further study are information on processed foods to be considered in epidemiological work, databases should be built to estimate the intake of compounds from processed foods, translation of in-vitro results to in-vivo relevance for human health should be worked on, thermal and non-thermal processes should be optimized by application of kinetic principles.

Impact of paper filtered coffee on oxidative DNA-damage: results of a clinical trial

Coffee is among the most frequently consumed beverages worldwide and epidemiological studies indicate that its consumption is inversely related to the incidence of diseases in which reactive oxygen species (ROS) are involved (liver cirrhosis, certain forms of cancer and neurodegenerative disorders). It has been postulated that antioxidant properties of coffee may account for this phenomenon. To find out if consumption of paper filtered coffee which is the most widely consumed form in Central Europe and the US protects humans against oxidative DNA-damage, a controlled intervention trial with a cross-over design was conducted in which the participants (n=38) consumed 800ml coffee or water daily over 5 days. DNA-damage was measured in peripheral lymphocytes in single cell gel electrophoresis assays. The extent of DNA-migration attributable to formation of oxidised purines (formamidopyrimidine glycosylase sensitive sites) was decreased after coffee intake by 12.3% (p=0.006). Biochemical parameters of the redox status (malondialdehyde, 3-nitrotyrosine and the total antioxidant levels in plasma, glutathione concentrations in blood, intracellular ROS levels and the activities of superoxide dismutase and glutathione peroxidase in lymphocytes) were not markedly altered at the end of the trial, also the urinary 8-isoprostaglandine F2α concentrations were not affected. Overall, the results indicate that coffee consumption prevents endogenous formation of oxidative DNA-damage in human, this observation may be causally related to beneficial health effects of coffee seen in earlier studies.

Cardiovascular friendly natural products: a promising approach in the management of CVD

Natural products play an important role as nutritional supplements and provide potential health benefits in cardiovascular diseases (CVD). Compiling data from experimental, epidemiological and clinical studies indicates that dietary nutrients have profound cardioprotective effects in the primary as well as secondary prevention of coronary heart disease, hence they are considered as cardiovascular friendly natural products. The mechanism of cardioprotection produced by dietary nutritional supplements such as flavonoids (citrus fruits, pulses, red wine, tea and cocoa), olive oil, omega-3 (omega-3) fatty acids (fish oil and fish-based products), lycopene (tomato and tomato-based products), resveratrol (grapes and red wine), coffee, and soy in the prevention and treatment of cardiovascular disorders have been discussed in the present review, with the emphasis of epidemiological and clinical studies. Based on the intriguing results of various studies, prophylactic and therapeutic potential of cardiovascular friendly natural products have been suggested. The supplementation of cardiovascular friendly natural products needs to be considered in all populations who have high prevalence of CVD.

Effects of coffee consumption on subclinical inflammation and other risk factors for type 2 diabetes: a clinical trial

BACKGROUND

Coffee consumption is associated with a decreased risk of type 2 diabetes. Suggested mechanisms underlying the association have included attenuation of subclinical inflammation and a reduction in oxidative stress.

OBJECTIVE

The aim was to investigate the effects of daily coffee consumption on biomarkers of coffee intake, subclinical inflammation, oxidative stress, glucose, and lipid metabolism.

DESIGN

Habitual coffee drinkers (n = 47) refrained for 1 mo from coffee drinking; in the second month they consumed 4 cups of filtered coffee/d and in the third month 8 cups of filtered coffee/d (150 mL/cup). Blood samples were analyzed by gas chromatography-mass spectrometry, bead-based multiplex technology, enzyme-linked immunosorbent assay, or immunonephelometry.

RESULTS

Coffee consumption led to an increase in coffee-derived compounds, mainly serum caffeine, chlorogenic acid, and caffeic acid metabolites. Significant changes were also observed for serum concentrations of interleukin-18, 8-isoprostane, and adiponectin (medians: -8%, -16%, and 6%, respectively; consumption of 8 compared with 0 cups coffee/d). Serum concentrations of total cholesterol, HDL cholesterol, and apolipoprotein A-I increased significantly by 12%, 7%, and 4%, respectively, whereas the ratios of LDL to HDL cholesterol and of apolipoprotein B to apolipoprotein A-I decreased significantly by 8% and 9%, respectively (8 compared with 0 cups coffee/d). No changes were seen for markers of glucose metabolism in an oral-glucose-tolerance test.

CONCLUSIONS

Coffee consumption appears to have beneficial effects on subclinical inflammation and HDL cholesterol, whereas no changes in glucose metabolism were found in our study. Furthermore, many coffee-derived methylxanthines and caffeic acid metabolites appear to be useful as biomarkers of coffee intake.

Coffee intake and risk of colorectal cancer among Chinese in Singapore: the Singapore Chinese Health Study

We prospectively investigated whether coffee consumption was associated with decreased risk of colorectal cancer and whether cigarette smoking and stage of disease modify the association in the Singapore Chinese Health Study. During the first 12 years of follow-up, 961 colorectal cancer cases occurred in the cohort of over 60,000 middle-aged or older Chinese men and women living in Singapore. Baseline dietary exposures were assessed through in-person interviews using a validated food frequency questionnaire. The relation between coffee consumption and colorectal cancer risk was assessed by proportional hazards (Cox) regression. No overall association between coffee intake and colorectal cancer was observed. However, in analysis by subsite and stage restricted to ever smokers, the coffee-colon cancer association became statistically significant for advanced disease (P for trend = 0.01). The hazard ratio was 0.56 (95% confidence interval = 0.35-0.90) for advanced colon cancer in drinkers of 2 or more cups per day compared with those who drank no coffee or less than 1 cup per day. Although there is a null association between coffee intake and risk of colorectal cancer overall, coffee may protect against smoking related advanced colon cancer.

Strategy for the study of the health impact of dietary Maillard products in clinical studies: the example of the ICARE clinical study on healthy adults

The study of the health impact of dietary Maillard products (MPs) in realistic clinical studies requires the design of nutritionally equivalent diets with high and low levels of MPs. This difficult challenge may be achieved by setting the high-MP diet at the regular daily level, where the common use of grilling, frying, and roasting processes allows significant amounts of carboxymethyllysine, hydroxymethylfurfural and acrylamide to be formed. In such conditions, we show that major lipid degradation does not occur, nor does degradation of vitamin E or thiamine. Based on this finding, the low-MP diet; must be constructed accordingly, by replacing all high-temperature techniques with steam cooking or the absence of cooking. The cooking fat must be replaced with similar raw fat as seasoning in the low-MP diet, the high caloric density resulting from water loss in the high-MP diet must be compensated by higher food quantities offered in the low-MP diet, and the vitamin loss in fruit and vegetables resulting from high temperatures in the high-MP diet can be circumvented by increasing the corresponding portion size. In the ICARE study, equilibrated diets were proposed, fulfilling all nutritional needs, but with a 3- to 45-fold difference in MP concentrations. Individual quantification of nutritional and MP intakes will ensure the nutritional equivalence of the two diets and allow for quantification of the specific impact of ingested MPs.

Coffee, caffeine, and coronary heart disease

PURPOSE OF REVIEW

This review summarizes and highlights recent advances in current knowledge of the relationship between coffee and caffeine consumption and risk of coronary heart disease. Potential mechanisms and genetic modifiers of this relationship are also discussed.

RECENT FINDINGS

Studies examining the association between coffee consumption and coronary heart disease have been inconclusive. Coffee is a complex mixture of compounds that may have either beneficial or harmful effects on the cardiovascular system. Randomized controlled trials have confirmed the cholesterol-raising effect of diterpenes present in boiled coffee, which may contribute to the risk of coronary heart disease associated with unfiltered coffee consumption. A recent study examining the relationship between coffee and risk of myocardial infarction incorporated a genetic polymorphism associated with a slower rate of caffeine metabolism and provides strong evidence that caffeine also affects risk of coronary heart disease. Several studies have reported a protective effect of moderate coffee consumption, which suggests that coffee contains other compounds that may be beneficial.

SUMMARY

Diterpenes present in unfiltered coffee and caffeine each appear to increase risk of coronary heart disease. A lower risk of coronary heart disease among moderate coffee drinkers might be due to antioxidants found in coffee.

Coffee consumption protects human lymphocytes against oxidative and 3-amino-1-methyl-5H-pyrido[4,3-b]indole acetate (Trp-P-2) induced DNA-damage: Results of an experimental study with human volunteers

Aim of the study was to investigate the impact of coffee on DNA-stability in humans. DNA-damage was monitored in lymphocytes of eight individuals with single cell gel electrophoresis assays before and after consumption of 600 ml coffee (400 ml paper filtered and 200 ml metal filtered/d) for five days. Under standard conditions, no alteration of DNA-migration was seen, but a strong reduction of DNA-migration attributable to endogenous formation of oxidised purines and pyrimidines was detected with restriction enzymes; furthermore DNA-damage caused by reactive oxygen radicals (H2O2 treatment) and by the heterocyclic aromatic amine 3-amino-1-methyl-5H-pyrido[4,3-b]indole-acetate was significantly reduced after coffee consumption by 17% and 35%, respectively. Also in in vitro experiments, inhibition of H2O2 induced DNA-damage was observed with coffee at low concentrations (<or= 25 microl/ml) whereas the diterpenoids cafestol and kahweol caused only marginal effects indicating that the effects of coffee are due to scavenging effects of other constituents. Enzyme measurements showed that additionally induction of antioxidant enzymes may play a role: while the activity of glutathione peroxidase was only marginally increased after coffee consumption, a significant (38%) increase of superoxide dismutase activity was detected. Comparisons with results of earlier studies suggest that coffee consumption may prevent oxidative DNA-damage to a higher extent as diets enriched in fruits and vegetables.