Chemical composition and health properties of coffee and coffee by-products

Coffee consumption, health benefits and side effects: a narrative review and update for dietitians and nutritionists

Coffee is one of the most popular beverages worldwide; however, its impact on health outcomes and adverse effects is not fully understood. The current review aims to establish an update about the benefits of coffee consumption on health outcomes highlighting its side effects, and finally coming up with an attempt to provide some recommendations on its doses. A literature review using the PubMed/Medline database was carried out and the data were summarized by applying a narrative approach using the available evidence based on the literature. The main findings were the following: first, coffee may contribute to the prevention of inflammatory and oxidative stress-related diseases, such as obesity, metabolic syndrome and type 2 diabetes; second, coffee consumption seems to be associated with a lower incidence of several types of cancer and with a reduction in the risk of all-cause mortality; finally, the consumption of up to 400 mg/day (1-4 cups per day) of caffeine is safe. However, the time gap between coffee consumption and some drugs should be taken into account in order to avoid interaction. However, most of the data were based on cross-sectional or/and observational studies highlighting an association of coffee intake and health outcomes; thus, randomized controlled studies are needed in order to identify a causality link.

Coffee and Arterial Hypertension

Purpose of Review

Coffee is a very popular drink and an estimated 2.25 billion cups worldwide are consumed daily. Such popularity of coffee makes it the most consumed drink next to water. Numerous studies have shown a beneficial effect of habitual and moderate coffee consumption on the functioning of the nervous, digestive, and cardiovascular systems, as well as on kidney function. Taking into account the very high prevalence of arterial hypertension in the world (31.1% of adults), much controversy has been raised about the influence of coffee consumption on blood pressure and the risk of arterial hypertension. Moreover, there have been extensive discussions about the safety of coffee consumption for hypertensive persons.

Recent Findings

There are over 1000 chemical compounds in coffee. The best characterized of these are caffeine, chlorogenic acid, trigonelline, kahweol, cafestol, ferulic acid, and melanoidins. These compounds have bidirectional influences on blood pressure regulation. The results of numerous studies and meta-analyses indicate that moderate and habitual coffee consumption does not increase and may even reduce the risk of developing arterial hypertension. Conversely, occasional coffee consumption has hypertensinogenic effects. Moderate habitual coffee consumption in hypertensive persons does not appear to increase the risk of uncontrolled blood pressure and may even reduce the risk of death from any cause.

Summary

Moderate and habitual consumption of coffee (1-–3 cups / day) does not adversely affect blood pressure in most people, including those with arterial hypertension.

Effect of Coffee and Cocoa-Based Confectionery Containing Coffee on Markers of DNA Damage and Lipid Peroxidation Products: Results from a Human Intervention Study

The effect of coffee and cocoa on oxidative damage to macromolecules has been investigated in several studies, often with controversial results. This study aimed to investigate the effect of one-month consumption of different doses of coffee or cocoa-based products containing coffee on markers of DNA damage and lipid peroxidation in young healthy volunteers. Twenty-one volunteers were randomly assigned into a three-arm, crossover, randomized trial. Subjects were assigned to consume one of the three following treatments: one cup of espresso coffee/day (1C), three cups of espresso coffee/day (3C), and one cup of espresso coffee plus two cocoa-based products containing coffee (PC) twice per day for 1 month. At the end of each treatment, blood samples were collected for the analysis of endogenous and H2O2-induced DNA damage and DNA oxidation catabolites, while urines were used for the analysis of oxylipins. On the whole, four DNA catabolites (cyclic guanosine monophosphate (cGMP), 8-OH-2'-deoxy-guanosine, 8-OH-guanine, and 8-NO2-cGMP) were detected in plasma samples following the one-month intervention. No significant modulation of DNA and lipid damage markers was documented among groups, apart from an effect of time for DNA strand breaks and some markers of lipid peroxidation. In conclusion, the consumption of coffee and cocoa-based confectionery containing coffee was apparently not able to affect oxidative stress markers. More studies are encouraged to better explain the findings obtained and to understand the impact of different dosages of these products on specific target groups.

Targeting Melanoma-Initiating Cells by Caffeine: In Silico and In Vitro Approaches

The beneficial effects of coffee on human diseases are well documented, but the molecular mechanisms of its bioactive compounds on cancer are not completely elucidated. This is likely due to the large heterogeneity of coffee preparations and different coffee-based beverages, but also to the choice of experimental models where proliferation, differentiation and immune responses are differently affected. The aim of the present study was to investigate the effects of one of the most interesting bioactive compounds in coffee, i.e., caffeine, using a cellular model of melanoma at a defined differentiation level. A preliminary in silico analysis carried out on public gene-expression databases identified genes potentially involved in caffeine’s effects and suggested some specific molecular targets, including tyrosinase. Proliferation was investigated in vitro on human melanoma initiating cells (MICs) and cytokine expression was measured in conditioned media. Tyrosinase was revealed as a key player in caffeine’s mechanisms of action, suggesting a crucial role in immunomodulation through the reduction in IL-1β, IP-10, MIP-1α, MIP-1β and RANTES secretion onto MICs conditioned media. The potent antiproliferative effects of caffeine on MICs are likely to occur by promoting melanin production and reducing inflammatory signals’ secretion. These data suggest tyrosinase as a key player mediating the effects of caffeine on melanoma.

Habitual coffee and caffeinated beverages consumption is inversely associated with arterial stiffness and central and peripheral blood pressure

The effects of chronic coffee consumption on the cardiovascular system are still under debate. Aortic stiffness, wave reflections, and central and peripheral blood pressure (BP) are milestone indicators of cardiovascular-risk. We sought to investigate the association between coffee and caffeine consumption, arterial stiffness, and central/peripheral BP. Aortic stiffness was evaluated via pulse wave velocity (PWV); wave reflections with the augmentation index (AIx);peripheral systolic BP (SBP), diastolic BP (DBP), and central BP (cSBP/cDBP) were non-invasively assessed. Coffee and caffeine consumption was ascertained using a questionnaire. A linear inverse relationship between coffee and caffeine consumption and arterial stiffness and central and peripheral BP was found.Light coffee and caffeine consumers showed β-coefficients for PWV-0.15, SBP-3.61, DBP-2.48, cSBP-3.21, and cDBP-2.18 (all p values < 0.05).Present findings suggest that coffee and caffeine consumption is inversely associated with arterial stiffness and central and peripheral BP in a large population sample. Interventional prospective studies are needed to demonstrate the causal association.

The relationship of coffee consumption and CVD risk factors in elderly patients with T2DM

OBJECTIVE

Clinical studies suggest increasing prevalence of cardiovascular disease (CVD) risk factors and diabetes among the elderly. Meanwhile, some food compounds, such as coffee, can also have beneficial effects on CVD risk factors. The aim of the present study was to examine the relationship between coffee consumption and CVD risk factors in the elderly with type 2 diabetes mellitus (T2DM).

METHODS

This cross-sectional study was performed during 2017 on 300 elderly people above 60 years of age with T2DM in Isfahan, Iran. Dietary assessment was performed using a food frequency questionnaire. Coffee consumption was classified into three groups including < 1, 1-3, and > 3 cups/day. Partial correlation test was used to investigate the relationship between CVD risk factors and usual coffee consumption.

RESULTS

The mean age and body mass index of participants were 70.04 ± 4.87 years and 24.74 ± 3.34 kg/m2 respectively. Coffee consumption had a significant inverse relationship with fasting plasma glucose (FPG) and diastolic blood pressure (DBP) in the elderly with T2DM (r: - 0.117, 0.134; p: 0.046, 0.022). Triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) had a significant positive relationship with coffee consumption levels (r: 0.636, 0.128; p: 0.028, 0.029). These results were obtained after controlling for potential confounders.

CONCLUSION

Increasing coffee consumption was linked to improved status of some CVD risk factors including FPG, HDL-C, and DBP in the elderly with T2DM. Nevertheless, increasing coffee consumption was also associated with higher TG level and had no significant effect on other risk factors. Further studies are required to confirm these results.

Fermented Gamma Aminobutyric Acid Improves Sleep Behaviors in Fruit Flies and Rodent Models

The aim of this study was to investigate the effect of Lactobacillus brevis-fermented γ-aminobutyric acid (LB-GABA) on sleep behaviors in invertebrate and vertebrate models. In Drosophila melanogaster, LB-GABA-treated group showed an 8-9%-longer sleep duration than normal group did. LB-GABA-treated group also showed a 46.7% lower level of nighttime activity with a longer (11%) sleep duration under caffeine-induced arousal conditions. The LB-GABA-mediated inhibition of activity was confirmed as a reduction of total movement of flies using a video tracking system. In the pentobarbital-induced sleep test in mice, LB-GABA (100 mg/kg) shortened the time of onset of sleep by 32.2% and extended sleeping time by 59%. In addition, mRNA and protein level of GABAergic/Serotonergic neurotransmitters were upregulated following treatment with LB-GABA (2.0%). In particular, intestine- and brain-derived GABAA protein levels were increased by sevenfold and fivefold, respectively. The electroencephalography (EEG) analysis in rats showed that LB-GABA significantly increased non-rapid eye movement (NREM) (53%) with the increase in theta (θ, 59%) and delta (δ, 63%) waves, leading to longer sleep time (35%), under caffeine-induced insomnia conditions. LB-GABA showed a dose-dependent agonist activity on human GABAA receptor with a half-maximal effective concentration (EC50) of 3.44 µg/mL in human embryonic kidney 293 (HEK293) cells.

Selenium biofortification enhances ROS scavenge system increasing yield of coffee plants

There are conclusive evidences of selenium (Se) deficiency in Brazilian soils and foods. Brazil is the largest producer and consumer of coffee worldwide, which favors agronomic biofortification of its coffee. This study aimed to evaluate effects of foliar application of three formulations and six rates of Se on antioxidant metabolism, agronomic biofortification and yield of coffee beans. Seven Se concentrations (0, 10, 20, 40, 80, 100 and 160 mg L^-1) were applied from three formulations of Se (sodium selenate, nano-Se 1500, and nano-Se 5000). Selenium application up to 40 mg L^-1 increased the concentration of photosynthetic pigments such as chlorophylls, pheophytins and carotenoids in coffee leaves. Foliar application of Se ranging from 20 to 80 mg L^-1 decreased lipid peroxidation and concentration of hydrogen peroxide, but increased superoxide dismutase, ascorbate peroxidase, catalase and glutathione reductase activities in coffee leaves. These results indicated that foliar Se application stimulates antioxidative metabolism to mitigate reactive oxygen species. Foliar application of 20 mg Se L^-1 of sodium selenate increased coffee yield by 38%, and 160 mg Se L^-1 of nano-Se 5000 increased dramatically coffee yield by 42%. Selenium concentration in grains ranged from 0.116 to 4.47 mg kg^-1 (sodium selenate), 4.84 mg kg^-1 (nano-Se 1500) and 5.82 mg kg^-1 (nano-Se 5000). The results suggest the beneficial effect of Se on the increment of photosynthetic pigments, antioxidative metabolism, increased coffee yield and nutritional quality of grains. The recommended foliar Se application in this study can mitigate abiotic stressors such as high temperatures resulting in higher yield of coffee plants.

A Review of Coffee By-Products Including Leaf, Flower, Cherry, Husk, Silver Skin, and Spent Grounds as Novel Foods within the European Union

The coffee plant Coffea spp. offers much more than the well-known drink made from the roasted coffee bean. During its cultivation and production, a wide variety of by-products are accrued, most of which are currently unused, thermally recycled, or used as animal feed. The aim of this review is to provide an overview of novel coffee products in the food sector and their current legal classification in the European Union (EU). For this purpose, we have reviewed the literature on the composition and safety of coffee flowers, leaves, pulp, husk, parchment, green coffee, silver skin, and spent coffee grounds. Some of these products have a history of consumption in Europe (green coffee), while others have already been used as traditional food in non-EU-member countries (coffee leaves, notification currently pending), or an application for authorization as novel food has already been submitted (husks, flour from spent coffee grounds). For the other products, toxicity and/or safety data appear to be lacking, necessitating further studies to fulfill the requirements of novel food applications.