Possible health effects of caffeinated coffee consumption on Alzheimer's disease and cardiovascular disease

High coffee consumption, brain volume and risk of dementia and stroke

BACKGROUND

Coffee is a highly popular beverage worldwide, containing caffeine which is a central nervous system stimulant.

OBJECTIVES

We examined whether habitual coffee consumption is associated with differences in brain volumes or the odds of dementia or stroke.

METHODS

We conducted prospective analyses of habitual coffee consumption on 398,646 UK Biobank participants (age 37-73 years), including 17,702 participants with MRI information. We examined the associations with brain volume using covariate adjusted linear regression, and with odds of dementia (4,333 incident cases) and stroke (6,181 incident cases) using logistic regression.

RESULTS

There were inverse linear associations between habitual coffee consumption and total brain (fully adjusted β per cup -1.42, 95% CI -1.89, -0.94), grey matter (β -0.91, 95% CI -1.20, -0.62), white matter (β -0.51, 95% CI -0.83, -0.19) and hippocampal volumes (β -0.01, 95% CI -0.02, -0.003), but no evidence to support an association with white matter hyperintensity (WMH) volume (β -0.01, 95% CI -0.07, 0.05). The association between coffee consumption and dementia was non-linear (P_{non-linearity}= 0.0001), with evidence for higher odds for non-coffee and decaffeinated coffee drinkers and those drinking >6 cups/day, compared to light coffee drinkers. After full covariate adjustment, consumption of >6 cups/day was associated with 53% higher odds of dementia compared to consumption of 1-2 cups/day (fully adjusted OR 1.53, 95% CI 1.28, 1.83), with less evidence for an association with stroke (OR 1.17, 95% CI 1.00, 1.37, p= 0.055).

CONCLUSION

High coffee consumption was associated with smaller total brain volumes and increased odds of dementia.

Decaffeination and Neuraminidase Inhibitory Activity of Arabica Green Coffee (Coffea arabica) Beans: Chlorogenic Acid as a Potential Bioactive Compound

Coffee has been studied for its health benefits, including prevention of several chronic diseases, such as type 2 diabetes mellitus, cancer, Parkinson’s, and liver diseases. Chlorogenic acid (CGA), an important component in coffee beans, was shown to possess antiviral activity against viruses. However, the presence of caffeine in coffee beans may also cause insomnia and stomach irritation, and increase heart rate and respiration rate. These unwanted effects may be reduced by decaffeination of green bean Arabica coffee (GBAC) by treatment with dichloromethane, followed by solid-phase extraction using methanol. In this study, the caffeine and chlorogenic acid (CGA) level in the coffee bean from three different areas in West Java, before and after decaffeination, was determined and validated using HPLC. The results showed that the levels of caffeine were reduced significantly, with an order as follows: Tasikmalaya (2.28% to 0.097% (97 ppm), Pangalengan (1.57% to 0.049% (495 ppm), and Garut (1.45% to 0.00002% (0.2 ppm). The CGA levels in the GBAC were also reduced as follows: Tasikmalaya (0.54% to 0.001% (118 ppm), Pangalengan (0.97% to 0.0047% (388 ppm)), and Garut (0.81% to 0.029% (282 ppm). The decaffeinated samples were then subjected to the H5N1 neuraminidase (NA) binding assay to determine its bioactivity as an anti-influenza agent. The results show that samples from Tasikmalaya, Pangalengan, and Garut possess NA inhibitory activity with IC₅₀ of 69.70, 75.23, and 55.74 μg/mL, respectively. The low level of caffeine with a higher level of CGA correlates with their higher levels of NA inhibitory, as shown in the Garut samples. Therefore, the level of caffeine and CGA influenced the level of NA inhibitory activity. This is supported by the validation of CGA-NA binding interaction via molecular docking and pharmacophore modeling; hence, CGA could potentially serve as a bioactive compound for neuraminidase activity in GBAC.

Association Between Coffee Intake and Incident Heart Failure Risk: A Machine Learning Analysis of the FHS, the ARIC Study, and the CHS

BACKGROUND

Coronary heart disease, heart failure (HF), and stroke are complex diseases with multiple phenotypes. While many risk factors for these diseases are well known, investigation of as-yet unidentified risk factors may improve risk assessment and patient adherence to prevention guidelines. We investigated the diet domain in FHS (Framingham Heart Study), CHS (Cardiovascular Heart Study), and the ARIC study (Atherosclerosis Risk in Communities) to identify potential lifestyle and behavioral factors associated with coronary heart disease, HF, and stroke.

METHODS

We used machine learning feature selection based on random forest analysis to identify potential risk factors associated with coronary heart disease, stroke, and HF in FHS. We evaluated the significance of selected variables using univariable and multivariable Cox proportional hazards analysis adjusted for known cardiovascular risks. Findings from FHS were then validated using CHS and ARIC.

RESULTS

We identified multiple dietary and behavioral risk factors for cardiovascular disease outcomes including marital status, red meat consumption, whole milk consumption, and coffee consumption. Among these dietary variables, increasing coffee consumption was associated with decreasing long-term risk of HF congruently in FHS, ARIC, and CHS.

CONCLUSIONS

Higher coffee intake was found to be associated with reduced risk of HF in all three studies. Further study is warranted to better define the role, possible causality, and potential mechanism of coffee consumption as a potential modifiable risk factor for HF.

History of Coffee Consumption and Risk of Alzheimer's Disease: a Meta-epidemiological Study of Population-based Cohort Studies

Background and Purpose

Four published quantitative systematic reviews showed conflicting results involving coffee consumption and the risk of Alzheimer's disease (AD). The aim of this meta-epidemiological meta-analysis (MEMA) was to evaluate the factors underlying the conflicting results and estimate the effect size and direction of the AD risk associated with coffee consumption in population-based cohort studies.

Methods

The primary subjects of MEMA were derived from 3 cohort studies selected by the related systematic reviews. Additional studies involving the primary subjects were searched using citation discovery tools. Prospective cohort studies evaluating the association between coffee consumption and AD risk were selected. A fixed effects model was applied to estimate the summary relative risk (sRR) and its 95% confidence intervals (CIs). Subgroup analysis was conducted according to the level of coffee consumption. Egger's test was used to evaluate publication bias.

Results

Four cohort studies were finally selected. A total of 36,300 participants from Finland, Sweden, Germany, and the United States of America were selected. The sRR (and its 95% CI) (I-squared value) by highest-versus-lowest method was 0.98 (0.92–1.05) (0.0%). In addition, none of the results of subgroup analyses by the level of coffee consumption showed any statistical significance.

Conclusions

This MEMA found that there was no association between coffee consumption and AD risk. Based on recent evidence suggesting that gene-environment interactions contribute to AD pathogenesis, it is necessary to conduct population-based cohort studies involving non-Caucasians.

Apoptosis of rats’ cardiomyocytes after chronic energy drinks consumption

Energy drinks (ED) are beverages containing caffeine, taurine, vitamins, herbal extracts, and sugar or sweeteners. They are marketed as capable of improving stamina, athletic performance and concentration, moreover, as serving as a source of energy. Still, there are very few papers describing the impact of ED on cell biology – including cell apoptosis within tissues. Therefore, in our study, we assessed the symptoms of rat cardiomyocytes apoptosis after 8 weeks consumption of ED.

For the research, we used male Wistar rats divided into 2 groups (experimental and control). The experimental animals received ED at a dose average of 0.190 ml per g of body weight per day for a period of 8 weeks. The animals of the control group received just water and food without limitation. After 8 weeks, the rats were decapitated; hearts and other organs were collected. After embedding in paraffin blocks, 5μm thick tissue slides were prepared and stained according to standard hematoxylin and eosine (H&E) staining protocol. Additional slides were stained by immunohistochemistry with antibodies directed against either caspaze-3 or p53 protein.

Our results showed that the expression of caspase 3 and p53 protein varied depending on the group of rats. The expression of caspase 3 observed in cardiomyocytes was much more intense in the experimental group compared to the control group. Furthermore, the immunoprecipitation of p53 protein was observed more frequently in the cardiomyocytes nuclei of the experimental group than in the control group.

Obtained results suggest that chronic use of ED induces intracellular disorders and apoptosis in consumer cardiomyocytes.

Coffee consumption and disease correlations

Coffee is one of the most widely consumed beverages in the world. It has primarily consumed due to its stimulant effect and unique taste since the ancient times. Afterwards, its consumption has been historically associated with a lower risk of some diseases such as type 2 diabetes mellitus, obesity, cardiovascular disease and some type of cancer and thus it has also consumed due to health benefits. It contains many bioactive compounds such as caffeine, chlorogenic acids and diterpenoid alcohols which have so far been associated with many potential health benefits. For example, caffeine reduces risk of developing neurodegenerative disease and chlorogenic acids (CGA) and diterpene alcohols have many health benefits such as antioxidant and chemo-preventive. Coffee also have harmful effects. For example, diterpenoid alcohols increases serum homocysteine and cholesterol levels and thus it has adverse effects on cardiovascular system. Overall, the study that supports the health benefits of coffee is increasing. But, it is thought-provoking that the association with health benefits of coffee consumption and frequency at different levels in each study. For this reason, we aimed to examine the health effect of the coffee and how much consumption is to investigate whether it meets the claimed health benefits.

The Effects of Caffeine on the Long Bones and Testes in Immature and Young Adult Rats

This study was to evaluate the age-dependent effects of caffeine exposure on the long bones and reproductive organs using male rats. A total of 15 immature male rats and 15 young adult male rats were allocated randomly to three groups: a control group and two groups fed caffeine with 120 and 180 mg/kg/day for 4 weeks. Exposure to caffeine at either dose significantly reduced body weight gain; a proportional reduction in muscle and fat mass in immature animals, whereas a selective reduction in fat mass with relatively preserved muscle mass in young adult animals. The long bones of immature rats exposed to caffeine were significantly shorter and lighter than those of control animals along with decreased bone minerals. However, there was no difference in the length or weight of the long bones in young adult rats exposed to caffeine. Exposure to caffeine reduced the size and absolute weight of the testes significantly in immature animals in comparison to control animals, but not in young adult animals exposed to caffeine. In contrast, the adrenal glands were significantly heavier in caffeine-fed young adult rats in comparison to control animals, but not in caffeine-fed immature rats. Our results clearly show that the negative effects of caffeine on the long bones and testes in rats are different according to the age of the rat at the time of exposure, and might therefore be caused by changes to organ sensitivity and metabolic rate at different developmental stages. Although the long bones and testes are more susceptible to caffeine during puberty, caffeine has negative effects on body fat, bone minerals and the adrenal glands when exposure occurs during young adulthood. There is a need, therefore, to educate the public the potential dangers of caffeine consumption during puberty and young adulthood.

Coffee induces vascular endothelial growth factor (VEGF) expression in human neuroblastama SH-SY5Y cells

Recent evidence indicates that hypoxia-inducible vascular endothelial growth factor (VEGF) has neurotrophic and neuroprotective effects on neuronal and glial cells. On the other hand, recent epidemiological studies showed that daily coffee consumption has been associated with a lower risk of several neuronal disorders. Therefore, we investigated the effect of coffee on VEGF expression in human neuroblastoma SH-SY5Y cells. We found that even low concentration of coffee (<2%) strongly induced VEGF expression via an activation of HIF-1α. The activation of HIF-1α by coffee was attributed to the coffee-dependent inhibition of prolyl hydroxylation of HIF1α, which is essential for proteolytic degradation of HIF-1α. However, no inhibition was observed at the catalytic activity in vitro. Coffee component(s) responsible for the activation of HIF-1α was not major constituents such as caffeine, caffeic acid, chlorogenic acid, and trigonelline, but was found to emerge during roasting process. The active component(s) was extractable with ethyl acetate. Our results suggest that daily consumption of coffee may induce VEGF expression in neuronal cells. This might be related to protective effect of coffee on neural disorders such as Alzheimer's disease and Parkinson's disease.