Cardiometabolic effects of two coffee blends differing in content for major constituents in overweight adults: a randomized controlled trial

Impact of a Low-Insulin-Stimulating Bread on Weight Development-A Real Life Randomised Controlled Trial

The impact on body weight development is usually analysed by comparing different diet types. Our approach was to change only one component, namely bread, common to most diets. In a single-centre triple-blind randomised controlled trial the effects of two different breads on body weight were analyzed without further lifestyle modification. Overweight adult volunteers (n = 80) were randomised 1:1 to exchange previously consumed breads for either a rye bread from milled whole grain (control) or a medium-carbohydrate, low-insulin-stimulating bread (intervention). Pre-tests demonstrated that the two bread types strongly differed in the glucose and insulin response elicited, but had similar energy content, texture and taste. The primary endpoint was the estimated treatment difference (ETD) in change of body weight after 3 months of treatment. Whereas body weight remained unchanged in the control group (-0.1 ± 2.0 kg), significant weight reduction was observed in the intervention group (-1.8 ± 2.9 kg), with an ETD of -1.7 ± 0.2 kg (p = 0.007), that was more pronounced in participants ≥ 55 years (-2.6 ± 3.3 kg), paralleled by significant reductions in body mass index and hip circumference. Moreover, in the intervention group, the percentage of participants with significant weight loss (≥1 kg) was twice as high as in the control group (p < 0.001). No other statistically significant changes in clinical or lifestyle parameters were noted. Simply exchanging a common insulinogenic bread for a low-insulin-stimulating bread demonstrates potential to induce weight loss in overweight persons, especially those at older age.

Coffee or tea: Anti-inflammatory properties in the context of atherosclerotic cardiovascular disease prevention

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of premature death worldwide. Inflammation and its biomarkers, like C-reactive protein (CRP), among the risk factors, such as hypertension, lipid disorders, and diabetes, may be also responsible for the residual cardiovascular disease (CVD) risk. Modern lipid-lowering treatment with statins, ezetimibe, PCSK9 inhibitors, or bempedoic acid does not fully protect against inflammation. The recommendations of the International Lipid Expert Panel (ILEP) indicate selected nutraceuticals with anti-inflammatory properties. Diet may have a significant impact on inflammation. Especially interesting in the context of inflammation is the consumption of coffee and tea. These drinks in many observational studies significantly reduced cardiovascular risk and mortality. The question is whether the anti-inflammatory effects of these drinks contribute significantly to the observed clinical effects. Thus, in this narrative review, we primarily discuss the anti-inflammatory properties of consuming tea and coffee. Based on a comprehensive analysis of the studies and their meta-analyses, inconsistent results were obtained, which makes it impossible to conclusively state how clinically significant the potential anti-inflammatory properties of black and green tea and coffee are. A number of confounding factors can cause the inconsistency of the available results. Consumption of tea and coffee appears to increase adiponectin concentrations, decrease reactive oxygen species, decrease low density lipoprotein (LDL) cholesterol concentrations (effect of green tea, etc.). Despite the still uncertain anti-inflammatory effect of tea and coffee, we recommend their consumption as a part of the healthy diet.

The magical smell and taste: Can coffee be good to patients with cardiometabolic disease?

Coffee is a beverage consumed globally. Although few studies have indicated adverse effects, it is typically a beneficial health-promoting agent in a range of diseases, including depression, diabetes, cardiovascular disease, and obesity. Coffee is rich in caffeine, antioxidants, and phenolic compounds, which can modulate the composition of the gut microbiota and mitigate both inflammation and oxidative stress, common features of the burden of lifestyle diseases. This review will discuss the possible benefits of coffee on complications present in patients with diabetes, cardiovascular disease and chronic kidney disease, outwith the social and emotional benefits attributed to caffeine consumption.

The Cardiovascular Benefits of Caffeinated Beverages: Real or Surreal? /"Metron Ariston - All in Moderation"

Caffeinated beverages are the most widely consumed beverages globally with coffee and tea as the two most prominent sources of caffeine. Caffeine content varies across different types of beverages. In addition to caffeine, coffee and tea have other biologically active compounds, and all may affect general and cardiovascular (CV) health. Moderate caffeine consumption (<300-400 mg/day), regardless of the source, is considered safe by both European and US Health Authorities, as it is not associated with adverse health and CV effects, while it may confer certain health benefits. There is a nonlinear association between coffee ingestion and CV risk; moderate coffee drinking is inversely significantly associated with CV risk, with the highest benefit at 2-4 cups per day, while heavy coffee drinking might confer increased risk. With regards to tea, due to a lower caffeine content per serving, its consumption is only limited by the total caffeine daily intake. Both these caffeinated beverages, coffee and tea, have additional phenolic compounds, with anti-oxidant and anti-inflammatory activities, which confer cardioprotective benefits. Of the several coffee compounds, chloroacetic acids and melanoidins offer such beneficial effects, while diterpenes may have unfavorable effects on lipids. Most of the tea ingredients (polyphenols) are cardioprotective. A major concern relates to energy drinks with their much higher caffeine content which puts individuals, especially adolescents and young adults, at high health and CV risk. All these issues are herein discussed, including pertinent studies and meta-analyses, pathogenetic mechanisms involved and relevant recommendations from health authorities.

The effects of foods on LDL cholesterol levels: A systematic review of the accumulated evidence from systematic reviews and meta-analyses of randomized controlled trials

AIMS

To systematically evaluate the evidence regarding the effects of foods on LDL cholesterol levels and to compare the findings with current guidelines.

DATA SYNTHESIS

From inception through June 2019, we searched PubMed, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials for guidelines, systematic reviews, and RCTs (for coffee intake only) of at least 13 days duration. Additionally, we searched Trip database for guidelines from 2009 through Oct 2019. Language was restricted to English. The strength of evidence was evaluated using The Grading of Recommendations Assessment, Development, and Evaluation (GRADE). A total of 37 guidelines, 108 systematic reviews, and 20 RCTs were included. With high evidence, foods high in unsaturated and low in saturated and trans fatty acids (e.g. rapeseed/canola oil), with added plant sterols/stanols, and high in soluble fiber (e.g. oats, barley, and psyllium) caused at least moderate (i.e. 0.20-0.40 mmol/L) reductions in LDL cholesterol. Unfiltered coffee caused a moderate to large increase. Soy protein, tomatoes, flaxseeds, and almonds caused small reductions. With moderate evidence, avocados and turmeric caused moderate to large reductions. Pulses, hazelnuts, walnuts, high-fiber/wholegrain foods, and green tea caused small to moderate reductions, whereas sugar caused a small increase. Other identified foods were either neutral or had low or very low evidence regarding their effects.

CONCLUSIONS

Several foods distinctly modify LDL cholesterol levels. The results may aid future guidelines and dietary advice for hypercholesterolemia.

Impact of Coffee Consumption on Physiological Markers of Cardiovascular Risk: A Systematic Review

BACKGROUND

Coffee is one of the most widely consumed beverages globally. A substantial number of observational data suggest an inverse relationship between coffee consumption and the risk for cardiovascular disease. The basis for this association is not clear. In this review, we specifically study the impact of coffee on inflammatory biomarkers as one potential mechanistic basis for this observation. Our objective was to systematically review randomized controlled trials that examined the effects of coffee consumption on selected cardiovascular biomarkers.

METHODS

We systematically reviewed bibliographic databases including PubMed (NCBI), Embase (Elsevier), CINAHL (EBSCO), Web of Science (Clarivate Analytics), Cochrane Central Register of Controlled Trials (EBSCO), and CAB Abstracts (Clarivate Analytics). We searched for randomized controlled trials that studied the effect of drinking coffee on inflammatory markers of cardiovascular risk.

RESULTS

The search of electronic databases returned 1631 records. After removing duplicate records and ineligible studies, we examined a total of 40 full-text documents, 17 of which were eligible for further analysis. In our review, boiled coffee, in particular, appeared to raise total and low-density lipoprotein cholesterol and apolipoprotein B, but evidence suggests no similar effect for filtered coffee. One study showed a significant increase in blood interleukin 6 levels among individuals who drank caffeinated coffee, compared with individuals consuming no coffee.

CONCLUSION

Based on our systematic review of randomized controlled studies, we cannot confidently conclude that an anti-inflammatory effect of coffee is a major contributing factor to the lower all-cause mortality reported in observational studies.

Coffee and Lower Risk of Type 2 Diabetes: Arguments for a Causal Relationship

Prospective epidemiological studies concur in an association between habitual coffee consumption and a lower risk of type 2 diabetes. Several aspects of these studies support a cause–effect relationship. There is a dependency on daily coffee dose. Study outcomes are similar in different regions of the world, show no differences between sexes, between obese versus lean, young versus old, smokers versus nonsmokers, regardless of the number of confounders adjusted for. Randomized controlled intervention trials did not find a consistent impact of drinking coffee on acute metabolic control, except for effects of caffeine. Therefore, lowering of diabetes risk by coffee consumption does not involve an acute effect on the post-meal course of blood glucose, insulin or insulin resistance. Several studies in animals and humans find that the ingestion of coffee phytochemicals induces an adaptive cellular response characterized by upregulation and de novo synthesis of enzymes involved in cell defense and repair. A key regulator is the nuclear factor erythroid 2-related factor 2 (Nrf2) in association with the aryl hydrocarbon receptor, AMP-activated kinase and sirtuins. One major site of coffee actions appears to be the liver, causing improved fat oxidation and lower risk of steatosis. Another major effect of coffee intake is preservation of functional beta cell mass via enhanced mitochondrial function, lower endoplasmic reticulum stress and prevention or clearance of aggregates of misfolded proinsulin or amylin. Long-term preservation of proper liver and beta cell function may account for the association of habitual coffee drinking with a lower risk of type 2 diabetes, rather than acute improvement of metabolic control.

Can pentoxifylline and similar xanthine derivatives find a niche in COVID-19 therapeutic strategies? A ray of hope in the midst of the pandemic

COVID-19 pandemic presents an unprecedented challenge to identify effective drugs for treatment. Despite multiple clinical trials using different agents, there is still a lack of specific treatment for COVID-19. Having the potential role in suppressing inflammation, immune modulation, antiviral and improving respiratory symptoms, this review discusses the potential role of methylxanthine drugs like pentoxifylline and caffeine in the management of COVID-19 patients. COVID-19 pathogenesis for clinical features like severe pneumonia, acute lung injury (ALI) / acute respiratory distress syndrome (ARDS), and multi-organ failures are excessive inflammation, oxidation, and cytokine storm by the exaggerated immune response. Drugs like pentoxifylline have already shown improvement of the symptoms of ARDS and caffeine has been in clinical use for decades to treat apnea of prematurity (AOP) in preterm infants and improve respiratory function. Pentoxifylline is well-known anti-inflammatory and anti-oxidative molecules that have already shown to suppress Tumor Necrosis Factor (TNF-α) as well as other inflammatory cytokines in pulmonary diseases, and this may be beneficial for better clinical outcomes in COVID-19 patients. Pentoxifylline enhances blood flow, improves microcirculation and tissue oxygenation, and caffeine also efficiently improves tissue oxygenation, asthma, decreases pulmonary hypertension and an effective analgesic. There are significant shreds of evidence that proved the properties of pentoxifylline and caffeine against virus-related diseases as well. Along with the aforementioned evidences and high safety profiles, both pentoxifylline and caffeine offer a glimpse of considerations for future use as a potential adjuvant to COVID-19 treatment. However, additional clinical studies are required to confirm this speculation.

Effects of consumption of coffee, tea, or soft drinks on open-angle glaucoma: Korea National Health and Nutrition Examination Survey 2010 to 2011

We sought to investigate the association between consumption of coffee, tea, or soft drinks and risk of open-angle glaucoma (OAG) among Koreans using nationwide population-based data. This cross-sectional survey was performed through the Korea National Health and Nutrition Examination Survey 2010 to 2011. Participants older than 19 years were included in the sample for analysis after excluding those with any missing data. The diagnosis of OAG was based on the International Society of Geographical and Epidemiological Ophthalmology criteria, and participants without glaucomatous optic neuropathy served as controls. The frequency of beverage consumption during the past 12 months was obtained through a questionnaire. Multivariate logistic regression models were used to determine the relationship between consumption of each type of beverage and prevalence of OAG. A total of 6,681 participants was included in the analysis. The prevalence of OAG was 4.4% (n = 323), including 5.4% (n = 169) among men and 3.5% (n = 154) among women. After adjusting for multiple covariates, coffee consumption was significantly associated with OAG, while no significant association was found between consumption of tea or soft drinks and OAG. Participants who drank coffee had a higher risk of having OAG compared with those who did not drink coffee (odds ratio [OR], 2.40; 95% confidence interval [CI], 1.22–4.72; p = 0.011). In sex-stratified analyses, the robust association of coffee consumption with OAG was observed in men (OR, 3.98; 95% CI, 1.71–9.25; p = 0.001) but not in women. Our results suggest that coffee consumption may affect the risk of OAG, particularly in men.

Health Effects of Coffee: Mechanism Unraveled?

The association of habitual coffee consumption with a lower risk of diseases, like type 2 diabetes mellitus, chronic liver disease, certain cancer types, or with reduced all-cause mortality, has been confirmed in prospective cohort studies in many regions of the world. The molecular mechanism is still unresolved. The radical-scavenging and anti-inflammatory activity of coffee constituents is too weak to account for such effects. We argue here that coffee as a plant food has similar beneficial properties to many vegetables and fruits. Recent studies have identified a health promoting mechanism common to coffee, vegetables and fruits, i.e., the activation of an adaptive cellular response characterized by the upregulation of proteins involved in cell protection, notably antioxidant, detoxifying and repair enzymes. Key to this response is the activation of the Nrf2 (Nuclear factor erythroid 2-related factor-2) system by phenolic phytochemicals, which induces the expression of cell defense genes. Coffee plays a dominant role in that regard because it is the major dietary source of phenolic acids and polyphenols in the developed world. A possible supportive action may be the modulation of the gut microbiota by non-digested prebiotic constituents of coffee, but the available data are still scarce. We conclude that coffee employs similar pathways of promoting health as assumed for other vegetables and fruits. Coffee beans may be viewed as healthy vegetable food and a main supplier of dietary phenolic phytochemicals.

Coffee Consumption and C-Reactive Protein Levels: A Systematic Review and Meta-Analysis

Coffee contains bioactive compounds with anti-inflammatory properties, and its consumption may reduce c-reactive protein (CRP) levels, a biomarker of chronic inflammation. A previous meta-analysis reported no overall association between blood CRP level and coffee consumption by modeling the coffee consumption in categories, with substantial heterogeneity. However, the coffee cup volume was not considered. We conducted a systematic review and dose–response meta-analysis investigating the association between coffee consumption and CRP levels reported in previous observational studies. A dose–response meta-analysis was conducted by mixed-effects meta-regression models using the volume of coffee consumed as metric. Eleven studies from three continents were identified using the PubMed database, totaling 61,047 participants. Three studies with the largest sample sizes observed a statistically significant association between coffee and CRP levels, which was inverse among European and United States (US) women and Japanese men (1.3–5.5% decrease in CRP per 100 mL of coffee consumed) and positive among European men (2.2% increase). Other studies showed no statistically significant associations. When all studies were combined in the dose–response meta-analysis, no statistically significant associations were observed among all participants or when stratified by gender or geographic location, reflecting the conflicting associations reported in the included studies. Further studies are warranted to explore these inconsistent associations.

The effect of coffee consumption on insulin sensitivity and other biological risk factors for type 2 diabetes: a randomized placebo-controlled trial

BACKGROUND

In observational studies, coffee consumption has been consistently associated with a lower risk of type 2 diabetes mellitus. Trials examining the effect of coffee consumption on glucose metabolism have been limited by the use of surrogate insulin sensitivity indices, small sample sizes, lack of blinding, and short follow-up duration.

OBJECTIVES

We aimed to overcome limitations of previously conducted coffee trials in a randomized placebo-controlled trial of the effect of coffee consumption on insulin sensitivity.

METHODS

We conducted a 24-wk randomized placebo-controlled trial in 126 overweight, non-insulin sensitive (HOMA-IR ≥1.30), Chinese, Malay, and Asian-Indian males and females aged 35-69 y. Participants were randomly assigned to receive 4 cups of instant regular coffee (n = 62) or 4 cups of a coffee-like placebo beverage (n = 64) per day. The primary outcome was the amount of glucose metabolized per kilogram of body weight per minute (Mbw) assessed during steady-state conditions with a hyperinsulinemic euglycemic clamp. Secondary outcomes included other clamp-based insulin sensitivity measures, biological mediators of insulin sensitivity, and measures of fasting glucose metabolism.

RESULTS

Coffee consumption did not significantly change insulin sensitivity compared with placebo (percentage mean difference in Mbw = 4.0%; 95% CI: -8.3, 18.0%; P = 0.53). Furthermore, no significant differences in fasting plasma glucose (2.9%; 95% CI: -0.4, 6.3%; P = 0.09) or biological mediators of insulin resistance, such as plasma adiponectin (2.3%; 95% CI: -1.4, 6.2%; P = 0.22), were observed between coffee and placebo groups over 24 wk of intervention. Participants in the coffee arm experienced a loss of fat mass (FM) (-3.7%; 95% CI: -6.3, -1.1%; P = 0.006) and reduction in urinary creatinine concentrations (-21.2%; 95% CI: -31.4, -9.5%; P = 0.001) compared with participants in the placebo arm over 24 wk of intervention.

CONCLUSIONS

Consuming 4 cups/d of caffeinated coffee for 24 wk had no significant effect on insulin sensitivity or biological mediators of insulin resistance but was associated with a modest loss of FM and reduction in urinary creatinine concentrations.This trial was registered at clinicaltrials.gov as NCT01738399. Registered on November 28, 2012. Trial sponsor: Nestlé Research, Lausanne, Switzerland. Trial site: National University of Singapore.

Impact of Foods and Dietary Supplements Containing Hydroxycinnamic Acids on Cardiometabolic Biomarkers: A Systematic Review to Explore Inter-Individual Variability

Plant-based diets rich in bioactive compounds such as polyphenols have been shown to positively modulate the risk of cardiometabolic (CM) diseases. The inter-individual variability in the response to these bioactives may affect the findings. This systematic review aimed to summarize findings from existing randomized clinical trials (RCTs) evaluating the effect of hydroxycinnamic acids (HCAs) on markers of CM health in humans. Literature searches were performed in PubMed and the Web of Science. RCTs on acute and chronic supplementation of HCA-rich foods/extracts on CM biomarkers were included. Forty-four RCTs (21 acute and 23 chronic) met inclusion criteria. Comparisons were made between RCTs, including assessments based on population health status. Of the 44 RCTs, only seven performed analyses on a factor exploring inter-individual response to HCA consumption. Results demonstrated that health status is a potentially important effect modifier as RCTs with higher baseline cholesterol, blood pressure and glycaemia demonstrated greater overall effectiveness, which was also found in studies where specific subgroup analyses were performed. Thus, the effect of HCAs on CM risk factors may be greater in individuals at higher CM risk, although future studies in these populations are needed, including those on other potential determinants of inter-individual variability. PROSPERO, registration number CRD42016050790.

Coffee Abundant in Chlorogenic Acids Reduces Abdominal Fat in Overweight Adults: A Randomized, Double-Blind, Controlled Trial

The components of roasted or green coffee beans that promote abdominal fat reduction are not clear. We investigated the effects of daily consumption of coffee enriched in chlorogenic acids (CGA) on abdominal fat area in a randomized, double-blind, parallel controlled trial. Healthy, overweight men and women (n = 150, body mass index (BMI) ≥25 to <30 kg/m²) were randomly allocated to high-CGA (369 mg CGA/serving) or control (35 mg CGA/serving) coffee groups. Instant coffee was consumed once daily for 12 weeks, with four-week pre- and post-observation periods. Abdominal fat area and anthropometric measurements were analyzed at baseline and at four, eight, and 12 weeks, and 142 subjects completed the trial. Visceral fat area (VFA), total abdominal fat area (TFA), body weight, and waist circumference significantly decreased in the CGA group compared with the control group, with a group × time interaction (p < 0.001, p = 0.001, p = 0.025, and p = 0.001, respectively). Changes in VFA and TFA from baseline to 12 weeks were significantly greater in the CGA group than in the control group (−9.0 ± 13.9 cm² vs. −1.0 ± 14.3 cm², p < 0.001; −13.8 ± 22.9 cm² vs. −2.0 ± 16.2 cm², p < 0.001). No severe adverse events occurred. Consumption of high-CGA coffee for 12 weeks by overweight adults might lower VFA, TFA, BMI, and waist circumference.

Coffee consumption and plasma biomarkers of metabolic and inflammatory pathways in US health professionals

BACKGROUND

Coffee consumption has been linked to lower risk of various health outcomes. However, the biological pathways mediating the associations remain poorly understood.

OBJECTIVES

The aim of this study was to assess the association between coffee consumption and concentrations of plasma biomarkers in key metabolic and inflammatory pathways underlying common chronic diseases.

METHODS

We investigated the associations of total, caffeinated, and decaffeinated coffee consumption with 14 plasma biomarkers, including C-peptide, insulin-like growth factor 1 (IGF-1), IGF binding protein (IGFBP) 1, IGFBP-3, estrone, total and free estradiol, total and free testosterone, sex hormone-binding globulin (SHBG), total adiponectin, high-molecular-weight (HMW) adiponectin, leptin, C-reactive protein (CRP), interleukin 6 (IL-6), and soluble tumor necrosis factor receptor 2 (sTNFR-2). Data were derived from 2 cohorts of 15,551 women (Nurses' Health Study) and 7397 men (Health Professionals Follow-Up Study), who provided detailed dietary data before blood draw and were free of diabetes, cardiovascular disease, or cancer at the time of blood draw. Multivariable linear regression was used to calculate the percentage difference of biomarker concentrations comparing coffee drinkers with nondrinkers, after adjusting for a variety of demographic, clinical, and lifestyle factors.

RESULTS

Compared with nondrinkers, participants who drank ≥4 cups of total coffee/d had lower concentrations of C-peptide (-8.7%), IGFBP-3 (-2.2%), estrone (-6.4%), total estradiol (-5.7%), free estradiol (-8.1%), leptin (-6.4%), CRP (-16.6%), IL-6 (-8.1%), and sTNFR-2 (-5.8%) and higher concentrations of SHBG (5.0%), total testosterone (7.3% in women and 5.3% in men), total adiponectin (9.3%), and HMW adiponectin (17.2%). The results were largely similar for caffeinated and decaffeinated coffee.

CONCLUSION

Our data indicate that coffee consumption is associated with favorable profiles of numerous biomarkers in key metabolic and inflammatory pathways. This trial was registered at clinicaltrials.gov as NCT03419455.

Chlorogenic acid attenuates high-carbohydrate, high-fat diet-induced cardiovascular, liver, and metabolic changes in rats

Chlorogenic acid as a constituent of coffee is consumed regularly in the human diet. Chlorogenic acid intake has been associated with decreased risk of cardiovascular disease and type 2 diabetes. We hypothesized that chlorogenic acid would improve cardiovascular, liver, and metabolic responses in a rat model of metabolic syndrome induced by a high-carbohydrate, high-fat diet. Male Wistar rats (8-9 weeks old, 335 ± 2 g, n = 48) were divided into 4 groups and fed with corn starch diet (16 weeks); corn starch diet with chlorogenic acid in food for the last 8 weeks; high-carbohydrate, high-fat diet (16 weeks); or high-carbohydrate, high-fat diet with chlorogenic acid (~100 mg/kg/d) in food for the last 8 weeks. In high-carbohydrate, high-fat diet-fed rats, chlorogenic acid reduced energy intake and food efficiency to reduce visceral fat, especially retroperitoneal fat, and abdominal circumference; reversed the elevated systolic blood pressure; and attenuated left ventricular diastolic stiffness with reduced collagen deposition and infiltration of inflammatory cells in the left ventricle. Chlorogenic acid decreased inflammation and fat deposition in the liver along with reduced plasma liver enzyme activities of obese rats but did not change the plasma lipid profile. Chlorogenic acid increased diversity of gut microbiota, which may improve overall metabolism in the body. Thus, chronic dietary chlorogenic acid attenuated diet-induced inflammation as well as cardiovascular, liver, and metabolic changes, suggesting that chlorogenic acid has potential for further clinical evaluation.

The Pocket-4-Life project, bioavailability and beneficial properties of the bioactive compounds of espresso coffee and cocoa-based confectionery containing coffee: study protocol for a randomized cross-over trial

Background

Coffee is an important source of bioactive compounds, including caffeine, phenolic compounds (mainly chlorogenic acids), trigonelline, and diterpenes. Several studies have highlighted the preventive effects of coffee consumption on major cardiometabolic diseases, but the impact of coffee dosage on markers of cardiometabolic risk is not well understood. Moreover, the pool of coffee-derived circulating metabolites and the contribution of each metabolite to disease prevention still need to be evaluated in real-life settings. The aim of this study will be to define the bioavailability and beneficial properties of coffee bioactive compounds on the basis of different levels of consumption, by using an innovative experimental design. The contribution of cocoa-based products containing coffee to the pool of circulating metabolites and their putative bioactivity will also be investigated.

Methods

A three-arm, crossover, randomized trial will be conducted. Twenty-one volunteers will be randomly assigned to consume three treatments in a random order for 1 month: 1 cup of espresso coffee/day, 3 cups of espresso coffee/day, and 1 cup of espresso coffee plus 2 cocoa-based products containing coffee twice per day. The last day of each treatment, blood and urine samples will be collected at specific time points, up to 24 hours following the consumption of the first product. At the end of each treatment the same protocol will be repeated, switching the allocation group. Besides the bioavailability of the coffee/cocoa bioactive compounds, the effect of the coffee/cocoa consumption on several cardiometabolic risk factors (anthropometric measures, blood pressure, inflammatory markers, trimethylamine N-oxide, nitric oxide, blood lipids, fasting indices of glucose/insulin metabolism, DNA damage, eicosanoids, and nutri-metabolomics) will be investigated.

Discussion

Results will provide information on the bioavailability of the main groups of phytochemicals in coffee and on their modulation by the level of consumption. Findings will also show the circulating metabolites and their bioactivity when coffee consumption is substituted with the intake of cocoa-based products containing coffee. Finally, the effect of different levels of 1-month coffee consumption on cardiometabolic risk factors will be elucidated, likely providing additional insights on the role of coffee in the protection against chronic diseases.

Trial registration

ClinicalTrials.gov, NCT03166540. Registered on May 21, 2017.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2271-2) contains supplementary material, which is available to authorized users.

Consumption of coffee or caffeine and serum concentration of inflammatory markers: A systematic review

Coffee consumption is associated with reduced risk of conditions that share low-grade inflammation as their physiopathological basis. We therefore summarized the effects of coffee or coffee components on serum levels of inflammatory markers. Clinical trials assessing the effect of coffee, caffeine or other coffee components on inflammatory markers were searched without restriction to publication date. Fifteen studies (8 involving coffee and 7 caffeine) were included. Increased adiponectin levels were found in four of seven trials comparing filtered coffee/caffeinated coffee with placebo or comparing its levels at baseline and after consumption of medium or dark roasted coffee, but no change was seen in caffeine trials. None of the five studies assessing the effects of coffee found changes in C-reactive protein (CPR), but one out of three trials found decreased CPR levels in response to caffeine. Interleukin (IL)-6 was increased by caffeinated coffee compared with placebo in one of four coffee trials, and by caffeine in three out of five studies. Caffeine increased IL-10 levels in two of three trials. These data suggest a predominant anti-inflammatory action of coffee but not of caffeine consumption. Moreover, the proinflammatory and anti-inflammatory responses to caffeine point to its complex effects on the inflammatory response.

How coffee affects metabolic syndrome and its components

Metabolic syndrome, with its increasing prevalence, is becoming a major public health problem throughout the world. Many risk factors including nutrition play a role in the emergence of metabolic syndrome. Of the most-consumed beverages in the world, coffee contains more than 1000 components such as caffeine, chlorogenic acid, diterpenes and trigonelline. It has been proven in many studies that coffee consumption has a positive effect on chronic diseases. In this review, starting from the beneficial effects of coffee on health, the relationship between coffee consumption and metabolic syndrome and its components has been investigated. There are few studies investigating the relationship between coffee and metabolic syndrome, and the existing ones put forward different findings. The factors leading to the differences are thought to stem from coffee variety, the physiological effects of coffee elements, and the nutritional ingredients (such as milk and sugar) added to coffee. It is reported that consumption of coffee in adults up to three cups a day reduces the risk of Type-2 diabetes and metabolic syndrome.

Chlorogenic acid from coffee beans: evaluating the evidence for a blood pressure-regulating health claim

The consumption of coffee has been associated with a number of health benefits, including a reduced risk of cardiovascular disease. Hypertension is an important risk factor for adverse cardiovascular events. Coffee may help reduce blood pressure (BP) in humans, which might be attributable to its polyphenolic compound, chlorogenic acid. The high incidence of hypertension among Canadians underscores the need for new and effective strategies to reduce BP. Dietary interventions may constitute such a strategy, but consumers need to be informed about which foods are most effective for regulating BP. To guide healthy eating, Health Canada permits the use of health claims on the labels of foods that confer health benefits. Currently, there is only one health claim for BP regulation. Additional health claims for foods that assist in BP regulation are therefore warranted. This review provides background information on chlorogenic acid and examines the evidence regarding the use of chlorogenic acid for BP regulation in the context of Health Canada's health claims framework.

Environmental/lifestyle factors in the pathogenesis and prevention of type 2 diabetes

BACKGROUND

Environmental and lifestyle changes, in addition to the ageing of populations, are generally believed to account for the rapid global increase in type 2 diabetes prevalence and incidence in recent decades.

DISCUSSION

In this review, we present a comprehensive overview of factors contributing to diabetes risk, including aspects of diet quality and quantity, little physical activity, increased monitor viewing time or sitting in general, exposure to noise or fine dust, short or disturbed sleep, smoking, stress and depression, and a low socioeconomic status. In general, these factors promote an increase in body mass index. Since loss of β-cell function is the ultimate cause of developing overt type 2 diabetes, environmental and lifestyle changes must have resulted in a higher risk of β-cell damage in those at genetic risk. Multiple mechanistic pathways may come into play.

CONCLUSIONS

Strategies of diabetes prevention should aim at promoting a 'diabetes-protective lifestyle' whilst simultaneously enhancing the resistance of the human organism to pro-diabetic environmental and lifestyle factors. More research on diabetes-protective mechanisms seems warranted.

Environmental/lifestyle factors in the pathogenesis and prevention of type 2 diabetes

BACKGROUND

Environmental and lifestyle changes, in addition to the ageing of populations, are generally believed to account for the rapid global increase in type 2 diabetes prevalence and incidence in recent decades.

DISCUSSION

In this review, we present a comprehensive overview of factors contributing to diabetes risk, including aspects of diet quality and quantity, little physical activity, increased monitor viewing time or sitting in general, exposure to noise or fine dust, short or disturbed sleep, smoking, stress and depression, and a low socioeconomic status. In general, these factors promote an increase in body mass index. Since loss of β-cell function is the ultimate cause of developing overt type 2 diabetes, environmental and lifestyle changes must have resulted in a higher risk of β-cell damage in those at genetic risk. Multiple mechanistic pathways may come into play.

CONCLUSIONS

Strategies of diabetes prevention should aim at promoting a 'diabetes-protective lifestyle' whilst simultaneously enhancing the resistance of the human organism to pro-diabetic environmental and lifestyle factors. More research on diabetes-protective mechanisms seems warranted.

Habitual coffee consumption and risk of type 2 diabetes, ischemic heart disease, depression and Alzheimer's disease: a Mendelian randomization study

Observationally, coffee is inversely associated with type 2 diabetes mellitus (T2DM), depression and Alzheimer’s disease, but not ischemic heart disease (IHD). Coffee features as possibly protective in the 2015 Dietary Guidelines for Americans. Short-term trials suggest coffee has neutral effect on most glycemic traits, but raises lipids and adiponectin. To clarify we compared T2DM, depression, Alzheimer’s disease, and IHD and its risk factors by genetically predicted coffee consumption using two-sample Mendelian randomization applied to large extensively genotyped case-control and cross-sectional studies. Childhood cognition was used as a negative control outcome. Genetically predicted coffee consumption was not associated with T2DM (odds ratio (OR) 1.02, 95% confidence interval (CI) 0.76 to 1.36), depression (0.89, 95% CI 0.66 to 1.21), Alzheimer’s disease (1.17, 95% CI 0.96 to 1.43), IHD (0.96, 95% CI 0.80 to 1.14), lipids, glycemic traits, adiposity or adiponectin. Coffee was unrelated to childhood cognition. Consistent with observational studies, coffee was unrelated to IHD, and, as expected, childhood cognition. However, contrary to observational findings, coffee may not have beneficial effects on T2DM, depression or Alzheimer’s disease. These findings clarify the role of coffee with relevance to dietary guidelines and suggest interventions to prevent these complex chronic diseases should be sought elsewhere.

Polyphenol-based nutraceuticals for the prevention and treatment of cardiovascular disease: Review of human evidence

BACKGROUND

In addition to prescription drugs, nutraceuticals/functional foods/medical foods are being increasingly added as adjunct treatment of cardiovascular disease (CVD), even though most of them have been exclusively studied in vitro.

HYPOTHESIS/PURPOSE

We review the available evidence (focusing on when the amount of polyphenols' intake was measured) coming from randomized controlled trials (RCTs) of (poly)phenol-based supplements.

CONCLUSION

We conclude that (poly)phenol-based nutraceuticals and functional foods might be indeed used as adjunct therapy of CVD, but additional long-term RCTs with adequate numerosity and with clinically relevant end points are needed to provide unequivocal evidence of their clinical usefulness.

A single serving of caffeinated coffee impairs postprandial glucose metabolism in overweight men

Previous studies regarding the acute effects of coffee on glycaemic control have used a single large dose of coffee, typically containing the caffeine equivalent of 2-4 servings of coffee. This study investigates whether the acute effects of coffee are dose-dependent, starting with a single serving. A total of ten healthy overweight males participated in a two-part randomised double-blind cross-over study. In the first part, they ingested 2, 4 or 8 g instant decaffeinated coffee (DC) dissolved in 400 ml water with caffeine added in proportion to the DC (total 100, 200 or 400 mg caffeine) or control (400 ml water) all with 50 g glucose. In the second part, they ingested the same amounts of DC (2, 4, 8 g) or control, but with a standard 100 mg caffeine added to each. Capillary blood samples were taken every 15 min for 2 h after each drink and glucose and insulin levels were measured. Repeated measures ANOVA on glucose results found an effect when caffeine was varied in line with DC (P=0·008). Post hoc analysis revealed that both 2 and 4 g DC with varied caffeine content increased the glycaemic response v.

CONTROL

There was no effect of escalating doses of DC when caffeine remained constant at 100 mg. These results demonstrate that one standard serving of coffee (2 g) is sufficient to affect glucose metabolism. Furthermore, the amount of caffeine found in one serving (100 mg) is sufficient to mask any potential beneficial effects of increasing other components. No dose-dependent effect was found.