Potential nutraceutical and food additive properties and risks of coffee: a comprehensive overview

Abstract

Coffee is a composite mixture of more than a thousand diverse phytochemicals like alkaloids, phenolic compounds, vitamins, carbohydrates, lipids, minerals and nitrogenous compounds. Coffee has multifunctional properties as a food additive and nutraceutical. As a nutraceutical, coffee has anti-inflammatory, anti-oxidant, antidyslipidemic, anti-obesity, type-2 diabetes mellitus (DM), and cardiovascular diseases (CVD), which can serve for the treatment and prevention of metabolic syndrome and associated disorders. On the other hand, as a food additive, coffee has antimicrobial activity against a wide range of microorganisms, inhibits lipid peroxidation (LPO), and can function as a prebiotic. The outcomes of different studies also revealed that coffee intake may reduce the incidence of numerous chronic diseases, like liver disease, mental health, and it also overcomes the all-cause mortality, and suicidal risks. In some studies, high intake of coffee is linked to increase CVD risk factors, like cholesterol, plasma homocysteine and blood pressure (BP). There is also a little evidence that associated the coffee consumption with increased risk of lung tumors in smokers. Among adults who consume the moderate amount of coffee, there is slight indication of health hazards with strong indicators of health benefits. Moreover, existing literature suggests that it may be cautious for pregnant women to eliminate the chances of miscarriages and impaired fetal growth. The primary purpose of this narrative review is to provide an overview of the findings of the positive impacts and risks of coffee consumption on human health. In conclusion, to date, the best available evidence from research indicates that drinking coffee up to 3–4 cups/day provides health benefits for most people.     

Role of unfamiliarity and information on consumers’ willingness to try new healthy foods

The purpose of this paper is to examine the role of type of unfamiliarity and information on willingness-to-try unfamiliar healthy native foods in males and females. Specifically, the intuition of “healthy = not tasty” is investigated by probing into the effect of high and low taste expectations in the presence and absence of information on health benefits. Defining Type of unfamiliarity of a dish based on its ingredient and format is a unique contribution of this research. This paper uses a 3 * 2 * 2 full factorial experimental design (Type of unfamiliarity * Health Benefits * Taste Expectations; n = 367). ANCOVA was performed to analyse the quantitative data. Findings suggest that the information on health benefits or taste expectations does not have a main effect on willingness to try a new healthy native food, in both males and females. Type of unfamiliarity does not matter for males but females consider it important to try a new food. Males may possibly be inclined towards choosing healthy foods that set high taste expectations; however, providing information on health benefits may lower their interest levels.     

Coffee and health: a review of recent human research

Coffee is a complex mixture of chemicals that provides significant amounts of chlorogenic acid and caffeine. Unfiltered coffee is a significant source of cafestol and kahweol, which are diterpenes that have been implicated in the cholesterol-raising effects of coffee. The results of epidemiological research suggest that coffee consumption may help prevent several chronic diseases, including type 2 diabetes mellitus, Parkinson's disease and liver disease (cirrhosis and hepatocellular carcinoma). Most prospective cohort studies have not found coffee consumption to be associated with significantly increased cardiovascular disease risk. However, coffee consumption is associated with increases in several cardiovascular disease risk factors, including blood pressure and plasma homocysteine. At present, there is little evidence that coffee consumption increases the risk of cancer. For adults consuming moderate amounts of coffee (3-4 cups/d providing 300-400 mg/d of caffeine), there is little evidence of health risks and some evidence of health benefits. However, some groups, including people with hypertension, children, adolescents, and the elderly, may be more vulnerable to the adverse effects of caffeine. In addition, currently available evidence suggests that it may be prudent for pregnant women to limit coffee consumption to 3 cups/d providing no more than 300 mg/d of caffeine to exclude any increased probability of spontaneous abortion or impaired fetal growth.     

The impact of live dietary microbes on health: A scoping review

A systematic approach to collect, peruse, and summarize the available information relating to the potential benefits of consuming dietary microbes was pursued in this scoping review. This review focused on the research endpoints, experimental designs, and microbial exposure in experimental as well as observational research work. Using a structured- set of keywords, scientific databases were systematically searched to retrieve publications reporting outcomes pertaining to the use of dietary microbes in healthy, nonpatient populations. Searches were further tailored to focus on eight different health categories, namely, “antibiotic associated diarrhoea” (AAD), “gastrointestinal health” (GIH), “immunological health” (ImH), “cardiovascular health and metabolic syndrome” (CvHMS), “cancer prevention” (CanPr), “respiratory health” (ReH), “weight management” (WtMgt), and “urogenital health” (UrGH). Quality of evidence available in each publication was assessed using the Jadad scoring system. The search yielded 228 relevant publications describing 282 experimental cases comprising 62 research endpoints overall. A microbial dose of $\ge 2\times {10}^9$ CFU.day⁻¹ was associated with non-negative reported outcomes. Older population groups with a median age of 39 years were associated with positive outcomes. More high-quality research is required investigating the role of dietary microbes in maintaining general health, particularly in the health categories of UrGH, WtMgt, and CanPr.     

Four-week coffee consumption affects energy intake,satiety regulation,body fat,and protects DNA integrity

Recent epidemiological studies suggest that coffee, one of the most widely consumed beverages worldwide, may reduce risks of degenerative diseases such as diabetes type 2, cardiovascular disease and certain types of cancer. These effects have partly been ascribed to coffee's antioxidant and body weight-reducing capacities. To explore the mechanisms involved, effects of coffee consumption on body weight/composition, food intake, satiety markers (serotonin and ghrelin) and DNA integrity were monitored in a four-week double-blind randomized crossover intervention study with 84 healthy subjects. Subjects consumed two different coffee blends (study blend, SB, and market blend, MB), with similar caffeine contents but substantially differing contents of chlorogenic acids and N-methylpyridinium. The consumption of both coffees (3 × 250 mL per day) was associated with a decrease in body fat over the whole study period (p < 0.001), which was more pronounced with SB. During intervention with MB, plasma serotonin levels increased (p < 0.001) whereas plasma ghrelin levels decreased (p < 0.001) relative to levels recorded during the preceding washout period. Consumption of both coffee blends was associated with DNA-protective effects (p < 0.001). These findings suggest that regular coffee consumption may provide health benefits in terms of reducing energy intake and body fat, regulating satiety and protecting DNA integrity.     

Caffeine metabolism rate influences coffee perception,preferences and intake

Several factors – genetic, demographic and environmental – contribute to individual differences in sensitivity to the pharmacological effects of caffeine. Caffeine metabolism influences coffee consumption, but its effect on bitterness perception in, and preference for, coffee is unknown.This study explores the possible relationship between caffeine metabolism rate and coffee preferences and consumption habits. In addition, the extent to which caffeine metabolism interacted with variations in bitterness perception was investigated. Caffeine metabolism rate was assayed by competitive immuno-enzymatic assay in one-hundred thirty-five coffee consumers who provided saliva samples after 12 h caffeine abstinence and at 30 and 90 min after ingestion of caffeine (100 mg). A caffeine metabolism index (CmI) was computed as the ratio between the amount of residual caffeine in saliva 60 min after the adsorption peak and the amount of caffeine at the adsorption peak corrected with the baseline. Ninety-one subjects were selected to investigate the relationships between inter-individual variation in caffeine metabolism, bitterness perception and coffee preference. Subjects rated liking for, and sourness, bitterness and astringency of, six unsweetened and freely sweetened coffee samples varying in roasting degree, caffeine content and bitterness. They also rated the bitterness of six caffeine and six quinine (equi-intense) solutions. Finally, subjects choose coffee to drink on the basis of a label (strong vs balanced flavor) both after caffeine abstinence and after no restrictions on caffeine intake. The CmI was strongly associated with the frequency of daily coffee consumption. Subjects with lower CmI gave higher bitterness ratings than other subjects for both coffee and caffeine solutions, but not for quinine solutions. They also added more sugar to the coffee samples. Following caffeine abstinence, all subjects chose the “strong flavor” coffee, while without caffeine restrictions, subjects with lower CmI preferentially tended to choose the “balanced flavor” coffee. These results provide the first link between caffeine metabolism and bitterness perception, and to the use of sugar to modify coffee bitterness.     

Just-about-right and ideal scaling provide similar insights into the influence of sensory attributes on liking

Just-about-right (JAR) scaling is criticized for measuring attribute intensity and acceptability simultaneously. Using JAR scaling, an attribute is evaluated for its appropriateness relative to one’s hypothetical ideal level that is pre-defined at the middle of a continuum. Alternatively, ideal scaling measures these two constructs separately. Ideal scaling allows participants to rate their ideal freely on the scale (i.e., without assuming the “Too Little” and “Too Much” regions are equal in size). We hypothesized that constraining participants’ ideal to the center point, as is done in the JAR scale, may cause a scaling bias and, thereby, influence the magnitude of “Too Little” and “Too Much”. Furthermore, we hypothesized that the magnitude of “Too Little” and “Too Much” would influence liking to different extents.Coffee-flavored dairy beverages (n = 20) were formulated using a fractional, constrained-mixture design that varied the ratio of water, milk, coffee extract, and sucrose. Participants tasted 4 of 20 prototypes that were served in a monadic sequential order using a balanced incomplete block design. Data reported here are for participants randomly assigned to one of two research conditions: ideal scaling (n = 129) or JAR scaling (n = 132). For both conditions, participants rated overall liking using a 9-point hedonic scale. Four attributes (sweetness, milk flavor, coffee flavor and thickness) were evaluated. The reliability of an individual participant’s ideal rating for an attribute was evaluated using the standard deviation of their ideal ratings (n = 4). All data from a participant were eliminated from further analyses when his/her standard deviation of the ideal ratings for any of the four rated attributes was identified as a statistical outlier. This resulted in the elimination of 15 of 129 (12%) of participants in the ideal scaling group. Multiple linear regression was employed to model liking as a function of “Too Little” or “Too Much” attribute intensities.Mean ideal ratings (averaged across participants) for all four attributes were significantly different from the central point of the scale (i.e., 50). However, coffee flavor was the only attribute for which the mean ideal rating (57.2) fell outside the central 10% (45.0–55.0). Even so, the magnitude of “Too Little” and “Too Much” was not affected by the scaling method. The influence of the magnitude of “Too Little” and “Too Much” on liking was asymmetrical. Both scaling methods agreed that sweetness and coffee flavor were the main sensory attributes affecting liking. Overall, JAR scaling and ideal scaling were comparable for measuring “Too Little” and “Too Much”, and identifying the main factors affecting liking.     

Consumer acceptability of coffee as affected by situational conditions and involvement

For understanding consumer behaviors more closely to what would be observed in real-life, “situational” tests has been widely studied using two main approaches: ‘physical environment’ or ‘cognitive evocation’. Both approaches have shown advantages in adopting consumption context in consumer tests. However, it has not been investigated whether either one of the approaches may be more effective or whether using these approaches together would be more advantageous than using each solely in terms of bring in consumption context. The aims were to understand the effects of evocation in different environmental settings on consumers liking and to explore the differences of these effects based on consumer involvement levels. Consumers participated in one of the 4 contextual conditions of 2 × 2 factorial design, consisting of ‘evocation’ factor (with vs. without evocation instruction) and ‘environment’ factor (booth vs. simulated café), respectively. Consumers evaluated liking for two coffee samples and responded to a coffee involvement questionnaire. The results showed that both factors have influenced on consumer liking. These effects were different according to coffee types differing in hedonic levels. Vividness of evocation lasted longer in the simulated café setting, implying physical cues reinforcing cognitive evocation. When consumers were classified according to involvement scores, liking score of the high involvement group was little affected by either situational factors, while low involvement group was highly affected by the ‘environment’ factor. The findings of the study provide important perspectives to be considered for researches into “situational” tests, including which situational approach to apply as well as consumer involvement.     

Relating consumer preferences to sensory attributes of instant coffee

The sensory profiles of 11 instant coffees including pure coffees (PC), coffee blends (CB) and a chicory instant drink (CID), commercially available in South Africa, were described and quantified. These were then related to consumer preferences (n=199) for the instant coffees using preference mapping. Based on consumer preferences, four consumer groups were identified, “pure coffee lovers” (23%), “coffee blend drinkers” (30%), “general coffee drinkers” (37%) and “not serious coffee drinkers” (10%). The “pure coffee lovers” prefer the more astringent, bitter, roasted, nutty and full-bodied flavour of the pure coffee samples. The less intense coffee flavour character, but higher sweetness and root flavour, typical of chicory blended instant coffee, were attributes that were preferred by the “coffee blend lovers”. The “general coffee drinkers” seem to consume coffee out of habit and are less concerned about the specific sensory properties of the coffee.     

Ochratoxin A in commercial soluble coffee and coffee substitutes

Coffee and cereals are recognized sources of ochratoxin A (OTA) in the human diet, but data concerning its amounts in soluble coffee substitutes are scarce. This work aimed to determine the amounts of OTA in commercial soluble coffee substitutes (mixtures of barley, malt, and chicory, either with or without coffee). OTA was isolated by immunoaffinity columns and quantified by HPLC with fluorescence detection.In a total of 40 samples analyzed, including 10 of soluble coffee, 13 mixtures with coffee and 17 mixtures without coffee, all commercialized in Portugal, 35 samples were positive for OTA, with concentrations ranging from < 0.15 to 11.8 μg/kg. Overall, coffee-containing samples had significantly higher amounts of OTA (p < 0.001) than substitutes without coffee. Indeed, coffee was the main determinant for the OTA content in the substitute beverages analyzed, with a highly significant linear correlation (r = 0.559, p < 0.001) between OTA amounts and coffee percentage in the mixtures. The high variability observed between samples is influenced by the “brand” effect as well as by raw-material quality.Globally, OTA amounts in coffee substitutes are generally low and within the regulated and safety limits. Their contribution to the provisional tolerable daily intake (PTDI) is therefore reduced (from 1.0 to 2.0% on average). Nevertheless, the high incidence of OTA contamination in these products should not be disregarded.     

Reliable estimation of dietary exposure to furan from coffee: An automatic vending machine as a case study

Worldwide Food Safety Agencies have classified furan as carcinogenic and cytotoxic due to its effects in animal studies, and it has been associated with harmful effects to human health. It has been pointed out that coffee consumption is the major contributor to dietary furan exposure for adults. However, furan is highly volatile and its losses due to volatilization in the cup during the time expend to consume the coffee brew should be taken into account for a realistic estimation of the levels of furan exposure for humans. The aim of this study was to estimate the furan exposure to humans considering the time for consumption after preparation of the fresh beverage. Furan was determined in coffee brews acquired from automatic coffee vending machines placed in areas with high density of population. Furan levels in coffee beverages ranged from 11 to 262 ng/mL (mean = 171 ± 59.8). Furthermore, five different scenarios were settled immediately after the acquisition of coffee brews from the coffee vending machines in order to assess a realistic estimation of furan exposure. Furan content in coffee decreased from 170 up to 4 ng/mL after simulating the behavior of coffee consumption (~ 74% after standing at room temperature for 5 min, ~ 64% after stirring for 30 s and standing at room temperature up to 5 min, ~ 94% after stirring for 5 min, ~ 97% after 8 h in a sealed thermo and ~ 37% after being cooled one week at a fridge). These results suggest that it is mandatory to establish very precisely the furan levels in the final ready-to-drink beverage in order to obtain reliable estimations of the daily intake from coffee and to define potential strategies for mitigation. Furan intake from coffee ranged from 0.02 to 0.43 μg/kg b.w./day, resulting in a mean exposure of 0.31 μg/kg b.w./day.     

Alkylpyrazine contents of coffee beverages using stable isotope dilution gas chromatography–mass spectrometry

In the presented study the effects of key brewing parameters (temperature, holding time and storage conditions of coffee powder) on 12 alkylpyrazines in coffee beverages were investigated. The results show that the alkylpyrazine profiles of coffee beverages are similar to those of the coffee used. In total, 70–82% of the alkylpyrazines (113.3 ± 3.5 to 132.6 ± 0.6 mg/kg), depending on the brewing method, passed into beverages during the brewing process. At temperatures higher than 50 °C the alkylpyrazine contents of coffee beverages were almost independent of the brewing temperature. During a 30 min holding time at room temperature the alkylpyrazine contents of a freshly brewed cup of coffee decreased by about 10%. Furthermore, storing coffee in closed systems for up to 29 days at +4 °C, −20 °C or room temperature (+22 °C) had minor effects on the alkylpyrazine contents of beverages produced from the coffee. The results show that under customary conditions more than 70% of the alkylpyrazines present in ground coffee are transferred to beverages during the brewing process. Estimated total amounts of alkylpyrazines ingested by the consumer per cup of coffee beverage are in the milligram range, sufficient to have significant potential health effects.     

The impact of sugar-related claims on perceived healthfulness,caloric value and expected taste of food products

Food packaging usually includes multiple cues, including claims about nutrients that may modulate how the consumer perceives (and behaves towards) the product. In the current work, we systematically examined how different types of claims about sugar influenced the perception of food product categories (i.e., yogurts, ice creams, cookies, and breakfast cereals). In two experiments (combined n = 406), participants were asked to evaluate the perceived healthfulness, caloric value, and expected taste of products with (vs. without) sugar-related claims. Specifically, the claims were on the sugar content (“0% sugar”, “sugar-free”, “no added sugars”, “low sugar” - Experiment 1) or on the type of sugars or sweeteners of natural origin (“sucrose”, “cane sugar”, “honey” and “stevia” - Experiment 2).Experiment 1 revealed that all products with sugar-related claims were rated as healthier, less caloric, and less tasty than the regular alternatives. Still, products with the “low sugar” claim were perceived as the least healthy, most caloric, and tastiest. In Experiment 2, we observed that products with “stevia” claim were rated as healthier, less caloric, and less tasty than regular products. In both experiments, the frequency of consumption of products with sugar-related claims was positively associated with the general perception of these products, the influence of nutritional information on consumption decisions, attention to sugar intake, and interest in nutrition.Overall, our results show that sugar-related claims may influence consumer's perceptions about food products, but the direction of that influence depends on the type of claim and evaluative dimension.     

Coffee and its consumption: benefits and risks

Coffee is the leading worldwide beverage after water and its trade exceeds US $10 billion worldwide. Controversies regarding its benefits and risks still exist as reliable evidence is becoming available supporting its health promoting potential; however, some researchers have argued about the association of coffee consumption with cardiovascular complications and cancer insurgence. The health-promoting properties of coffee are often attributed to its rich phytochemistry, including caffeine, chlorogenic acid, caffeic acid, hydroxyhydroquinone (HHQ), etc. Many research investigations, epidemiological studies, and meta-analyses regarding coffee consumption revealed its inverse correlation with that of diabetes mellitus, various cancer lines, Parkinsonism, and Alzheimer's disease. Moreover, it ameliorates oxidative stress because of its ability to induce mRNA and protein expression, and mediates Nrf2-ARE pathway stimulation. Furthermore, caffeine and its metabolites help in proper cognitive functionality. Coffee lipid fraction containing cafestol and kahweol act as a safeguard against some malignant cells by modulating the detoxifying enzymes. On the other hand, their higher levels raise serum cholesterol, posing a possible threat to coronary health, for example, myocardial and cerebral infarction, insomnia, and cardiovascular complications. Caffeine also affects adenosine receptors and its withdrawal is accompanied with muscle fatigue and allied problems in those addicted to coffee. An array of evidence showed that pregnant women or those with postmenopausal problems should avoid excessive consumption of coffee because of its interference with oral contraceptives or postmenopausal hormones. This review article is an attempt to disseminate general information, health claims, and obviously the risk factors associated with coffee consumption to scientists, allied stakeholders, and certainly readers.     

Hot towels: The bedrock of Meibomian gland dysfunction treatment – A review

BackgroundMeibomian gland dysfunction (MGD) reduces quality-of-life and hinders work productivity of millions of patients, with high direct and indirect societal costs. Thickened meibum obstructs the glands and disrupts ocular surface health. Heating the eyelids to soften and express meibum from the glands can be beneficial. The most accessible method for eyelid warming uses heated, wet towels. However, the efficacy of this treatment is reliant on the methodology, and evidence-based best-practice recommendations are needed.PurposeTo evaluate the literature on hot towels in MGD treatment and recommend a best-practice protocol for future research and patient treatment.MethodsStudies were identified through PubMed on the May 28, 2021, with the search terms: (warm* OR heat* OR thermal* OR towel OR wet towel) AND (meibomian OR MGD OR eyelid OR “dry eye” OR DED). All relevant original articles with English full-text were included.ResultsThe search yielded 903 results, of which 22 met the inclusion criteria. Across studies, hot towels were found to be effective at reducing ocular symptoms. However, without reheating, the temperature quickly fell below the therapeutic range, which was deemed to be between 40 °C and 47 °C. Towels heated to around 45 °C and reheated every-two minutes were most effective at increasing eyelid temperature, comparable or better than several commercially available eyelid warming devices. No adverse effects were reported in the studies.ConclusionHot towel treatment effectively warms the eyelids and reduces ocular symptoms, but must be standardized, and towels reheated to achieve maximum benefit. Future research should assess patient satisfaction with different hot towel treatment methods that reheat or replace the towel at least every-two minutes, to establish which methods yield the greatest compliance. Guidelines or clinical recommendations that do not mention the need for regular reheating during hot towel compress treatment should be updated to include this.     

Survey of methylmercury in fish and seafood from the southwestern German market

Mercury is an environmental contaminant and may occur as methylmercury in marine organisms. Methylmercury is considered as having higher toxicity than the inorganic form; therefore, it is important to differentiate the mercury species in order to evaluate the potential risk for seafood consumers. In the largest study of the German market to date, 536 marine foods from the state of Baden-Württemberg (southwestern Germany) were analyzed using gas chromatography with atomic emission detection. Methylmercury was found at levels ranging from non-detectable (below 6 μg/kg) up to 567 μg/kg. The average, median, 90th, 95th, and 99th percentile contents were 38, 22, 78, 117, and 316 μg/kg, respectively. The average methylmercury proportion of total mercury was 70%. Based on a daily total fish and seafood consumption of 30 g according to the German National Nutrition Survey II, the methylmercury exposure was estimated to range between 5 μg/week (median) and 67 μg/week (99th percentile), which was below the provisional tolerable weekly intake (PTWI) established by the Joint FAO/WHO Expert Committee on Food Additives. The risk of methylmercury for the German fish consumer was judged to be rather low, being restricted to the unlikely worst-case scenario of daily consumption of highly contaminated fish, which could exceed the PTWI. In conclusion, the previous opinions that the benefits of the moderate fish consumption appear to outweigh the risks associated with methylmercury exposure were confirmed by our survey.     

Resveratrol,human health and winemaking perspectives

Resveratrol, (3, 5, 4′-trihydroxystilbene) is a non-flavonoid polyphenol stilbene synthesized by plants when damaged by infectious diseases or ionizing radiation. Although present in more than seventy plant species, grapes and wine are the major dietary contributors of resveratrol, responsible for 98% of the daily intake. In 1992, Renaud and De Lorgeril first linked wine polyphenols, including resveratrol, to the potential health benefits ascribed to regular and moderate wine consumption (the so called “French Paradox”). Since then, resveratrol has received increasing scientific interest, leading to research on its biological actions, and to a large number of published papers, which have been collected and discussed in this review. The relatively low amounts of resveratrol measured in wine following moderate consumption, however, may be insufficient to mitigate biological damage, such as that due to oxidative stress. On this basis, the authors also highlight the importance of viticulture and the winemaking process to enhance resveratrol concentrations in wine in order to bolster potential health benefits.     

Assessment of instructions on panelist cognitive framework and free sorting task results: A case study of cold brew coffee

As the free sorting task becomes more common in sensory science, methodological research is needed to determine best practices for the test. Previous studies have shown that asking attribute-specific, “analytical” questions can bias the answers participants give to later “holistic” questions in a survey. For the free sorting task, this has led researchers to recommend only asking subjects to label or describe groups of products after they have finished sorting, but this approach is not based on empirical research. The present study investigated whether the separation of sorting and labeling steps is necessary by having 80 panelists sort 12 cold brew coffee samples in 3 conditions: labeling and describing the groups afterwards, at the same time, or not at all. Results were analyzed with DISTATIS, Hierarchical DISTATIS, and permutation tests. This work is novel in investigating the effect of labeling instructions on sorting results and provides some interesting insight into sensory impact of coffee bean parameters on cold brew coffees. No configurational differences were found based on the timing of labeling instructions and 38% of panelists labeled their groups without being told, suggesting future researchers may request that subjects label when convenient. While the most distinctive samples were the dark roast coffees, a large subgroup (n = 36) sorted the coffee samples partially based on country of origin. Given the lack of effect from different sorting instructions and the tendency for spontaneous, simultaneous labeling, simultaneous labeling is suggested as best practice for future sorting tasks.