Interactions between volatile and nonvolatile coffee components. 1. Screening of nonvolatile components.
This study is the first of two publications that investigate the phenomena of coffee nonvolatiles interacting with coffee volatile compounds. The purpose was to identify which coffee nonvolatile(s) are responsible for the interactions observed between nonvolatile coffee br ew constituents and thiols, sulfides, pyrroles, and diketones. The overall interaction of these compounds with coffee br ews prepared with green coffee beans roasted at three different roasting levels (light, medium, and dark), purified nonvolatiles, and medium roasted coffee brew fractions (1% solids after 1 or 24 h) was measured using a headspace solid-phase microextraction technique. The dark roasted coffee br ew was slightly more reactive toward the selected compounds than the light roasted coffee br ew. Selected pure coffee constituents, such as caffeine, trigonelline, arabinogalactans, chlorogenic acid, and caffeic acid, showed few interactions with the coffee volatiles. Upon fractionation of medium roasted coffee br ew by solid-phase extraction, dialysis, size exclusion chromatography, or anion exchange chromatography, characterization of each fraction, evaluation of the interactions with the aromas, and correlation between the chemical composition of the fractions and the magnitude of the interactions, the following general conclusions were drawn. (1) Low molecular weight and positively charged melanoidins present significant interactions. (2) Strong correlations were shown between the melanoidin and protein/peptide content, on one hand, and the extent of interactions, on the other hand (R = 0.83-0.98, depending on the volatile compound). (3) Chlorogenic acids and carbohydrates play a secondary role, because only weak correlations with the interactions were found in complex matrixes.
J Agric Food Chem. 2005 Jun 1;53(11):4417-25
Dietary polyphenols and the prevention of diseases.
Polyphenols are the most abundant antioxidants in the diet and are widespread constituents of fruits, vegetables, cereals, dry legumes, chocolate, and beverages, such as tea, coffee, or wine. Experimental studies on animals or cultured human cell lines support a role of polyphenols in the prevention of cardiovascular diseases, cancers, neurodegenerative diseases, diabetes, or osteoporosis. However, it is very difficult to predict from these results the effects of polyphenol intake on disease prevention in humans. One of the reasons is that these studies have often been conducted at doses or concentrations far beyond those documented in humans. The few clinical studies on biomarkers of oxidative stress, cardiovascular disease risk factors, and tumor or bone resorption biomarkers have often led to contradictory results. Epidemiological studies have repeatedly shown an inverse association between the risk of myocardial infarction and the consumption of tea and wine or the intake level of some particular flavonoids, but no clear associations have been found between cancer risk and polyphenol consumption. More human studies are needed to provide clear evidence of their health protective effects and to better evaluate the risks possibly resulting from too high a polyphenol consumption.
Crit Rev Food Sci Nutr. 2005;45(4):287-306
Effects of coffee consumption on oxidative susceptibility of low-density lipoproteins and serum lipid levels in humans.
Since little is known about how coffee intake affects low-density lipoprotein (LDL) oxidative susceptibility and serum lipid levels, we conducted an in vivo study in 11 healthy male students of Wakayama Medical University aged between 20 and 31 years fed an average Japanese diet. On days 1-7 of the study, the subjects drank mineral water. On day 7, the subjects began drinking coffee, 24 g total per day, for one week. This was followed by a one week "washout period" during which mineral water was consumed. Fasting peripheral venous blood samples were taken at the end of each one-week period. LDL oxidation lag time was approximately 8% greater (p < 0.01) after the coffee drinking period than the other periods. Serum levels of total cholesterol and LDL-cholesterol (LDL-C) and malondialdehyde (MDA) as thiobarbituric acid reactive substances (TBARS) were significantly decreased after the coffee drinking period. Finally, regular coffee ingestion may favorably affect cardiovascular risk status by modestly reducing LDL oxidation susceptibility and decreasing LDL-cholesterol and MDA levels.
Biochemistry (Mosc). 2004 Jan;69(1):70-4
Isolation and characterization of polyphenol type-A polymers from cinnamon with insulin-like biological activity.
The causes and control of type 2 diabetes mellitus are not clear, but there is strong evidence that dietary factors are involved in its regulation and prevention. We have shown that extracts from cinnamon enhance the activity of insulin. The objective of this study was to isolate and characterize insulin-enhancing complexes from cinnamon that may be involved in the alleviation or possible prevention and control of glucose intolerance and diabetes. Water-soluble polyphenol polymers from cinnamon that increase insulin-dependent in vitro glucose metabolism roughly 20-fold and display antioxidant activity were isolated and characterized by nuclear magnetic resonance and mass spectroscopy. The polymers were composed of monomeric units with a molecular mass of 288. Two trimers with a molecular mass of 864 and a tetramer with a mass of 1,152 were isolated. Their protonated molecular masses indicated that they are A type doubly linked procyanidin oligomers of the catechins and/or epicatechins. These polyphenolic polymers found in cinnamon may function as antioxidants, potentiate insulin action, and may be beneficial in the control of glucose intolerance and diabetes.
J Agric Food Chem. 2004 Jan 14;52(1):65-70
Cinnamon extract (traditional herb) potentiates in vivo insulin-regulated glucose utilization via enhancing insulin signaling in rats.
Cinnamon has been shown to potentiate the insulin effect through upregulation of the glucose uptake in cultured adipocytes. In the present study, we evaluated the effect of the cinnamon extract on the insulin action in awaked rats by the euglycemic clamp and further analyzed possible changes in insulin signaling occurred in skeletal muscle. The rats were divided into saline and cinnamon extract (30 and 300 mg/kg BW-doses: C30 and C300) oral administration groups. After 3-weeks, cinnamon extract treated rats showed a significantly higher glucose infusion rate (GIR) at 3 mU/kg per min insulin infusions compared with controls (118 and 146% of controls for C30 and C300, respectively). At 30 mU/kg per min insulin infusions, the GIR in C300 rats was increased 17% over controls. There were no significant differences in insulin receptor (IR)-beta, IR substrate (IRS)-1, and phosphatidylinositol (PI) 3-kinase protein content between C300 rats and controls. However, the skeletal muscle insulin-stimulated IR-beta and the IRS-1 tyrosine phosphorylation levels in C300 rats were 18 and 33% higher, respectively, added to 41% higher IRS-1/PI 3-kinase association. These results suggest that the cinnamon extract would improve insulin action via increasing glucose uptake in vivo, at least in part through enhancing the insulin-signaling pathway in skeletal muscle.
Diabetes Res Clin Pract. 2003 Dec;62(3):139-48
Cardiovascular effects of coffee: is it a risk factor?
Intake of coffee, one of the most common beverages worldwide, is often reported as a cardiovascular risk factor; however, definitive data are lacking. Acute intake of coffee or beverages containing caffeine can increase blood pressure, heart minute volumes, and cardiac index, as well as activate the sympathetic nervous system in nonhabitual coffee drinkers. Interestingly, this is not observed in habitual coffee drinkers. Restriction of coffee or caffeinated beverages is no longer indicated in the seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) guidelines for the treatment of hypertension. In fact, no clear association between coffee and the risk of hypertension, myocardial infarction, or other cardiovascular diseases has been demonstrated. In contrast to early studies, recent research indicates that habitual moderate coffee intake does not represent a health hazard and may even be associated with beneficial effects on cardiovascular health.
Prog Cardiovasc Nurs. 2005 Spring;20(2):65-9
Coffee consumption and risk for type 2 diabetes mellitus.
BACKGROUND: In small, short-term studies, acute administration of caffeine decreases insulin sensitivity and impairs glucose tolerance. OBJECTIVE: To examine the long-term relationship between consumption of coffee and other caffeinated beverages and incidence of type 2 diabetes mellitus. DESIGN: Prospective cohort study. SETTING: The Nurses' Health Study and Health Professionals' Follow-up Study. PARTICIPANTS: The authors followed 41 934 men from 1986 to 1998 and 84,276 women from 1980 to 1998. These participants did not have diabetes, cancer, or cardiovascular disease at baseline. MEASUREMENTS: Coffee consumption was assessed every 2 to 4 years through validated questionnaires. RESULTS: The authors documented 1,333 n ew cases of type 2 diabetes in men and 4,085 n ew cases in women. The authors found an inverse association between coffee intake and type 2 diabetes after adjustment for age, body mass index, and other risk factors. The multivariate relative risks for diabetes according to regular coffee consumption categories (0, <1, 1 to 3, 4 to 5, or > or =6 cups per day) in men were 1.00, 0.98, 0.93, 0.71, and 0.46 (95% CI, 0.26 to 0.82; P = 0.007 for trend), respectively. The corresponding multivariate relative risks in women were 1.00, 1.16, 0.99, 0.70, and 0.71 (CI, 0.56 to 0.89; P < 0.001 for trend), respectively. For decaffeinated coffee, the multivariate relative risks comparing persons who drank 4 cups or more per day with nondrinkers were 0.74 (CI, 0.48 to 1.12) for men and 0.85 (CI, 0.61 to 1.17) for women. Total caffeine intake from coffee and other sources was associated with a statistically significantly lower risk for diabetes in both men and women. CONCLUSIONS: These data suggest that long-term coffee consumption is associated with a statistically significantly lower risk for type 2 diabetes.
Ann Intern Med. 2004 Jan 6;140(1):1-8
Reduced insulinotropic effect of gastric inhibitory polypeptide in first-degree relatives of patients with type 2 diabetes.
In patients with type 2 diabetes, gastric inhibitory polypeptide (GIP) has lost much of its insulinotropic activity. Whether this is similar in first-degree relatives of patients with type 2 diabetes is unknown. A total of 21 first-degree relatives, 10 patients with type 2 diabetes, and 10 control subjects (normal oral glucose tolerance) were examined. During a hyperglycemic "clamp" (140 mg/dl for 120 min), synthetic human GIP (2 pmol. kg(-1). min(-1)) was infused intravenously (30-90 min). With exogenous GIP, patients with type 2 diabetes responded with a lower increment (Delta) in insulin (P = 0.0003) and C-peptide concentrations (P < 0.0001) than control subjects. The GIP effects in first-degree relatives were diminished compared with control subjects (Delta insulin: P = 0.04; Delta C-peptide: P = 0.016) but significantly higher than in patients with type 2 diabetes (P < or = 0.05). The responses over the time course were below the 95% CI derived from control subjects in 7 (insulin) and 11 (C-peptide) of 21 first-degree relatives of patients with type 2 diabetes. In conclusion, a reduced insulinotropic activity of GIP is typical for a substantial subgroup of normoglycemic first-degree relatives of patients with type 2 diabetes, pointing to an early, possibly genetic defect.
Diabetes. 2001 Nov;50(11):2497-504
Coffee consumption and risk of type 2 diabetes mellitus among middle-aged Finnish men and women.
CONTEXT: Only a few studies of coffee consumption and diabetes mellitus (DM) have been reported, even though coffee is the most consumed beverage in the world. OBJECTIVE: To determine the relationship between coffee consumption and the incidence of type 2 DM among Finnish individuals, who have the highest coffee consumption in the world. DESIGN, SETTING, AND PARTICIPANTS: A prospective study from combined surveys conducted in 1982, 1987, and 1992 of 6,974 Finnish men and 7,655 women aged 35 to 64 years without history of stroke, coronary heart disease, or DM at baseline, with 175 682 person-years of follow-up. Coffee consumption and other study parameters were determined at baseline using standardized measurements. MAIN OUTCOME MEASURES: Hazard ratios (HRs) for the incidence of type 2 DM were estimated for different levels of daily coffee consumption. RESULTS: During a mean follow-up of 12 years, there were 381 incident cases of type 2 DM. After adjustment for confounding factors (age, study year, body mass index, systolic blood pressure, education, occupational, commuting and leisure-time physical activity, alcohol and tea consumption, and smoking), the HRs of DM associated with the amount of coffee consumed daily (0-2, 3-4, 5-6, 7-9, > or =10 cups) were 1.00, 0.71 (95% confidence interval [CI], 0.48-1.05), 0.39 (95% CI, 0.25-0.60), 0.39 (95% CI, 0.20-0.74), and 0.21 (95% CI, 0.06-0.69) (P for trend<.001) in women, and 1.00, 0.73 (95% CI, 0.47-1.13), 0.70 (95% CI, 0.45-1.05), 0.67 (95% CI, 0.40-1.12), and 0.45 (95% CI, 0.25-0.81) (P for trend =.12) in men, respectively. In both sexes combined, the multivariate-adjusted inverse association was significant (P for trend <.001) and persisted when stratified by younger and older than 50 years; smokers and never smokers; healthy weight, overweight, and obese participants; alcohol drinker and nondrinker; and participants drinking filtered and nonfiltered coffee. CONCLUSION: Coffee drinking has a graded inverse association with the risk of type 2 DM; however, the reasons for this risk reduction associated with coffee remain unclear.
JAMA. 2004 Mar 10;291(10):1213-9
Coffee consumption and risk of type 2 diabetes mellitus.
Coffee is a major source of caffeine, which has been shown to acutely reduce sensitivity to insulin, but also has potentially beneficial effects. We prospectively investigated the association between coffee consumption and risk of clinical type 2 diabetes in a population-based cohort of 17,111 Dutch men and women aged 30-60 years. During 125,774 person years of follow-up, 306 n ew cases of type 2 diabetes were reported. After adjustment for potential confounders, individuals who drank at least seven cups of coffee a day were 0.50 (95% CI 0.35-0.72, p=0.0002) times as likely as those who drank two cups or f ewer a day to develop type 2 diabetes. Coffee consumption was associated with a substantially lower risk of clinical type 2 diabetes.
Lancet. 2002 Nov 9;360(9344):1477-8