Association of serum lipids with coffee, tea, and egg consumption in free-living subjects

Conflicting Effects of Coffee Consumption on Cardiovascular Diseases: Does Coffee Consumption Aggravate Pre-existing Risk Factors?

Coffee is one of the most popular beverages worldwide. Its effect on health is generally regarded as beneficial in many studies. However, there are growing concerns about the adverse effect of coffee consumption on cardiovascular disease (CVD) due to the potential aggravating impact on the cardiovascular system attributed to various compounds within coffee. This review is focused on deteriorative effects of coffee consumption on CVDs with possible mechanisms. Patients with risk factors of CVDs should prudently consider heavy consumption of coffee as it may exacerbate hypertension, dyslipidemia, and atherosclerosis, and increase the odds of cardiovascular events. J-shaped or U-shaped dose-response graphs of coffee consumption and CVD parameters partially explain the inconsistency of conclusions between coffee studies on CVD, highlighting a moderate intake of coffee. Moreover, there are discrepancies in results from clinical studies elucidating considerable influences of confounding factors including gender and smoking status on outcomes of those conducted to reveal the actual impact of coffee consumption on CVDs. Physical features of subjects including genetic variations and body mass index (BMI) make it difficult to determine moderate intake of coffee for individuals in terms of caffeine metabolism. Further epidemiological studies with consideration about characteristics of the study population are needed to determine the exact effect of coffee consumption on CVD.

Effect of oral theaflavin administration on body weight, fat, and muscle in healthy subjects: a randomized pilot study

Theaflavins are reddish-colored polyphenols in black tea. To test the efficacy of theaflavin administration on body fat and muscle, we performed a randomized, double-blind, placebo-controlled study and investigated the effect of theaflavins administration on the body composition using of healthy subjects. In this study, 30 male and female Japanese were enrolled and participants were randomly allocated to receive placebo, theaflavin (50 or 100 mg/day), or catechin (400 mg/ml) for 10 weeks. The effects were evaluated using body weight, body fat percentage, subcutaneous fat percentage, and skeletal muscle percentage. Theaflavin administration significantly improved body fat percentage, subcutaneous fat percentage, and skeletal muscle percentage when compared to with the placebo. In contrast, there was no significant difference in all measured outcomes between the catechin and the placebo groups. The results indicate that oral administration of theaflavin had a beneficial effect on body fat and muscle in healthy individuals.

Effect of black tea intake on blood cholesterol concentrations in individuals with mild hypercholesterolemia: a diet-controlled randomized trial

Habitual intake of black tea has been associated with relatively lower serum cholesterol concentrations in observational studies. However, clinical trial results evaluating the effects of black tea on serum cholesterol have been inconsistent. Several factors could explain these mixed results, in particular, uncontrolled confounding caused by lifestyle factors (eg, diet). This diet-controlled clinical trial estimates the effect of black tea flavonoid consumption on cholesterol concentrations in 57 borderline hypercholesterolemic individuals (total cholesterol concentrations between 190 and 260 mg/dL [4.9 and 6.7 mmol/L]). A double-blind, randomized crossover trial was conducted in Minneapolis, MN, from April 2002 through April 2004 in which key conditions were tightly controlled to minimize possible confounding. Participants consumed a controlled low-flavonoid diet plus 5 cups per day of black tea or tea-like placebo during two 4-week treatment periods. The flavonoid-free caffeinated placebo matched the tea in color and taste. Differences in cholesterol concentrations at the end of each treatment period were evaluated via linear mixed models. Differences among those treated with tea vs placebo were 3.43 mg/dL (0.09 mmol/L) (95% CI -7.08 to 13.94) for total cholesterol, -1.02 mg/dL (-0.03 mmol/L) (95% CI -11.34 to 9.30) for low-density lipoprotein cholesterol, 0.58 mg/dL (0.02 mmol/L) (95% CI -2.98 to 4.14) for high-density lipoprotein cholesterol, 15.22 mg/dL (0.17 mmol/L) (95% CI -40.91 to 71.35) for triglycerides, and -0.39 mg/dL (-0.01 mmol/L) (95% CI -11.16 to 10.38) for low-density lipoprotein plus high-density lipoprotein cholesterol fraction. The low-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio decreased by -0.1 units (95% CI -0.41 to 0.21). No results were statistically or clinically significant. The intake of 5 cups of black tea per day did not alter the lipid profile of borderline hypercholesterolemic subjects significantly.

Antioxidant and lipid lowering activities of Indian black tea

Indian black tea; CTC leaf and dust, produced by Tata Tea Limited, Kolkata, (India) was studiedin vitro as potential scavenger of oxygen free radicals. Super oxide anions were generated in a system containing xanthine-xanthine oxidase (enzymic system) and by NADH- phenozine methosulphate (non enzymic system). Anions were assayed in terms of uric acid formation and reduction of nitroblue tetrazolium salt, which were shown to be suppressed by tea extracts. Extracts from both leaf and dust also inhibted the formation of hydroxyl radicalsin vitro in the enzymic system comprising hypoxanthine-Cu(+2)-sodium ascorbate and xanthine oxidase and in non enzymic system of deoxyribose-Cu(+2)-sodium ascorbate and H(2)O(2) as well as the Cu(+2) induced lipid peroxidation in human low density lipoprotein. Feeding with black tea in normal rats for sixty days increased their antioxidant activity and their liver microsomes were shown to be protected against peroxidation of lipids as stimulated by metal ions with enzymic or non enzymic reactants. Furthermore feeding with tea extracts in normal as well as triton WR-1339 induced hyperlipidemic rats caused decrease in their plasma levels of total cholesterol, phospholipids and triglycerides. The antioxidant and lipid lowering activities of both extracts from CTC leaf and dust tea was comparable and may be due to the presence of natural products like catechin and others.

Tea and health

Tea is a pleasant, popular, socially accepted, economical, and safe drink that is enjoyed every day by hundreds of millions of people across all continents. Tea also provides a dietary source of biologically active compounds that help prevent a wide variety of diseases. It is the richest source of a class of antioxidants called flavonoids and contains many other beneficial compounds such as vitamins and fluoride. A growing body of evidence suggests that moderate consumption of tea may protect against several forms of cancer, cardiovascular diseases, the formation of kidney stones, bacterial infections, and dental cavities. Future research needs to define the actual magnitude of health benefits, establish the safe range of tea consumption associated with these benefits, and elucidate potential mechanisms of action.

The impact of changes in coffee consumption on serum cholesterol

To investigate the possible association between changes in coffee consumption and serum cholesterol levels, information was obtained from 2109 healthy nonsmokers aged 25-65 years at two clinic visits to a preventive medical center between 1987 and 1991 (mean interval between visits: 16.7 months). After adjusting for age and changes in other potential confounders, about 2 mg/dl total cholesterol increase was associated with an increase of one cup of regular coffee per day (p < 0.001). A dose-response was found among those who decreased regular coffee consumption, those who continued the same dose, and those who increased consumption. The same trend was observed among those who quit drinking regular coffee, those who never drank coffee, and those who started to drink coffee. No change in cholesterol level was found among those continuing to consume the same quantity of regular coffee compared to those who never drank coffee. The change in cholesterol level was not related to consumption of decaffeinated coffee, regular tea, decaffeinated tea, or cola with caffeine. To our knowledge, this is the first follow-up study correlating change in coffee consumption with change in serum cholesterol in a large group of men and women.

Frequency of consumption of selected indicator foods and serum cholesterol. GISSI-EFRIM investigators. Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto--Epidemiologia dei Fattori di Rischio dell'Infarto Miocardico

The relationship between frequency of consumption of eleven indicator foods (milk, meat, liver, carrots, green vegetables, fruit, eggs, ham, fish, cheese and alcohol) and serum cholesterol was investigated in the comparison group of a case-control study of acute myocardial infarction conducted in Italy. Data were collected on 792 subjects from various Italian regions, admitted to hospital for acute conditions unrelated to any known or potential risk factor for myocardial infarction or to long-term modifications in diet. No statistically or epidemiologically meaningful relationship emerged between serum cholesterol level and frequency of consumption of any of these foods. Cholesterol levels rose according to increasing consumption tertiles for most of the indicator foods considered. Higher values for the higher tertile of consumption were observed for meat, ham and eggs, but also for fruit, carrots and green vegetables. However, correlation coefficients between frequency of consumption of various food items and serum cholesterol level were uniformly low for all food items considered, ranging between -0.09 (for milk) and 0.19 (for ham). Although a more comprehensive diet history may lead to different indications, the present data are not suggestive of any major influence of long-term frequency of consumption of a few selected indicator foods on serum cholesterol levels.

Association of serum lipoproteins and health-related habits with coffee and tea consumption in free-living subjects examined in the Israeli CORDIS Study

BACKGROUND

A positive association between coffee consumption and serum cholesterol levels has been demonstrated and recent results indicate that this may be due to a lipid-rich fraction present mainly in boiled coffee. The possible effects of tea consumption are less clear, although evidence has been presented which suggests that tea drinkers have lower cholesterol levels. The associations between serum lipids and lipoproteins and coffee and tea consumption were examined in the Israel CORDIS study.

METHODS

Employees of 21 factories were screened for cardiovascular disease risk factors between 1985 and 1987. Detailed data on coffee and tea consumption and serum lipids and lipoproteins were available for 3,858 men and 1,511 women.

RESULTS AND CONCLUSIONS

Consumption of five or more cups of coffee per day was reported by 10.1% of men and 8.7% of women, whereas only 3.4% of men and 2.2% of women consumed similar quantities of tea. After controlling for a number of potential confounders, coffee consumption (particularly "mud" coffee) was strongly and positively associated with higher serum total and low-density lipoprotein cholesterol levels in both sexes (consumers of five or more cups per day had cholesterol levels up to 18 mg/dl higher than abstainers) and with high-density lipoprotein cholesterol in women. There was a nonsignificant negative association between tea consumption and serum cholesterol (cholesterol levels about 5 mg/dl more in abstainers than in those consuming five or more cups per day). In general, more negative health-related habits were reported with increased coffee consumption, whereas this relationship was not found for tea drinking. The relatively small percentage of heavy tea drinkers limits the conclusions that one can draw from this study and controlled trials are needed to evaluate possible lipid-lowering effects of tea consumption.

Tea consumption. relationship to cholesterol, blood pressure, and coronary and total mortality

BACKGROUND AND METHODS

The relation of tea to cholesterol, systolic blood pressure, and mortality from coronary heart disease and all causes was studied in 9,856 men and 10,233 women without history of cardiovascular disease or diabetes. All men and women 35-49 years of age from the county of Oppland (Norway) were invited to participate; the attendance rate was 90%.

RESULTS

Mean serum cholesterol decreased with increasing tea consumption, the linear trend coefficient corresponded to a difference of 0.24 mmol/liter (9.3 mg/dl) in men and 0.15 mmol/liter (5.8 mg/dl) in women between drinkers of less than one cup and those of five or more cups/day, when other risk factors were taken into account. Systolic blood pressure was inversely related to tea with a difference between the same two tea groups of 2.1 mm in men and 3.5 mm in women. Altogether 396 men and 237 women died from all causes, and of these 141 and 18, respectively, died from coronary heart disease during the 12-year follow-up period. The mortality rate was higher (not statistically significant) among persons drinking no tea or less than one cup compared with persons drinking one or more cups/day. This applies to men and women and to coronary heart disease and all-cause mortality. For men, the relative risk (one or more versus less than one cup) for coronary death from Cox regression was 0.64 (95% CI:0.38, 1.07).

Coffee consumption and serum lipids: a randomized, crossover clinical trial

PURPOSE

The purpose of this study was to determine the effect of consuming three or more cups of filter-brewed coffee per day on levels of serum lipids.

SUBJECTS AND METHODS

A prospective, randomized crossover clinical trial was performed. Twenty-one healthy white male subjects completed the trial, and consumed an average of 3.6 cups of coffee a day. Data were evaluated by analysis of variance for repeated measures and t-test for paired means.

RESULTS

No effect of coffee consumption on serum total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, or apolipoprotein B was found. Diet, creamer use, and cigarette use as well as group assignment and time factors were controlled for in the analysis.

CONCLUSION

We found no effect of moderate consumption of filter-brewed coffee on serum levels of atherogenic lipids. This study supports previous work that filtered coffee has no adverse effect on serum lipids. This has far-reaching implications given the widespread use of coffee and the current concern over coronary risk factors.

The effect on serum cholesterol levels of coffee brewed by filtering or boiling

Previous reports have indicated that coffee consumption may increase serum cholesterol levels. We studied the effects of coffee prepared by two common brewing methods (filtering and boiling) on serum lipid levels in a 12-week randomized trial involving 107 young adult subjects with normal serum cholesterol levels. After a three-week run-in period during which they all consumed filtered coffee, the participants were randomly assigned to one of three groups receiving four to six cups of boiled coffee a day, four to six cups of filtered coffee a day, or no coffee, for a period of nine weeks. As compared with the change from base line in the filtered-coffee group, the serum total cholesterol level increased after the consumption of boiled coffee by 0.48 mmol per liter (95 percent confidence limits, 0.13 and 0.83), and the low-density lipoprotein cholesterol level increased by 0.39 mmol per liter (95 percent confidence limits, -0.04 and 0.82). There was no significant difference in the change in serum total or low-density lipoprotein cholesterol levels between the filtered-coffee group and the group that drank no coffee. The levels of high-density lipoprotein cholesterol and apolipoproteins were not affected by boiled or filtered coffee. We conclude that drinking filtered coffee does not affect serum lipid levels. The consumption of boiled coffee, however, has an effect on serum cholesterol levels amounting to a mean net increase of 10 percent of the base-line level after nine weeks.

Coffee and cholesterol in epidemiological and experimental studies

Twenty-two cross-sectional studies involving 130,000 persons from 8 different countries have reported their findings on the association between coffee consumption and cholesterol levels. Results of these reports display a variety of trends in the association between coffee intake and serum cholesterol concentrations: 8 (36%) studies demonstrated a significant positive association in both sexes, and 5 (23%) studies showed no association in men or women. In 3 other reports where both sexes were included, significant positive association was observed only in women. The remaining 6 investigations examined only men with 4 (18%) reporting a significant correlation between coffee and cholesterol. This unexplained incongruity of cross-sectional data points to a relationship between coffee and cholesterol in some populations, which needs to be further explored. In addition, HDL cholesterol levels appeared unrelated to coffee intake in the 11 studies in which it was measured. The 7 available human experiments showed the same low level of agreement in the results among small numbers of volunteers. Experiments involving different brewing methods suggest that a major part of the cholesterol-increasing effect can be explained by different brewing methods. A critical assessment of the published reports leads to the conclusion that the data are insufficient to warrant public health admonitions against coffee drinking, but that it may be of clinical importance in some hypercholesterolemic individuals.