Research - Coffee
Coffee consumption and total mortality: a meta-analysis of twenty prospective cohort studies
Youjin Jea1 c1 and Edward Giovannuccia2a
1 Department of Food and Nutrition, Kyung Hee University, 26 Kyunghee-daero, Dongdaemun-gu, Seoul 130-701, South Korea
a2 Departments of Nutrition and Epidemiology, Harvard School of Public Health, Boston, MA, USA
Coffee consumption has been shown to be associated with various health outcomes, but no comprehensive review and meta-analysis of the association between coffee consumption and total mortality has been conducted. To quantitatively assess this association, we conducted a meta-analysis of prospective cohort studies. Eligible studies were identified by searching the PubMed and EMBASE databases for all articles published through June 2013 and reviewing the reference lists of the retrieved articles. Pooled relative risks (RR) with 95 % CI were calculated using a random-effects model. We identified twenty studies of coffee consumption and total mortality, including 129 538 cases of deaths among the 973 904 participants. The RR of total mortality for the high v. low category of coffee consumption was 0·86 (95 % CI 0·80, 0·92). The pooled RR for studies using ≥ 2–4 cups/d as a cut-off for the high category was similar to that for studies using ≥ 5–9 cups/d as the cut-off. By geographical region, the inverse association tended to be stronger for the eight studies conducted in Europe (RR 0·78, 95 % CI 0·70, 0·88) and three studies carried out in Japan (RR 0·82, 95 % CI 0·73, 0·92) than for the nine studies conducted in the USA (RR 0·92, 95 % CI 0·84, 1·00). The inverse association was similar for men (RR 0·81, 95 % CI 0·73, 0·90) and women (RR 0·84, 95 % CI 0·79, 0·89). A weak, but significant, inverse association was found with moderate coffee consumption (1–2 cups/d; RR 0·92, 95 % CI 0·87, 0·98). High decaffeinated coffee consumption was also found to be associated with a lower risk of death, but the data are limited. Our findings indicate that coffee consumption is associated with a reduced risk of total mortality.
Source : British Journal of Nutrition
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Coffee consumption and risk of prostate cancer: an up-to-date meta-analysis
S Zhong1, W Chen2, X Yu3, Z Chen4, Q Hu5 and J Zhao1
- 1Center of Clinical Laboratory Science, Jiangsu Cancer Hospital Affiliated to Nanjing Medical University, Nanjing, China
- 2The Fourth Clinical College of Nanjing Medical University, Nanjing, China
- 3Department of Hematology (Key Department of Jiangsu Medicine), Zhongda Hospital, Medical School, Southeast University, Nanjing, China
- 4Department of General Surgery, The Affiliated Hospital of Xuzhou Medical College, Xuzhou, China
- 5Teaching and Research Office of General Surgery, Xuzhou Medical College, Xuzhou, China
Epidemiologic findings concerning the association between coffee consumption and prostate cancer risk yielded mixed results. We aimed to investigate the association by performing a meta-analysis of all available studies.
We searched PubMed, Web of Science and EMBASE for studies published up to July 2013. We calculated the summary relative risk (RR) and 95% confidence intervals (CIs) for ever, moderate and highest consumption of coffee vs non/lowest consumption. The dose–response relationship was assessed by restricted cubic spline model and multivariate random-effect meta-regression.
A total of 12 case–control studies and 12 cohort studies with 42 179 cases were selected for final meta-analysis. No significant associations were found among overall analysis. A borderline positive association was found for highest drinkers in five small hospital-based case–control (HCC) studies involving 2278 cases. However, compared with non/lowest drinkers, the summary RRs were 0.92 (95% CI=0.85–0.99) for ever drinkers, 0.92 (95% CI=0.85–1.00) for moderate drinkers and 0.83 (95% CI=0.72–0.96) for highest drinkers from 12 cohort studies, comprising a total of 34 424 cases. An increase in coffee intake of two cups/day was associated with a 7% decreased risk of prostate cancer according to cohort studies. A significant inverse relationship was also found for fatal prostate cancers and high-grade prostate cancers.
Case–control studies especially HCC ones might be prone to selection bias and recall bias that might have contributed to the conflicting results. Therefore, the present meta-analysis suggests a borderline significant inverse association between coffee consumption and prostate cancer risk based on cohort studies.
Source : EU Journal of Clinical Nutrition
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Coffee consumption and risk of prostate cancer: a meta-analysis of prospective cohort studies
Observational studies and animal evidence suggest an association between coffee consumption and the risk of prostate cancer. However, the results are inconsistent. We evaluated the association by conducting a meta-analysis of prospective cohort studies. PubMed and Embase were searched through June 2013 to identify studies that met predetermined inclusion criterion. A random-effects model was used to calculate the pooled risk estimates. Ten prospective cohort studies involving 8973 patients with prostate cancer and 206 096 participants were included in this systematic review. Compared with individuals who seldom or never drink coffee, the pooled relative risk of prostate cancer was 0.88 (95% confidence interval: 0.82–0.95) for regular coffee drinkers. Exclusion of any single study did not materially alter the combined risk estimate. Visual inspection of a funnel plot and Begg’s and Egger’s tests did not indicate evidence of publication bias. In summary, integrated evidence from prospective cohort studies supports the hypothesis that coffee consumption may decrease the risk of prostate cancer.
Source : Carcinogenesis
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Four or More Cups of Coffee a Day May Keep Prostate Cancer Recurrence and Progression Away
Bioactive compounds in coffee may have anti-inflammatory and antioxidant effects
Coffee consumption is associated with a lower risk of prostate cancer recurrence and progression, according to a new study by Fred Hutchinson Cancer Research Center scientists that is online ahead of print in Cancer Causes & Control. Corresponding author Janet L. Stanford, Ph.D., co-director of the Program in Prostate Cancer Research in the Fred Hutch Public Health Sciences Division, conducted the study to determine whether the bioactive compounds in coffee and tea may prevent prostate cancer recurrence and delay progression of the disease.
Stanford and colleagues found that men who drank four or more cups of coffee per day experienced a 59 percent reduced risk of prostate cancer recurrence and/or progression as compared to those who drank only one or fewer cups per week.
They did not, however, find an association between coffee drinking and reduced mortality from prostate cancer, although the study included too few men who died of prostate cancer to address that issue separately.
First study to assess the link between tea and prostate cancer outcomes
Regarding tea consumption, the researchers did not find an associated reduction of prostate cancer recurrence and/or progression. The study also did not draw any conclusions regarding the impact of tea drinking on prostate-specific death.
“To our knowledge, our study is the first to investigate the potential association between tea consumption and prostate cancer outcomes,” the authors wrote. “It is important to note, however, that few patients in our cohort were regular tea drinkers and the highest category of tea consumption was one or more cups per day. The association should be investigated in future studies that have access to larger populations with higher levels of tea consumption.”
The population-based study involved 1,001 prostate cancer survivors, aged 35-74 years old at the time of diagnosis between 2002-2005, who were residents of King County, Wash. Participants answered questions regarding their diet and beverage consumption two years prior to prostate cancer diagnosis using a validated food frequency questionnaire, and were interviewed about demographic and lifestyle information, family history of cancer, medication use and prostate cancer screening history.
The researchers followed up with patients more than five years after diagnosis to ascertain whether the prostate cancer had recurred and/or progressed. Those who were still living, willing to be contacted and had been diagnosed with non-metastatic cancer were included in the follow-up effort.
Of the original 1,001 patients in the cohort, 630 answered questions regarding coffee intake, fit the follow-up criteria and were included in the final analysis. Of those, 61 percent of the men consumed at least one cup of coffee per day and 12 percent consumed the highest amount: four or more cups per day.
The study also evaluated daily coffee consumption in relation to prostate cancer-specific death in 894 patients using data from the initial food frequency questionnaire. After the median follow-up period of eight-and-a-half years, 125 of the men had died, including 38 specifically from prostate cancer. Daily coffee consumption was not associated with prostate cancer-specific mortality or other-cause mortality, but with few deaths these analyses were limited.
“Our study differs from previous ones because we used a composite definition of prostate cancer recurrence/progression,” said first author Milan Geybels, a doctoral student at Maastricht University in the Netherlands who was a graduate student in Stanford’s Prostate Studies group at Fred Hutch when the study was conducted. “We used detailed information on follow-up prostate-specific antigen levels, use of secondary treatment for prostate cancer and data from scans and biopsies to assess occurrence of metastases and cause-specific mortality during follow up. Using these detailed data, we could determine whether a patient had evidence of prostate cancer recurrence or progression.”
The results are consistent with findings from Harvard’s Health Professionals Follow-up Study, which found that men who drank six or more cups of coffee per day had a 60 percent decreased risk of metastatic/lethal prostate cancer as compared to coffee abstainers.
Phytochemicals in coffee have anti-inflammatory and antioxidant effects
Further research is required to understand the mechanisms underlying the results of the study, but biological activities associated with consumption of phytochemical compounds found in coffee include anti-inflammatory and antioxidant effects and modulation of glucose metabolism. These naturally occurring compounds include:
• Caffeine, which has properties that inhibit cell growth and encourage apoptosis, or programmed cell death. Previous studies have found that caffeine consumption may reduce the risk of several cancer types, including basal-cell carcinoma, glioma (a cancer of the brain and central nervous system) and ovarian cancer.
• Diterpenes cafestol and kahweol, which may inhibit cancer growth.
• Chlorogenic acid, which, along with caffeic acid, can inhibit DNA methylation, a biochemical process involved in the development and progression of many cancer types.
Additional studies needed to confirm whether coffee can prevent cancer recurrence
The researchers emphasize that coffee or specific coffee components cannot be recommended for secondary prevention of prostate cancer before the preventive effect has been demonstrated in a randomized clinical trial. Further, there’s ongoing debate about which components in coffee are anti-carcinogenic, and additional large, prospective studies are needed to confirm whether coffee intake is beneficial for secondary prevention.
Coffee drinking may even be problematic for some men, Geybels said.
“Although coffee is a commonly consumed beverage, we have to point out that increasing one’s coffee intake may be harmful for some men. For instance, men with hypertension may be vulnerable to the adverse effects of caffeine in coffee. Or, specific components in coffee may raise serum cholesterol levels, posing a possible threat to coronary health. Patients who have questions or concerns about their coffee intake should discuss them with their general practitioner,” he said.
The investigators also noted limits to their study, which included a lack of data on how coffee consumption might have changed following diagnosis, whether the coffee that participants consumed was caffeinated or decaffeinated, and how the coffee was prepared (espresso, boiled or filtered), a factor that may affect the bioactive properties of the brew.
Source : Newswise
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Coffee and Tea May Contribute to a Healthy Liver
Your morning cup of tea or coffee may be doing more than just perking you up before work.
An international team of researchers led by Duke-NUS Graduate Medical School (Duke-NUS) and the Duke University School of Medicine suggest that increased caffeine intake may reduce fatty liver in people with non-alcoholic fatty liver disease (NAFLD).
Worldwide, 70 percent of people diagnosed with diabetes and obesity have NAFLD, the major cause of fatty liver not due to excessive alcohol consumption. It is estimated that 30 percent of adults in the United States have this condition, and its prevalence is rising in Singapore. There are no effective treatments for NAFLD except diet and exercise.
Using cell culture and mouse models, the study authors -- led by Paul Yen, M.D., associate professor and research fellow, and Rohit Sinha, Ph.D of the Duke-NUS Graduate Medical School's Cardiovascular and Metabolic Disorders Program in Singapore -- observed that caffeine stimulates the metabolization of lipids stored in liver cells and decreased the fatty liver of mice that were fed a high-fat diet. These findings suggest that consuming the equivalent caffeine intake of four cups of coffee or tea a day may be beneficial in preventing and protecting against the progression of NAFLD in humans.
The findings will be published in the September issue of the journal Hepatology.
"This is the first detailed study of the mechanism for caffeine action on lipids in liver and the results are very interesting," Yen said. "Coffee and tea are so commonly consumed and the notion that they may be therapeutic, especially since they have a reputation for being "bad" for health, is especially enlightening."
The team said this research could lead to the development of caffeine-like drugs that do not have the usual side effects related to caffeine, but retain its therapeutic effects on the liver. It could serve as a starting point for studies on the full benefits of caffeine and related therapeutics in humans.
Source : Newswise
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Inhibition of planktonic and biofilm growth of Candida albicans reveals novel antifungal activity of caffeine
Jayant S. Raut, Nitin M. Chauhan, Ravikumar B. Shinde and S. Mohan Karuppayil*
Infections associated with drug resistant strains and biofilms of Candida albicans have necessitated search for novel molecules with antifungal properties. Caffeine, a major component of the most widely consumed beverages, coffee and tea, is known to possess various biological properties. To evaluate antifungal potential, its effect on growth and virulence attributes of C. albicans was studied using standard methodologies. Caffeine showed fungistatic effect on planktonic growth of two strains of C. albicans (including a fluconazole resistant strain), exhibiting minimum inhibitory concentration (MIC) at 12.5 mM concentration. Around 30% decrease in the adhesion of cells in the presence of caffeine indicated considerable anti-adhesion activity. Caffeine prevented formation of biofilms (which are drug resistant forms), in a concentration dependent manner. Analysis by 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) metabolic assay and microscopic observations showed inhibition of biofilm development at 25 mM concentration. This study, for the first time demonstrates dietary chemical, caffeine, as a potential inhibitor of growth, adhesion and biofilm formation by C. albicans.
Source : Journal of Medicinal Plant Research
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Coffee, Green Tea, May Help Lower Stroke Risk
Green tea and coffee may help lower your risk of having a stroke, especially when both are a regular part of your diet, according to research published in Stroke: Journal of the American Heart Association.
"This is the first large-scale study to examine the combined effects of both green tea and coffee on stroke risks," said Yoshihiro Kokubo, M.D., Ph.D., F.A.H.A., F.A.C.C., F.E.S.C., lead author of the study at Japan's National Cerebral and Cardiovascular Center. "You may make a small but positive lifestyle change to help lower the risk of stroke by adding daily green tea to your diet."
Researchers asked 83,269 Japanese adults about their green tea and coffee drinking habits, following them for an average 13 years. They found that the more green tea or coffee people drink, the lower their stroke risks.
- People who drank at least one cup of coffee daily had about a 20 percent lower risk of stroke compared to those who rarely drank it.
- People who drank two to three cups of green tea daily had a 14 percent lower risk of stroke and those who had at least four cups had a 20 percent lower risk, compared to those who rarely drank it.
- People who drank at least one cup of coffee or two cups of green tea daily had a 32 percent lower risk of intracerebral hemorrhage, compared to those who rarely drank either beverage. (Intracerebral hemorrhage happens when a blood vessel bursts and bleeds inside the brain. About 13 percent of strokes are hemorrhagic.)
During the 13-years of follow-up, researchers reviewed participants' hospital medical records and death certificates, collecting data about heart disease, strokes and causes of death. They adjusted their findings to account for age, sex and lifestyle factors like smoking, alcohol, weight, diet and exercise.
Green tea drinkers in the study were more likely to exercise compared to non-drinkers.
Previous limited research has shown green tea's link to lower death risks from heart disease, but has only touched on its association with lower stroke risks. Other studies have shown inconsistent connections between coffee and stroke risks.
Initial study results showed that drinking more than two cups of coffee daily was linked to increasing coronary heart disease rates in age- and sex-adjusted analysis. But researchers didn't find the association after factoring in the effects of cigarette smoking -- underscoring smoking's negative health impact on heart and stroke health.
A typical cup of coffee or tea in Japan was approximately six ounces. "However, our self-reported data may be reasonably accurate, because nationwide annual health screenings produced similar results, and our validation study showed relatively high validity." Kokubo said. "The regular action of drinking tea, coffee, largely benefits cardiovascular health because it partly keeps blood clots from forming."
Tea and coffee are the most popular drinks in the world after water, suggesting that these results may apply in America and other countries.
It's unclear how green tea affects stroke risks. A compound group known as catechins may provide some protection. Catechins have an antioxidant anti-inflammatory effect, increasing plasma antioxidant capacity and anti-thrombogenic effects.
Some chemicals in coffee include chlorogenic acid, thus cutting stroke risks by lowering the chances of developing type 2 diabetes.
Further research could clarify how the interaction between coffee and green tea might help further lower stroke risks, Kokubo said.
Source : Science Daily
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A Cup of Joe May Help Some Parkinson’s Disease Symptoms
While drinking caffeine each day does not appear to help improve sleepiness among people with Parkinson’s disease, it may have a benefit in controlling movement, according to new research published in the August 1, 2012, online issue of Neurology®, the medical journal of the American Academy of Neurology. “Studies have shown that people who use caffeine are less likely to develop Parkinson’s disease, but this is one of the first studies in humans to show that caffeine can help with movement symptoms for people who already have the disease,” said study author Ronald Postuma, MD, MSc, with McGill University in Montreal and the Research Institute of the McGill University Health Center. Postuma is also a member of the American Academy of Neurology.
For the study, 61 people with Parkinson’s disease who showed symptoms of daytime sleepiness and some motor symptoms were given either a placebo pill or a pill with 100 milligrams of caffeine two times a day for three weeks, then 200 milligrams twice a day for three weeks, which was the equivalent of between two and four cups of coffee per day.
After six weeks, the half that took the caffeine supplements averaged a five-point improvement in Parkinson’s severity ratings compared to those who didn’t consume caffeine. “This is a modest improvement, but may be enough to provide benefit to patients. On the other hand, it may not be sufficient to explain the relationship between caffeine non-use and Parkinson's, since studies of the progression of Parkinson’s symptoms early in the disease suggest that a five-point reduction would delay diagnosis by only six months,” said Postuma.
The caffeine group also averaged a three-point improvement in the speed of movement and amount of stiffness compared to the placebo group. Caffeine did not appear to help improve daytime sleepiness and there were no changes in quality of life, depression or sleep quality in study participants.
“The study is especially interesting since caffeine seems to block a malfunctioning brain signal in Parkinson’s disease and is so safe and inexpensive,” said Michael Schwarzschild, MD, PhD, of Massachusetts General Hospital in Boston, who wrote an accompanying editorial. “Although the results do not suggest that caffeine should be used as a treatment in Parkinson’s disease, they can be taken into consideration when people with Parkinson’s are discussing their caffeine use with their neurologist.” Schwarzschild is also a member of the American Academy of Neurology.
The study authors noted that the length of the study was short and that the effects of caffeine may lessen over time.
Source : Newswise
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Caffeine May Lower Risk of Common Skin Cancer
Relatively modest caffeine consumption was associated with a significantly lower relative risk of basal cell carcinoma (BCC), data from two large cohort studies showed.
People who consumed more than three cups of coffee a month had a 17% reduction in the relative risk of BCC versus individuals who drank less than one cup per month.
The association pertained to men and women and to sources of caffeine other than coffee.
Investigators found no association between caffeine consumption and squamous-cell carcinoma (SCC) or melanoma, as reported in the July 1 issue of Cancer Research.
"Given that nearly one million new cases [of BCC] are diagnosed each year in the U.S., modification in daily dietary factors with even small protective effects may have great public health impact," Jilali Han, PhD, of Harvard and Brigham and Women's Hospital in Boston, and co-authors wrote in conclusion.
Skin cancers are the most common malignancy among white people in the U.S. White Americans have an estimated 1 in 5 lifetime risk of developing skin cancer.
Laboratory studies have consistently shown that oral and topical caffeine prevents SCC in mice exposed to ultraviolet (UV) light, the authors wrote in their introduction. Other preclinical studies have suggested a potential mechanistic explanation, as topical caffeine has been shown to induce apoptosis in UV-damaged keratinocytes in mice.
Observational data have been less convincing, as studies have shown inconsistent associations between caffeine and skin cancer, including melanoma and nonmelanoma. None of these studies distinguished between caffeinated and decaffeinated coffee or tea, a key piece of evidence that might show whether other components of coffee or tea have anticancer activity.
To address limitations of current information, Han and co-authors reviewed data from the Nurses' Health Study (NHS) and the Health Professionals Follow-up Study (HPFS). The NHS included 121,700 women ages 30 to 55 at enrollment in 1976. HPFS enrolled 51,529 men ages 40 to 75 when the study began in 1976.
NHS participants provided information on caffeine intake on several occasions from 1984 to 2006, as did the HPFS participants from 1986 to 2006.
Han and co-authors analyzed data for 112,897 participants from the two studies (72,921 women and 39,976 men). During 24 and 22 years of follow-up in the NHS and HPFS, respectively, 22,786 participants developed BCC, 1,953 developed SCC, and 741 developed melanoma.
Using U.S. Department of Agriculture data, Han and co-authors estimated caffeine content 137 mg per cup of caffeinated coffee, 47 mg per cup of tea, 46 mg per 12-oz container of caffeinated soda, and 7 mg per 1-oz serving of chocolate.
Investigators stratified the study participants into quintiles of daily caffeine consumption, which range from 31 to 604 mg in NHS and 8 to 584 mg in the HPFS. The analysis showed an inverse association between caffeine consumption from all sources combined and the risk of BCC.
Comparison of the highest and lowest quintile of caffeine consumption resulted in a relative risk of 0.82 for BCC in women and 0.87 in men (P<0.0001 for trend in both groups). The relative risk was 0.84 for men and women combined.
Coffee accounted for 78.5% of all caffeine consumption. A separate comparison of skin cancer risk by coffee consumption produced a relative risk of 0.83 for the highest versus lowest quintile (95% CI 0.77 to 0.87). Investigators found a dose-response relationship between caffeine and BCC risk in women (P<0.0001 for trend) and men (P=0.003 for trend).
Caffeine from sources other than coffee tended to have an inverse association with BCC (0.88 in women, 0.93 in men), although the effect did not achieve statistical significance.
The authors noted a number of limitations including the reliance on self-report of BCC without confirmation from histology. Also, they noted that statistical power to calculate any relationship between caffeine and melanoma or SCC was lacking because the number of those cancers in the population was much lower than BCC.
Finally, they said they were "not able to rule out other differences between caffeinated and decaffeinated coffee that could also be etiologically relevant."
Primary source: Cancer Research
Song F, et al "Increased caffeine intake is associated with reduced risk of basal cell carcinoma of the skin" Cancer Res 2012; 72: 3282-3289.
Source : Medpage Today
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A Prospective Cohort Study of Coffee Consumption and Risk of Endometrial Cancer over a 26-Year Follow-Up
Youjin Je1, Susan E. Hankinson2,3, Shelley S. Tworoger2,3, Immaculata DeVivo2,3, and Edward Giovannucci1,2,3_
Background: Coffee has been reported to lower levels of estrogen and insulin, two hormones implicated in endometrial carcinogenesis, but prospective data on the relation between coffee consumption and risk of endometrial cancer are limited.
Methods: We prospectively assessed coffee consumption in relation to endometrial cancer risk in the Nurses' Health Study (NHS) with 67,470 female participants aged 34 to 59 in 1980. Cumulative average coffee intake was calculated with all available questionnaires to assess long-term effects. Cox regression models were used to calculate incidence rate ratios (RR), controlling for other risk factors.
Results: Fewer than 4 cups of coffee per day were not associated with endometrial cancer risk. However, women who consumed 4 or more cups of coffee had 25% lower risk of endometrial cancer than those who consumed less than 1 cup per day (multivariable RR = 0.75; 95% CI = 0.57–0.97; Ptrend = 0.02). We found the similar association with caffeinated coffee consumption (RR for ≥4 vs. <1 cup/d = 0.70; 95% CI = 0.51–0.95). For decaffeinated coffee consumption, a suggestive inverse association was found among women who consumed 2 or more cups per day versus <1 cup/mo. Tea consumption was not associated with endometrial cancer risk.
Conclusions: These prospective data suggest that four or more cups of coffee per day are associated with a lower risk of endometrial cancer.
Impact: Drinking of coffee, given its widespread consumption, might be an additional strategy to reduce endometrial cancer risk. However, addition of substantial sugar and cream to coffee could offset any potential benefits.
Source : Cancer Epidemiol Biomarkers Prev; 20(12); 1–9.
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A Couple Cups of Java May Keep the Blues Away
Coffee appears to protect against depression in women, and the more the better, researchers found.
In a prospective cohort study, women who drank two or three cups of coffee a day were 15% less likely to develop depression than those who drank one cup or less, according to Alberto Ascherio, MD, DrPH, of Harvard School of Public Health in Boston, and colleagues.
And the effect was slightly more pronounced for women who drank four or more cups a day, Ascherio and colleagues reported in the Sept. 26 issue of Archives of Internal Medicine.
There was no association between depression and decaffeinated coffee, suggesting that it's the caffeine, and not other components of the beverage, that is involved, the researchers reported. However, they cautioned that the longitudinal study can only suggest, but not prove, that is true.
There was also an interaction that the researchers described as "marginally significant" -- at P=0.06 – between smoking and coffee drinking that appeared to increase the benefit for smokers. Caffeine is regarded as the most widely used central nervous system stimulant in the world, with about 80% of consumption in the form of coffee, the researchers noted. Many studies have looked at caffeine and other disorders, including cardiovascular disease and inflammation, but few have examined psychiatric illness.
The findings come from the Nurses Health Study, which has been following more than 120,000 women since 1976. For this analysis, the researchers studied 50,739 women who were free of depressive symptoms in 1996, when study questionnaires started to ask about use of antidepressants, and followed them through June 1, 2006.
Ascherio and colleagues measured caffeine consumption -- including caffeine from coffee -- using validated questionnaires completed from May 1, 1980, through April 1, 2004, and computed cumulative average consumption with a two-year latency period.
They defined incident clinical depression as self-reported physician-diagnosed depression and beginning antidepressant use, and found that over the study period, there were 2,607 new cases of depression.
Both caffeine intake and coffee consumption showed an inverse dose-response association with depression, Ascherio and colleagues found. Specifically:
- Compared with women drinking one cup or less of caffeinated coffee per week, the multivariate relative risk of depression was 0.85 for those drinking two or three cups per day, with a 95% confidence interval from 0.75 to 0.95.
- Similarly, the relative risk for those drinking four or more cups a day, compared with women drinking a cup or less a week, was 0.80, with a 95% confidence interval from 0.64 to 0.99.
- The trend was significant at P=0.001.
- Compared with women consuming the least caffeine (less than 100 milligrams a day), the multivariate relative risk of depression was 0.80 for those consuming the most (at least 500 milligrams a day). The 95% confidence interval ranged from 0.68 to 0.95, and the trend was significant at P=0.02.
However, the authors noted, the interaction "was unexpected and may be due to chance."
They cautioned that they can't exclude reverse causation: The possibility that mild depressive symptoms led to low caffeine consumption.
They added that some misclassification of depression is "inevitable because of a combination of errors in reporting depression and antidepressant use, low recognition of depression by physicians, under-treatment of depression, and use of antidepressant medication for indications other than depression."
Source : MedPage Today
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High daily intakes of coffee may significantly reduce the risks of certain types of breast cancer by about 60 per cent, according to new research.
The study, published in Breast Cancer Research, suggests that drinking over five cups of coffee per day may significantly reduce the risks of developing a sub type of breast cancer known as anti-oestrogen-resistant oestrogen-receptor (ER-negative) breast cancer.
The team of Swedish researchers, based at the Karolinska Institutet, compared lifestyle factors including coffee consumption between women with breast cancer and age-matched women without, finding that coffee drinkers had a lower incidence of breast cancer than women who rarely drank coffee.
“We found no evidence that coffee consumption increases the overall risk of postmenopausal breast cancer. However, a high daily intake of coffee was found to be associated with a significant decrease in ER-negative breast cancer among postmenopausal women,” wrote the researchers, led by Jingmei Li.
The authors reported that five cups of coffee per day were 57 per cent less likely to develop ER-negative breast cancer than a low consumption reference group.
Coffee and cancer
Breast cancer is a complex disease which can be sub-divided into hormone-responsive (estrogen receptor (ER) positive) and non-hormone-responsive subtypes (ER-negative) sub types.
However, Li and her colleagues noted that some evidence has suggested that there is a link between coffee consumption and breast cancer risk, according to different oestrogen receptor subtypes.
Coffee is one of the most popular beverages in the world, with production amounting to 7.4 billion kg in 2009/2010, according to the International Coffee Organization .
The Swedish team noted that coffee “is interesting in the light of breast cancer aetiology because of its complex make-up of chemicals, several of which have been shown in experimental studies to have cancer risk altering potential through meaningful biological mechanisms.”
However, they added that the scientific community “stands divided over toxicity of the beverage.”
Previous experimental and clinical studies have suggested that coffee – a complex mixture of caffeine and polyphenols – may play a dual role as both a carcinogen and a chemo-preventive agent.
The new researcher assessed the association between coffee consumption and postmenopausal breast cancer risk in a large population-based study of nearly 6,000 people.
The authors reported that coffee consumption was associated with a modest decrease in overall breast cancer risk.
When separated by breast cancer sub types, Li and her co-workers found a significant reduction in the risk of ER-negative breast cancer for ‘heavy coffee drinkers’ who consume more than five sups per day.
The researchers noted that the risk of breast cancer risk reduction associated with high coffee consumption was significantly higher for ER-negative compared to ER-positive cancer.
Li and her colleagues added that future studies should now be conducted to confirm the effects of coffee consumption with respect to breast cancer subtypes.
Source: NutraIngredients via Breast Cancer Research 13:R49, doi:10.1186/bcr2879
“Coffee consumption modifies risk of estrogen-receptor negative breast cancer”
Authors: J. Li, P. Seibold, J. Chang-Claude, D. Flesch-Janys, et al
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