A cup or two a day predicts lower risk of chronic disease

Drinking lots of coffee predicts higher risk

Coffee is the world’s leading beverage except for water. A recent review concluded that moderate caffeinated coffee consumption (3-5 8 ounce cups per day) does not increase risk of cardiovascular disease. To the contrary, evidence suggests that moderate consumption predicts lower risks of mortality and certain chronic diseases. That said, heavy caffeinated coffee consumption can have adverse effects. Adults generally and pregnant or lactating women should limit their caffeine intake to 400 and 200 mg per day, respectively. One 8-fluid ounce cup of coffee has about 95 mg of caffeine. Moderate coffee or tea consumption comports with a healthy lifestyle.

Coffee contains several compounds that possess antioxidant, anti-inflammatory, and insulin-sensitizing effects. These chemicals may promote anticancer activity. Longitudinal studies found that increased coffee consumption predicted decreased recurrence and mortality of colorectal cancer. Does greater coffee intake predict greater survival in patients with advanced or metastatic colorectal cancer? A study of 1171 patients with advanced or metastatic colorectal cancer found that increased coffee (both decaffeinated and regular) consumption at baseline predicted lower risk of disease progression and death over a median follow-up of 5 years. More specifically, the risk of cancer progression and death declined in a step-wide manner by 5 and 7 percent, respectively, for each one-cup increase in coffee intake. Thus, greater coffee intake (up to a point) predicted better prognosis for patients with advanced or metastatic colorectal cancer.

Studies have reported associations between higher coffee consumption and reduced risk of liver, colorectal, and breast cancer. But studies show mixed results regarding links between coffee consumption and prostate cancer. A new systematic review and meta-analysis of 16 longitudinal studies showed an inverse relationship between coffee consumption and risk of prostate cancer. Specifically, compared to the lowest level of daily coffee consumption, the highest level (up to 10 cups per day) predicted significant 9 and 7 percent lower risks of prostate cancer and localized prostate cancer, respectively. Plausible biological mechanisms could account for an apparent protective effect of coffee on prostate cancer. Constituents in coffee improve glucose metabolism and reduce blood insulin, increase insulin sensitivity, and have anti-inflammatory and anti-oxidant effects. Drinking coffee may modestly help men avoid prostate cancer.

Studies that investigated the health impacts of coffee and/or tea drinking have produced mixed results. Some of the uncertainty may arise from small sample sizes. A new study that used data from 365,682 participants with an average of 60 years in the UK Biobank Study overcomes this barrier. Coffee and tea consumption were measured in cups per day from self-reports at baseline. Health outcomes included stroke (ischemic and hemorrhagic), dementia (Alzheimer’s disease and vascular dementia), and post-stroke dementia.

In general, the risks of these health outcomes in relation to coffee intake were non-linear over a median follow-up of 11 years. The lowest risks occurred at moderate levels of consumption and increased at high consumption. The lowest risks of stroke occurred at 2, 3, and 4 cups of coffee, tea, and coffee and tea combined daily, respectively. The lowest risks of dementia occurred at 2, 4, and 4.5 cups of coffee, tea, and coffee and tea combined, respectively. For post-stroke dementia, only the combination of coffee and tea showed a significant relationship with the lowest risk at 4 cups of coffee per day. After multivariable adjustment and compared to non-coffee or tea drinkers, participants who reported drinking 2-3 cups of coffee and 2-3 cups of tea daily had a 38 and 28 percent lower risks of having an ischemic stroke and dementia, respectively, during follow-up. Based on this study, drinking modest amounts of coffee and tea might reduce risk of stroke and dementia, two of the most debilitation conditions medical conditions.

The presence of the stimulant, caffeine, and other phytochemicals in coffee might affect the brain and the risk of brain-related diseases. Researchers in Australia used data from 17,702 participants (age 37-73 years) with brain neuro-imaging information in the UK Biobank. Coffee intake was measured with self-reports. Higher consumption of coffee predicted significantly lower total brain volume, grey matter, white matter, and hippocampal volume, even after accounting for a host of potential confounding factors.

In addition, after multivariable statistical adjustment, consumption of five or more cups of coffee daily predicted a significant increase in risk of developing dementia but not stroke during follow-up. The relationship between coffee consumption and risk of dementia was non-linear. This meant that, compared to drinking 1-2 cups of coffee per day,  drinking 6 or more cups of coffee per day predicted a 53 percent higher risk of developing dementia. Avoiding coffee completely predicted a marginally significant 9 percent increase in dementia risk.

Based on this and other studies, drinking a cup or two of coffee each day might reduce your risk of dementia and other chronic diseases but drinking lots of coffee each day might have the opposite effect.