Recently there have been studies with conflicting results about the health benefits or harms from coffee consumption. Overall, it seems like moderate intake is OK and beneficial for adults, but too much may cause harm. And avoid caffeinated coffee if pregnant. Yesterday I posted about several recent studies finding health benefits from daily coffee consumption.
Coffee has anti-inflammatory effects, and contains more than a thousand chemical compounds. Over the years many studies found health benefits with regular and decaffeinated coffee, especially when a filter is used in the brewing process (e.g. drip coffee). But when the coffee is made by methods that don't filter the coffee (e.g. French press) the results may show harm, especially if large quantities are consumed daily.
The following are two recent studies finding that coffee consumption is associated with health benefits, and two studies finding potential harm from coffee consumption of over 6 cups a day. Note that whether the coffee is filtered or not may make a difference in results (the last 2 studies).
From (Jan. 11, 2021) Science Daily: Higher coffee intake may be linked to lower prostate cancer risk
Drinking several cups of coffee every day may be linked to a lower risk of developing prostate cancer, suggests a pooled data analysis of the available evidence, published in the online journal BMJ Open. Each additional daily cup of the brew was associated with a reduction in relative risk of nearly 1%, the findings indicate.
From (March 22, 2021) Science Daily: A strong coffee half an hour before exercising increases fat-burning
Scientists from the Department of Physiology of the University of Granada (UGR) have shown that caffeine (about 3 mg/kg, the equivalent of a strong coffee) ingested half an hour before aerobic exercise significantly increases the rate of fat-burning. They also found that if the exercise is performed in the afternoon, the effects of the caffeine are more marked than in the morning.
When drinking unfiltered coffee, researchers found a dose dependent effect with blood lipid levels (the more you drink, the more it raises blood lipid levels), due to cafestol in coffee beans. Cafestol is mainly present in unfiltered brews, such as French press, Turkish and Greek coffees, as well as espressos. Not with filtered coffee such as drip coffee (the filters filter out cafestol). From (Feb. 18, 2021) Science Daily: Long-term, heavy coffee consumption and CVD risk
In a world first genetic study, researchers found that that long-term, heavy coffee consumption - six or more cups a day - can increase the amount of lipids (fats) in your blood to significantly heighten your risk of cardiovascular disease (CVD). Importantly, this correlation is both positive and dose-dependent, meaning that the more coffee you drink, the greater the risk of CVD.
"Cafestol is mainly present in unfiltered brews, such as French press, Turkish and Greek coffees, but it's also in espressos, which is the base for most barista-made coffees, including lattes and cappuccinos. There is no, or very little cafestol in filtered and instant coffee, so with respect to effects on lipids, those are good coffee choices."
Researchers found that non-coffee drinkers and those drinking decaf coffee, and people drinking more than 6 cups of coffee a day - was associated with smaller total brain (gray matter, white matter, hippocampal) volumes and increase in dementia. Moderate daily coffee consumption was best for brain health. This is a U-shaped association. However, the type of coffee (filtered or not) was not looked at. Filters remove cafestol, which raises blood lipid levels. From (July 22, 2021) Science Daily: Excess coffee: A bitter brew for brain health
In the largest study of its kind, researchers have found that high coffee consumption is associated with smaller total brain volumes and an increased risk of dementia.
Conducted at UniSA's Australian Centre for Precision Health at SAHMRI and a team of international researchers, the study assessed the effects of coffee on the brain among 17,702 UK Biobank participants (aged 37-73), finding that those who drank more than six cups of coffee a day had a 53 per cent increased risk of dementia.