The results of a dose-response meta-analysis published online on August 24, 2014 in the American Journal of Epidemiology indicate an association between increased coffee consumption and a lower risk of dying from cardiovascular disease or any cause over up to 23 years of follow-up.

"Coffee is one of the most commonly consumed beverages around the world," write Alessio Crippa and colleagues in their introduction. "Because of its popularity, even small health effects could have important public health consequences."

Researchers at Sweden's Karolinska Institutet selected 21 prospective studies that included a total of 997,464 participants for their analysis. Over the studies' follow-up periods, which ranged from 7.1 to 23 years, 121,915 deaths occurred.

In comparison with subjects who reported no coffee consumption, the greatest reduction in the risk of all-cause mortality over follow-up was found among those who consumed four cups coffee per day. For cardiovascular disease mortality, three cups per day conferred the greatest amount of protection. No effect for coffee on cancer mortality was observed.

The authors remark that coffee's phenolic compounds make the beverage a significant source of antioxidants that provide potential health benefits. They observe that studies have documented protective effects for coffee intake against the risk of Parkinson's disease, gallstones, suicide, and elevations in markers of inflammation related to cardiovascular disease and cancer.

"Findings from this meta-analysis indicate that coffee consumption is inversely associated with all-cause and cardiovascular disease mortality," they conclude. The results suggest that only moderate levels of coffee drinking may be needed to provide the greatest amount of protection against premature mortality.

Parkinson's disease is a degenerative disease of the central nervous system resulting from depletion of dopamine-producing cells in a region of the brain called the substantia nigra. A variety of genetic and environmental factors underlie this loss of brain cells. However, emergent research implicates oxidative stress, inflammation, and dysfunctional mitochondria as major contributors to neurodegeneration in Parkinson's disease.

Coffee contains a multitude of pharmacologically active compounds, some of which have been shown to suppress oxidative stress and protect against diabetes, cancer, cognitive decline, and so on (Butt 2011). Additionally, several epidemiological studies have found that those who consume large amounts of coffee are much less likely to develop Parkinson's disease (Hu 2007; Saaksjarvi 2008; Tan 2003).

Coffee constituents (compounds) protect brain cells which can be extremely beneficial for Parkinson's disease patients. Coffee extracts have been shown to inhibit MAO-A and -B enzymes, a mechanism similar to that of some pharmaceutical Parkinson's therapies (Herraiz 2006). Experimental models suggest that coffee constituents promote neuronal development and increase antioxidant defense systems in the brain (Abreu 2011; Tohda 1999).

Green coffee extract contains more of the active antioxidant compounds than brewed coffee, and may be a promising option for Parkinson's disease patients (Farah 2008). However, clinical trials have yet to confirm this potential benefit.