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Arguably one of the most popular beverages in the world, perhaps second only to water, coffee is extensively consumed around the globe. The relevance of its potential impact on health derives precisely from its worldwide consumption, which can reach an astonishing 7 million tons per year.
For years, coffee has had a poor reputation, but as more information on its phytochemical properties emerges, it appears that, in fact, this natural compound isn’t as negative as people had originally thought it was. This is strengthened by the knowledge of the substances that make up coffee – a long list indeed, that includes not only caffeine (the most widely known), but also phenols, lactones, niacin, vitamin B3, magnesium and potassium.
The diversity of coffee constituents leads to a high number of biological targets where this beverage can exert potentially serious effects. Naturally, this has raised great interest among the medical community.
Coffee and diabetes
One of the most significant potential health benefits of coffee is related to the decreased risk of type 2 diabetes mellitus.
In a smaller cohort of Swedish women who were investigated during a period of 18 years, those who drank at least 3 cups of coffee daily had a risk of type 2 diabetes mellitus that was 50% lower than the risk for those who consumed less than 2 cups daily.
Robust, randomized clinical trials have also been conducted to look into this potential effect. However, since most of them take place during a relatively short period of time, no improvements in glucose tolerance or insulin sensitivity were observed. Seeing that the opposite was found in much longer epidemiological studies (such as the ones described above), it is thought that it is long-term, routine coffee consumption that may contribute to the normalization of glucose tolerance.
Coffee and Parkinson’s disease
Parkinson’s Disease is neurological disorder that develops, essentially, subsequently to motor neuron degeneration. Epidemiological studies have consistently demonstrated an inverse association between coffee consumption and Parkinson’s disease. Studies in animal models suggest that caffeine consumption decreases the risk of Parkinson’s disease by protecting against dopaminergic neurotoxicity. More specifically, caffeine appears to stimulate the antioxidant defense mechanism of the immune system by inducing the expression of mRNA and enzymes mitigating the negative effects of free radical on neurodegeneration.
Coffee and cancer
Evidence also exists supporting a chemopreventing role of coffee consumption.
Researchers observed the declines in colorectal cancer among individuals consuming two or more cups of decaffeinated coffee daily. Later, other studies further suggested that such a risk reduction was due to the diterpene content of coffee.
Other type of cancer – hepatocellular carcinoma – has gotten plenty of attention as well, due to its risk being potentially influenced by coffee consumption. Several case-control studies in Europe and at least two prospective cohort studies in Japan have observed signiﬁcant inverse associations between coffee consumption and the risk of hepatocellular carcinoma. Nevertheless, the mechanism behind this risk decline is not yet clear. Although caffeine and chlorogenic acid have been found to inhibit chemically induced hepatic carcinogenesis in animal models, more research is needed to determine the nature of the relationship between coffee and caffeine intake and hepatocellular carcinoma in humans.