The Lowdown On Coffee: Good Or Bad?

Coffee is one of the most popular drinks worldwide and has a long history of debate regarding its health benefits vs costs. In the past, it was listed as a potential carcinogen and later exonerated as research on the topic progressed.

So, what does the literature on coffee really say?

Cancer

A meta-analysis reviewing the impact of coffee ingestion on cancer risk found that increasing consumption of just one cup a day reduced risk by 3%. It was noted that coffee drinking reduced the risk of bladder, breast, prostate, endometrial, leukaemic, pancreatic and throat cancer.

A correlation between coffee consumption and liver cancer has also been observed. Coffee was found to reduce fibrosis, decrease oxidative DNA damage and increase virus-infected cell death resulting in decreased risk of cancer progression.

Type II Diabetes

Coffee beans are rich in polyphenols and minerals, including magnesium, which have been linked to improved insulin sensitivity and glucose metabolism, suggesting coffee may have a protective role in type II diabetes.

A meta-analysis conducted on over 45 000 people with type II diabetes found coffee consumption decreased risk by 8% with 1 cup per day and up to 33% with 6 cups per day. Another study observed a 30% decreased risk associated with caffeinated coffee and a 20% decreased risk with decaffeinated coffee intake.

Depression

The link between coffee and mental health is a tricky one. It reduces oxidative stress and inflammation thanks to the polyphenol content and increases mental alertness, attention and improves mood and anxiety. On the other hand, intake has been linked to an increase in anxiety, restlessness and insomnia in sensitive individuals.

However, researchers found drinking 4 cups or more a day reduced the likelihood of depression by almost 10% compared to non-coffee drinkers. Comparably, a meta-analysis found a 24% reduced risk with the greatest benefits observed in caffeine intakes between 68 and 509 mg a day.

While consumption of coffee can lead to dependance and withdrawal symptoms ranging from headaches, fatigue and difficulty concentrating, one could argue these withdrawal symptoms are actually a good thing by encouraging the drinker to sustain daily consumption.

It’s important to note, however, that adding dairy milk can inhibit the phytonutrients in coffee, thereby decreasing the antioxidant activity and reducing the benefits by up to 95%.

Does this mean you have to drink your coffee black? Fortunately, no. Soy milk was found to have no effect on its phytonutrient profile.

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References

Bravi, F., Bosetti, C., Tavani, A., Gallus, S., & La Vecchia, C. (2013). Coffee reduces risk for hepatocellular carcinoma: an updated meta-analysis. Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association, 11(11), 1413–1421.e1. https://doi.org/10.1016/j.cgh.2013.04.039 

Ding, M., Bhupathiraju, S. N., Chen, M., van Dam, R. M., & Hu, F. B. (2014). Caffeinated and decaffeinated coffee consumption and risk of type 2 diabetes: a systematic review and a dose-response meta-analysis. Diabetes care, 37(2), 569–586. https://doi.org/10.2337/dc13-1203 

Ding, M., Satija, A., Bhupathiraju, S. N., Hu, Y., Sun, Q., Han, J., Lopez-Garcia, E., Willett, W., van Dam, R. M., & Hu, F. B. (2015). Association of Coffee Consumption With Total and Cause-Specific Mortality in 3 Large Prospective Cohorts. Circulation, 132(24), 2305–2315. https://doi.org/10.1161/CIRCULATIONAHA.115.017341 

Duarte, G. S., & Farah, A. (2011). Effect of simultaneous consumption of milk and coffee on chlorogenic acids' bioavailability in humans. Journal of agricultural and food chemistry, 59(14), 7925–7931. https://doi.org/10.1021/jf201906p 

Guo, X., Park, Y., Freedman, N. D., Sinha, R., Hollenbeck, A. R., Blair, A., & Chen, H. (2014). Sweetened beverages, coffee, and tea and depression risk among older US adults. PloS one, 9(4), e94715. https://doi.org/10.1371/journal.pone.0094715 

Jiang, X., Zhang, D., & Jiang, W. (2014). Coffee and caffeine intake and incidence of type 2 diabetes mellitus: a meta-analysis of prospective studies. European journal of nutrition, 53(1), 25–38. https://doi.org/10.1007/s00394-013-0603-x 

Wang, L., Shen, X., Wu, Y., & Zhang, D. (2016). Coffee and caffeine consumption and depression: A meta-analysis of observational studies. The Australian and New Zealand journal of psychiatry, 50(3), 228–242. https://doi.org/10.1177/0004867415603131 

Yu, X., Bao, Z., Zou, J., Dong, J. (2011). Coffee consumption and risk of cancers: a meta-analysis of cohort studies. BMC Cancer, 11(96). https://doi.org/10.1186/1471-2407-11-96