Coffee is a staple of many breakfast routines, thanks to the energy boost it provides. One 8oz cup typically contains 95mg of caffeine. The Dietary Guidelines for Americans defines a moderate amount of coffee as 3 to 5 cups per day (about 400mg caffeine). In addition to caffeine, coffee also contains vitamin B12, magnesium, and polyphenols.¹ 

Consuming low-to-moderate amounts of caffeine is associated with increased energy, alertness, and concentration, whereas higher amounts can cause negative symptoms, including increased heart rate, anxiety, restlessness, and insomnia.¹ The response to caffeine differs from person to person,¹ so it is important for coffee drinkers to understand how much coffee they can safely consume.  

Much research has been conducted to study the effects of coffee intake on human health. Below is a brief overview of the various effects of coffee intake on health.

The Impact of coffee on Health

Cancer. There is a plethora of research on the relationship between coffee consumption and cancer. Coffee consumption has been associated with a decreased risk of liver cancer, particularly hepatocellular carcinoma, the most common form of liver cancer.^2–4 Greater coffee intake (>2–3 cups/day) is associated with increased protection against liver cancer.^3,4 Both caffeinated and decaffeinated coffee are linked to reduced liver cancer risk,³ though the association with decaffeinated coffee is weaker.⁴ One study that focused on the United States (US) population found that caffeinated coffee consumption was associated with a nonsignificant reduced risk of hepatocellular carcinoma.⁵

Research has demonstrated a significant inverse association between coffee intake and risk of endometrial cancer in a dose-dependent manner, with greater coffee consumption associated with greater reductions in endometrial cancer risk.^5,6 This association might be stronger in individuals with a higher body mass index (BMI)^2,6 and postmenopausal individuals.⁶

Limited evidence indicates that coffee intake might be associated with a decreased risk of breast cancer, particularly among postmenopausal individuals, but some studies have shown no association between coffee and breast cancer.^2,4 The relationship between coffee consumption and colorectal cancer is mixed, with some studies suggesting that coffee might decrease colorectal cancer risk, and others indicating that coffee might increase the risk.^2–4 The impact of coffee intake on stomach cancer is also unclear, but high daily intake (≥5–6 cups) has been associated with increased risk.^3,4 Caffeinated coffee intake has been associated with a decreased risk of developing melanoma and nonmelanoma skin cancers in the US.⁵

Cardiovascular disease (CVD). Evidence indicates that coffee has a protective effect on cardiovascular health. Multiple studies have shown an association between moderate coffee consumption and decreased risk of CVD.^1,5,7 However, the impact of coffee consumption in individuals with hypertension is less clear. One study showed that caffeinated coffee consumption elevated blood pressure for about 1 to 3 hours, but longer-term consumption did not increase blood pressure, nor was the risk of CVD increased.⁸ According to another study, individuals with severe hypertension experienced an increased risk of CVD-related mortality with an intake of two or more cups of coffee per day, compared to non-coffee drinkers.⁹

Gastrointestinal health. Research has shown that coffee consumption can reduce the risk of chronic liver disease. Elevated coffee intake has also been linked to a decreased risk of liver fibrosis, even among patients with nonalcoholic fatty liver disease (NAFLD) and those coinfected with human immunodeficiency virus and hepatitis C virus. Coffee does not appear to increase the risk of peptic ulcers.³

Mortality. Moderate-to-high daily coffee intake is linked to decreased risk of all-cause mortality.^1,2 However, according to one study, daily consumption of four or more cups of coffee was associated increased risk of all-cause and CVD-related mortality among patients with CVD, whereas decaffeinated coffee intake was associated with a decreased risk of both.¹⁰  

Neurodegenerative diseases. Some research has shown a positive relationship between coffee intake and risk of neurodegenerative diseases, including Parkinson’s disease, stroke, and dementia.^1,2 However, further research is needed in this area.

Type 2 diabetes. Habitual coffee consumption is associated with a decreased risk of Type 2 diabetes.^1,2,5 Disease risk has been shown to decrease with increasing daily coffee consumption.^1,5 Both caffeinated and decaffeinated coffee can reduce this risk.^1,11,12

Bottom Line

There are many benefits to drinking a moderate amount of coffee, whether it’s caffeinated or decaffeinated. 

Sources

1. Harvard T.H. Chan School of Medicine. Coffee. Reviewed Jul 2020. https://www.hsph.harvard.edu/nutritionsource/food-features/coffee/. Accessed 29 Jan 2024.
2. Safe S, Kothari J, Hailemariam A, et al. Health benefits of coffee consumption for cancer and other diseases and mechanisms of action. Int J Mol Sci. 2023;24(3):2706. 
3. Nehlig A. Effects of coffee on the gastro-intestinal tract: a narrative review and literature update. Nutrients. 2022;14(2):399. 
4. Pauwels EKJ, Volterrani D. Coffee consumption and cancer risk: an assessment of the health implications based on recent knowledge. Med Princ Pract. 2021;30(5):401–411. 
5. Di Maso M, Boffetta P, Negri E, et al. Caffeinated coffee consumption and health outcomes in the US population: a dose-response meta-analysis and estimation of disease cases and deaths avoided. Adv Nutr. 2021;12(4):1160–1176.
6. Lafranconi A, Micek A, Galvano F, et al. Coffee decreases the risk of endometrial cancer: a dose-response meta-analysis of prospective cohort studies. Nutrients. 2017;9(11):1223. 
7. Ding M, Bhupathiraju SN, Satija A, et al. Long-term coffee consumption and risk of cardiovascular disease. Circulation. 2014;129(6):643–659.
8. Mesas AE, Leon-Muñoz LM, Rodriguez-Artalejo F, Lopez-Garcia E. The effect of coffee on blood pressure and cardiovascular disease in hypertensive individuals: a systematic review and meta-analysis. Am J Clin Nutr. 2011;94(4):1113–1126. 
9. Teramoto M, Yamagishi K, Muraki I, et al. Coffee and green tea consumption and cardiovascular disease mortality among people with and without hypertension. J Am Heart Assoc. 2023;12(2):e026477.
10. Zheng H, Lin F, Xin N, et al. Association of coffee, tea, and caffeine consumption with all-cause risk and specific mortality for cardiovascular disease patients. Front Nutr. 2022;9:842856. 
11. Ding M, Bhupathiraju SN, Chen M, et al. Caffeinated and decaffeinated coffee consumption and risk of type 2 diabetes: a systematic review and a dose-response meta-analysis. Diabetes Care. 2014;37(2):569–586. 
12. Kolb H, Martin S, Kempf K. Coffee and lower risk of Type 2 diabetes: arguments for a causal relationship. Nutrients. 2021;13(4):1144.