The world’s most popular morning beverage has been alternately praised and condemned. In addition to its beckoning aroma, coffee has many potent chemical entities and is far from a benign drink.

Coffea arabica is believed to have been first grown in the ninth century in what is now Yemen.1 North and South Americans began growing coffee plants in the early 1700s.1 South America now produces more than 50% of the world’s coffee.

Science

Because of the stimulant effect caffeine has on the central nervous system, concerns regarding hypertension and cardiac issues have been intensely studied.

More than 1,000 men were followed for up to 33 years with periodic assessments of BP and daily coffee intake.2 This trial failed to show a strong link between coffee intake and the development of hypertension. A cohort of the Nurses’ Health Study followed more than 150,000 women who had no prior diagnosis of hypertension. After 12 years of monitoring, no linear association was found between coffee consumption and hypertension development.3

Another trial followed 44,000 men and 84,000 women for up to 20 years. Participants were monitored for the development of coronary heart disease as evidenced by either a fatal or nonfatal MI occurrence. Again, after all the data was examined, no evidence was found to link coffee consumption with an increased risk of heart disease.4

Coffee consumption has also been looked at in relation to the development of Alzheimer disease and Parkinson disease. The Cardiovascular Risk Factors, Aging and Dementia trial examined multiple factors. Among the more than 1,400 participants followed for up to 21 years, Alzheimer risk was 64% lower for those who had consistently consumed three to five cups of coffee per day since midlife compared with those drinking no or only little coffee.5 Although the effect of caffeine on cognitive function is assumed to be protective, it is not clearly understood. The proposed mechanism of action focuses on caffeine’s ability to interact with the dopaminergic and cholinergic systems in the brain, exerting a preservative effect on these functions where dementia diseases degrade them.5

In a 30-year longitudinal study of more than 8,000 men, the primary outcome measure was the incidence of the development of Parkinson disease relative to the estimated average daily coffee intake. Findings were highly suggestive of a protective mechanism of coffee intake against the development of Parkinson disease. The standard age-adjusted incidence of Parkinson was 10.4/10,000 person-years for the men with no coffee intake, but only 1.9/10,000 person-years for men who drank at least 28 ounces of coffee per day.6 It was proposed that caffeine may prevent the inhibition of dopaminergic transmission by adenosine, which then reduces the clinical symptoms of Parkinsonism.6

Other studies of coffee and caffeine’s impact on neurodegenerative diseases show what appears to be an actual reduction in beta-amyloid production.7 Amyloids — chemical byproducts of multiple metabolic mechanisms — develop into thickened layers that block and inhibit normal function of cells and nerves, much like atherogenic plaque.

Finally, coffee consumption has been shown to reduce the incidence of certain cancers. A recent meta-analysis found an estimated 24% lower risk of colon cancer per cup consumed.8 This protective effect, however, did not correlate with breast-cancer risk.

Safety, interactions

Pregnant women who consumed <200 mg of caffeine per day had a 1.4 times higher rate of miscarriage than did non-coffee drinkers. When intake was >200 mg/day, the risk increased to 2.2 times greater.9

Coffee itself has few interactions but will accentuate the effects of any stimulant drug. Migraine medications as well as amphetamine-type drugs for behavior disorders show an additive effect when taken with coffee.

Dose, how supplied, and cost

Regular coffee contains 1% to 2% caffeine as an active ingredient. A 6-oz. cup of coffee has anywhere from 60 mg to 120 mg of caffeine, depending on the brewing method. Coffee is found in multiple forms, from instant powders and crystals to whole roasted beans that may be ground to each consumer’s preference. The cost is very reasonable; however, it has increased by 44% since mid-2010, primarily due to a poor harvest, increased demand, and other international economic issues.

Summary

Contrary to popular belief, coffee will not stunt your growth or contribute to your early demise. Although there are obvious situations in which coffee should be avoided, (e.g., pregnancy), moderate consumption is perfectly safe. 

References

1. Purdue University Center for New Crops & Plant Products. Coffea Arabica L.

2. Klag MJ, Wang NY, Meoni LA, et al. Coffee intake and risk of hypertension: the Johns Hopkins precursors study. Arch Intern Med. 2002;162:657-662.

3. Winkelmayer WC, Stampfer MJ, Willett WC, Curhan GC. Habitual caffeine intake and the risk of hypertension in women. JAMA. 2005;294:2330-2335.

4. Lopez-Garcia E, van Dam RM, Willett WC, et al. Coffee consumption and coronary heart disease in men and women: a prospective cohort study. Circulation. 2006;113:2045-2053.

5. Eskelinen MH, Ngandu T, Tuomilehto J, et al. Midlife coffee and tea drinking and the risk of late-life dementia: a population-based CAIDE study. J Alzheimers Dis. 2009;16:85-91.

6. Ross GW, Abbott RD, Petrovitch H, et al. Association of coffee and caffeine intake with the risk of Parkinson disease. JAMA. 2000 May 24-31;283(20):2674-9. 

7. de Mendonça A, Cunha RA. Therapeutic opportunities for caffeine in Alzheimer’s disease and other neurodegenerative disorders. J Alzheimers Dis. 2010; 20 Suppl 1:S1-S2.

8. Arab L. Epidemiologic evidence on coffee and cancer. Nutr Cancer. 2010;62:271-283.

9. Weng X, Odouli R, Li DK. Maternal caffeine consumption during pregnancy and the risk of miscarriage: a prospective cohort study. Am J Obstet Gynecol. 2008;198:279.

All electronic documents accessed August 15, 2011