Coffee

Synonym(s) and related species Arabian coffee is from Coffea arabica. Robusta coffee is from Coffea canephora (Pierre ex Froehner) also known as Coffea robusta (Linden ex De Wild.) Other species include Coffea liberica.

Constituents

The kernel of the dried coffee bean contains xanthine derivatives, the main one being caffeine (1 to 2%), with some theobromine and theophylline. It also contains polyphenolic acids such as chlorogenic acids and various diterpenes (e.g. kahweol, cafestrol).

Use and indications

Coffee has been used as a stimulant and diuretic. However, when roasted, coffee beans are most commonly used as a beverage.

Coffee + Antihypertensives

Coffee may have a small adverse effect on blood pressure control.

Mechanism

• Acute intake of caffeine raises blood pressure, but partial tolerance to this effect might possibly develop with regular consumption

• Polyphenolic compounds in coffee might improve endothelial function, and might therefore lower blood pressure.

Coffee + Antidiabetics

Evidence is conflicting, but in general the long-term use of coffee does not appear to be detrimental to the control of diabetes.

Evidence, mechanism, importance and management

• There is a lot of epidemiological evidence that coffee consumption is associated with a reduced risk of type 2 diabetes (this has been the subject of a review).

• In addition, a large prospective cohort study in Finland found that coffee drinking was associated with reduced total and cardiovascular disease mortality.

• In contrast, some short-term randomised studies have found that coffee consumption had detrimental effects on insulin sensitivity in healthy subjects (high consumption of filtered coffee over 4 weeks) and increased postprandial hyperglycaemia in patients with type 2 diabetes taking unnamed oral antidiabetic drugs (caffeine added to decaffeinated coffee, single dose).

• However the Finnish study does provides some reassurance that use of coffee may not be detrimental in the long term, and may even be beneficial.

Coffee + Aspirin

• Coffee does not appear to affect aspirin absorption.

Evidence, mechanism, importance and management

A study in 5 healthy subjects found that 200mL of coffee had no effect on the rate and extent of absorption of a single 500-mg dose of aspirin, whereas 200mL of milk reduced the bioavailability and maximum concentration of salicylates from the same dose of aspirin by a modest 30%.

No significant reduction in the bioavailability of aspirin would be expected with black coffee; however the addition of milk, depending on the quantity, may possibly reduce the absorption of aspirin.

Coffee + Nicotine

Coffee drinking may reduce the absorption of nicotine from chewing gum.

Drinking coffee beverages during or immediately before nicotine gum use might therefore decrease the efficacy of this form of nicotine replacement therapy.

References

1. Smits P, Hoffmann H, Thien T, Houben H, van’t Laar A. Hemodynamic and humoral effects of coffee after β1-selective and nonselective β-blockade. Clin Pharmacol Ther (1983) 34, 153–8.

2. Noordzij M, Uiterwaal CS, Arends LR, Kok FJ, Grobbee DE, Geleijnse JM. Blood pressure response to chronic intake of coffee and caffeine: a meta-analysis of randomized controlled trials. J Hypertens (2005) 23, 921–8.

3. Rakic V, Beilin LJ, Burke V. Effect of coffee and tea drinking on postprandial hypotension in older men and women. Clin Exp Pharmacol Physiol (1996) 23, 559–63.

4. Hu G, Jousilahti P, Nissinen A, Bidel S, Antikainen R, Tuomilehto J. Coffee consumption and the incidence of antihypertensive drug treatment in Finnish men and women. Am J Clin Nutr (2007) 86, 457–64.

5. Winkelmayer WC, Stampfer MJ, Willett WC, Curhan GC. Habitual caffeine intake and the risk of hypertension in women. JAMA (2005) 294, 233–5.

6. Watanabe T, Arai Y, Mitsui Y, Kusaura T, Okawa W, Kajihara Y, Saito I. The blood pressure-lowering effect and safety of chlorogenic acid from green coffee bean extract in essential hypertension. Clin Exp Hypertens (2006) 28, 439–49.

7. Kozuma K, Tsuchiya S, Kohori J, Hase T, Tokimitsu I. Antihypertensive effect of green coffee bean extract on mildly hypertensive subjects. Hypertens Res (2005) 28, 711–18.

8. Van Dam RM. Coffee and type 2 diabetes: from beans to beta-cells. Nutr Metab Cardiovasc Dis (2006) 16, 69–77.

9. Bidel S, Hu G, Qiao Q, Jousilahti P, Antikainen R, Tuomilehto J. Coffee consumption and risk of total and cardiovascular mortality among patients with type 2 diabetes. Diabetologia (2006) 49, 2618–26.

10. Van Dam RM, Pasman WJ, Verhoef P. Effects of coffee consumption on fasting blood glucose and insulin concentrations: randomized controlled trials in healthy volunteers. Diabetes Care (2004) 27, 2990–2.

11. Lane JD, Hwang AL, Feinglos MN, Surwit RS. Exaggeration of postprandial hyperglycemia in patients with type 2 diabetes by administration of caffeine in coffee. Endocr Pract (2007) 13, 239–43.

12. Odou P, Barthelemy C, Robert H. Influence of seven beverages on salicylate disposition in humans. J Clin Pharm Ther (2001) 26, 187–93.

13. Henningfield JE, Radzius A, Cooper TM, Clayton RR. Drinking coffee and carbonated beverages blocks absorption of nicotine from nicotine polacrilex gum. JAMA (1990) 264, 1560–4.