Caffeine and hypertension

Posted on 6 March 2008

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(Above: The RNA expresion pattern of ADORA1 (more info here), representing only a fraction of the targets of the components of coffee. Image source: AndrewGNF/Novartis, via wikipedia.org.)

Coffee is not a perfect drug delivery system; it exerts effects upon multiple tissues and there are many side-effects, any one of which may be experienced to a greater or lesser degree depending upon your current state of health. Still, it appears to be a good thing for lots of people. Consider reading the following articles if you have access, or at least glance through the free abstracts:

Blood pressure response to chronic intake of coffee and caffeine: a meta-analysis of randomized controlled trials.

  • Regular caffeine intake increases blood pressure, but when delivered in coffee the effect observed is small. For equal caffeine doses, coffee produced 2-3 times lower increases in blood pressure than when the delivery system was a caffeine tablet.

The effect of chronic coffee drinking on blood pressure: a meta-analysis of controlled clinical trials.

  • Still, “…coffee administration was associated with an average net change in blood pressure that ranged from �2.1 to 6.1 mm Hg for systolic and 0.9 to 3.1 mm Hg for diastolic blood pressure…”, and “The pooled effect of drinking 1 cup of coffee, estimated in linear regression analysis, was 0.8 mm Hg for systolic pressure and 0.5 mm Hg for diastolic pressure.” Those figures are NOT large; they represent an increase of like less than 1 percent. The half-life of caffeine, depending upon an individual’s genetic complement, is from 3-10 hours. That’s not a huge dose of extra vascular pressure.

Genetic polymorphism of the adenosine A2A receptor is associated with habitual caffeine consumption.

  • ADORA2A is a major target of caffeine; it is associated with lower caffeine consumption. It is know that certain genotypes conferpredispostion to caffeine-related anxiety. This study argues that it is an alternate allele coding for ADORA2A, a receptor protein, rather than one of CYP12A, a metabolic protein, that confers the likelihood of rejecting caffeine habituation.

Effect of chronic coffee consumption on aortic stiffness and wave reflections in hypertensive patients.

  • Coffee impairs the function of the heart, although its effect is less detrimental in individuals who are already hypertensive.

Does coffee consumption reduce the risk of type 2 diabetes in individuals with impaired glucose?

  • Yep; “this study confirms a striking protective effect of caffeinated coffee against incident diabetes…”.

Coffee and health: a review of recent human research.

  • The amount of caffeine in coffee is quite variable (72-150mg per 8oz cup black coffee, 58-76 in a single shot of espresso). French press coffee, while not boiled, contains a significant amount of the diterpene components associated with a rise in total and LDL cholesterol. Cigarette smoking induces CYP1A2 activity, which accelerates caffeine metabolism and results in lowered dose-responses for these individuals. Coffee studies are extensively complicated by confounding factors and genetic factors affecting metabolism and thus metabolite exposure dosage. Significant coffee intake appears to be associated with protection from Type 2 Diabetes Mellitus. Coffee has been associated with protection from Parkinson disease, but the results are very weak; it’s probably not a strong enough result to recommend coffee consumption strictly for this purpose.

Coffee, caffeine, and coronary heart disease.

  • Curr Opin Lipidol. 2007 Feb;18(1):13-9.
  • Coffee, especially when prepared without a paper filter, contains a significant amount of diterpene compounds associated with a detrimnetal serum lipid profile. Paradoxically, coffee is associated with a lower risk of coronary heart disease, possibly because of the antioxidants also present in the coffee.

Coffee consumption and human health–beneficial or detrimental?–Mechanisms for effects of coffee consumption on different risk factors for cardiovascular disease and type 2 diabetes mellitus.

  • “Coffee is also a rich source of many other ingredients that may contribute to its biological activity, like heterocyclic compounds that exhibit strong antioxidant activity. Based on the literature reviewed, it is apparent that moderate daily filtered, coffee intake is not associated with any adverse effects on cardiovascular outcome. On the contrary, the data shows that coffee has a significant antioxidant activity, and may have an inverse association with the risk of type 2 diabetes mellitus.”
…and slightly off-topic, but interesting:

Effect of coffee and tea drinking on postprandial hypotension in older men and women.

  • Tea or coffee with lunch prevents falls related to the “post-prandial” drop in blood pressur, but coffee presents the risk of increased diastolic bp in untreated hypertensives; not exactly a suprise, but useful knowledge for geriatric nursing.

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    Posted in: Coffee, Health Care