| Title | Habitual coffee and tea drinkers experienced increases in blood pressure after consuming low to moderate doses of caffeine; these increases were larger upright than in the supine posture |
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| Authors | McMullen, M.K., Whitehouse, J., Rhodes, G. and Towell, A. |
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| Abstract | Caffeine users have been encouraged to consume caffeine regularly to maintain their caffeine tolerance
and so avoid caffeine’s acute pressor effects. In controlled conditions complete caffeine tolerance to
intervention doses of 250 mg develops rapidly following several days of caffeine ingestion, nevertheless,
complete tolerance is not evident for lower intervention doses. Similarly complete caffeine tolerance to
250 mg intervention doses has been demonstrated in habitual coffee and tea drinkers’ but for lower
intervention doses complete tolerance is not evident. This study investigated a group of habitual
caffeine users following their self-determined consumption pattern involving two to six servings daily.
Cardiovascular responses following the ingestion of low to moderate amounts caffeine (67, 133 and
200 mg) were compared with placebo in a double-blind, randomised design without caffeine abstinence.
Pre-intervention and post-intervention (30 and 60 min) 90 s continuous cardiovascular recordings were
obtained with the Finometer in both the supine and upright postures. Participants were 12 healthy
habitual coffee and tea drinkers (10 female, mean age 36). Doses of 67 and 133 mg increased systolic
pressure in both postures while in the upright posture diastolic pressure and aortic impedance increased
while arterial compliance decreased. These vascular changes were larger upright than supine for 133 mg
caffeine. Additionally 67 mg caffeine increased dp/dt and indexed peripheral resistance in the upright
posture. For 200 mg caffeine there was complete caffeine tolerance. Cardiovascular responses to
caffeine appear to be associated with the size of the intervention dose. Habitual tea and coffee drinking
does not generate complete tolerance to caffeine as has been previously suggested. Both the type and the
extent of caffeine induced cardiovascular changes were influenced by posture. |
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| Keywords | Caffeine, decaffeinated, blood pressure, DPTI/SPTI, Finometer, barosensitivity |
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| Journal | Food & Function |
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| Journal citation | 2 (3-4), pp. 197-203 |
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| ISSN | 2042-6496 |
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| Year | 2011 |
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| Publisher | Royal Society of Chemistry |
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| Digital Object Identifier (DOI) | https://doi.org/10.1039/c0fo00166j |
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| Publication dates |
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| Published | 17 Mar 2011 |
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