Caffeine administration does not alter salivary α-amylase activity in young male daily caffeine consumers

Abstract

BackgroundTo follow up on a recent report from our lab [Hum Psychopharmacol 25:359–367, 2010.] we examined the effects of caffeine on salivary α-amylase (sAA) activity in response to an engaging, non-stressful task in healthy young males (age 18–30 yrs) who consumed caffeine on a daily basis. Using a placebo-controlled, double-blind, between-subjects design, 45 men received either placebo, 200 mg or 400 mg of caffeine (Vivarin®). Participants then rested for 20 minutes, and performed a 20-minute computerized air traffic controller-like task that was cognitively engaging but not stressful. Saliva samples (assayed for sAA and cortisol), blood pressure, and heart rate were taken before (baseline) and 15 minutes after the computerized task.ResultsSystolic and diastolic blood pressure and sAA activity increased across the laboratory session (F’s > 9.20, p’s < 0.05); salivary cortisol levels decreased (F = 16.17, p < 0.05). There were no main effects for caffeine administration on sAA, salivary cortisol, or cardiovascular measures, and caffeine did not interact with the task to alter these measures.ConclusionsLaboratory administered caffeine does not alter sAA activity, even when sAA activity is stimulated by participating in a cognitively engaging task. These data demonstrate that caffeine administration does not affect sAA activity, at least in healthy young men who regularly consume caffeine. Results support recent findings that basal caffeine levels in habitual caffeine users are not associated with basal sAA activity and that daily caffeine intake and diurnal sAA activity are not related.

Acute effects of coffee consumption on self-reported gastrointestinal symptoms, blood pressure and stress indices in healthy individuals

“…Furthermore, another study showed that caffeine intake, was the only statistically significant predictor of higher sAA levels among nurses at a paediatric intensive care unit [ 67 ]. Contrary to our findings, another study showed that caffeine intake in combination with an engaging non-stressful task did not affect sAA activity in healthy young male daily caffeine consumers [ 35 ]. However, due to the limited available literature, it is difficult to explain our sAA findings in regards to the sAA response to different coffee types.…”

“…In our study, we found that coffee consumption significantly increased BP, within the healthy physiological levels, in a gender specific manner in normotensive healthy individuals 3 h post-consumption, without differences between coffee types; which may be partially explained by SNS activation. Our results are in agreement with studies showing a temporary hypertensive coffee effect [ 35 , 64 , 68 – 70 ], even after small doses of consumed caffeine (80 mg/day) [ 31 ]. However, other studies have shown that the type of coffee may have a different impact on BP suggesting that boiled coffee may cause a higher increase in BP compared to filtered coffee, whereas instant coffee and decaf do not affect BP, after daily consumption of large coffee doses (>5 cups) for several days and/or weeks [ 71 , 72 ].…”

“…Another study showed increased cortisol after coffee consumption only during an examination period compared to periods without examination [ 64 ]. Lastly, another study showed that caffeine administration in combination with an engaging non-stressful task decreased salivary cortisol in healthy, young, male, daily caffeine consumers [ 35 ]. The differences noted between studies may also be explained by the fact that salivary cortisol responses to caffeine intake in non-stressful conditions or diverse acute challenge paradigms show large intra- and inter-individual variability [ 65 ].…”

“…Moreover, a few studies [ 34 ], but not all [ 35 ], have suggested that caffeinated coffee may activate the sympathetic nervous system (SNS), via secretion of salivary alpha-amylase (sAA) [ 36 – 40 ], an enzyme involved in polysaccharide digestion [ 41 ]. sAA is a convenient marker and is easily collected and measured in saliva [ 36 , 42 – 44 ]; it is recognized as both a soothing/relaxation index [ 45 ] and a stress response marker [ 36 ].…”

Longitudinal and immediate effect of Kundalini Yoga on salivary levels of cortisol and activity of alpha-amylase and its effect on perceived stress

“…In literature, there are described factors that might modify the concentrations of cortisol and activity of alpha-amylase in saliva, such as the age, sex, use of oral contraceptives, menstrual cycle,[ 30 38 ] cycles of dream, and consumption of caffeine[ 39 ] and nicotine. [ 40 ] These factors were not controlled or used as criteria of exclusion because our sample size was very limited.…”