Hypertension: Soy, Caffeine, Stress, ALLHAT, and AASK
Hypertension: Soy, Caffeine, Stress, ALLHAT, and AASK
This month's news on hypertension includes reports from the American Heart Association's (AHA) Scientific Sessions 2002 held November 17-20 in Chicago, Illinois, including:
Other news comes from the publication of the first results of the African-American Study of Kidney Disease and Hypertension (AASK) trial and the surprising results of an investigation into the (non) effects of caffeine in coffee on blood pressure.
Blood pressure control rates could be improved -- from the present abysmal 30% of all hypertensive patients to at least 66% of the hypertensive population controlled to guideline blood pressure levels -- by using adequate dosages of as few as 2 of the currently available antihypertensive medications, according to data from ALLHAT. These early results were recently reported at the American Heart Association's Scientific Sessions 2002 and simultaneously published in the Journal of Clinical Hypertension.
The data from ALLHAT were used to identify blood pressure control rates in a variety of practice settings and geographic regions, along with the factors that could predict improved blood pressure control. ALLHAT was a randomized, double-blind, controlled clinical trial that began in February 1994 and enrolled high-risk hypertensive patients at 623 centers in the United States, Canada, and the Caribbean. Follow-up was completed in March 2002, after an average period of 4.9 years. The primary objective of ALLHAT was to compare coronary heart disease (CHD) event rates in patients receiving 1 of 4 different antihypertensive regimens. The study's final results are due to be announced December 17 at the National Institutes of Health (Bethesda, Maryland), and will be featured shortly thereafter on Medscape. In advance of the results of the primary interdrug efficacy results, the ALLHAT analysis presented and published in association with the AHA meeting thus concerned only the success and predictors of blood pressure control in the trial's geographically and ethnically diverse population.
The original trial population comprised 42,418 patients aged ≥ 55 years with systolic blood pressure (SBP) ≥ 140 mm Hg and/or diastolic blood pressure (DBP) ≥ 90 mm Hg or who were taking antihypertensive medication and who had ≥ 1 other risk factor for CHD. Patients were randomized to 1 of 4 antihypertensive agents:
It should be noted that the doxazosin arm of the study was stopped several years ago because of an excess of cardiovascular events compared with chlorthalidone; therefore, long-term blood pressure control data for an alpha-blocker were not included in the blood pressure control analysis.
With the closing of the doxazosin arm, a total of 33,357 patients were randomized to 1 of the 3 other blinded study drugs: chlorthalidone 12.5-25.0 mg/day (n = 15,255), amlodipine 2.5-10.0 mg/day (n = 9048), or lisinopril 10-40 mg/day (n = 9054). Doses were increased and additional drugs from other classes (but not the study drugs) were added as needed to achieve blood pressure control. The mean age of this population was 67 years; 47% were women, 35% were black, 36% had diabetes, 90% had received prior antihypertensive drug treatment, 22% were smokers, and 3% had left ventricular hypertrophy (LVH) on echocardiogram (ECG). The mean body mass index (BMI) was 30.
Over the course of 5 years of follow-up, mean blood pressure decreased from 145/83 mm Hg at baseline to 135/75 mm Hg. Blood pressure was controlled in 27.4% of patients, and after 5 years, the percentage of patients who had achieved target blood pressure levels had increased to 65.6%. The mean number of drugs increased from 1.3 at 6 months to 2.0 at 5 years.
Factors that independently predicted a lower likelihood of blood pressure control at 36 months were higher baseline SBP, older age, female gender, African-American ethnicity, living in the southern United States, type 2 diabetes, obesity, prior antihypertensive therapy, serum creatinine ≥ 1.5 mg/dL, LVH on ECG, and clinical research experience. The greatest difference in blood pressure control was seen in African-Americans, who were 31% less likely to be controlled than non-African-Americans. Patients who were enrolled at clinics with no research experience tended to have better blood pressure levels than those enrolled at clinics with such experience. Blood pressure control also tended to be better in patients enrolled at nonprivate practice clinics than in those enrolled in private clinics.
Analysis of the different geographic regions showed that patients in Canada, Puerto Rico, and the Virgin Islands tended to have the best blood pressure control, whereas patients living in the southern United States had the worst control. Patients in the eastern or southern United States, Puerto Rico, and the Virgin Islands were less likely to be on ≥ 2 drugs.
William C. Cushman, MD (VA Medical Center, Memphis, Tennessee), who presented these results at the AHA meeting in Chicago, noted that most of the patients who were not controlled had persistent elevation of SBP. Many of these patients were not on maximal doses of their medications or were not receiving the maximum numbers of drugs permitted in the trial, and they probably could have achieved levels < 140/90 mm Hg with more aggressive treatment. Dr. Cushman noted that ALLHAT had limitations on how drugs could be combined, and he believes that without these limitations, blood pressure control could have been even further improved.
Many cardiovascular benefits have been attributed to the consumption of soy by men and women, including lowering of blood lipids, oxidized low-density lipoprotein (LDL)-cholesterol, homocysteine, and blood pressure. In Asian women, low incidences of breast cancer and menopausal symptoms have been widely attributed to high soy bean intake. At the AHA meeting, researchers from Beth Israel Deaconess Medical Center, Boston, Massachusetts, reported blood pressure-lowering effects in menopausal women due to short-term consumption of soy nuts that were comparable to those seen with antihypertensive medications. They carried out a randomized, crossover, controlled trial in 60 menopausal women who consumed 58 g (one half cup) of dry-roasted soy nuts (25 g soy protein and 101 g aglycone isoflavones) daily for 8 weeks. The soy diet was accompanied by a therapeutic lifestyle change (TLC) diet. The women also spent 8 weeks on the TLC diet alone.
A 9.9% decrease in SBP (P = .003) and a 6.8% decrease in DBP (P = .001) occurred with the soy diet in the 12 hypertensive women enrolled in the study. The 48 normotensive women in the study also showed significant decreases in blood pressure (SBP 5.2%, P < .001; DBP 2.9%, P = .03). The researchers suggested that soy may be of interest to women seeking an alternative to hormone replacement therapy, but pointed out that these results need to be confirmed in longer-term trials.
Young adults who display a major type A behavior trait known as time urgency/impatience (TUI) may later develop hypertension at a relatively early age, according to the results of a study reported at the AHA. This was the first study to investigate a link between hypertension and this type of behavior. Researchers at Northwestern University (Chicago, Illinois), the University of Pittsburgh (Pennsylvania), and the University of Alabama at Birmingham examined a sample of 3138 people aged 18-30 years who participated in the Coronary Artery Risk Development In Young Adults (CARDIA) study. The sample included 586 black men, 825 black women, 822 white men, and 905 white women. On enrollment in 1985, participants in CARDIA were asked how traits such as "eating too quickly," "getting upset when having to wait for anything," "usually feeling pressed for time," and "often feeling time pressures at the end of a work day" described them. Responses ranged from "very well" to "not at all." Positive responses to all questions put participants at the highest level of TUI (6% of the sample population). TUI was rated at years 0 and 2. Only participants who were not hypertensive at year 0 or 2 were followed for 13 years.
After 13 years, the incidence of hypertension was 17% in the participants who had registered the highest TUI score compared with 10% for those with the lowest score. After adjusting for age, race, gender, BMI, physical activity, alcohol consumption, and SBP, the researchers found that people with the highest TUI scores were more than twice as likely to have developed hypertension as those with the lowest scores. Lead researcher LiJing L. Yan, PhD (Department of Preventive Medicine, Northwestern University) noted that people with higher TUI scores were more likely to be white, female, and better educated, but were less likely to have a healthy lifestyle (eg, they smoked more, drank more alcohol, and had less physical activity) compared with those who had lower TUI scores. The probability of developing hypertension after 13 years was almost twice as high for black men (22%) and black women (21%) as for white men (12%). White women, however, had the lowest overall probability.
The researchers pointed out that TUI is related to a poor health-risk profile that includes smoking, drinking alcohol, high hostility levels, and a lack of social support, most of which are associated with hypertension. They stressed the importance of modifying these factors so as to reduce TUI tendency and possibly decrease future health risks related to TUI.
Lowering blood pressure beyond the usual blood pressure goals does not appear to slow progression of hypertensive renal disease, according to the recently published results of the AASK trial. Hypertension is the second leading cause of end-stage renal disease (ESRD) in the United States, and there is no known treatment to prevent the progressive decline leading to ESRD. African-Americans are 6 times more likely to develop ESRD than whites.
In AASK, Jackson T. Wright, Jr, MD, PhD (Case Western Reserve University, Cleveland, Ohio) and colleagues compared the effects of 2 levels of blood pressure control and 3 antihypertensive drug classes in 1094 African-Americans aged 18-70 years with hypertensive renal disease. Patients were recruited from 21 clinical centers around the United States from February 1995 through September 1998 and followed for 3.0 to 6.4 years. A total of 554 patients were assigned to a usual mean arterial pressure goal of 102-107 mm Hg and 540 patients were assigned to a lower mean arterial pressure goal of =/< 92 mm Hg. All participants were also assigned to receive either a beta-blocker, metoprolol (n = 441), an ACE inhibitor, ramipril (n = 436), or a dihydropyridine calcium channel blocker, amlodipine (n = 217).
No significant difference was found between the "usual" and "lower" blood pressure groups with regard to change of ≥ 50% from baseline in glomerular filtration rate (GFR), development of ESRD, or death. There were also no differences between the 3 antihypertensive drug groups with regard to rate of change in GFR from baseline.
However, the ACE inhibitor ramipril was associated with a 22% risk reduction in experiencing 1 of the clinical outcome measures compared with metoprolol (P = .04) and a 38% risk reduction for ramipril vs amlodipine (P = .004). No significant differences were seen in outcomes between amlodipine and metoprolol.
The AASK investigators concluded that although blood pressure reduction to levels below those specified in current guidelines for cardiovascular risk reduction are achievable, these results do not support additional reduction as a strategy to prevent progression of hypertensive nephrosclerosis. The investigators also concluded that their findings do support the use of ACE inhibitors as first-line therapy over beta-blockers and calcium channel blockers in African-American patients with hypertensive renal disease. This is the first time that this effect of ACE inhibitors has been demonstrated in such a large population of African-Americans.
Commenting on the AASK results in the same issue of JAMA, Michael H. Alderman, MD (Albert Einstein College of Medicine, Bronx, New York) noted that the primary and secondary endpoints of the study "largely depended on GFR, a surrogate endpoint for which the relation to health outcomes is, at best, uncertain." He pointed out that cardiovascular mortality and hospitalizations were 18% more likely to occur in those assigned to the higher blood pressure goal than in those assigned to the lower goal and that, over the long term, most morbidity and mortality in patients with renal disease is due to stroke and hypertension. Most cautious physicians may continue to attain target blood pressure levels of ≤ 140/90 mm Hg because the evidence indicates that those levels prevent morbidity and mortality, Dr. Alderman suggested.
With regard to how widely the findings of AASK can be applied, Dr. Alderman pointed out that the criteria for classification of hypertensive nephrosclerosis in AASK were more rigorous in the trial than those usually applied. He suggested that most black patients currently identified as having hypertensive nephrosclerosis would be excluded by the AASK criteria; many of the study patients may have actually had treatable underlying renal disease that was overlooked. Dr. Alderman concluded that the AASK patients probably did not differ from white patients with regard to hypertensive nephrosclerosis, and these findings may apply to all otherwise phenotypically similar patients.
Increases in blood pressure seen in habitual coffee drinkers are not due to the caffeine in the coffee, a recently published study from Switzerland has concluded. The Swiss researchers measured blood pressure, heart rate, and muscle sympathetic nervous system activity (MSA) in a group of 15 healthy volunteers, 6 of whom were habitual and 9 of whom were nonhabitual coffee drinkers. Responses were recorded after they drank a triple espresso or a decaffeinated triple espresso and after intravenous administration of caffeine (250 mg) or saline. None of the subjects knew whether they were receiving caffeine.
Habitual and nonhabitual coffee drinkers showed similar changes in MSA and blood pressure after intravenous caffeine. Coffee drinking, however, increased SBP in the nonhabitual coffee drinkers by 12 mm Hg after 60 min, whereas no increase was seen in the habitual coffee drinkers, despite similar changes in MSA and plasma caffeine levels. When the nonhabitual coffee drinkers drank decaffeinated espressos, SBP levels increased despite no increase in plasma caffeine levels. Heart rate and DBP levels remained unchanged. Lead researcher Roberto Corti, MD (University Hospital Zurich, Switzerland) believes that this is the first time that such disparities in reactions to coffee have been reported, and he believes they support the hypothesis that ingredients other than caffeine are responsible for the stimulating effects of coffee on the cardiovascular system. The researchers concluded that the potential adverse effects attributed to coffee may be less hazardous in regular consumers with normal blood pressure and that in people without a hereditary predisposition to hypertension, coffee drinking cannot be considered a risk factor for hypertension.
The AHA commented that studies investigating a direct link between caffeine, coffee drinking, and coronary heart disease have produced conflicting results, but that coffee drinking in moderation (1-2 cups per day) does not appear to be harmful.
This month's news on hypertension includes reports from the American Heart Association's (AHA) Scientific Sessions 2002 held November 17-20 in Chicago, Illinois, including:
Early news from the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) about hypertension control in North America and the Caribbean;
Further support for soy-protein foods as a means of blood pressure control; and
The development of hypertension in later life in young adults with type A personalities.
Other news comes from the publication of the first results of the African-American Study of Kidney Disease and Hypertension (AASK) trial and the surprising results of an investigation into the (non) effects of caffeine in coffee on blood pressure.
Blood pressure control rates could be improved -- from the present abysmal 30% of all hypertensive patients to at least 66% of the hypertensive population controlled to guideline blood pressure levels -- by using adequate dosages of as few as 2 of the currently available antihypertensive medications, according to data from ALLHAT. These early results were recently reported at the American Heart Association's Scientific Sessions 2002 and simultaneously published in the Journal of Clinical Hypertension.
| Full text of the first publication of the epidemiologic implications of the ALLHAT study published in the Nov/Dec issue of the Journal of Clinical Hypertension is available on Medscape Cardiology. (see left hand column above) |
The data from ALLHAT were used to identify blood pressure control rates in a variety of practice settings and geographic regions, along with the factors that could predict improved blood pressure control. ALLHAT was a randomized, double-blind, controlled clinical trial that began in February 1994 and enrolled high-risk hypertensive patients at 623 centers in the United States, Canada, and the Caribbean. Follow-up was completed in March 2002, after an average period of 4.9 years. The primary objective of ALLHAT was to compare coronary heart disease (CHD) event rates in patients receiving 1 of 4 different antihypertensive regimens. The study's final results are due to be announced December 17 at the National Institutes of Health (Bethesda, Maryland), and will be featured shortly thereafter on Medscape. In advance of the results of the primary interdrug efficacy results, the ALLHAT analysis presented and published in association with the AHA meeting thus concerned only the success and predictors of blood pressure control in the trial's geographically and ethnically diverse population.
The original trial population comprised 42,418 patients aged ≥ 55 years with systolic blood pressure (SBP) ≥ 140 mm Hg and/or diastolic blood pressure (DBP) ≥ 90 mm Hg or who were taking antihypertensive medication and who had ≥ 1 other risk factor for CHD. Patients were randomized to 1 of 4 antihypertensive agents:
chlorthalidone (diuretic)
lisinopril (angiotensin-converting enzyme [ACE] inhibitor)
amlodipine (calcium channel blocker)
doxazosin (alpha-blocker)
It should be noted that the doxazosin arm of the study was stopped several years ago because of an excess of cardiovascular events compared with chlorthalidone; therefore, long-term blood pressure control data for an alpha-blocker were not included in the blood pressure control analysis.
| For a more complete discussion of the doxazosin arm in the ALLHAT trial, see: "Alpha-adrenergic Blockade and Its Role in Hypertension" on Medscape Cardiology. (see left hand column above) |
With the closing of the doxazosin arm, a total of 33,357 patients were randomized to 1 of the 3 other blinded study drugs: chlorthalidone 12.5-25.0 mg/day (n = 15,255), amlodipine 2.5-10.0 mg/day (n = 9048), or lisinopril 10-40 mg/day (n = 9054). Doses were increased and additional drugs from other classes (but not the study drugs) were added as needed to achieve blood pressure control. The mean age of this population was 67 years; 47% were women, 35% were black, 36% had diabetes, 90% had received prior antihypertensive drug treatment, 22% were smokers, and 3% had left ventricular hypertrophy (LVH) on echocardiogram (ECG). The mean body mass index (BMI) was 30.
Over the course of 5 years of follow-up, mean blood pressure decreased from 145/83 mm Hg at baseline to 135/75 mm Hg. Blood pressure was controlled in 27.4% of patients, and after 5 years, the percentage of patients who had achieved target blood pressure levels had increased to 65.6%. The mean number of drugs increased from 1.3 at 6 months to 2.0 at 5 years.
Factors that independently predicted a lower likelihood of blood pressure control at 36 months were higher baseline SBP, older age, female gender, African-American ethnicity, living in the southern United States, type 2 diabetes, obesity, prior antihypertensive therapy, serum creatinine ≥ 1.5 mg/dL, LVH on ECG, and clinical research experience. The greatest difference in blood pressure control was seen in African-Americans, who were 31% less likely to be controlled than non-African-Americans. Patients who were enrolled at clinics with no research experience tended to have better blood pressure levels than those enrolled at clinics with such experience. Blood pressure control also tended to be better in patients enrolled at nonprivate practice clinics than in those enrolled in private clinics.
Analysis of the different geographic regions showed that patients in Canada, Puerto Rico, and the Virgin Islands tended to have the best blood pressure control, whereas patients living in the southern United States had the worst control. Patients in the eastern or southern United States, Puerto Rico, and the Virgin Islands were less likely to be on ≥ 2 drugs.
William C. Cushman, MD (VA Medical Center, Memphis, Tennessee), who presented these results at the AHA meeting in Chicago, noted that most of the patients who were not controlled had persistent elevation of SBP. Many of these patients were not on maximal doses of their medications or were not receiving the maximum numbers of drugs permitted in the trial, and they probably could have achieved levels < 140/90 mm Hg with more aggressive treatment. Dr. Cushman noted that ALLHAT had limitations on how drugs could be combined, and he believes that without these limitations, blood pressure control could have been even further improved.
Many cardiovascular benefits have been attributed to the consumption of soy by men and women, including lowering of blood lipids, oxidized low-density lipoprotein (LDL)-cholesterol, homocysteine, and blood pressure. In Asian women, low incidences of breast cancer and menopausal symptoms have been widely attributed to high soy bean intake. At the AHA meeting, researchers from Beth Israel Deaconess Medical Center, Boston, Massachusetts, reported blood pressure-lowering effects in menopausal women due to short-term consumption of soy nuts that were comparable to those seen with antihypertensive medications. They carried out a randomized, crossover, controlled trial in 60 menopausal women who consumed 58 g (one half cup) of dry-roasted soy nuts (25 g soy protein and 101 g aglycone isoflavones) daily for 8 weeks. The soy diet was accompanied by a therapeutic lifestyle change (TLC) diet. The women also spent 8 weeks on the TLC diet alone.
A 9.9% decrease in SBP (P = .003) and a 6.8% decrease in DBP (P = .001) occurred with the soy diet in the 12 hypertensive women enrolled in the study. The 48 normotensive women in the study also showed significant decreases in blood pressure (SBP 5.2%, P < .001; DBP 2.9%, P = .03). The researchers suggested that soy may be of interest to women seeking an alternative to hormone replacement therapy, but pointed out that these results need to be confirmed in longer-term trials.
Young adults who display a major type A behavior trait known as time urgency/impatience (TUI) may later develop hypertension at a relatively early age, according to the results of a study reported at the AHA. This was the first study to investigate a link between hypertension and this type of behavior. Researchers at Northwestern University (Chicago, Illinois), the University of Pittsburgh (Pennsylvania), and the University of Alabama at Birmingham examined a sample of 3138 people aged 18-30 years who participated in the Coronary Artery Risk Development In Young Adults (CARDIA) study. The sample included 586 black men, 825 black women, 822 white men, and 905 white women. On enrollment in 1985, participants in CARDIA were asked how traits such as "eating too quickly," "getting upset when having to wait for anything," "usually feeling pressed for time," and "often feeling time pressures at the end of a work day" described them. Responses ranged from "very well" to "not at all." Positive responses to all questions put participants at the highest level of TUI (6% of the sample population). TUI was rated at years 0 and 2. Only participants who were not hypertensive at year 0 or 2 were followed for 13 years.
After 13 years, the incidence of hypertension was 17% in the participants who had registered the highest TUI score compared with 10% for those with the lowest score. After adjusting for age, race, gender, BMI, physical activity, alcohol consumption, and SBP, the researchers found that people with the highest TUI scores were more than twice as likely to have developed hypertension as those with the lowest scores. Lead researcher LiJing L. Yan, PhD (Department of Preventive Medicine, Northwestern University) noted that people with higher TUI scores were more likely to be white, female, and better educated, but were less likely to have a healthy lifestyle (eg, they smoked more, drank more alcohol, and had less physical activity) compared with those who had lower TUI scores. The probability of developing hypertension after 13 years was almost twice as high for black men (22%) and black women (21%) as for white men (12%). White women, however, had the lowest overall probability.
The researchers pointed out that TUI is related to a poor health-risk profile that includes smoking, drinking alcohol, high hostility levels, and a lack of social support, most of which are associated with hypertension. They stressed the importance of modifying these factors so as to reduce TUI tendency and possibly decrease future health risks related to TUI.
Lowering blood pressure beyond the usual blood pressure goals does not appear to slow progression of hypertensive renal disease, according to the recently published results of the AASK trial. Hypertension is the second leading cause of end-stage renal disease (ESRD) in the United States, and there is no known treatment to prevent the progressive decline leading to ESRD. African-Americans are 6 times more likely to develop ESRD than whites.
In AASK, Jackson T. Wright, Jr, MD, PhD (Case Western Reserve University, Cleveland, Ohio) and colleagues compared the effects of 2 levels of blood pressure control and 3 antihypertensive drug classes in 1094 African-Americans aged 18-70 years with hypertensive renal disease. Patients were recruited from 21 clinical centers around the United States from February 1995 through September 1998 and followed for 3.0 to 6.4 years. A total of 554 patients were assigned to a usual mean arterial pressure goal of 102-107 mm Hg and 540 patients were assigned to a lower mean arterial pressure goal of =/< 92 mm Hg. All participants were also assigned to receive either a beta-blocker, metoprolol (n = 441), an ACE inhibitor, ramipril (n = 436), or a dihydropyridine calcium channel blocker, amlodipine (n = 217).
No significant difference was found between the "usual" and "lower" blood pressure groups with regard to change of ≥ 50% from baseline in glomerular filtration rate (GFR), development of ESRD, or death. There were also no differences between the 3 antihypertensive drug groups with regard to rate of change in GFR from baseline.
However, the ACE inhibitor ramipril was associated with a 22% risk reduction in experiencing 1 of the clinical outcome measures compared with metoprolol (P = .04) and a 38% risk reduction for ramipril vs amlodipine (P = .004). No significant differences were seen in outcomes between amlodipine and metoprolol.
The AASK investigators concluded that although blood pressure reduction to levels below those specified in current guidelines for cardiovascular risk reduction are achievable, these results do not support additional reduction as a strategy to prevent progression of hypertensive nephrosclerosis. The investigators also concluded that their findings do support the use of ACE inhibitors as first-line therapy over beta-blockers and calcium channel blockers in African-American patients with hypertensive renal disease. This is the first time that this effect of ACE inhibitors has been demonstrated in such a large population of African-Americans.
Commenting on the AASK results in the same issue of JAMA, Michael H. Alderman, MD (Albert Einstein College of Medicine, Bronx, New York) noted that the primary and secondary endpoints of the study "largely depended on GFR, a surrogate endpoint for which the relation to health outcomes is, at best, uncertain." He pointed out that cardiovascular mortality and hospitalizations were 18% more likely to occur in those assigned to the higher blood pressure goal than in those assigned to the lower goal and that, over the long term, most morbidity and mortality in patients with renal disease is due to stroke and hypertension. Most cautious physicians may continue to attain target blood pressure levels of ≤ 140/90 mm Hg because the evidence indicates that those levels prevent morbidity and mortality, Dr. Alderman suggested.
With regard to how widely the findings of AASK can be applied, Dr. Alderman pointed out that the criteria for classification of hypertensive nephrosclerosis in AASK were more rigorous in the trial than those usually applied. He suggested that most black patients currently identified as having hypertensive nephrosclerosis would be excluded by the AASK criteria; many of the study patients may have actually had treatable underlying renal disease that was overlooked. Dr. Alderman concluded that the AASK patients probably did not differ from white patients with regard to hypertensive nephrosclerosis, and these findings may apply to all otherwise phenotypically similar patients.
Increases in blood pressure seen in habitual coffee drinkers are not due to the caffeine in the coffee, a recently published study from Switzerland has concluded. The Swiss researchers measured blood pressure, heart rate, and muscle sympathetic nervous system activity (MSA) in a group of 15 healthy volunteers, 6 of whom were habitual and 9 of whom were nonhabitual coffee drinkers. Responses were recorded after they drank a triple espresso or a decaffeinated triple espresso and after intravenous administration of caffeine (250 mg) or saline. None of the subjects knew whether they were receiving caffeine.
Habitual and nonhabitual coffee drinkers showed similar changes in MSA and blood pressure after intravenous caffeine. Coffee drinking, however, increased SBP in the nonhabitual coffee drinkers by 12 mm Hg after 60 min, whereas no increase was seen in the habitual coffee drinkers, despite similar changes in MSA and plasma caffeine levels. When the nonhabitual coffee drinkers drank decaffeinated espressos, SBP levels increased despite no increase in plasma caffeine levels. Heart rate and DBP levels remained unchanged. Lead researcher Roberto Corti, MD (University Hospital Zurich, Switzerland) believes that this is the first time that such disparities in reactions to coffee have been reported, and he believes they support the hypothesis that ingredients other than caffeine are responsible for the stimulating effects of coffee on the cardiovascular system. The researchers concluded that the potential adverse effects attributed to coffee may be less hazardous in regular consumers with normal blood pressure and that in people without a hereditary predisposition to hypertension, coffee drinking cannot be considered a risk factor for hypertension.
The AHA commented that studies investigating a direct link between caffeine, coffee drinking, and coronary heart disease have produced conflicting results, but that coffee drinking in moderation (1-2 cups per day) does not appear to be harmful.
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