Study: coffee and high blood pressure

reference

chei cl, Loh JK, Soh a, Yuan jm, koh wp. Coffee, tea, caffeine and risk of high blood pressure: The Singapore Chinese Health Study. EUR J Nutr . March 1, 2017. DOI: 10.1007/S00394-017-1412-4. [Epub Ahead of Print]

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population -based prospective cohort

Study goal

Determination of the connection between coffee and tea consumption and high blood pressure.

participant

The data was collected from the Singapore Chinese Health Study, a population -related prospective cohort that recruited 63,257 Chinese participants aged 45 to 74, who lived in Singapore from 1993 to 1998. Information on coffee and tea consumption and other lifestyle factors was collected at the beginning. The self-reported high blood pressure diagnosed by the doctor was assessed in 2 follow-up interviews (1999-2004, 2006-2010).

medication and dosage study

Personal interviews were used in recruitment to collect information on demography, size, weight, lifelong tobacco consumption, current physical activity, sleeping time and medical history. A detailed questionnaire was used to collect information on food consumption, including alcohol, coffee and tea. These questionnaires included the frequency of the use of standard portions of coffee, black tea and green tea using 9 categories: never or almost never; 1 to 3 times a month; weekly; 2 to 3 times a week; 4 to 6 times a week; once a day; 2 to 3 times a day; 4 to 5 times a day; and 6 or more times a day.

target parameter

COX-proportional hazard models were used to estimate the Hazard Ratios (HRS) and 95 %confidence intervals (CIS) for the risk of high blood pressure in connection with the use of coffee, black tea, green tea and caffeine.

important knowledge

Over an average follow -up period of 9.5 years, 13,658 cases of high blood pressure were diagnosed in the cohort. The high blood pressure patients were more of women, kidney and non -drinkers from alcohol. They were also older, less educated, had a higher body mass index (BMI) and were physically more active. The results of the multivariable analysis showed an inverse U-shaped association between coffee consumption and risk of high blood pressure. Compared to drinking 1 cup a day, the rarer drinking of coffee was associated with a lower risk of high blood pressure. Similarly, the risk was reduced by those who drank more than 2 cups a day. In the multivariables analysis, compared to those who drank 1 cup a day, the heart frequencies of the hypertension occurred were as follows: 0.94 (95 % AI: 0.88–1.00) for weekly to

Think about how this could be put into clinical practice: If you speak to a patient with a slight high blood pressure who admits that you drink 1 cup of coffee every morning, your advice is based on this study: "Either stop drinking coffee or start drinking much more. '

The connection between coffee consumption and the occurrence of high blood pressure does not differ significantly between men and women ( p <0.5 for all interactions). See illustration.

figure

participants who drank black tea every day had a slightly increased risk (9 %) compared to those who drank less than weekly black tea (Mr.: 1.09; 95 % AI: 1.03-1.15). Similar results were observed for green tea (HR: 1.06; 95 % KI: 1.00–1.11). However, these associations were not statistically significant if they were adjusted for the caffeine content.

There was a statistically significant positive connection between caffeine intake and the risk of high blood pressure; Compared to a caffeine recording of <50 mg/day, all 4 higher categories of caffeine recording had a statistically significant increase in risk of high blood pressure, but without a clear dose -dependent trend.

After adapting to coffee (so that the caffeine was recording from other sources), the gradual dose-effect relationship between caffeine intake and the risk of high blood pressure became clearer. Compared to the lowest intake (<50 mg/day), the multivariables HRS for 50 to <100, 100 to <300, ≥ 300 mg per day was 1.07 (95 % KI: 1.00–1.15), 1.10 (95 % KI: 1.02–1.18), 1.08 (95 % AI: 0.98–1.19) and and 1.16 (95 % KI: 1.04–1.31; p for trend = 0.02).

practice implications

participants who drank less than 1 cup of coffee a week or more than 2 cups of coffee a day, had a significantly lower risk of high blood pressure compared to those who drank 1 cup per day.

Think about how this can be transferred to clinical practice: When you speak to a patient with a slight high blood pressure who admits that you drink 1 cup of coffee every morning, your advice should be based on this study: "Either stop drinking coffee or start drinking much more."

As strange that sounds, we should take these results seriously. With the conclusions from a dose-effect meta-analysis from 2011, they agree with 5 cohort studies, which also suggested an inverse U-shaped or J-shaped connection between coffee and the risk of high blood pressure. Day, but the risk decreased with higher coffee consumption. These current Chei results also resemble several prospective studies that have found a non-linear connection between cohorts of European men and women. ^{2.3 US medical sisters, 4 and other members of the health profession. Compared to light drinkers, which drank less than 1 cup a day, and strong drinkers that drank more than 3 cups a day, have high blood pressure. A Dutch study from 2007 reported on a similar inverse J-shaped association, in which the high blood pressure risk for those who drank less than 1 cup of coffee a day, and for those who drank more than 3 cups a day, compared to those who drank 1 to 3 cups a day. At first glance, strange phenomenon, the reverse U-shaped dose-effect curve.}

It is not surprising that caffeine increases blood pressure; This is done by "mechanisms that include a likeable overactivation, antagonism of adenosine receptors, an increase in the noradrenaline release through direct effects on the adrenalmark, direct kidney effects and activation of the Renin Angiotensin system. weaken.

coffee is a rich potassium source and 5 cups per day deliver about 26 % of the daily potassium intake. ^{8 potassium promotes the relaxation of the vascular smooth muscles and the endothelic vasodilation, increases the endothelial nitrogen oxide production and has a blood pressure -lowering effect in animals and humans. Chlorogenic acid, an important polyphenol in coffee, can also be responsible for the blood pressure -lowering effect of coffee. It has been shown that chlorogenic acid reduces blood pressure and improves endothelial dysfunction in hypertensive rats 10 and with slightly hypertensive people.}

What is going on is that moderate coffee cans in the range of 1 to 2 cups per day increase the risk of high blood pressure due to the influence of caffeine. In the case of higher doses, these other chemicals can counteract caffeine and reduce blood pressure.

If the effect of coffee on blood pressure is actually dose-specific, this could explain the inconsistencies that were found in other epidemiological studies that were looking for relationships between coffee consumption and cardiovascular diseases.

By the way, although technically a cup of coffee is usually defined as 150 ml of liquid or about 5 liquid ounce, and not as the 8 ounces that normally make a cup, a cup of coffee was defined as 237 ml in this current study. an almost full 8-disorder cup.

U-shaped dose-effect curves are reported more often in the literature, and we have to assume that this form of effect occurs more frequently than originally assumed. As a result, it is likely that our diet and nutritional recommendations will become more complex in the future, as we can see that the effects can change with changes in the dose size. While more is not always better, it can be just like that in the case of coffee.