Caffeine, Obesity and Hypertension

Recently the media has reported on a study looking into caffeine and hypertension. The study focussed on caffeine consumption and the development of hypertension in women who did not have physician-diagnosed hypertension.

The study published in the November issue of the Journal of The American Medical Association administered questionnaires to 155 594 US women at various stages during the 12 year period between 1991 and 2003. Of these women, 33 077 cases of physician-diagnosed hypertension were reported.

After analyzing the data on caffeine and hypertension, researchers found that there was no link between caffeine and the risk of developing hypertension. They did however, find that there was an increased risk of developing hypertension when cola was consumed.[1] The mechanisms by which cola could induce high blood pressure is not known and further research needs to be done.[1,2]

Does this mean you should not drink Cola?

Given what they know about cola and hypertension, researchers still feel that it is extreme to exclude soft drinks such as Cola for the sake of lowering blood pressure. However, because of the high sugar content of soft drinks such as Cola, these drinks should be consumed in moderation.

Does Caffeine React The Same Way for Obese Individuals?

If you're here now, my guess is that you are overweight to some degree. Obesity has unfortunately, been associated with hypertension, because the heart needs to work harder to deliver blood all around the body in people who are overweight.[4]

Being obese does not automatically mean you will get hypertension, however, having more of the risk factors such as obesity, means that you will have a heightened risk of developing the condition.

While this study analyzing the responses of over 155 000 women had some interesting results, it tells a story with only a limited amount of scope. It shows the long-term affect of caffeine and hypertension on women who do not already have hypertension, but it does not show what affect caffeine has on women who do.

In many cases, women who are overweight, may also have hypertension. NAASO (The Obesity Society) reports that the prevalence of hypertension associated with obesity varies widely according to age, race and sex. However, roughly they estimate that 30% of cases of hypertension may be attributable to obesity. In men under 45 years of age, this figure is estimated to be around 60%.[5]

Caffeine is a complex chemical whose affects can differ. Research has shown that caffeine behaves differently within different populations. For example, researchers have been able to show that at rest, obese individuals absorb caffeine at a faster rate and the caffeine stays within their bodies for longer than their lean counterparts.

This research examined untrained, non-smoking college males. Subjects were given 5.83 mg/kg of caffeine or a placebo before a three hour period of rest and prior to 90 minutes on the treadmill - also followed by 90 minutes rest.[3]

While this research could not determine whether it was the exercise or obesity that altered the way in which caffeine behaved within the body, it shows that the pharmacological processes of caffeine is affected when either of these two variables are added to the equation.[3]

Should Individuals With Hypertension Consume Caffeine?

Some experts feel that there may be a link between caffeine and hypertension for individuals who are already hypertensive, and recommend that hypertensive individuals should at least limit their consumption of caffeine,[6] while others recommend that these individuals discuss this issue with their medical practitioner.[7]

One literature review published in 2000 in Hypertension and supported by the National Heart, Lung and Blood Institute, looked at the affects of caffeine and hypertension in men divided into 5 risk groups. 73 men were identified as having optimal blood pressure. 28 men had normal blood pressure. 26 of the men had high to normal blood pressure. 27 had stage 1 hypertension and 18 of the men were diagnosed with hypertension. On average the men had abstained from caffeine consumption 17.75 hours prior to testing.

Blood pressure was measured after 20 minutes of rest and again at 45 to 60 minutes after participants were given 3.3mg/kg of caffeine orally.

The results of the study showed that caffeine raised both systolic and diastolic blood pressure in all groups, however, the strongest response to caffeine was observed in the men with diagnosed hypertension who experienced a blood pressure change 1.5 times greater than that of the men in the optimal blood pressure group. 89% of the diagnosed hypertensive group experienced blood pressures in the hypertension range after caffeine ingestion.[10]

According to this review, caffeine and hypertension may be an issue for individuals who are already diagnosed-hypertensive, experiencing blood pressure elevations 45 to 60 minutes after ingestion. No other readings were taken, so it is not known how quickly the blood pressure returned to baseline levels. Further investigation may be warranted to find out whether hypertensive individuals develop a tolerance to the effects of caffeine or develop chronically raised blood pressure levels.

While the authors of this study into caffeine and hypertension conclude that caffeine may play a role in increasing blood pressure, it is still a controversial area.

The 2003 Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure does not make mention of caffeine as a risk factor for high blood pressure.[7,8] By this omission, caffeine is not considered by the committee to pose a significant risk to those who already have high blood pressure.

Should You Exclude Caffeine From Your Diet If You Are Hypertensive?

If you are thinking of excluding items from your diet that contain caffeine such as coffee, you also need to consider that often pure caffeine will react differently when compared to the consumption of food containing caffeine, probably because there are other food chemicals consumed as well. Coffee is reported to also contain anti-oxidants which could have beneficial affects in other areas.[9]

While there are experts on both sides regarding caffeine and hypertension - for and against the consumption of caffeine by individuals prone to high blood pressure, it would be wise, in cases of pre-hypertension or diagnosed hypertension to discuss the issue of caffeine and your blood pressure with your doctor and find out what the best course of action is for your circumstances.

Source:

[1]  Winkelmayer WC, Stampfer MJ, Willett WC, Curhan GC. Habitual Caffeine Intake and the Risk of Hypertension in Women. JAMA. 2005 Nov 9;294(18):2330-5. Abstract

[2]  Article - Medpage Today

[3]  Kamimori GH, Somani SM, Knowlton RG, Perkins RM. The effects of obesity and exercise on the parmacokinetics of caffeine in lean and obese volunteers. Eur J Clin Pharmacol. 1987;31(5):595-600. Abstract

[4]  Article - Risk Factors Of Hypertension Debra Wood RN.

[5]  Article - NAASO The Obesity Society.

[6]  Q & A Ask Alice Health Services at Columbia

[7]  Article - International Food Information Council

[8]  Education Brochure PDF File - National High Blood Pressure Education Program

[9]  Article - Anti-oxidants In Coffee

[10]  Terry R. Hartley; Bong Hee Sung; Gwendolyn A. Pincomb; Thomas L. Whitsett; Michael F. Wilson; William R. Lovallo. Hypertension Risk Status and Effect of Caffeine on Blood Pressure. Hypertension. 2000;36:137 Free Full Text

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