Having an energy drink will raise your blood pressure by an average of 4.44/2.73 mmHg, according to a recent study. Drinks that contain 200mg or more of caffeine have the greatest effect, and can cause your blood pressure to soar by as much as 10/2 mmHg – and that’s in healthy people who do not have high blood pressure. If you have hypertension, the rise is significantly higher.
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What is an energy drink?
There is no standard definition, but the term energy drink usually refers to a beverage that contains caffeine plus other ingredients that have an alerting or revitalising effect, such as taurine, B vitamins, guarana or Korean ginseng (Panax ginseng).
These ingredients, especially the caffeine, can improve stamina, concentration, memory and reaction time. Some energy drinks are available as a quickly consumed, concentrated shot.
Energy drinks are so popular that, internationally, they account for 47% of market share for non-alcoholic drinks – a figure that rises to 63% in the US. Most are consumed by young adults (18 to 34 years) but they are growing in popularity among older people, too.
The dangers of energy drinks
In the US alone, over 13,000 people a year need emergency treatment as a result of energy drinks, including teenagers who present with symptoms such as palpitations, high blood pressure and even collapse. In 2015, 34 deaths in the US were related to energy drink consumption. It’s therefore not surprising that some countries, such as Denmark and France, have banned the sale of some energy drink brands (forcing reformulations), while in Norway, some energy drinks are only available in pharmacies.
The caffeine content of energy drinks and shots ranges from 50 to 505 mg caffeine per serving, compared with 34mg to 54mg caffeine per serving for colas, and 77mg to 150mg for a 6 ounce (177ml) cup of coffee.
The FDA allowable limit for caffeine in cola-type drinks is 0.02% (equivalent to 71 mg maximum per 12 fluid ounces) but this limit does not extend to energy drinks (although that is under review) and some contain significantly higher levels.
In Australia and New Zealand, the caffeine content of energy drinks is limited to 320 mg/L (9.46 mg/oz) and for soft-drinks is limited to 145 mg/L (4.29 mg/oz).
The European Food Safety Authority recommend that healthy adults should have no more than 200mg caffeine in a single dose. Most countries suggest that, for the average healthy, non-pregnant adult, a moderate daily caffeine intake of up to 400mg per day is not expected to cause any adverse effects.
NB The FDA declared in 2010 that caffeine is an unsafe additive in alcoholic beverages and several premixed alcoholic energy drinks were prohibited from sale in the United States.
Energy drinks raise blood pressure
If you have hypertension, energy drinks are best avoided. Energy drinks cause a rapid rise in blood pressure, and the effects last for 5 hours or more.
A recent analysis of 15 studies, involving over a thousand healthy people, without hypertension, found that consuming an energy drink caused blood pressure to rise by 4.44/2.73 mmHg compared with placebo.
Effects were seen within 30 minutes and lasted for at least 5 hours. When caffeine content was less than 200mg, the rise in systolic blood pressure was under 4mmHg, but when caffeine consumption was 200mg or more, the increase in systolic blood pressure was over 6 mmHg.
In one study, in which healthy volunteers consumed energy drinks supplying 400mg caffeine, their blood pressure rose, on average, by 10/2 mmHg, showing a clear effect of caffeine dose.
These studies involved healthy young adults. In older people, and those who have hypertension, the effects of energy drinks on blood pressure responses are more exaggerated – possibly due to having less effective baroreceptor reflexes which normally help to maintain normal blood pressure levels.
In people with hypertension, for example, consuming 200mg to 300 mg caffeine in coffee produces an average increase in blood pressure of 8.1/5.7 mmHg, whether or not they were on medical treatment – all those taking part who were on antihypertensive medication continued to take them. Increases in blood pressure occurred within the first hour after caffeine intake and lasted for at least 3 hours.
Other studies have found that:
- In men with hypertension, caffeine caused a 10/8 mmHg rise in blood pressure
- In men with stage 1 (untreated) hypertension or high normal BP, caffeine increased readings by 8/7 mmHg.
- In men with optimal or normal blood pressure, readings rose by 6/5 mmHg.
How energy drinks raise blood pressure
Caffeine, whether included as a pure ingredient, or as a constituent of guarana, is the main culprit when it comes to raising blood pressure. The exact mechanism is unclear, but the hypertensive effect of caffeine is believed to result from:
- activation of the sympathetic nervous system which stimulates release of adrenaline (epinephrine) from the adrenal glands
- stimulation of the release of corticosteroids
- the blocking of adenosine receptors (involved in blood vessel dilation)
- effects on phosphodiesterase enzymes (involved in blood vessel dilation)
- activation of the renin-angiotensin-aldosterone system (which regulate blood pressure).
Taurine in energy drinks
The amino acid, taurine, is often added to energy drinks. Unlike other amino acids, it is not used as a structural protein building block in the body, but mostly exists as a free amino acid within cells, where it promotes fat burning and energy metabolism in mitochondria.
Taurine is also present in high concentrations in the brain, where it is the second most prevalent amino acid after GABA (gamma aminobutyric acid).
Both taurine and GABA act as inhibitor neurotransmitters and taurine does have a blood pressure lowering effect at high doses. When people with borderline hypertension gook 6g taurine per day, for 7 days, their adrenaline/epinephrine levels and blood pressure decreased, so the addition of taurine to energy drinks may help to offset some of the effects of caffeine.
Ginseng in energy drinks
Panax ginseng is a revitalising, adaptogenic herb that is often added to energy drinks. The results from 17 studies suggest that ginseng has a neutral effect on blood pressure producing no significant effects on systolic or diastolic readings (if anything, readings were slightly reduced although this was not statistically significant). The Panax ginseng within energy drinks is therefore not a culprit when it comes to hypertensive effects.