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science nutrition blog

science nutrition <strong>blog</strong>

 By Steve Blechman




It was reported in the Journal of the American Heart Association on June 4th, 2019 that several hours after drinking 32 ounces of energy drinks, the heart’s electrical activity was abnormal compared to a placebo drink. ScienceDaily recently reported on this study on May 29th, 2019. “We found an association between consuming energy drinks and changes in QT intervals and blood pressure that cannot be attributed to caffeine. We urgently need to investigate the particular ingredient or combination of ingredients in different types of energy drinks that might explain the findings seen in our clinical trial,” said lead author Sachin A. Shah, PharmD, professor of pharmacy practice at University of the Pacific, Thomas J. Long School of Pharmacy and Health Sciences in Stockton, California. The study is the largest controlled study of the effects of energy drinks on the heart and blood pressure in young healthy volunteers. The study included only healthy individuals between the ages of 18 to 40, and the results may be different in other populations.

Both energy beverages tested contained 304 to 320 milligrams of caffeine per 32 fluid ounces. Caffeine at doses under 400 milligrams is not expected to induce any electrocardiographic changes. Other common ingredients in the energy drinks in the study included taurine (an amino acid), glucuronolactone (found in plants and connective tissues) and B vitamins. The placebo drink contained carbonated water, lime juice and cherry flavoring.

At the 2018 Annual American Heart Association’s meeting and Scientific Sessions, it was reported that “young, healthy adults experienced notably diminished blood vessel function soon after consuming one energy drink,” according to preliminary research from a small study that was presented in Chicago at the American Heart Association’s Scientific Sessions 2018. The presentation was made at 1:00 p.m. CST (Central Standard Time) on Monday, November 12, 2018.

The article further stated, “John Higgins, M.D., M.B.A., of McGovern Medical School at UTHealth in Houston and colleagues, studied 44 non-smoking, healthy medical students in their 20s by testing their endothelial function before each of the students drank a 24-ounce energy drink. Researchers repeated endothelial function testing 90 minutes later.

“One and a half hours after consuming the energy drink, researchers checked the young adults’ artery flow-mediated dilation – an ultrasound measurement that indicates overall blood vessel health. They found vessel dilation was on average 5.1 percent in diameter before the energy drink and fell to 2.8 percent diameter after, suggesting acute impairment in vascular function.

“Higgins and colleagues believe that the negative effect may be related to the combination of ingredients in the energy drink, such as caffeine, taurine, sugar and other herbals on the endothelium (lining of the blood vessels).”

Research has shown that the amino acid taurine can have adverse effects on the cardiovascular system when combined with caffeine. A study published on April 26, 2017 in the Journal of the American Heart Association found that energy drinks containing taurine and caffeine had a negative effect on the heart compared to caffeine-only beverages. Also, in the study an irregular heart rhythm resulted two hours after consuming an energy drink containing caffeine and taurine, compared to a caffeine-only drink. This randomized, double‐blind, controlled, crossover study tested 18 young, healthy volunteers. There was also a greater increase in blood pressure in caffeine with taurine combination compared to caffeine alone. 400 mg of caffeine, which is equivalent to about 4 cups of coffee, is generally regarded as safe by the U.S. Food and Drug Administration (FDA). Other studies have also shown that taurine can have adverse effects when combined with caffeine! (Pharmacotherapy, February 2012; 46(2):192-9, Amino Acids 2001; 20(1):75-82, Int J Cardiovasc Imaging 2015 Mar; 31(3):595-601).

The taurine in energy drinks may also be of concern in people with genetic heart conditions. A randomized, double-blind, crossover study published in the International Journal of Cardiology in March 2017 reported 24 people who had inherited genetic long QT syndrome (LQTS). When supplemented with caffeine combined with taurine, people with this condition have irregular heartbeat (arrhythmia). Twenty-four members of the study consumed two sugar-free energy drinks containing 100 mg of caffeine and 2000 mg of taurine, or a controlled drink consisting of juice, free of any caffeine or taurine. The subjects in the study were not aware of receiving the energy drink or the control drink. The results demonstrated that the participants consuming an energy drink containing caffeine combined with taurine experienced a significant increase in blood pressure compared to the group that consumed the control drink. The potential cardiovascular risk of energy drinks containing taurine and caffeine is concerning!

Energy drinks have become a billion-dollar industry. Obviously, the main component of energy drinks is caffeine, with some being more potent than others. However, manufacturers add taurine to their drinks to “boost” their energizing effects without scientific merit!

One of the most popular additives to energy drinks is the amino acid taurine. Taurine is an antioxidant. Research has shown that antioxidant supplements taken before exercise have negative effects on exercise-induced adaptation processes (BMC Sports Sci Med & Rehab, July, 2014). It also has been reported in the scientific literature that taurine, before exercise, may also inhibit nitric oxide (JAMA Network - Archives of Surg, 1996, The Journal of Immun, May, 1995).

Bottom line: based on the recent research, it is not recommended that people combine caffeine with taurine in their energy or pre-workout drinks. Taurine is perfectly safe when taken without caffeine. In fact, the research has shown many health benefits of taurine when taken without caffeine! Taurine is an inhibitory neurotransmitter and has been shown to have a positive effect of the cardiovascular system and lowering stress-induced increase in blood pressure especially when combined with magnesium. Some studies have also shown that taurine may be beneficial for enhancing weight loss/fat loss. Once again, do not take energy drinks combining caffeine and taurine. Better to be safe than sorry!



Sachin A. Shah, Andy H. Szeto, Raechel Farewell, Allen Shek, Dorothy Fan, Kathy N. Quach, Mouchumi Bhattacharyya, Jasmine Elmiari, Winny Chan, Kate O'Dell, Nancy Nguyen, Tracey J. McGaughey, Javed M. Nasir, Sanjay Kaul. Impact of High Volume Energy Drink Consumption on Electrocardiographic and Blood Pressure Parameters: A Randomized Trial. Journal of the American Heart Association, 2019; 8 (11) DOI: 10.1161/JAHA.118.011318

American Heart Association. Energy drinks may increase risk of heart function abnormalities and blood pressure changes. ScienceDaily. ScienceDaily, 29 May 2019.

American Heart Association Meeting News Brief – Poster Presentation Mo1189 – Session: AT.APS.16 November 12, 2018.

American College of Cardiology, CardioSmart, Non-caffeine Ingredients in Energy Drinks Linked to Negative Heart Effects June 06, 2017.

Potentially harmful effects of energy drinks - it's not the caffeine. Will Boggs MD April 26, 2017.

Randomized Controlled Trial of High‐Volume Energy Drink Versus Caffeine Consumption on ECG and Hemodynamic Parameters. Emily A, Fletcher, PharmD, et al.

Jeffries O, Hill J, et al. Energy Drink Doses Of Caffeine And Taurine Have A Null Or Negative Effect On Sprint Performance. The Journal of Strength & Conditioning Research 2017.

Bichler A, Swenson A and Harris MA. A combination of caffeine and taurine has no effect on short-term memory but induces changes in heart rate and mean arterial blood pressure. Amino Acids 2006, 31(4), 471-476.

Giles GE, Mahoney CR, et al. Differential cognitive effects of energy drink ingredients: caffeine, taurine, and glucose. Pharmacology, Biochemistry, and Behavior 2012, 102(4), 569-577.

Peacock A, Martin FH and Carr A. Energy drink ingredients. Contribution of caffeine and taurine to performance outcomes. Appetite. 2013;64:1-4.

Effects of energy drink major bioactive compounds on the performance of young adults in fitness and cognitive tests: a randomized controlled trial. Maximiliano Kammerer. Email author, Jaime A Jaramillo, Adriana García, Juan C Calderín and Luis H Valbuena. Journal International Society Sports Nutrition 11:44, 2014.

Wassef B, Kohansieh M and Makaryus AN. Effects of energy drinks on the cardiovascular system. World Journal of Cardiology 2017; 9(11), 796-806.

Comparison of the effects of energy drink versus caffeine supplementation on indices of 24-hour ambulatory blood pressure. Franks AM, Schmidt JM, et al. Ann Pharmacother 2012 Feb; 46(2):192-9 

The influence of a taurine containing drink on cardiac parameters before and after exercise measured by echocardiography. Baum M, Weiss M. Amino Acids 2001; 20(1):75-82.

Caffeine and taurine containing energy drink increases left ventricular contractility in healthy volunteers. Doerner JM, Kuetting DL, et al. Int J Cardiovasc Imaging 2015 Mar; 31(3):595-601.

Cardiovascular Effects of Energy Drinks in Familial Long QT Syndrome: A Randomized Crossover Study. Gray, Belinda et al. International Journal of Cardiology, Volume 231, 150-154.

Journal International Society Sports Nutrition 11:44, 2014

Paulsen G, Cumming KT, et al. Can supplementation with vitamin C and E alter physiological adaptations to strength training? BMC Sports Science, Medicine & Rehabilitation, July, 2014; 6, 28. doi:10.1186/2052-1847-6-28.

Redmond HPWang, JHBouchier-Hayes D. Taurine attenuates nitric oxide- and reactive oxygen intermediate-dependent hepatocyte injury. Arch Surg 1996;1311280-1288.

Taurine chloramine inhibits production of nitric oxide and TNF-alpha in activated RAW 264.7 cells by mechanisms that involve transcriptional and translational events. E Park, G Schuller-Levis, M R Quinn. The Journal of Immunology May 1, 1995, 154 (9) 4778-4784.

Haidari F, Asadi M, Mohammadi-Asl J, Ahmadi-Angali K. Evaluation of the effect of oral taurine supplementation on fasting levels of fibroblast growth factors, beta-Klotho co-receptor, some biochemical indices and body composition in obese women on a weight-loss diet: a study protocol for a double-blind, randomized controlled trial. Trials. 2019;20(1):315. Published 2019 May 31. doi:10.1186/s13063-019-3421-5