HealthLeader

An Online Wellness Magazine produced by The University of Texas Health Science Center at Houston (UTHealth)

Cutting Back

The effects of caffeine might break your heart

Cutting Back

Whether it’s a coffee, cola or an energy beverage, this month of romance and heart health may be time for a wake-up call about our longtime love affair with our energizer of choice — caffeine. 

Like illicit drugs, caffeine taxes the heart while delivering its buzz within two hours. Our pulse jumps by 5 to 7 beats per minute and our systolic blood pressure by 10 mm HG, propelling blood at a faster rate through our body’s most vital muscle, the heart. 

Be it speed in a can or a cup, caffeine simulates the same surge of adrenaline we feel in fight-or-flight danger. We go on high-alert, enabling our muscles to make us faster and stronger. 

“Like any drug, caffeine has side effects, and they can be harmful and fatal,” says cardiologist John P. Higgins, MD, associate professor of internal medicine at The University of Texas Health Science Center at Houston (UTHealth) Medical School and director of exercise physiology at the Memorial Hermann Ironman Sports Medicine Institute. “Also, caffeine is the only psychoactive drug legally available over the counter to kids.” 

Pile on strenuous activity, fear, anger or any other stressors, and heart rates jump even further, “which is even riskier,” Higgins says. “You’re flogging yourself more than you need. Your body knows how to regulate its heart rate and blood pressure perfectly during exercise and doesn’t need to be whipped along with extra caffeine.” 

Caffeine also can be counterproductive, slowing blood vessels’ ability to widen and deliver more oxygen as fuel, as they normally would under duress. 

That’s when things go awry. A heart starved of oxygen will struggle, which may cause chest pain, irregular heartbeats, palpitations, dizziness, vomiting, seizures and, ultimately, a work stoppage — also known as a heart attack. 

“If blood isn’t being pumped properly through the body, it could be dangerous and even fatal,” Higgins says. “All it takes is the wrong product with the wrong person.” 

And it doesn’t take much. Among the fatalities are a 14-year-old from Maryland who drank two 24-ounce Monster Energy Drinks within 24 hours and an 18-year-old who downed two cans of Red Bull before shooting hoops.  

A study published in 2011 by the American Academy of Pediatrics (AAP) found that 46 percent of the 5,448 caffeine overdoses reported were in teens and younger. 

Teens are more sensitive 

Healthy, young — what’s happening? Adolescents are at greater risk than adults, partially due to lower body weights, undiagnosed heart problems, irregular consumption and interaction with attention-deficit/hyperactivity-disorder (ADHD) meds, all of which magnify caffeine’s effects. Dehydration from the heat and air-conditioning in the summer alone can throw off essential body salts — magnesium, calcium, phosphorus and potassium — imperative for a smoothly-running ticker. 

“Children’s systems aren’t fully developed,” says Higgins, noting that while caffeine may help concentration, benefits are lost as erratic sleep mars long-term memory. “They’re more sensitive to the effects of caffeine and have a lower threshold for seizures.” 

Alarming to Higgins is youths’ chief vehicle for vroom. “Energy drinks are just bad, bad, bad,” he says of Red Bull, Full Throttle, Rock Star and other energizers in the beverage market’s fastest growing segment, topping $9 billion in sales. “You’ve got the caffeine, plus the natural caffeine booster guarana, and on top of that very high levels of glucose. They’re bad for the cardiovascular system all around.” 

A reputation as liquid cocaine or speed, along with hardcore names and graphics, make them especially alluring to younger people. 

Combined with alcohol, energy drinks are particularly lethal. In fact, though they’re popular in bars, you can’t find them in stores. The U.S. Food and Drug Administration (FDA) has banned such premixed beverages since declaring caffeine an “unsafe food additive” to alcohol in November 2010. 

“Yet, when we surveyed bars, we found that Red Bull with Vodka was the fifth most ordered drink on a Friday or Saturday night,” Higgins says. “That’s true nationwide.” 

Booze and buzz battle each other within the brain. The former impairs judgment and motor skills, while also prolonging the heart-racing effect of the latter. 

“The combination significantly increases arrhythmias in people with underlying heart disease,” he says. “Plus, drinkers have an over-inflated view of their sobriety level. They continue to drink and end up doing things they shouldn’t, like driving cars and taking dares or doing other drugs.” 

What are we drinking? 

It’s time to sober up. The AAP advises teens consume no more than 100 milligrams of caffeine daily, and children under 12 should have none, Higgins notes. 

Whether it’s a jolt of java, cola or energy beverage, the average American adult drinks 230 milligrams of caffeine daily (about 2-3 cups of coffee). The average 13- to 17-year-old gulps 60-70 mg — though some as many as 800 mg daily, according to recent studies. 

Up to 400 mg is considered safe in most adults, though pregnant women should have 300 mg or less, and anyone who’s had heart-pounding or palpitations in the past should forsake it altogether, he says. 

Disturbed by the frequency of seemingly healthy young runners collapsing near the finish line, the International Marathon Medical Directors Association warns athletes to limit themselves to no more than 200 mg of caffeine before or during a race. 

Like many of us, runners may not realize how much caffeine they’re consuming. Along their routes, volunteers offer free gels and beverages. Who stops to study the ingredients list? 

And off the track, who among us pulls out a calculator to determine how many “servings” are in a bottomless cup, Super Gulp or giant energy drink? 

“One cup of coffee (just 5 ounces) could vary from less than 50 milligrams of caffeine in a decaf to 400 milligrams in a super-sized double espresso,” Higgins notes. “You could hit your limit in one cup — or four.” 

Even when we do the math, we may be misled, he says. When Consumer Reports checked the true caffeine levels of 27 energy drinks last year, it found five of 16 products had 20 percent more caffeine than the label vowed. The other 11 drinks didn’t even specify their caffeine content. 

“The makers’ strategy is to list non-core ingredients in an exact way to create an illusion of being completely honest,” Higgins says. “It's similar to giving the exact amount of lesser ingredients, such as lettuce, tomato and pickles used in a burger, while giving no information on the key ingredient, meat. 

“Energy drink makers may admit to 70 to 80 milligrams per 8-ounce serving – three times that of a regular cola — but they’re only talking about caffeine additives, not natural forms,” Higgins adds. “Guarana, which also is in a lot of over-the-counter herbal pick-me-ups, has one of the highest concentrations of natural caffeine.” Sixty plant-based sources of caffeine include kola nut, yerba, tea leaves and cocoa. 

Worse, we’re surrounded by other surprising sources of caffeine. Not only is it added to some gums, waffles, jelly beans and jerkys, but it’s also found in common over-the-counter drugs, including nonsteroidal pain relievers, diet pills and cold and allergy medicines. Another common ingredient — pseudoephedrine — only hikes its heart harm. 

The lesson is this: Think before you drink, because that “kick” can make you sick.