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Food & Drink

Scientists uncover health concerns with caffeine megadoses

| Thursday, March 17, 2016, 8:55 p.m.
Energy drinks can contain extra caffeine in the form of stimulants like guarana, a seed that contains more caffeine than coffee.
Energy drinks can contain extra caffeine in the form of stimulants like guarana, a seed that contains more caffeine than coffee.

Whether it's on a long car drive or a marathon session at the office, most of us need an energy boost from time to time. Many people turn to super-caffeinated beverages to get them through the task at hand.

Although the stimulant caffeine is generally regarded as safe — it has been linked with improved alertness, focus, short-term memory, exercise performance and even protection from Parkinson's disease and depression when used judiciously — health experts are increasingly sounding the alarm over megadoses consumed in caffeinated beverages.

What's in the mix?

Energy drinks are typically a mix of caffeine, sugars or artificial sweeteners, flavorings and add-ins, such as taurine, vitamins and Ginkgo biloba.

Ragavendra R. Baliga, M.D., a cardiologist with the Ohio State University Wexner Medical Center, cautions against such drinks because they have unknown health effects. A 2012 Nutrition Reviews report found that the majority of these extras in energy drinks do little to charge your energy levels or alleviate brain fog; basically, pure caffeine is the engine behind these drinks.

Bottled coffee drinks are a blend of strong coffee, often paired with sugar and dairy ingredients. The high-caffeine elixir market even includes bottled waters and tea bags infused with added caffeine.

Caffeine confusion

When you pick up an energy drink, you may have no idea how much caffeine you're getting, because manufacturers aren't required by the FDA to disclose the levels of caffeine. These products can contain extra caffeine in the form of stimulants, such as guarana, a seed that contains more caffeine than coffee. And when you walk into a coffee shop for a java jolt, who knows how much caffeine is in that brew; levels vary with the type of bean and brewing.

Overload side effects

Scientists have uncovered several health concerns related to overdoing caffeine and energy drinks.

Cardiovascular concerns. “Too much caffeine can overstimulate the nervous system, leading to increased or irregular heart rate and a rise in blood pressure,” Baliga says. A 2014 American Journal of Cardiology review found adverse cardiovascular events, even cardiac arrest, among heavy energy-drink users. With caffeine-spiked drinks skyrocketing, you can see why emergency room visits related to these products have increased at least tenfold in recent years.

Insomnia. Because caffeine can remain in your system for several hours, drinking super-caffeinated beverages later in the day may contribute to insomnia. That's because caffeine can alter your circadian clock (a process responsible for sleep-wake timing), making it harder to fall asleep at your normal time, according to a 2015 study from the University of Colorado. Caffeine also blocks your receptors for adenosine, a neurotransmitter that sends fatigue signals to your body.

Poor food choices. A 2015 University of Texas study found that energy drink users were more likely to make poor dietary choices, such as lower intake of fruits and vegetables, skipping breakfast and consuming more soda and frozen meals.

Risky behavior. A perilous trend among the young is to mix energy drinks with alcohol. The stimulatory effects of an energy drink can counteract the sedation normally brought on by alcohol, which can result in more drinking and risky behavior. A 2015 study discovered that the instances of brain injury during sports were higher among adolescents who consumed energy drinks.

Sugar blues. These drinks often come laced with sugar — another vehicle for a short-term energy boost. “The elevated blood sugar can lead to increased risk for obesity, diabetes and heart disease,” Baliga says.

Dental problems. The high acidity levels in energy drinks can erode tooth enamel.

Caffeine naive

If you're not a regular caffeine user, you're what researchers call “caffeine naive,” and you could be even more susceptible to side effects. Researchers at the Mayo Clinic found that healthy adults who normally consumed little, if any, caffeine (no more than 160 milligrams daily) experienced a significantly greater rise in blood pressure in response to drinking an energy drink than those who normally consume higher amounts (more than 160 milligrams daily). Baliga notes that the degree of caffeine sensitivity among individuals can be highly variable; some people never develop a tolerance to caffeine.

Registered dietician Matthew Kadey writes for Environmental Nutrition, the independent newsletter by nutrition experts. Details:

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