Energy drinks aren't technically a "food". That's not to trash them - it's just a fact,and an important one at that. The Food & Drug Administration regulates all products defined as food to ensure they're safe for human consumption. Coffee drinks and soda, for instance, aren't allowed to be too high in caffeine in case they cause heart problems. But energy drinks are classified as supplements,which means they're unregulated. Hence, manufacturers are free to add as much caffeine inside a single can as they please. They can even mix caffeine with other stimulants（兴奋剂）in such a way that could cause cardiovascular or nervous system problems.
That's why physicians have been trying to investigate what the health effects of these caffeinated drinks might be. A new study showing that a single drink can diminish blood vessel （血管）function is making headlines, but similar findings have been increasing for years now.
A lot of the concern about these drinks comes from their high concentrations of stimulants. It's entirely possible to overdose on caffeine alone, and in combination with guarana, another stimulant, smaller amounts might have severe effects. Overdosing on caffeine doesn't necessarily result in death, but it can cause heart palpitations（心悸），nausea, vomiting, and hypertension. The WHO study also reports that adults who consume energy drinks may be increasing their risk of hypertension and type 2 diabetes.
Despite the WHO's recommendation that caffeine content be limited per beverage,energy drinks in the U. S. are still totally unregulated and will remain that way unless they get reclassified as a food. They may not be dangerous in small quantities,but nothing about them is healthy. Switch to coffee or tea,both of which will energize you in the morning and will be much harder to overdo it with. Or you could just go ahead and work on kicking your caffeine habit for good.



Why energy drinks are hard to regulate？ ______

A. Because they contain a lot of caffeine.
B. Because they cause heart problems.
C. Because they are not categorized as food.
D. Because they are allowed to be high caffeine.

What does the underlined word "That" in Paragraph 2 mean？ ______

A. A new study shows that energy drinks are harmful to humans.
B. As for now, energy drinks are not regulated in the United States.
C. Physician are going to evaluate the effect of energy drinks in the following studies.
D. Energy drinks together with other harmful ingredients could damage one's well-being.

Which of the following statements about energy drinks is TRUE？ ______

A. Overdosing on caffeine directly contributes to death.
B. Energy drinks play a negative role on affecting people's well-being.
C. People won't get addicted to caffeine only by consuming energy drinks.
D. Adults' consuming energy drinks may increase the possibility of the risk of diabetes.

What's the author's attitude towards energy drinks？ ______

A. Favorable.
B. Ambiguous.
C. Disapproving.
D. Indifferent.