Caffeine is, according to New Scientist, the planet´s most popular "psychoactive drug." In the United States alone, more than 90% of adults are estimated to use it every day.

But now even the US – home of Coca-Cola, Starbucks and the 5-Hour Energy shot – is questioning the wisdom of adding it to everyday foodstuffs like waffles, sunflower seeds, trail mix and jelly beans.

In a statement, the Food and Drug Administration (FDA) highlighted the "unfortunate example" of Wrigley chewing gum producing packs of eight sticks which each contained as much caffeine as half a cup of coffee. Subsequently, Wrigley said it would "pause" production of the product.

The agency is also looking at highly-caffeinated energy drinks, and said it was concerned about the "cumulative impact" of adding stimulants to products.

According to the US Substance Abuse and Mental Health Services Administration, the number of people seeking emergency treatment after ingesting energy drinks doubled to more than 20,000 in 2011.

Scientists at Johns Hopkins University, studying its addictive properties, found that withdrawal symptoms included tiredness, headaches, difficulty concentrating, muscle pain and nausea.

But there is far from any kind of scientific consensus that caffeine use is harmful. A recent study by the Harvard School of Public Health suggested that "coffee drinking doesn´t have any serious detrimental health effects" and that drinking up to six cups a day was "not associated with increased risk of death from any cause".

In moderation, caffeine may have some positive effects. Research suggests it could be associated with a reduced risk of prostate cancer and breast cancer. A recent study linked drinking coffee and tea with a lower risk of type two diabetes.

As a result, the FDA has pledged to "determine what is a safe level" of caffeine use.

The agency´s move has been welcomed by those who fear caffeine is already encroaching too much into our daily lives – often in products where it may not be expected.