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Note: Each mint contains 40 mg of caffeine. According to the Mayo Clinic, up to 400 mg of caffeine is safe for most healthy adults. NeuroGum is a small business that specializes in caffeinated gum and mints. Promising review: "I've been using these NeuroMints for the past four years now, and absolutely love them. They have completely transformed my productivity — I'm not exaggerating. Coffee is great, but it gives me this high for like an hour or two followed by a horrible energy crash. These NeuroMints are on a whole different level. The level of focus and concentration I get from these is incredible. I guess their caffeine/l-theanine ratio is ideal because I am able to code for hours with these. They first got me through college, helping me focus on my studies. Now that I work in software, they keep my brain running." —JetDriveSolutions Price: $24.99 for a six-pack with 12 mints each (available in three flavors).