Both Pepsi and Coca-Cola recently began disclosing the amount of caffeine in each 8-ounce serving (up to 50 mg). That’s not necessarily bad, as long as you cap your total daily caffeine intake at 200 to 300 mg (or 2 to 3 cups of coffee); research suggests that this amount is safe, boosts your alertness, and may even reduce your risk of Alzheimer’s disease.   However, if you go overboard or show signs of caffeine sensitivity–such as headaches, anxiety, or gastrointestinal distress–or are taking certain antibiotics or anti-anxiety meds, cutting back on soda or coffee (your choice!) may be wise.