Most of us associate caffeine with coffee, but it can also be found in tea, dark sodas, chocolate, energy drinks, and pep pills. If your caffeine intake is limited to one or two normal-size cups of coffee or 2 or 3 cups of tea a day, it is probably okay. But any more than that can cause problems.

Caffeine restricts blood flow to the brain, and anything that compromises blood flow leads to premature aging.

Caffeine dehydrates the brain, which makes it harder to think quickly.

Caffeine interferes with sleep, which is essential for good brain health, appetite control, and skin rejuvenation.

Caffeine can be addictive in high amounts. When you try to kick the habit, you are likely to experience withdrawal symptoms, including severe headaches, fatigue, and irritability.

Caffeine can accelerate heart rate and raise blood pressure. In some people, drinking too much caffeine lead to a temporary spike in blood pressure and a racing heart.

Caffeine can give you the jitters and an upset stomach. Ingesting more caffeine than you normally do can leave you feeling jittery and nervous. Gastrointestinal troubles are also common with excessive caffeine use.

Caffeine increases muscle tension. Tight muscle have been linked to caffeine intake.

Caffeine can elevate inflammatory markers. Two studies showed the 200mg of caffeine (equivalent to 2 cups of coffee) raised homocysteine levels, a marker for inflammation and heart disease.

Caffeine can interfere with fertility. pregnant women should be careful with caffeine because it has been associated with premature births, birth defects, inability to conceive, low bright weight, and miscarriage.