Medically speaking, Caffieine works by preventing the calming chemical adenosine from binding to nerve cell receptors in the brain. The result is increased mental alertness. Caffeine heightens the senses and quickens physical reaction time. It may also help to set the body's biological clock and in some people, help depression.

Caffeine can help relieve migraine headaches by constricting blood vessels in the brain and is included in some cold and allergy drugs because it offsets the drowsiness caused by antihistamines. Researchers have found that some patients with high blood pressure who exercise immediately after consuming caffeine, can result in a temporary rise in blood pressure. I recommend my patients with hypertension to avoid or limit their caffeine intake.

Over the years, reports have linked caffeine with bladder, pancreatic, colon and ovarian cancers. These studies have been criticized for not being properly controlled. To date, no link has been found between caffeine and cancer.

Because caffeine keeps people awake, I recommend to avoid it within 2 to 3 hours of bedtime, some patients with insomnia, I tell to avoid caffeine as early as noon.

Too much caffeine can cause irritability, nervousness, frequent urination and diarrhea in some people. If you are on medication, ask your doctor how much caffeine you can drink.

Dr. Lorne Stitsky is the owner and founder of Personal Choice Family Practice, an "Old-Fashioned" Family Practice in Jupiter, Florida. Please call 561-779-1520 or visit www.drstitsky.com for a free consultation on this membership practice.