The third annual all-Q&A issue of the Harvard Health Letter offers answers to readers' serious, whimsical, and just plain curious questions ranging from whether vitamin B₁₂ supplements are safe to what causes excessive belching, how coffee can help with migraine, and what to do about an asymptomatic H. pylori infection. All of the answers are provided by doctors from Harvard Medical School.

Most issues of the Harvard Health Letter answer one or two reader questions in the "By the Way, Doctor" feature. The newsletter's May 2010 issue answers 13 such reader questions:

• Is not washing your face good for your skin?
• Should I stop taking vitamin B₁₂ supplements?
• When is the best time to check your own blood pressure?
• Will a fiber supplement interfere with my medications?
• Should boys be getting the HPV vaccine?
• How can caffeine help migraines?
• Could swimming in cool water give me a heart attack?
• Will thiazide diuretics increase my chances of getting diabetes?
• Are gourmet salts better for you?
• Is Avastin a good choice for treating macular degeneration?
• What can I do about excessive belching and feeling full?
• Does an H. pylori infection without symptoms need to be treated?
• Can even one fatty meal cause heart problems?

As an added feature, you can see and hear three of the doctors answer their questions at www. health.harvard.edu/healthextra.