Q: Everyone is on the gluten-free bandwagon these days, but I can't figure out if it's something I should avoid or not? What's the story? -- Daisy F., Durham, N.C.

A: Gluten-free diets are more popular now because we've developed ways -- some based in science and some using trial and error -- to identify who has trouble digesting this protein found in wheat, rye, barley and countless processed foods (including soy sauce and ketchup!).

There are three conditions that make it necessary to avoid gluten or wheat: celiac disease, wheat allergy and gluten sensitivity. CD is an autoimmune condition in which eating gluten causes inflammation of the mucosal lining and the villi (tiny fingerlike tissue that help the body absorb nutrients) in the small intestine. People with this condition are vulnerable to malnutrition, anemia, osteoporosis, unexplained neurological syndromes and infertility, not to mention severe gastrointestinal upset. A wheat allergy triggers a histamine reaction in the gut, on the skin and/or in the respiratory system. Gluten sensitivity is neither autoimmune nor allergic, but it can cause gastrointestinal upset as well as bone or joint pain, muscle cramps, weight loss and fatigue.

More than 2 million people in North America have CD, and a large number of others have a negative reaction to gluten or wheat. For all these folks, eliminating wheat or gluten from their diet is essential for improved health. Their challenge is to find other sources for the nutritional bounty that 100 percent whole wheat, rye and barley contain: soluble and insoluble fiber, many B vitamins, protein and a wide range of essential minerals such as selenium, copper, magnesium, zinc and manganese.

Daisy, if you don't have unexplained skin irritation or rashes, cramping and diarrhea after eating, or chronic fatigue, chances are your body can handle wheat and gluten.

Q: I'm 25, and I just broke up with my high school boyfriend -- the only guy I've ever been with. I've never had to worry about STDs, but I read they're epidemic in the U.S. Before I start dating again, what's your medical advice? -- Randi G., Delray Beach, Fla.

A: It's true that sexually transmitted diseases are reaching epidemic proportions here and in Canada. But safe sex can be fun sex -- if you're smart, with a loving partner, are both committed to each other's health and happiness and, of course, if you use condoms. (They do come in all kinds of keep-you-safe-and-entertained versions!)

But first some facts: The Centers for Disease Control and Prevention says about 20 million new STD cases are reported annually, on top of the 110 million that already exist. They include everything from HIV and gonorrhea to chlamydia (very common, it can cause infertility if untreated; women should be tested for it annually) and trichomoniasis (the most common curable STD, caused by a parasite, it affects 3.7 million people, 70 percent without symptoms; but it can lead to preterm births and make you more susceptible to HIV). And then there's HPV (human papilloma virus), that's associated with cervical cancer in women and more rarely throat and penis cancer in men. It accounts for the majority of new infections.

Here's what you can do to protect yourself:

» First, get an HPV vaccine if you haven't contracted the virus already -- it's usually covered by insurance for anyone up to age 26. Condoms don't completely protect against HPV or herpes, unfortunately. (We suggest that those of you who are older than 26 and starting to date anew ask your doctor about getting the vaccine.)

Then have any new partner get tested for HIV; it's just smart.

» Have an annual pelvic exam at your gynecologist's office to check for various STDs, such as trich, chlamydia and bacterial vaginosis (caused by an imbalance of good and bad bacteria in the vagina).

» Be safe and find someone who cares as much about a healthy relationship as you do.

Mehmet Oz, M.D. is host of "The Dr. Oz Show," and Mike Roizen, M.D. is chief wellness officer and chair of the Wellness Institute at Cleveland Clinic. Email your health and wellness questions to Dr. Oz and Dr. Roizen at youdocsdaily@sharecare.com.