You know that antibiotics can upset your stomach, and have probably heard that when taking them you should eat yogurt to help re-populate your gut with the "healthy" bacteria that antibiotics eliminate along with the bad kind. But new research indicates that the damage antibiotics do to your gut lasts a whole lot longer than was previously realized. Stanford researchers analyzed the beneficial gut bacteria in three healthy adult women both before and after each of two cycles on the antibiotic Cipro and found that the drug altered the population of "good" bacteria in their guts significantly, maybe even permanently, and that the effect was exponentially greater after the second round of Cipro (the two rounds were spaced six months apart).
Why should you pay attention to this? The main reason is that experts are increasingly convinced that the flora in our guts are among our most important lines of defense against sickness, both of the short term (read cold and flu) and, possibly, long term variety (think cancer and chronic illness). Also, there's some evidence that lacking the right mix of healthy bacteria inside your belly can cause it to grow thicker on the outside—multiple studies have found differences between the gut flora of obese people and normal-weight people.
All of which makes me want to avoid taking antibiotics if I possibly can. Of course, if your doctor insists on prescribing antibiotics for a bacterial infection, obviously you should follow his or her advice. But what I'm talking about are those times when you go to the doctor looking for a quick fix for the cough/sore throat/inflamed sinuses that have been dragging you down, and your doctor writes you an Rx just in case it will help. Instead of trying to cajole your doctor into giving you something, ask if he or she is positive that you have a bacterial infection, if the antibiotics will definitely help, and if you'd get better just as quickly without them.
And if you're worried that you've wiped out too much of the good bacteria in your belly through past antibiotic use (in my early 20s I took antibiotics every day to keep my skin clear—yikes!), start consuming more probiotic-rich foods such as yogurt (though check the labels to make sure that your brand of choice contains multiple strains of healthy bacteria, because not all of them do). There are also tons of probiotic pills and powders out there in the supplement section, though I'm a little hesitant to recommend them because they're expensive and there seems to be lots of debate on which ones are truly helpful. One more gut-healthy move you can make is to eat more foods considered "prebiotics." While the probiotics found in yogurt are the healthy bacteria themselves, prebiotics are foods that feed them when they're in the gut. Foods including almonds, bananas, berries, and whole grains (the Mayo Clinic site has a longer list) can't be entirely digested in our small intestines, so the bacteria in our large intestines gobble them up instead, meaning adding more prebiotic foods to your diet will result in a healthier digestive system and a healthier (and maybe even thinner?) you.