My question is about nutritional supplements, specifically androstenedione and its closely related cousins. I have a five-day-a-week workout routine, and I have been searching for a supplement that will give me the greatest benefit for all of that hard work. I am, however, very concerned about the negative effects of some of these unregulated supplements. My question then is, what kind of side effects can I truly expect from using one of the male hormone precursors like androstenedione? And, in your opinion, is it safe?

For as long as I can remember, I've been using my back muscles when I did sit-ups. In fact, I distinctly remember the first time we did them in second grade. After a few reps, it was already so painful that I was having trouble breathing properly. Being eight years old, however, I didn't realize this was a warning sign and assumed it was normal.

Flash forward ten years, and I have almost no strength in my abdominal muscles. I've tried to teach myself to do curl-ups properly, but no matter how hard I try, I can't even lift my head without using my back muscles. Exercise balls are no help either. Even when I concentrate on using my abs to keep myself steady, my back is still doing 95% of the work.

So, in short, I have two questions: Am I at risk for having damaged my back from years of abuse, and how can I work on strength training my abs now?

Almost every place that I go to, I see stores and stores just devoted to selling vitamins and more vitamins, and I was wondering what the benefits are of a normal healthy person taking vitamins daily. Are there any risks for a normal healthy person who doesn't take vitamins? Will the person taking vitamins' health be improved or have longer longevity? Will the person not taking any vitamins be as healthy as the person who is taking them? And also, what will happen if a person takes more than he or she should consume every day?

I eat lots of different kinds of lentils but don't know much about their individual nutritional properties. Are certain kinds of lentils healthier than others? What are the different calorie and protein figures for different kinds of lentils?

Is milk good or bad for you?

I have bowlegs. It is quite frustrating because I cannot do exercises that isolate and tone the thighs (lunges, squats, etc). When I do squats, my pressure/force comes from the calves and the knees, but not the thighs. Reason being is that the legs are not properly aligned, and pressure/force cannot go up to the thighs. It even hurts when I do squats because they involve bending the (crooked) knees. Are there any alternative thigh exercises?

I am 18 years old and I am determined to lose a few pounds and tone my body by the end of May. I just began running and I'm starting off by running a mile and hope to work up to a four-mile run four or five days a week. My diet is generally a bowl of cereal in the morning, and a turkey or ham sandwich with some type of fruit and a bottle of water. Dinner is something different every day, but usually healthy. I also have been doing an ab workout for about seven minutes after I run. Is what I'm doing effective? What are your suggestions?

I was told to eat foods with pectin. All I know is that apples have pectin. Do any other foods contain pectin?

Do dried blueberries have the same health benefits as fresh blueberries?

I know most of us have seen the ads to buy various muscle toning equipment that uses electric pulses to "build more tissue" (hypertrophy), and I was wondering what you thought about this way of "toning muscle." Also, if you knew where else I could go to further my research on these sorts of devices?

Thank you very much for your help in advance.