1) I often have a bad taste in my mouth, and bad breath as well, I assume. This doesn't stem from poor hygiene: I brush my teeth at least three times a day, and usually more. I'm wondering if there is anything I can do about this. Could this be a symptom of some sort of nutritional deficiency? I think my diet is pretty bad, although I'm working pretty hard on getting more protein and eating less fat. I've also been nauseous a lot lately, and vomiting some. Could that be related?

2) Like many people, I often have an embarrassing bad breath. Listerine and other mouthwashes won't be of any help for this chronic problem. There are lots of products available to get rid of "volatile sulfur compounds (VSC)" - that supposedly cause this — and I just don't know which one I should try. Also, what's your opinion on tongue-brushing?

1) Which is better for you, tap or bottled water?

2) How bad is the water here in New York City? Do you recommend drinking filtered water, or does it really make a difference?

1) This is in reference to your Missed periods Q&A. Another cause of missed or late periods is PCOS (polycystic ovary syndrome). A lot of health care providers don't seem to be aware of this syndrome. In this syndrome, missed or irregular periods are caused by unusual hormone levels, sometimes in combination with insulin intolerance. Because missed and irregular periods cause scar tissue build-up in the uterus (which may cause endometrial cancer) and may cause infertility, it is important that your readers know to ask their health care provider about this syndrome. There are obviously other symptoms and complications, but I just thought that I might mention it to you so that you might read up on it for your readers. Thank you.

2) I was recently diagnosed with polycystic ovary syndrome (PCOS). I'm only 17 and am afraid that this will affect my chance of having children. Should I worry? Also, I know birth control pills will help me regulate my period, but if I take them, will it stop the effects PCOS has on me? Like me gaining rapid weight, missed periods, and losing my hair? This is really worrying me. Can you inform me on this syndrome?

What is the significant difference between a product that is antiseptic and one that is antibacterial? All of the antiseptic mouthwashes I find have a great amount of alcohol in them. This can be very irritating to the mouth. I have found one that is alcohol free, but it says it is antibacterial.

Thanks for your help.