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?

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.

So far I have been extremely impressed by your service. I trust you with a question which I know many people share: Are whitening toothpastes detrimental to the longevity of one's teeth?

I was told by my dentist that my teeth eroded, due to consumption of too much acidic food. I would like to know what kind of food causes tooth erosion. Do you have a list of these foods?

I was having a conversation with my roommates about pop and coffee and we were wondering which is worse for your teeth, the pop or the coffee? And what do they do to your teeth when you drink them?

What causes fever blisters on lips and how should they be treated? Also, what is the difference between fever blisters and shingles?

What are the long-term side effects of substituting Vivarin for sleep? Last semester, I averaged only about three hours of sleep a day, and it doesn't look like this semester will be terribly different.

Thanks in advance.

I just came here this fall. Since then, my nose has been bleeding occasionally without any injury. My friend told me it was because of the dry air of U.S. Is he right? How can I prevent this situation? I also have a problem when I brush my teeth. My gums are always bleeding and not just a little!! What should I do? Thanks.