I'd like to try a teeth whitener, but worry it will be harmful or painful.

I'm no expert on teeth, so I asked my favourite orthodontist. Teeth whiteners do work, but there may be a price to pay: if you have gum recession and exposed roots, you will have heightened sensitivity - in other words, pain. Also, caps and bridges don't take up the bleach in the same way as natural teeth, and it's hard to get them all the same colour; the enamel becomes slightly more porous, too, which will have future implications. In-practice whitening produces a faster result than home-whitening at night. The pain after home-whitening can be intense, and the effect is only temporary, so you'll need to re-whiten when the teeth eventually darken. And ensure your dentist is registered with the General Dental Council - otherwise, if things go wrong, you may have difficulties with repair or compensation.

What are the main symptoms of ovarian cancer? Two friends weren't diagnosed until fairly late in its course, and I don't want that to happen to me or my daughters. My mother's sister died from it.

Early symptoms are unfortunately relatively vague and very similar to those of irritable bowel or menstrual fluid retention. The best advice comes from a group of experts supported by the Eve Appeal and Ovacome, a patients' support group. They list pelvic and abdominal pain, increasing waist measurements, persistent bloating, difficulty in eating and feeling full all the time as symptoms given by women who were later found to have ovarian cancer. With your family history, let your doctor know about your fears. Survival rates are improving - 90% of women diagnosed early survive for more than five years.

We're travelling to south-east Asia. What foods should we avoid to prevent us getting diarrhoea?

Raw or undercooked meat, fish and shellfish, unpasteurised dairy products, tap water and ice cubes, cold sauces, greens, cooked food that's been allowed to stand at room temperature for any time, and anything from street vendors, unless cooked in front of you and still hot. Even then, you may not be able to avoid illness. Wash your hands before eating. Travellers' diarrhoea is the most common illness of people who travel internationally, affecting 20-60%, depending on destination.

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