My 13-month-old granddaughter has suffered two tummy bugs in quick succession since starting nursery. How can we build her up again?

In the acute stage, dehydration is the main concern, so encourage her to drink filtered water, fresh fruit and vegetable juices, peppermint, ginger, camomile or rooibosch teas. Avoid dairy products (they irritate the gut), except plain live yogurt, which replaces beneficial bacteria in the gut. A probiotic, multivitamin and mineral supplement daily can also help. Biocare's (0121-433 3727) banana or strawberry acidophilus and Vitaforte banana MVM are both designed for babies. Include fish, chicken broth, and plenty of fruit and vegetables in her diet - particularly bananas, leeks, alfalfa, cabbage, raw crushed garlic and onions - all of which provide nutrients, kill bacteria and boost immunity.

I never had any problems with milk and wheat until after I came down with a stomach bug while travelling, three years ago. I now have stomach cramps with diarrhoea shortly after eating these foods.

Exotic stomach bugs can have a long-term effect on the intestines, and often lead to insensitivities to certain foods. You need comprehensive tests and natural treatment under the guidance of a knowledgeable nutritionist (the British Register of Nutritional Therapists, 0870 606 1284; bant.org.uk). This treatment might include killing off any remaining parasites, avoiding allergenic foods, boosting your immunity and rebalancing digestive function by paying attention to diet, supplements, homeopathics and herbs.

· Emma Mitchell is a natural health therapist. Before following Emma's recommendations, you should consult your GP about any medical problems or special health conditions.

· Send your questions to Wellbeing, Guardian Weekend, 119 Farringdon Road, London EC1R 3ER. Email: ask.emma@theguardian.com.