Dr Larry Goodyer replies: Monosodium glutamate (MSG) can be used in cooking to impart a meaty taste to the food, and is quite popular among Chinese chefs in some restaurants.
Occasionally, people do report having an intolerance to MSG - suffering from so-called "Chinese Restaurant Syndrome" after eating a meal in which the substance has been used.
This consists of flushing, facial pressure and chest pain, among other symptoms.
By no means everyone seems to be MSG-sensitive and if you feel all right after Chinese restaurant meals in the UK, you will probably not have any problems in Hong Kong.
One word of warning: stay clear of the seafood, however tempting, as there can be an increased risk of food poisoning.
In general, it is safe to eat ethnic food, providing it has been properly prepared.
Dr Larry Goodyer is a lecturer in clinical pharmacy at King's College, London. Contact the Nomad Travel Health Helpline (tel: 0891 633414; calls cost 50p per minute).