Crabs are considered a 'cooling' food, and it is believed that eating too many upsets the yin and yang balance of the body. To maintain the balance, strong ginger tea, which is 'heating', is served after the meal.
But another, bigger worry about hairy crabs is that they are high in fat and cholesterol. The Hong Kong Food and Environmental Hygiene website says consumers should 'avoid eating too many hairy crabs, particularly the cholesterol-rich roe and sperm' which, of course, are the very things diners enjoy. Dr Georges Halpern, professor of pharmaceutical sciences at Hong Kong Polytechnic University, says that a crab containing about 50 grams (slightly less than four tablespoons) of roe will have no more than 80mg of fat.
The US Food and Drug Administration guidelines state that an adult should consume no more than 65 grams of fat each day. Fat, scientists now say, comprises 'good' cholesterol and 'bad' cholesterol - HDLs (high-density lipoprotein) and LDLs (low-density lipoprotein). There haven't been any published studies on the breakdown of HDL and LDL levels in hairy crabs, but the 80mg of fat in the crab roe is unlikely to be pure LDL. Besides, as Halpern says, the cholesterol from crab roe 'will not make a lasting difference in your blood level because between 92 and 98 per cent of the cholesterol you have is made by the person.'
And allergy specialist Dr Robert Tseng says: 'If you look at what hairy crabs feed on, they eat healthy things.'
Diners who dissect and eat the whole crab have a better chance of enjoying its nutritional benefits, he says. 'In breaking down the shell in your mouth, your teeth will chew off small but significant amounts of chitin which has the effect of lowering cholesterol,' Tseng says. Chitin tablets, made from crab, shrimp and lobster shells, are claimed to reduce plasma cholesterol. So, hairy crabs seem fine to eat, if you're healthy, as long as you don't over-indulge. 'Enjoy your crab roe,' Halpern says. 'Guilt is much worse.'