WHAT IT IS: The consumption of bird's nest is seen as a symbol of wealth, power and prestige.
Known as yanwo in Chinese, it has been used medicinally in traditional Chinese medicine (TCM) as far back as the Tang and Song dynasties.
The journal Food Research International reported in 2005 that the majority of edible bird's nest that is traded worldwide comes from just two species of swiftlets.
They are the white-nest swiftlet and the black-nest swiftlet, whose habitats range from the Nicobar Islands in the Indian Ocean to the sea caves in the coastal regions of Thailand, Vietnam, Indonesia, Borneo and the Palawan Islands in the Philippines.
The nests are built almost exclusively by the male swiftlet in approximately 35 days and they are composed almost entirely of a glutinous material found in its saliva.
The journal reported that the cleaning process is so tedious that it takes a person eight hours or so to clean about 10 nests.
It involves soaking the nests in water until they grow soft, then manually removing small feathers with tweezers.
After that, the nest strands are rearranged and moulded into various shapes.
Often referred to as the "caviar of the East", a tael (37.6g) of bird's nest sold at Eu Yan Sang retail outlets costs between $128 and $788, depending on their grade and whether they are house nests or the less common cave nests.
HOW TCM USES IT: Bird's nest is classified as a neutral food that is neither heaty nor cooling. Its sweet flavour means it exhibits a nourishing property as well.
It is said to move through the meridians of the lungs, stomach and kidneys.
Meridians are channels in the body through which qi (vital energy) travels.
Bird's nest is used to moisten the lungs and stomach when they lack yin, the element responsible for cooling organs.
A balance of yin and yang - which is linked to heat - in the body is required for good health.
Mr Sim Beng Choon, a TCM physician at Fu Yang Tang Medical Hall, said a person whose lungs lack yin may experience thirst, a dry and sore throat, as well as a red tongue and a dry cough, possibly with blood-streaked sputum.
A person who does not have enough yin in his stomach may lose his appetite and suffer from a dry mouth and constipation.
TCM believes that the health of the lungs affects that of the skin, so nourishing the lungs with bird's nest can improve one's complexion and address dry skin too, he added.
However, bird's nest is rarely used in TCM prescriptions because of its steep price, he said. It is usually cooked with rock sugar or red dates.
Ms Zhang Ruifen, a TCM physician at Eu Yan Sang, said bird's nest is used to boost qi in the body, a lack of which can give rise to fatigue and breathlessness, among other symptoms. Yet the effect of bird's nest on the body's qi is not as strong as that of ginseng, she added.
WHO IT IS FOR: Mr Sim said elderly people, especially those who have battled illnesses, tend to be weak in yin and qi and can benefit from eating bird's nest.
It would help to resolve prolonged ailments like chronic coughs, but is not intended to treat acute coughs.
He advised people to eat bird's nest in the mornings - the time when the digestive system, according to TCM principles, is believed to be the most active - for optimal absorption of nutrients.
Ms Zhang said cancer patients undergoing radiation or chemotherapy tend to exhibit "dry symptoms", such as dry mouths, throats and skin, which bird's nest can help with.
Who should avoid it
WHO SHOULD AVOID IT: Those who have a lot of phlegm in their throats, a sign of dampness which causes illnesses, should refrain from taking bird's nest, said Ms Zhang.
She advised adults to consume no more than one big raw bird's nest a day, while a 12-year-old should have about half of this portion.
Younger children should consume a correspondingly smaller portion of the Chinese delicacy, she added.
WHAT RESEARCH HAS SHOWN: A 2001 clinical study in Singapore found that bird's nest is the most common cause of food-induced anaphylaxis (a serious allergic reaction) in children, even surpassing other well-recognised food allergens, such as cow's milk or eggs for younger children and peanut or crustacean seafood for older children.
This severe allergic reaction can cause breathing difficulties, dizziness and hives - symptoms which are similar to those induced by egg-like proteins.
Recipe: Peppermint bird's nest porride
RECIPE: Peppermint bird's nest porridge
15g dried or fresh peppermint leaves 37.5g uncooked white rice 2 tsp bottled bird's nest Dried tangerine peel, a pinch Sugar or salt, to taste 250ml water
1. Soak the dried tangerine peel in water until it becomes soft. Remove its pith before use.
2. In a pot with 250ml of hot water, add the peppermint leaves and cover with a lid.
3. Filter out the peppermint leaves after soaking them for 10 to 20 minutes. Keep them for use later.
4. Use the mint-flavoured water to cook the rice and tangerine peel for 30 to 40 minutes, until it becomes porridge.
5. While the porridge is hot, add the bird's nest and peppermint leaves.
6. Finally, add salt or sugar to taste.
Source: Eu Yan Sang International
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