What it is: Cassia seeds are unusual in appearance, being cylindrical and flat on either end.
The seeds, measuring 2 to 4mm in length, are valued in traditional Chinese medicine (TCM) for their host of health benefits.
Ms Joanna Liew, a TCM practitioner at BaoZhong Tang TCM Centre, said the trees, which are in the Fabaceae family, are grown in the provinces of Jiangsu, Anhui, Guangxi and Sichuan in China.
They are typically grown on slopes or beside river streams. The seeds, known as juemingzi in Chinese, are collected in the autumn when they have ripened and then dried in the sun.
Both the raw and the stir-fried seeds are used as medicine, Ms Liew said. The third edition of Chinese Herbal Medicine Materia Medica noted that the untreated herb is better for cooling the liver and expelling wind, and somewhat more moistening for the bowels than the prepared product.
According to the guide, dry, full, brown and glossy seeds of a consistent size are regarded as good quality.
Cassia seeds are sold at 50 cents for a tael (37.5g) at some medical halls here.
How TCM uses it: The cassia seeds, which have a combined taste of sweet, bitter and salty, are considered slightly cold in nature.
They move through the meridians of the liver and large intestine.
Meridians are channels in the body through which qi (vital energy) travels. A good flow of qi in the body is needed for good health.
When there is a build-up of heat in the liver, it is said to lead to the phenomenon of "liver fire", which flares up in the body to affect the eyes and head.
As a result, said Ms Liew, a person would have red, bloodshot eyes which are sometimes swollen. Vision becomes blurred and the eyes are often dry, as heat consumes the fluids in the body. It is likely that the person would also suffer from headaches and high blood pressure.
Besides being linked to eye health, the liver is also related to the state of one's emotions. The condition of "liver fire" will cause one to be irritable and lead to a restless sleep, she said.
A slightly cold herb, such as the cassia seed, is then used to douse this excessive heat in the liver.
According to Ms Liew, heat can also accumulate in the liver when one overstrains the eyes with activities such as prolonged use of the computer and late-night reading.
Someone who sleeps late regularly or consumes a diet of fried and spicy food, may also have "liver fire".
The second use of cassia seeds is to moisten the intestines to promote bowel movements.
Ms Liew said the slimy texture of the seed is probably how it helps move stools along the large intestines to alleviate heat-related constipation.
This may arise from consuming heaty food, not drinking enough fluids and not clocking sufficient sleep. Sleeping recharges the body and is important in maintaining its balance of yin and yang.
Yin is the element responsible for cooling organs in the body and this dominates at night, while yang is the element linked to heat and reaches its peak in the day.
If a person stays awake at night, he continues to use his yang which should, in fact, be dormant. This disrupts the balance in the body and gives rise to ailments.
Constipation arising from heatiness results in small, dry and hard stools that are so difficult to pass it may lead to bleeding, Ms Liew said. TCM practitioners would then recommend the use of cassia seeds for the patient.
Who it is for: The elderly are prone to developing constipation and are likely to benefit from the use of cassia seeds.
Young people who spend long hours playing computer games, keep late nights or love spicy and fried food could also benefit, as they would probably have "liver fire".
Who should avoid it: This herb is not suitable for people who have normal-sized but loose stools that are difficult to excrete, Ms Liew cautioned. This is because their problem is likely due to having insufficient qi to move the stools along the intestines, which would require other herbs to treat.
Those with weak spleens and stomachs and, hence, are prone to diarrhoea, should not use it too, as cold herbs tend to aggravate digestive problems.
Pregnant women are generally advised not to consume any cold herbs which may cause contractions in the womb and threaten the pregnancy.
What research has shown: The journal Nutrition Research And Practice reported in 2008 that cassia seeds had a beneficial effect on the control of blood glucose in rats after a meal.
Normal and diabetic rats fasted for 12 hours overnight before being divided into two groups. One group was fed maltose and cassia seed extract, while the control group had the same dosage of maltose and water.
The study found that among normal rats, those in the control group had a blood glucose increment of 96.5 per cent compared with 9.5 per cent in the cassia seed group.
For the diabetic rats, blood glucose rise was 83.4 per cent in the control group and just 28.9per cent in the cassia seed group, showing the efficacy of the cassia seeds in preventing big spikes in blood glucose levels.
Modern medicine says
Modern medicine says
Red and swollen eyes are signs of inflammation, which is the body's own immune response to disease, said Dr Julian Theng, medical director of Eagle Eye Centre.
Common eye ailments that give rise to red, swollen and painful eyes include dry eyes, conjunctivitis (often referred to as sore eyes), corneal ulcer, acute uveitis, acute glaucoma and injury or trauma to the eye.
A corneal ulcer is an open sore on the transparent front part of the eye known as the cornea.
Acute uveitis is an inflammation of the inside of the eyes that occurs suddenly and typically lasts up to six weeks, while acute glaucoma is a sudden increase in eye pressure.
A person suffering from any of the above conditions may also experience tearing and have sticky eye discharge. Those with acute glaucoma also have a marked loss in visual acuity, said DrTheng.
Doctors address the symptoms by treating the underlying cause, but do not use cassia seeds for this.
Dr Theng said there is no medical evidence to suggest that consuming cassia seeds has any direct beneficial effect on the eyes.
Doctors typically prescribe topical eyedrops to lubricate dry eyes, and antibiotic or antiviral eyedrops and creams to treat conjunctivitis and corneal infections caused by bacteria and viruses.
When it comes to acute uveitis, anti-inflammation eyedrops or oral medication is given.
Patients with acute glaucoma require eye pressure lowering eyedrops, oral medication and, often, laser treatment to burn a minute hole in the iris to alleviate a sudden rise in eye pressure, he added.
Dr Theng advised people to consult an ophthalmologist if their red eyes are persistent, painful or cause blurred vision.
For healthy eyes, have a well-balanced diet, regular exercise, ample rest and practise proper eye hygiene, he said.
Most eye infections are spread via hands and fingers, when a person rubs his eyes.
He said: "Ensure your hands are always washed and clean before you touch your eyes, such as when putting on contact lenses or when removing discharge or dirt from your eyes.
"Clean tissues or towels are useful for this purpose too."
While it may be instinctive for one to rub one's eyes when they are itchy, Dr Theng warned that doing so vigorously can cause accidental abrasions on the cornea.
Instead, he advised people to use lubricants or sterile or clean saline washes to rinse the eyes to ease the itch.
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