In recent years, the idea that alcohol flush reaction is a sign of high alcohol tolerance and fast metabolism has become a mainstream view. Is it true that those who get flushed while drinking alcohol have high alcohol tolerance?

A glass of wine is enough to turn my face red, get my pulse racing and make me feel ill, so I for one don't agree with the above belief, it does not apply to me at least.

From a physiological point of view, alcohol is not needed by the body and it cannot be transformed into energy for later use. Once it enters the body, it is metabolised in one go. Only about 10% of it will be discharged in its original form directly from the body through urine, sweat or respiration. The remaining 90% will eventually be subject to oxidative metabolism through the liver. In view of this, I try my best to refrain from alcoholic beverages lest my health be gone forever. However, with luscious wines and choicest delicacies lavished upon me, how could I decline my friends’ hospitality? And so, I put my own alcohol tolerance to the test over and over again.

The way the body breaks down alcohol is rather complicated; it involves various enzymatic hydrolysis and metabolic systems. The major pathway is via the liver where ethanol is transformed into acetaldehyde by alcohol dehydrogenase (ADH), and then into ethanoic acid by acetaldehyde dehydrogenase (ALDH). Through the citric acid cycle, the ethanoic acid will be converted into carbon dioxide and water, which will eventually be discharged from the body.

Due to genetic variation, about 40% to 50% of Han Chinese and Japanese have inactive ALDH, inhibiting acetaldehyde metabolism. With the body unable to break down the acetaldehyde, it builds up in the blood. This affects the nervous system and leads to symptoms such as nausea, faster heartbeat, headache, as well as rapid capillary dilation in the chest, neck and face, which gives the redness of alcohol flush reaction. This is in fact an effective self-protection mechanism against alcohol intoxication—the body is sending out a signal that no more alcohol should be consumed. I am glad I am one of those people with this alert system.

Gehua tea as a hangover cure

As I know I have a low alcohol tolerance, I usually drink some Chinese herbal teas before consuming alcoholic drinks to help limit the effects of alcohol. 

Gehua tea: brew 15g of gehua with boiled water and drink it before consuming alcoholic beverages in order to prevent a hangover.

Gehua, also called Pueraria Flower, is among the entries in Chinese Materia Medica known to be efficacious in relieving effects of alcohol and enlivening the spleen. According to research findings, Gehua, which contains isoflavone, is able to activate the ADH and ALDH in the liver as well as accelerate the breakdown and absorption of ethanol and acetaldehyde in the blood and the liver, lowering the concentration of ethanol therein. It is also proven effective in absorbing and metabolising the ethanol and acetaldehyde in the blood and the liver, hence improving ethanol- and acetaldehyde-related metabolic disorders.

Flushing alcohol out of the system

Lobed kudzuvine root and edible kudzuvine root: can be used to make a decoction or administered as a powder and stirred in hot water until it resembles porridge. 

Both types of kudzuvine root are listed in Chinese Pharmacopoeia as efficacious in expelling pathogenic factors from muscles for clearing heat as well as stimulating saliva production and quenching thirst. They are good for curing dizziness and headache as well as relieving the toxic effects of alcohol. Research findings show that the puerarin, daidzin and daidzein in lobed kudzuvine root are able to regulate the activeness of enzymes involved in alcohol metabolism.

Zhi Ju Zi (Semen Hoveniae) can be prepared as a decoction. It is documented in the Drug Standards of the Ministry of Public Health: Chinese Herbal Medicines as a cure for alcohol-related diseases. It is efficacious in clearing the inner heat and inducing urination as well as relieving the toxic effects of alcohol. Research findings show that Zhi Ju Zi, which contains glucose, fructose and peroxidase, is able to clear the body of the free radicals produced when alcohol is metabolised, hence minimising the damage to the liver caused by ethanol. Extracts from Zhi Ju Zi water-based infusion can reduce the amount of ethanol absorbed by the gastrointestinal tract and strengthen the gastrointestinal first-pass effect, in other words, the concentration of ethanol is greatly reduced before it reaches the systemic circulation which supplies oxygenated blood to and returns deoxygenated blood from the tissues of the body. Zhi Ju Zi can also enhance the activeness of dehydrogenase, an enzyme in the liver, and thereby speed up the breakdown of ethanol. Moreover, it can speed up the excretion of alcohol by inducing urination.

The above herbs, which function as both medicine and functional health supplement, are relatively mild in nature and to a certain extent useful for relieving the effects of alcohol. It is more efficacious to take them before rather than after alcohol intake.

(This article first appeared on Hong Kong Economic Journal on 1st March, 2018.)