Facial flushing is a sign of 'alcohol intolerance'
“Flushing red after drinking is bad sign for boozers,” Metro reports.
A Korean study suggests that people who do flush after drinking could be more vulnerable to the harmful effects of alcohol on blood pressure.
The study compared the risk of high blood pressure in men who flush after consuming alcohol, compared with “non-flushers”.
It found that when “flushers” have more than four drinks a week their risk of high blood pressure was increased to a potentially hazardous level. While in non-flushers the risk only increased when they had more than eight drinks weekly.
Researchers speculate that “flushers” may have a faulty version of a gene ALDH2, which, when working, breaks down a substance in alcohol called acetaldehyde. And it could be excess amounts of acetaldehyde that is causing both facial flushing and high blood pressure.
However, a causal relationship between the two remains unproven.
It would also be dangerous to conclude that, if you are not a flusher, you can happily booze with impunity. Excess alcohol consumption, whether or not it turns the face red, can increase the risk of liver disease, many types of cancer and mental health problems. Read more about the dangers of drinking too much alcohol.
Where did the story come from?
The study was carried out by researchers from Chungnam National University and University of Ulsan, both in South Korea. There is no information about external funding.
The study was published in the peer-reviewed medical journal, Alcoholism: Clinical and Experimental Research.
It was covered fairly, if uncritically, in the Mail Online, who pointed out that no direct link between flushing and high blood pressure has been established.
Metro’s coverage was not so good. It reported that a “stingy” five drinks a week is enough to do damage for “scarlet-cheeked tipplers”, but did not point out that in the study a “drink” was defined as 14g of alcohol according to US guidelines. (In the UK a unit equals 8g of alcohol).
What kind of research was this?
This was a cross-sectional study that looked at the role of facial flushing after drinking, in the relationship between alcohol consumption and high blood pressure.
Cross-sectional studies look at all data at the same time, so cannot be used to see if one thing follows another, but they are useful for showing up patterns or links in the data.
The researchers point out that excessive drinking is a known risk factor for high blood pressure and that facial flushing is a well-known symptom of alcohol intolerance.
It indicates a gene mutation with the ALDH2 gene that makes it hard for the body to break down acetaldehyde, the compound produced when alcohol is metabolised by the liver.
They also point out that the prevalence of alcohol-related facial flushing differs across ethnic groups, and is more commonly found in Asians, including Koreans. They suggest that acetaldehyde, which causes facial flushing, may also be one of the causes of alcohol-related high blood pressure.
What did the research involve?
The participants in this cross-sectional study consisted of 1,763 healthy adult men who received comprehensive medical health check-ups between June and December 2010. They were categorised as:
- non-drinkers (288)
- those who drank and experienced facial flushing with alcohol consumption (527)
- those who drank and did not experience the flushing response (948)
Men who had taken any medication except anti-blood pressure drugs were not eligible.
Data on all the participants was collected from their medical records. This included information on blood pressure, drugs to control blood pressure, age, body mass index (BMI), waist circumference, smoking, exercise, drinking status and flushing response related to drinking.
The researchers defined 14g of alcohol as a standard drink, according to US guidelines. The men’s weekly drinking was calculated based on drinking frequency per week and drinks per drinking day. Drinkers were divided into categories:
- four drinks or less
- more than four and up to eight drinks
- above eight drinks per week
They say these drinking categories are relatively easy to use in Korean medical interviewing because one bottle of soju contains four standard drinks. Soju, hugely popular in Korea, is a vodka-type drink traditionally distilled from rice.
A simple questionnaire was used to assess the facial flushing response. People were asked if they experienced flushing in the face immediately after drinking a glass of beer, with responses categorised as always, sometimes, or never. All three categories of flushing (current always, former always, and sometimes) were classified as flushing.
They analysed their results using standard statistical methods. They adjusted their results for age, body mass index, exercise status and smoking status.
What were the basic results?
Researchers found that 35.7% of the men had facial flushing reaction to alcohol (a higher percentage than that found in Westerners). When compared to a reference group of non-drinkers:
- In flushers, the risk of high blood pressure was significantly increased when they consumed more than four drinks per week and up to eight drinks (odds ratio (OR) 2.23, 95% confidence interval (CI) 1.22 to 4.08) and above eight drinks (OR 2.35, 95% CI 1.52 to 3.63).
- In non-flushers, the risk of high blood pressure was increased with alcohol consumption of more than eight drinks per week (OR 1.61, 95% CI 1.15 to 2.27).
- The risk of flushers having high blood pressure was greater in the flushing groups compared with the non-flushers. For those consuming more than four and up to eight drinks (OR 2.27, 95% CI 1.16 to 4.43), and above eight drinks (OR 1.52, 95% CI 1.02 to 2.26).
Other comparisons made, including those for people drinking less than four drinks a day, were not statistically significant.
How did the researchers interpret the results?
The researchers say their findings suggest that high blood pressure associated with alcohol consumption has a “lower threshold value” and higher risk in flushers than in non-flushers.
Koreans and other Asian groups, who have higher rates of flushing after alcohol, may therefore be at increased risk of high blood pressure. The researchers also point out that overall, the drinking amount that increased the risk of high blood pressure was lower than in Western studies, because of ethnic differences in body type and weight.
Doctors, they argue, should consider evaluating their patients’ ethnic group and flushing response as well as drinking amount, when assessing health.
There are several limitations to this cross-sectional study:
- This type of study cannot tell us if facial flushing is related to a higher risk for high blood pressure, a health problem that is associated with many factors.
- It relied on men self-reporting both drinking habits and whether or not they flushed afterwards.
- The subjects were all Korean adult males, so the conclusions may not apply to other groups.
That said, the study may be useful in pointing up differences in the risks of alcohol consumption for Koreans and other Asian groups and points the way to further study of the mechanisms for any increased risk.
However, it would be dangerous to conclude from this study that “non-flushers” can drink with impunity. Excess alcohol consumption, whether or not it turns the face red, is associated with many risks to health, of which high blood pressure is just one.
While the association between flushing and a dangerous spike in blood pressure levels is inconclusive, if you do find yourself flushing after a few beers, it could be that you are intolerant to alcohol – in addition to the normal toxic effects.
Excess levels of acetaldehyde could have other dangerous effects aside from blood pressure levels.