Can one drink of alcohol increase risk of heart disease? Reporters are saying a new study says “Yes”. Many people have been advised through print or conversation that a daily glass of wine or beer is a healthy practice. And it might be for some. Many studies have found a longer lifespan in people who drink moderately. People who are heavier drinkers have higher death rates, but so do people on the lower end of the scale when compared to “light to moderate” drinkers. Heavy drinkers have been advised to drink less, while very light drinkers have been encouraged to drink a little more. It has been thought that there is an ideal level of alcohol consumption for best heart health.
The idea that some people are genetically vulnerable to alcoholism is widely known. However, some people seem to be genetically-disposed to drink less. It was assumed that people genetically-disposed to drink less alcohol would have poorer heart health on average than people who drank lightly to moderately because so many of them miss the “golden window” of optimal intake.
Genetic variant is associated with some measures of better heart health
A new study has looked at data on drinking habits health data from over a quarter of a million people who had participated in dozens of different studies. The large amount of pooled data allows for a more powerful analysis and reduces the likelihood that any differences among groups was due to chance. In this pooled data study, researchers compared drinking habits and health of people with a particular gene variant called ADH1B rs 1229984 A-allele had
- lower BMI
- lower blood pressure,
- less interleukin-6 (a marker of inflammation)
- lower levels of C-RP (C-reactive protein, another protein involved in inflammation and associated with poorer health)
- narrower waists
- lower risk of stroke.
Their risk factors for heart disease were 10% lower than non-carriers at each drinking level.
People with theADH1B are faster at metabolizing alcohol. This leads to a rapid increase in acetyl aldehyde (which is toxic and makes you feel crappy and can give you a hangover.) People with this gene variant drink 17% less alcohol than people without the gene. Apparently it puts them off alcohol a bit, but not really all that much. Possibly they just don’t need as much alcohol to feel it’s effects.
One of the things the researchers mentioned in the paper was the possibility that reducing alcohol intake, even if you are a light to moderate drinker might improve your health.
Why this study may be important to the genetically “normal” person.
Many studies have shown that the dose-response relationship between alcohol intake and cardiovascular disease is U-shaped. This is what you would see with vitamin A. Too little is bad for you and too much is bad for you. Moderate is best. This study shows that people with the ADH1B have a linear curve for alcohol. Their risk factors decrease steadily as intake moves from high to low: / that brown slash there is supposed to represent a linear relationship. This means we might want to look a bit more into the dose-response curves for everyone. Or dose-responses for specific groups.
Study limitations and things to consider
Articles in the press are starting to appear stating that lowering alcohol intake is better for everyone’s health. It might. But it might not. It may be true only for ADH1B. They seem to have better heart health even when you compare heavy drinking ADH1B with heavy drinking “normals”.
Correlational studies matter.
As many like to remind themselves and others: Correlation does mean causality (if only I had a quarter for every time the phrase wafts by my ears!) Statistics are a wonderful tool. Epidemiology studies, which are correlational studies, have been incredibly valuable in figuring out what factors influence our health. Human experimental studies are better in many respects. Researchers can control many of the variables. But they are extremely difficult to do and very expensive.
Final take-away: People with gene variant ADH1B may be able to lower their risk of heart disease by drinking less alcohol. This effect has not been observed in people who have other forms of the gene.
Read the original BMJ article here.
Other WODMASTERS articles about alcohol and health:
Holmes, M., M., Asselbergs, F., Sattar, N., Lawlor, D., Whittaker, J., Davey Smith, G., Mukamal, K., Psaty, B., Wilson, J., Lange, L., Hamidovic, A., Hingorani, A., Nordestgaard, B., Bobak, M., Leon, D., Langenberg, C., Palmer, T., Reiner, A., Keating, B., Dudbridge, F., Casas, J. et al . (2014). Association between alcohol and cardiovascular disease: Mendelian randomisation analysis based on individual participant data BMJ, 349 (jul10 6) DOI: 10.1136/bmj.g4164