Wine is known to be good for heart. However, are other forms of alcoholic drinks, viz. beer, malt liquor, as well as distilled spirits, equally beneficial for heart? And if yes, how much alcohol one should drink daily to get this benefit?
How does alcohol consumption help cardiovascular health?
Past studies have shown that moderate level of alcohol consumption is beneficial for the heart health. It reduces the risk of developing cardiovascular disease.
The exact mechanism by which the alcohol consumption helps the heart is not known. One guess is that alcohol consumption increases HDL-cholesterol. Another mechanism proposed is the reduction in the stickiness of the platelets to the inner lining of the arteries, which in turn reduces the chances of blockage formation.
A good way to quantity heart health is to measure Arterial Stiffness, which shows how inelastic the inner walls of the artery are. An artery that is stiff, or hard, will not be able to adjust to blood pressure changes. So, the stiffness alters functioning as well as the structure of the artery.
Arterial stiffness has been found to correlate independently with both cardiac morbidity (illness) as well as mortality (death). As a result, researcher consider arterial stiffness as a surrogate marker (or a proxy) for heart health.
Arterial stiffness can be measured using Pulse Wave Velocity (PWV) estimation. Arterial pulses move faster in stiffer arteries. So PWV estimation can give a very accurate measure of the arterial stiffness. It is also a non-invasive technique, which means nothing is inserted in the body, increasing its safety.
In earlier studies, the level of alcohol consumption have been found to have a U-shaped relation with arterial stiffness. That means, low consumption means higher stiffness. Moderate consumption means lower stiffness, while high consumption again increases the stiffness.
The increase in stiffness with high alcohol consumption is perhaps because of increased alcohol-related metalloproteinase activity.
The past studies have been cross-sectional studies. Such a study is a snapshot at a particular time. One takes a certain number of candidates and measures various parameters at the same time: alcohol consumption, arterial stiffness, and many other variables. However, since they measure everything at the same time, such studies fail to account for changes in drinking over time (did the person start drinking more recently?). Such studies also put ex-drinkers on par with non-drinkers, since neither of them are drinkers when the study is done.
A better way to study the relation is a longitudinal study. In such a study, you observe candidates over a period of time. This helps you get a better understanding of development of arterial stiffness over a period of time with alcohol consumption. Such study also helps you note the improvement with discontinuation of alcohol.
The cross-sectional as well as longitudinal studies are observational studies. They do not interfere with their subjects. However, because of the nature of the longitudinal study, it can give a better understanding of the cause-and-effect relationship between the variables studied.
Results of the earlier studies
Four earlier studies have shown these results:
- Over 9 years, daily consumption of more than 23 g of alcohol increased arterial stiffness (two studies).
- Over 5 years, twice-a-week or more consumption of alcohol is associated with significant arterial stiffening.
- Over 6 years, moderate drinkers with normal BP had significantly lesser arterial stiffening than non-drinkers; while heavy drinkers with normal BP had significantly higher arterial stiffening than non-drinkers.
Results of the new study
A study published in 2017 in the Journal of American Heart Association tracked alcohol consumption over 25 years and measured arterial stiffness. The study involved nearly 7,000 men and 3,500 women between the ages of 34 to 56 years. Their arterial stiffness assessment was done every 4-5 years. After 25 years, here are the conclusions:
- Moderate drinking (less than 112 g alcohol per week) was found to be associated with lower arterial stiffness
- Heavy drinking (more than 112 g alcohol per week) was found to be associated with higher arterial stiffness
- People who stopped drinking was found to show accelerated arterial stiffening with time
- These effects were more pronounced (significant) in men than in women
Understanding the results
Let us first put these numbers in perspective. It is hard to understand drinking in terms of grams of alcohol. Let us see if we can grasp these in terms of our regular alcohol glasses, or pegs.
Definition of a Standard Drink
Here is the definition of a standard drink in the USA.
One fluidic ounce is roughly 30 ml of liquid. So we can calculate alcohol contents of a standard drink as follows:
1 regular beer has 12 fl oz or 360 ml of beer. 5% of it is alcohol. So it has about 18 ml of alcohol.
Similarly, one standard drink of other alcoholic drinks, viz. 255 ml of malt liquor, 150 ml of table wine, 105 ml of fortified wines (such as sherry or port wine), 75 ml of liqueurs, cordials or aperitifs, and 45 ml of hard liquors (such as whiskey, rum, gin, vodka, tequila — the 80-proof distilled spirits) will also have 18 ml of pure alcohol.
Specific gravity of alcohol is 0.78 g/ml. So 18 ml of alcohol will be 14 g of alcohol.
Thus, one standard drink of any spirit will have the same amount of alcohol, 14 g. Since a standard drink of any alcoholic kind contains the same amount of pure alcohol, it represents the same amount of drunkenness.
Since the study considers moderate drinking as less than 112 g of alcohol a week, it refers to 8 standard drinks a week.
Now if you think you understood it all, consider this:
A standard drink in the USA is 18 gm of pure alcohol. But the definition of a standard drink is different for different countries: Japan and Austria (25 gm), Hungary (21.5 gm), Switzerland and Finland (15 gm), the UK and Iceland (10 gm), and luckily, for most of the other countries, it is 12.7 gm. Read: What is a Standard drink?
So, remember that the study talked about moderate drinking being less than 112 g of alcohol a week. And adjust the number of standard drinks accordingly, based on your country.
Why former drinkers might be getting worsening heart health?
The study authors have commented that the increase in heart disease in former drinkers could be because of ‘sit-quitter’ phenomenon, where people quit or reduce drinking because of ill-health. So such people may be getting worse heart health not as a result of stopping drinking but maybe as a cause of stopping to drink.
Drink less than eight standard drinks (the USA definition) a week for heart protective benefits.
This benefit is not coming from any special ingredients in alcoholic drinks such as wines. All alcoholic drinks confer the same benefit. So it must be originating from the pure alcohol itself.
Please do not start drinking alcohol for this benefit. There are numerous bad effects of alcohol.
First published on: 23rd February, 2017