Is moderate alcohol consumption healthy?

Moderate alcohol consumption small beer mug

I’m going to start this article by revealing my own biases. I’m not sure where the idea that alcohol might be healthy comes from. It’s pretty well established that alcohol is poisonous to all living organisms. That’s why we use it to disinfect surfaces, and why I lather my hands in it several times per hour when I’m working in the hospital. It interferes with the functioning of cell membranes, and at high enough doses it causes the cell membranes to fall apart completely, killing the immersed organisms. That’s the reason it is such an effective disinfectant. It doesn’t take a great leap to think that something that interferes with the functioning of our cell membranes might not be too good for us.

As an interesting aside, the alcohol disinfectant I use to rub my hands in at work is perfectly drinkable, if you’re desperate enough. Which is why the nurses generally remove all the disinfectant containers from the patient’s room if they know the patient has an alcohol addiction.

Alcohol is a very energy dense molecule. One gram of alcohol (a.k.a. ethanol) contains 7 calories. This can be compared to carbohydrates and protein, which both provide 4 calories per gram, and fat, which provides 9 calories. This is probably why we’ve evolved the ability to metabolize alcohol and turn it in to energy in the first place. Those of our ancestors who could eat any fermented fruit they happened to come across were less likely to starve. Which is the reason why it’s possible to subsist (for a while at least) on a diet consisting entirely of alcohol. It’s also the reason alcoholics generally develop severe vitamin deficiencies – they’re getting most of their energy needs met from a source that is completely devoid of other nutrients. I don’t recommend.

So where does the idea that moderate alcohol consumption is healthy come from? My guess would be that the companies that sell alcohol have something to do with it. I wouldn’t be the least bit surprised to find that they’d seeded the scientific literature with articles supporting the healthiness of alcohol, just as the sugar industry has seeded the literature with articles supporting the healthiness of sugar. It could also have something to do with the fact that moderate alcohol consumption is part of the mediterranean diet, which we’ve been told for decades is one of the healthiest ways to eat.

Anyway, enough about my various preconceptions. Let’s get to the science. I’m going to focus here on overall mortality, because it doesn’t matter if alcohol for example were to decrease your risk of getting cardiovascular disease but at the same time increased your risk of getting cancer by as much or more. What matters is the overall effect on longevity.

A systematic review and meta-analysis was published in The Journal of Studies on Alcohol and Drugs in March 2016. It sought to answer the question of whether moderate alcohol consumption has a beneficial effect on overall mortality.

The study did one thing in particular that was very important. It sought to correct a mistake that is common in studies of the effects of alcohol on health, which is to lump former alcoholics who are now abstainers in to the same category as people who have been abstainers their whole lives. Obviously, lumping the two groups together will tend to make abstinence look worse than it is, because former alcoholics generally have pretty bad health to begin with, and will tend to have worse than average outcomes going forward, regardless of how much (or little) they now drink.

Support for thinking that this might be a big problem comes from the fact that the J-shaped curves (i.e. the curves that slope down first, and then up, thereby suggesting that moderate alcohol consumption is healthier than both abstinence and heavy consumption) can be seen in observational studies correlating alcohol with a wide range of different disease states. It defies belief that the same curve would be seen for pretty much any disease you care to look at, from deafness to the common cold to dementia, which suggests strongly that the J-curve is caused by underlying poor health in general, and not by the alcohol itself.

Even liver cirrhosis, a disease primarily caused by heavy alcohol consumption, has been found in observational studies to be more prevalent among abstainers than among moderate drinkers, a clear sign that former alcoholics are being lumped in with life-long abstainers, and that this is confounding the results. So in order to truly see if there is any benefit to moderate consumption, these groups need to be separated out from each other, which is what this systematic review did.

The review included 87 studies with a total of four million people. Participants were followed for an average of 13 years. Note that all the studies were observational in nature. Unfortunately, people aren’t generally willing to be randomized to a certain amount of alcohol consumption, so that is the type of data we have to work with. Most likely there never will be a randomized controlled trial in which people are randomly assigned to a certain amount of alcohol consumption.

Unlike randomized trials, observational studies cannot prove the existence of cause and effect relationships, all they can do is show correlations and thereby provide clues. However, if observational studies fail to show any correlation, then you can usually be pretty certain that no meaningful cause and effect relationship exists.

Participants with less than moderate alcohol consumption were divided in to three separate categories. One of these categories consisted of people who had never consumed any alcohol. One consisted of people who had previously consumed alcohol but had now stopped completely – a category that likely to a large extent consisted of recovered alcoholics. And one consisted of people who drank alcohol occasionally, but consumed less than one drink per week.

These categories were compared with people with a “moderate” consumption, here defined as more than one drink per week but not more than two drinks per day. They were also compared with three additional categories representing ever higher alcohol intakes. Just to clarify what we mean by “one drink” – In this case, one drink was defined as around 10-12 grams of alcohol, which is equivalent to a small glass of wine. So, when we say one drink, we don’t mean a gigantic American size wine glass filled to the brim.

So, what were the results?

After adjusting for confounders, the mortality rate was the same among life-time abstainers, people with a low alcohol consumption, people with a moderate alcohol consumption, and even with people with slightly higher than moderate consumption (up to four drinks per day).

When I say it was the same, I mean there were no statistically significant differences in mortality between the groups. Remember that we’re talking about four million people here who were followed for an average of 13 years, so if there is no meaningful difference in a study with that much data, then there is no meaningful difference in reality.

Former drinkers who had now stopped, on the other hand, had a mortality rate in line with that seen in current heavy drinkers (roughly a 40% increased relative risk of dying during follow-up, as compared to lifetime abstinence).

So, what can we conclude?

The J-curve commonly seen in studies of alcohol consumption, suggesting that moderate alcohol consumption is beneficial, is purely a statistical artifact, produced by lumping former heavy drinkers in with people who have never drunk. Moderate alcohol consumption is not healthier than abstinence. So, if you’ve been feeling pressured to drink alcohol because you think it’s good for your health, you can relax. It isn’t.

Interestingly, never drinking any alcohol and drinking up to four drinks per day are equivalent from a longevity perspective. So, if you are one of those people who drink a glass of wine or two with dinner, and you’re concerned that it might be harming your health, you can also relax. The evidence suggests you don’t need to worry.

This is quite surprising to me. I’ve been trained to view someone who drinks four drinks per day as borderline alcoholic, and certainly at high risk of long term health issues. The current official NHS guidelines, for example, say that you should consume at most 10 drinks per week, which is far lower than this data suggests you can safely consume without having to worry about harming your long term health.

So who does need to worry according to this review? Everyone consuming more than four drinks per day on average. As alcohol consumption increases beyond that point, there is a sharp increase in mortality.

Unfortunately, former drinkers who stop drinking appear to remain in the same risk bracket as continuing heavy drinkers, suggesting that the ability to roll back the damage done by prolonged heavy drinking is limited. To be fair though, this is probably another statistical artifact, as many heavy drinkers won’t stop drinking until they’re really sick and quite close to the end of life.

So, to sum up: moderate consumption of alcohol is not correlated with any beneficial effect on longevity, as compared with avoiding alcohol completely. Nor is it correlated with any harmful effect on longevity.

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38 thoughts on “Is moderate alcohol consumption healthy?”

  1. There was a studie somewhere in Sweden where a group of people were taking Vine in a controlled study.
    The aim was to see how it affected the blood fat level. It showed that a low consumption of alcohol was very beneficial. It was among “young” adults. This was with red vine. I saw it on TV a few years ago. So 2 glass of vine for a man and 1 glass for a grown up woman should then be good for you.

  2. I am well into the “Higher volume” category of alcohol consumer, and I accept that this is a somewhat risky activity, but I value the pleasure that drinking nice wine brings me. I am undoubtedly an alcoholic.
    However, it seems to me, just intuitively, that the risks of drinking, say, a bottle of wine per evening (about 10 of your standard 10ml of alcohol drinks) with a reasonably well balanced diet (perhaps a little heavy on carbs, but plenty of fruit, vegetables, legumes; plus supplements earlier in the day to compensate for vitamins and minerals that I read are poorly absorbed in the presence of alcohol) is likely to be far less detrimental to my health than the risk associated with a steretypical down-and-out chugging vodka from the bottle on a park bench with a very poor quality diet.
    But perhaps that is just wishful thinking on my part.

    Are you aware of any studies that have attempted to study different “types” of alcoholism in this way?

  3. 40% relative risk reduction says nothing if we cannot see the absolute risk reduction, and not just in percentage points but also in years – or maybe just months?

    1. I agree, I would like to see absolute numbers, but unfortunately standard practice in systematic reviews is to only provide relative numbers. But the study ran for 13 years and the group studied was middle-aged on average, so it’s reasonable to think at least 10% died over the course of the study. If we guess 10%, we’re probably not far off, in which case a 40% relative difference becomes a 4% absolute difference.

  4. Excellent! It is good to know that I can still occasionally enjoy a dirty martini or glass of wine and not endanger my liver. There are some alcoholic tipples that I enjoy from time to time for the flavor but have never liked the feeling of being even slightly inebriated. It is surprising that consuming twice Ainsley’s Limit does not appear to be harmful so another myth exposed. Many thanks!

  5. There is likely an overlooked variable. Fructose metabolism is essentially identical to ethanol metabolism. Unless this variable is isolated and controlled all association studies, which are suspect from the beginning, are useless (except to give academics something to publish). All association studies without mechanistic evaluation should be banned from the medical literature (unless there is a warning: listening to these studies is likely to be hazardous to your enjoyment of life).

  6. Dear Sebastian, Just out of further curiosity….. Did this study also analysed the differences in sexe? More specific; Does the consumption of alcohol have different effects on women?

  7. I wonder if many heavy drinkers have “addictive personalities” (i.e. more likely to become addicted to something) because of negative experiences in their early years (i.e. 0-5 years old). If a heavy drinker is able to quit drinking, other addictions (i.e. smoking, drug abuse) may start/ continue, which might keep them in the same risk bracket. I say this because, typically, the body is amazing at recovering from poor life choices.

  8. I think this is an excellent article, not for what it says about alcohol consumption especially, but for the way in which is discusses finding the evidence to reach a considered view.

  9. I wonder to what extent the distribution of alcohol consumption would make a difference. For instance, how does a person who has “one drink” every day compare to a person who has seven “drinks” on one day of the week, but then does not drink alcohol on the other six days? Presumably, the latter is more problematic for the liver, but is it more problematic in other respects?

    And what about people who do not drink any alcohol at all **most of the time**, but who drink on special occasions? Is there a risk of harm from lack of acclimatisation to alcohol? (personally, my own approach is that I only ever drink alcohol in a social situation, and, not being very sociable, even before COVID-19 restrictions, the result is that I do not drink any alcohol in a typical week)

    1. My guess would be that intermittent heavy drinking is probably worse for the body, because it’s harder as you suggest for the liver to handle an occasional big load than a frequent small load, and I think it’s also worse because it’s more likely to lead to destructive behaviours.

      The second group would be included in the “occasional drinkers” bracket, which was statistically no different from the complete abstainers and the moderate drinkers.

  10. Have you read Monte’s book, While Science Sleeps? He makes a good case that the health benefits of small amounts of alcohol are real, and are due to the reduction in injury from methanol. The same alcohol dehydrogenase (ADH) that converts ethanol to acetaldehyde also converts methanol to formaldehyde. Formaldehyde is extremely toxic, and methanol will kill/injure you if enough of it is converted to formaldehyde. The treatment for methanol poisoning is ethanol, because ADH has a strong preference for ethanol, and as long as there is enough ethanol in your blood, the methanol will not hurt you. It will passively offgas through lungs/skin.

    You will always have some exposure to methanol from foods and gut bacteria. A low dose of ethanol reduces the injury from this exposure, and results in less overall damage.

    1. That’s an interesting hypothesis. If there’s good evidence that alcohol is good for your health, then I think it makes sense to look for explanations as to why it’s good. But since there’s no good evidence that it’s good for you, I don’t really see the point. It just becomes baseless speculation.

  11. Thank you for an interesting article. I think the idea that moderate alcohol consumption is healthy, is put about by people who like to drink alcohol now and then.

  12. 4% absolute risk reduction in 13 years for four million people: does that translate to something like 0,000001% absolute risk reduction per person? haha

  13. I worked with a chap that was formerly a research scientist. He once explained to me in some detail (over my head) that we do not process the enzymes to convert alcohol into fat and that it was a falsehood that drinking spirits would put on weight. He said it was the carbohydrates that contained the calories. True or false?

  14. I don’t drink alcohol very often, but when I do I seem able to handle a lot more of it than most people, and I never get hangovers. This is said to be due to enzymes in the liver. Which causes me to wonder if such enzymes have any other implications for my health. Could it be for example that my body would also very effectively reduce the harm from other toxins? Have there been any studies on the health of those with a high tolerance to alcohol? I suppose it would be very easy for them to become functioning alcoholics, but I don’t intend to fall into that trap.

    1. That’s a possible explanation. The reason East Asians generally have a very low tolerance for alcohol is that they have less of the enzyme aldehyde dehydrogenase, which is responsible for the second step in the metabolism of alcohol, turning acetaldehyde in to acetate. This causes a buildup of acetaldehyde, which is responsible for a large part of the sensation of being hung over. The medication Antabuse, which is used as a treatment for alcohol addiction, works in the same way. It blocks aldehyde dehydrogenase, which causes a buildup of acetaldehyde if you drink alcohol, which causes you to feel like crap. Since this is a very specific enzyme with a very specific function, having a high amount of it and thereby a higher tolerance for alcohol doesn’t mean you also have a higher tolerance for other substances.

  15. Being around different kinds of functional and not so functional alcoholics, for me someone who has one or two drinks daily is a borderline alcoholic. It might not be measurable in terms of longevity but the the signs of psychological dependency are quite easy to identify. The number of people “just having a beer after work” or “drinking some wine with most evening meals” are often self-medicating underlying psychological conditions.

    Alas these kinds of things are hard to quantify unfortunately. Maybe we could then keep people from slipping further into real addiction.

  16. En svensk kvinna, My Nillson, som bor i Frankrike och hennes far Willy Nilsson, som bor i Skåne har skrivit en bok som heter “Drick för livet”,ISBN 978-91-633-9816-2. Den handlar om hälsofördelarna med att dricka ett glas rött ekologiskt vin om dagen. Med referenser till många forskningsrapporter från hela världen, bland annat Sahlgrenska och Karolinska.
    De beskriver flera huncra år gamla lagar som gör att man måste odla samma druva på samma plats århundrade efter århundrade (skydd för vinbönderna mot konkurens) vilket gör att jordarna utarmas och att det krävs mer och mer kemikalier i jordbruket varav flera också är tillåtna i ekologiska viner.

  17. You all are too young to feel the wide variability of animals. In this case of humans. I’ve partly ‘inherited’ my father’s clinic. So I had a vast human experience, mainly during 3 or 4 generations.
    I’ve seen all type of exceptions (they confirm the rules). And those people deserve our dearest attention because they are humans.
    Here (Portugal) people enjoy wine 12% (Gay‑Lussac). As an Internist, I don’t see an alcoholic cirrhosis since the beginning of the 1980’s. Now people drink more ‘spirits’ 42% (Gay‑Lussac). There are 4 times more car accidents without alcohol than with alcohol.
    I’ve treated several people with type 2 diabetes who lived free of whatever you think a diabetic is cursed of.You all are too young to feel the wide variability of animals. In this case of humans. I’ve partly ‘inherited’ my father’s clinic. So I had a vast human experience, mainly during 3 or 4 generations.
    I’ve seen all type of exceptions (they confirm the rules). And those people deserve our dearest attention because they are humans.
    Here (Portugal) people enjoy wine 12% (Gay‑Lussac). As an Internist, I don’t see an alcoholic cirrhosis since the beginning of the 1980’s. Now people drink more ‘spirits’ 42% (Gay‑Lussac). There are 4 times more car accidents without alcohol than with alcohol.
    I’ve treated several people with type 2 diabetes who lived free of whatever you think a diabetic is cursed of.
    People, our patients, are as human as we are. God blessed them for the tons of things they had taught to me.
    À votre santé, Salud, Cheers, Salute, Saúde, Tchin-tchin, and so on…

  18. Dr Sebastian Rushworth, please have a look at this potential treatment for long haulers covid. Key words: NAD+ depletion, niacin (nicotinic acid), seretonin.
    Simply, their theory is that COVID19 causes NAD+ depletion, some people with vitamin deficiencies, existing NAD+ depletion or genetic deficits in energy metabolism have long term NAD+ dysfunction. The body tries to make up for low NAD+ by feeding in tryptophan, which is the precursor for serotonin, causing low serotonin. Mast cells are activated locally to release serotonin instead, leading to histamine release and mast cell activation issues. Neurological effects are due to low serotonin and NAD+, which also effects the microbiome and general homoeostasis. Energy disruptions are specific to high metabolically active tissues such as the heart and brain. This is further complexed with disruption of the gut-immune axis, mobilization of bacteria, secondary infections – both bacterial and reactivation of dormant neurotrophic viruses. Reactivation of dormant Epstein-Bar virus can open the door to bacterial infections and it is known to trigger the creation of complex and unrelated auto-antibodies, leading to downstream issues.”

  19. Actually, as soon as you store food it starts to ferment. More or less everything we eat, unless it is still alive, fresh off the tree, bushes or out of the ground contains alcohol in varying degrees. This is also why it is practically impossible to have a zero-tolerance against alcohol and countries like sweden settled for a 0.2 promille limit for drunk driving (which in practice, is zero tolerance), as you can get that from a simple meal even without consuming any alcoholic beverages …

    As humans is the only animal on earth that actively harvest and store food for longer periods, we have developed an unique ability to digest alcohol. No other animal on earth has the same ability to break down alcohol.

  20. How about impact on longevity if you have the “alcohol gene” which I believe is carried by around 80% of Asians?

  21. i’m curious about your view on caffeine, if its relation to health is somewhat analogous to alcohol.

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