“Alcohol is generally absorbed very quickly in the stomach and the upper part of the intestines and goes into the bloodstream quickly,” he says. “It’s the other parts of that drink – for example, the grape skins from wine, the hops in beer – that interfere with the gut microbes in the lower intestine and some can actually have a beneficial effect.”
Spector was the lead author of a 2019 study that found that people who drank red wine had an increased gut microbiota diversity (a sign of gut health) compared to non-red wine drinkers and was also associated with lower levels of obesity and “bad” cholesterol.
“This was down to the polyphenols in red wine, which are the defence chemicals naturally present in many fruits and vegetables,” explains Prof Spector. “They have many beneficial properties, including antioxidants, and mainly act as a fuel for the microbes present in our system.”
On the basis of his research Prof Spector advocates drinking red wine over any other alcoholic drink, even white wine, when it comes to gut health – “the grape skins for red wine are left on longer than on white wine so have a higher rate of polyphenols” – but all alcohol should be consumed in moderation.
“All alcohol affects your brain and liver to some extent and high levels – anything over three glasses at one time – will have a negative effect on the gut microbiome,” he adds.
Registered dietitian Dr Megan Rossi believes that some beers can do your gut good, too.
“Some stronger beers have been fermented twice and so supposedly contain beneficial live bacteria that often come with fermented food and drink,” explains Dr Rossi, also known as The Gut Health Doctor and author of Eat Yourself Healthy. “However, even though beer is fermented, most of the live microbes die off in the processing. On the upside, dark beers like Guinness contain beneficial plant chemicals like polyphenols, many of which your gut microbes love to eat. However, having any more than one or two switches those ‘potential’ benefits into negative effects.”
Like Prof Spector, Dr Rossi asserts that drinking in moderation can be part of a healthy lifestyle.
“But it really is about the amount and the type,” she says. “Overdoing it will absolutely have the opposite effect on your gut health, heart health and your mind. For some, abstinence is bliss and avoiding alcohol and loading up on plenty of plants, getting plenty of sleep, managing stress and moving your body are all important ways to look after your gut health. And to look after your gut microbiota (the trillions of microbes living inside your gut), it is a good idea to take it easy with alcohol. Consider switching every second alcoholic drink for something refreshing like kombucha and, if you’re drinking wine or other alcohol, try topping it up with soda water for hydration without feeling like you’re missing out.”
The good news with the gut is that any damage done by excessive drinking is reversible.
“Gut microbes, including bacteria, can begin to change within days of making changes to your diet, depending on how drastic the changes are, but the long-term benefits can take several months to show,” says Dr Rossi. “One clinical trial observed changes in the gut microbes when switching people from a plant-based diet (rich in fruits, vegetables and wholegrains) to an animal-based diet within days, and vice versa. Interestingly, the participants’ gut microbes returned to their original make-up soon after stopping the diet, highlighting just how adaptable our GM can be. That being said, no two people have the same gut bacteria, so it can be very individualised in terms of how long it takes for changes to take effect.”
So the message is: enjoy the sunshine and friends but perhaps slow down on the drinking a bit.