With most of the UK now finally basking in warm sunshine, it’s no surprise that boozy picnics, barbecues and drinks after work are back on the agenda. After a year spent indoors, who can blame us for wanting to enjoy a tipple in the sun with friends?
But while we’re all familiar with the negative effect alcohol has on our liver, less is known about its impact on our gut health; an area that needs more attention as mounting research suggests that poor gastrointestinal health plays a significant role in our body’s overall health.
“Our gut is the central system that’s core to everything,” says nutritional therapist VJ Hamilton. “It’s where you absorb your nutrients, it hosts 70 per cent of your immune system which is what keeps you healthy and it’s also where you create serotonin which is responsible for mood.”
In fact, researchers have begun to discover that alcohol, particularly if consumed chronically and in large amounts, induces a process in the gut that promotes inflammation throughout the body and may be at the root of organ dysfunctions and disorders such as chronic liver disease, neurological disease, gut-related cancers and inflammatory bowel syndrome.
“This is because alcohol can cause ‘leaky gut syndrome’ as it increases intestinal permeability and lets toxins into the bloodstream,” says Hamilton.
When the gut is working well, the intestinal barrier – made up of a layer of water, mucous gel and connective tissue – regulates the passage of materials between the gastrointestinal tract and the bloodstream, allowing for the absorption by the blood of key nutrients and preventing the absorption of noxious substances. If it becomes leaky from drinking too much alcohol, it allows in toxins that can cause inflammatory responses.
“70 per cent of our immune system is in the gut and if there’s inflammation, it can create an environment where ‘bad bacteria’ slide in, causing further irritation to the digestive lining and disrupting our entire system,” added Hamilton. “People often get alcohol-induced rashes or headaches when they eat and drink at the same time as the alcohol triggers the food sensitivity because the leaky guts are allowing the food particles through.”
Putting your liver under pressure by drinking alcohol doesn’t help your gut either.
“The liver is very important in the digestive process as it helps with bile production, breaks down fat and releases gastric juices,” says Hamilton, “But if the liver’s having to work hard to detox all the alcohol the digestive process won’t work as well.”
According to Tim Spector, professor of genetic epidemiology at Kings College, London and author of Spoon-Fed, drinking in moderation – one to two glasses of wine a day – should have little effect on the gut microbiome; the microorganisms, including bacteria, fungi and viruses, that live in the digestive tracts of humans.
“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.