Long before gut health became a buzzword, a curious fermented milk drink appeared in UK supermarkets in the 1990s. With its thumb-sized bottle and sweet-yet-sour flavour, Yakult was slightly baffling: a product containing live bacteria that was supposedly good for your health.
Today, in a crowded market of gut-health supplements, kefir shots and fermented tonics, Yakult has become the world’s best-selling probiotic drink. More than 40 million bottles are consumed everyday worldwide, and it’s enjoying something of a resurgence as interest in the microbiome – the collection of bacteria that lives in our bodies – grows.
Yakult was invented in 1935 by Japanese microbiologist Dr Minoru Shirota who uncovered that lactic acid bacteria in the milk could suppress harmful microbes in the intestine. He managed to isolate a strain resilient enough to survive the journey through the stomach and devised his recipe as an easy way for people to consume these “friendly” bacteria.
The claims behind Yakult include that it supports gut health, improves bowel function and helps maintain immunity – but do these really all stack up? We consulted the experts.
What exactly is Yakult?
Yakult Original is a lemon-vanilla flavoured, fermented milk drink, containing a single probiotic strain Lacticaseibacillus paracasei Shirota.
When you drink Yakult, the bacteria travel through the stomach into the intestine where they interact with your microbiome. Research from University of Reading shows the Shirota strain survives digestion and can be detected in stools – confirming it reaches the gut alive.
Each 65ml bottle provides at least 20 billion colony-forming units (CFUs) of the bacteria, along with skimmed milk, water, sugars and flavourings.
Nutritionally, one bottle (a single serving) contains just over calories, around 8.8g sugar and less than 1g of protein.
Lower-sugar versions are also available which use the sweeteners, maltitol syrup and stevia, to replace some of the sugar.
What are the health benefits?
1. Supports gut health
Yakult is designed to help maintain a resilient gut, encouraging beneficial bacteria to thrive.
“It works a bit like a sticking plaster,” says Anthony Hobson, professor of GI science and clinical director of The Functional Gut Clinic. “If there are small gaps in the system – perhaps after antibiotics or during periods of stress – it can help the gut repair.”
The Shirota bacteria stimulate the production of protective mucus and short-chain fatty acids – compounds that help maintain the intestinal lining. “You’re strengthening that barrier and reducing irritation,” Hobson explains. “Other good bacteria benefit from that – it becomes a domino effect.”
Studies suggest that drinking Yakult daily can increase levels of beneficial bacteria, especially lactobacilli and bifidobacteria, which can improve digestion and reduce inflammation.
“The benefits you see will depend on your existing microbiome,” says professor Paul Cotter, head of food bioscience at Teagasc Food Research Centre. “Someone who is already healthy may not see dramatic changes – though it may still provide some supportive effects.”
2. Eases constipation
Yakult may help keep you regular – provided you take it consistently.
“Research suggests it can support digestion and encourage healthier bowel habits,” says Katie Sanders, a registered nutritionist.
A placebo-controlled trial, in the Canadian Journal of Gastroenterology, found patients with chronic constipation who drank a 65ml fermented milk beverage containing LcS reported improvements in bowel movements within two weeks.
“If you struggle with irregular bowel habits, Yakult is worth considering,” says Sanders. “Other options may also help. For instance, Activia Gut Health yogurt contains Bifidobacterium animalis lactis, which studies suggest can offer modest improvements for symptoms of mild constipation. I usually recommend a short, four-week trial, alongside ensuring adequate fibre and fluids.”
3. Strengthens immunity
Around 70 per cent of our immune system resides in the gut so it makes sense to find a way to boost it.
By interacting with immune cells and strengthening the gut barrier, the Lacticaseibacillus paracasei Shirota strain in Yakult may help in that matter.
“Some studies have found it increases an antibody that helps defend the gut and airways against infection,” says Professor Cotter. “There’s also evidence it can reduce the risk, or duration, of certain upper respiratory-tract infections in children, older people and those under stress.”
In a four-month study of endurance athletes at Loughborough University, those who consumed the drink reported fewer respiratory infections during winter training.
The effects, however, are not universal, Prof Cotter cautions. “They depend on who is taking it and what is being measured,” he says. “The evidence is strongest for markers of mucosal immunity [the immune defence which is our first barrier against infection] and benefits are generally seen while people continue drinking it.”
What are the drawbacks to Yakult?
Like most probiotics, Yakult isn’t a guaranteed fix. “Its effects vary widely from person to person,” says Sanders. “Some people notice improvements; others may see little change.”
Any benefits also depend on continued use. The strain doesn’t permanently colonise the gut, meaning once you stop drinking it, your microbiome gradually returns to its previous state.
“It’s like a guest at a party,” says Prof Hobson. “It arrives, mingles, then leaves again – it doesn’t set up home or repopulate the gut. For substantial change, you need long-term dietary adjustments.”
Yakult is also a sweetened drink. Although the serving size is small, it contains around 8g of sugar which should be factored into your daily intake. “As with any sweetened product, its impact depends on your wider dietary pattern rather than the drink in isolation,” says Sanders.
Cost is another potential drawback. While Yakult sits at the more affordable end of the probiotic market, costing roughly 45p per serving, the price can still add up. “For general gut health, a sensible and affordable starting point is to focus on eating more fibre and plant-based foods, and view supplements as complementary,” says Sanders.
How does Yakult compare to other probiotic fermented drinks?
Yakult and Actimel are two of the most extensively researched probiotic drinks on the market. “Actimel contains a closely related strain, Lacticaseibacillus paracasei Danone, along with traditional yogurt cultures,” says Prof Cotter.
While the two drinks share some similar benefits, Actimel’s research has focused more on immunity and infection with studies showing particular benefits for antibiotic-associated diarrhoea and respiratory infections.
Yakult provides a single, well-studied probiotic strain in a convenient daily dose.
As with all probiotics, responses vary, so it’s about finding the product that suits you best.
“Patients often tell me, ‘I tried a probiotic and it didn’t help’,” says Sanders. “However, most people don’t realise that probiotics are strain specific and taking different strains is like taking different medications. You really need to select the strain for the outcome you want.”
Fermented drinks, like kefir, offer a wider – though inconsistent – mix of microbes. The choice depends on whether you’re looking for a targeted effect, such as improving constipation, or broader gut diversity to support broader digestive and metabolic health.
“Always read the label,” advises Prof Hobson. “Look for evidence of live bacteria and check if it’s full of sugar, or ultra-processed, with a long list of added ingredients.” While Yakult is technically a UPF because it is industrially made, its formulation is relatively simple with just six ingredients, plus the probiotic strain.
“At our Microbiome Clinic we offer a stool analysis as a first step,” says Prof Hobson. “This tells you exactly what gut bacteria you’re lacking.”
The verdict: Is it good for you or not?
Experts broadly agree that, alongside a healthy diet, Yakult can be a useful way to support digestion and gut health – but it’s not a cure-all.
“There’s solid evidence behind Yakult and it has a good history,” says Prof Hobson. “As an addition to a healthy diet, it can support gut function or offer a useful kickstart. But it’s not a miracle product – it’s a supplement to a healthy diet, not a replacement.”
Sanders agrees. “For overall gut health, a diverse, fibre-rich diet, good sleep and regular physical activity will have a far greater and more consistent impact than any probiotic drink.”
Yakult FAQs
How many calories does Yakult have?
A bottle of Yakult Original contains 43 calories. For a lower calorie option, Yakult Balance provides 27 calories while Yakult Plus has 29 calories.
Who should avoid drinking Yakult?
Avoid Yakult if you have a dairy allergy or intolerance, fructose sensitivity or SIBO, a gastrointestinal disorder.
“Most people tolerate Yakult well,” says Prof Hobson. “However, those with small intestine bacterial overgrowth (SIBO) can feel worse on probiotics because they add more bacteria to the gut. If you experience bloating, brain fog or cramping, stop taking it and try dietary changes.”
Is it healthy to drink Yakult every day?
Tolerance of probiotics varies between people, but a daily bottle of Yakult is generally safe, agree experts. “Try a short trial,” suggests Sanders. “If you have a medical condition, check with your GP first.”