While foods such as sourdough and kimchi are often promoted for their digestive benefits, health experts say beverages can play an equally important role in shaping gut health — sometimes for the worse.

The gut microbiome, made up of trillions of bacteria and other microorganisms, supports digestion, immunity, metabolism and inflammation control. When this ecosystem becomes imbalanced — a state known as dysbiosis — it can lead to bloating, fatigue and irregular bowel habits, and has been linked to conditions such as obesity, type 2 diabetes and heart disease.

Nutritionist Rhiannon Lambert notes that while alcohol and sugary soft drinks are widely recognised as problematic, other commonly consumed drinks can also disrupt gut balance, particularly when consumed frequently or in large quantities. “Hydration choices matter,” she says, adding that fluid intake can subtly influence gut bacteria over time.

According to nutritional therapist Hanieh Vidmar, the most gut-supportive drinks tend to be simple: water, herbal teas, lightly brewed green tea and fermented beverages such as kefir or kombucha. These options are typically low in additives and easier for the digestive system to process. In contrast, several popular drinks may undermine gut health.

Highly concentrated juice shots — often marketed as “gut shots” — are one example. Nutritionist Rob Hobson explains that these products are usually high in sugar, acidic and low in fibre, which can irritate the stomach lining, particularly when consumed on an empty stomach. While ingredients such as ginger or turmeric may offer benefits in food form, evidence that small liquid shots improve gut bacteria remains limited.

Commercial barista-style oat milks have also drawn scrutiny. Although oat milk itself is not inherently harmful, some versions contain added oils, gums and emulsifiers that may irritate sensitive digestive systems. Researchers are investigating whether certain emulsifiers can disrupt the gut’s protective mucus layer and increase intestinal permeability.

Unfiltered coffee, including French press and Turkish coffee, can stimulate stomach acid and speed up gut motility. While this may aid regularity for some people, others may experience reflux or cramping. Dietitian Federica Amati notes that unfiltered coffee also contains compounds that can raise LDL cholesterol levels.

Sugar-free or “diet” fizzy drinks are another area of debate. Lambert says the effects of artificial sweeteners vary widely between individuals, depending on dose and existing gut bacteria. Some studies suggest certain sweeteners can alter microbial composition, while others show minimal impact. Many diet drinks are also highly processed and contain additives under investigation for their effects on gut health.

Alcohol, particularly beer and lager, has one of the strongest evidence bases for gut-related harm. Regular consumption can increase intestinal permeability — sometimes referred to as “leaky gut” — and promote inflammation. Beer combines alcohol, carbonation and fermentable carbohydrates, which can worsen bloating in sensitive individuals.

Sugar-sweetened drinks have been shown to reduce beneficial gut bacteria and overall microbial diversity, shifting the microbiome toward a less healthy state. Registered dietitian Nichola Ludlam-Raine suggests fermented alternatives such as kombucha, which provide carbonation alongside live cultures.

Energy drinks may pose a significant challenge for gut health due to their combination of caffeine, sweeteners, acidity and additives. Hobson describes them as a “perfect storm,” particularly for people prone to digestive sensitivity. Unsweetened tea or coffee, which contain polyphenols that support microbial diversity, are considered gentler options.

Some protein shakes can also be problematic. Many contain artificial sweeteners, sugar alcohols and thickeners linked to bloating and diarrhoea, while whey protein may trigger symptoms in people sensitive to lactose. Vidmar recommends choosing products with minimal ingredients or prioritising whole-food protein sources.

Experts stress that gut health is shaped by long-term habits rather than occasional indulgences. A balanced diet, adequate hydration and moderation — rather than reliance on functional drinks — remain the foundation of a healthy digestive system.