If your pre-trip ritual includes packing a tub of probiotic capsules alongside the sunscreen, new research suggests you might be wasting your money — and your suitcase space.

A study published in the journal Clinical Gastroenterology and Hepatology tracked American supplement habits from 2009 to 2023 and found that probiotic use among adults more than tripled, from under 2% of the population to roughly 7%. Usage rose among under-20s too. Yet over the same period, consumption of fermented foods and fibre-rich plants barely budged. That's a problem, because the evidence points squarely at food, not pills, as the way to a healthier gut.

Lead author Kira Newman, a microbiome researcher at the University of Michigan Medical School, says patients routinely ask her about supplements while showing far less interest in changing what they eat. Her findings back the food-first approach. Probiotic supplements typically contain concentrated doses of just a few bacterial strains, and studies suggest that for healthy people they offer little benefit — and in some cases may actually reduce microbiome diversity. A Stanford clinical trial even found that adults with metabolic syndrome taking a multi-strain probiotic for 18 weeks saw mixed results: some improved, while others saw their blood sugar and insulin levels worsen.

Fibre, by contrast, is well-established fuel for gut microbes. Because our bodies can't digest most fibre, it reaches the colon intact, where trillions of microbes convert it into short-chain fatty acids that lower inflammation, improve blood sugar and even stimulate appetite-suppressing hormones. A diverse microbiome — built by eating a wide variety of plants — is linked to lower risk of Type 2 diabetes and high blood pressure. Fermented foods such as yoghurt, kimchi, sauerkraut, kefir and kombucha add live microbes that further boost diversity and help the body absorb minerals like iron and zinc.

Here's where it gets interesting for travellers: many of the world's best gut-friendly foods are also its best cultural ones. Think miso in Japan, kimchi in Korea, kefir in Eastern Europe, sauerkraut in Germany, fresh cheeses and yoghurt across the Mediterranean and Middle East. Eating for your microbiome on the road essentially means eating adventurously and locally — loading plates with different vegetables, beans, nuts, grains and whatever the local fermented specialty happens to be.

It doesn't have to cost much either. Budget-friendly fibre sources like dried lentils, apples, sweet potatoes and oat bran all do the job, which is handy for self-catering holidays or long stays.

Why it matters: the average American adult consumes only about 8.5 grams of fibre per 1,000 calories — well below the recommended 14 grams — so most of us have room to improve, and holidays are a natural moment to reset eating habits. As gastroenterologist Chris Damman of the University of Washington puts it, it's easier to pop a pill, but dietary change delivers the greater return. In practice: skip the supplements, seek out the local ferment, and let your trip feed your gut the way nature intended.

For the rare exceptions — like reducing the risk of C. difficile infection while on antibiotics — specific probiotic strains do have evidence behind them, so it's worth discussing with a doctor if that applies to you.

Via NZ Herald Travel