Asian Probiotics vs Western Probiotics

Asian probiotics and Western probiotics can both work, because a probiotic's effect is decided by its strain, its dose and the gut it lands in. Some strains first studied in Europe have shown similar results when tested again in Asia, while others have given mixed results from one country's trials to the next. What changes in Asia is the gut a probiotic meets: the bacteria already living there, shaped by what people here eat. Before picking up a probiotic on a shelf where most products were developed and tested elsewhere, it helps to know what that difference means for you.

How do gut microbiomes differ across Asia?

Gut microbiomes across Asia vary by country, between city and countryside, and above all with diet. In a study of 303 schoolchildren in China, Japan, Taiwan, Thailand and Indonesia, the children's gut bacteria fell into two broad types:

• Prevotella-led. Most common in Indonesia and in Khon Kaen in north-east Thailand, and linked to diets rich in resistant starch.
• Bifidobacterium and Bacteroides-led. Most common in China, Japan and Taiwan. Children in Japan had especially high levels of Bifidobacterium.

The differences were clear enough that the children's country could be predicted from their gut bacteria.

Much of this variety is missing from the reference data used worldwide. In a study of 109 people from Singapore's Chinese, Malay and Indian communities, more than 80% of the strains belonging to the 10 most common gut species were missing from global reference databases. A count of nearly 445,000 public microbiome samples found that research is concentrated in Europe and North America, while India, Pakistan and Bangladesh, home to more than a quarter of the world's people, made up 1.8% of samples.

Diet keeps these patterns moving. On Leyte island in the Philippines, rural children eating traditional diets mostly had the Prevotella-led type, while city children who ate more fast food, meat and sweets mostly had the other type. When Hmong and Karen people moved from Thailand to the United States, they began losing native gut bacteria within six to nine months, as Bacteroides strains displaced Prevotella strains, and diversity fell further the longer they stayed.

What about probiotics for Southeast Asia?

Probiotics for Southeast Asia meet a wide mix of guts, since the region holds both main types. Prevotella-led communities, which are geared to break down complex carbohydrates, are more common where traditional rice- and plant-based diets hold, and in Bangkok the two types were mixed. City diets are moving guts towards the Bacteroides-led type. Your own diet and lifestyle tell you more about your gut than the country you live in, which is also why the next section matters.

Why does your gut change how a probiotic works?

A probiotic joins a community of bacteria already established in your gut, so the same strain can behave differently from one person to the next. The resident bacteria compete with new arrivals for food and space, and together with your gut lining they limit which strains can settle, which researchers call colonisation resistance. A new strain is more likely to settle where it can fill a niche, a role in the community that no resident already fills. Two studies show this clearly:

• A strain settles where there is an open niche. In a placebo-controlled study, Bifidobacterium longum AH1206 stayed in the gut for at least six months in about 30% of people who took it. They were the people who started with little B. longum and fewer of the genes it uses to digest certain carbohydrates.
• The gut lining sets its own terms. At the Weizmann Institute in Israel, researchers sampled the gut lining directly in people taking an 11-strain probiotic. How well the strains settled varied by person, by part of the gut and by strain, and could be predicted from each person's starting microbiome.

Because of colonisation resistance, most probiotic strains do not settle. They act while you take them and fade after you stop. The good news is that a strain does not need to settle to have an effect, since it can still interact with your resident bacteria and gut lining as it passes through. The useful question for any probiotic, wherever it was developed, is how its strains fit the community already in your gut.

Do probiotics tested in Western trials work in Asia?

Some do, though the same strain can give different results from one country's trials to the next. Lactiplantibacillus plantarum 299v, a strain sold by a Swedish company, has been tested for irritable bowel syndrome (IBS) in four-week trials in several countries. In Sweden, 60 people with IBS had less flatulence than with placebo, but their abdominal pain fell no more than in the placebo group. In Poland, all 20 people taking it reported less abdominal pain, compared with 11 of 20 on placebo. A trial of 214 people in India found the widest gap. 78% rated the strain's effect good or excellent, compared with 8% on placebo, and that trial was funded by the companies that make and sell the strain. A later placebo-controlled trial in Pakistan found no benefit over placebo. Side effects were no more common than with placebo across these trials.

Lacticaseibacillus paracasei strain Shirota, developed in Japan and formerly called Lactobacillus casei Shirota, shows the same unevenness for constipation. In a four-week trial of 70 adults with chronic constipation in Germany, 89% of those drinking it said it helped, compared with 56% on placebo, and no side effects were reported. In a four-week trial of 90 adults with constipation in Malaysia, both groups improved by a similar amount. In a two-week trial in Japan, 40 healthy adults who passed stools less often took the drink and a placebo in turn. Bowel movements were more frequent than with placebo only in those who started at four or fewer a week. Researchers from the company that makes the strain took part in the Japanese trial.

These trials differ in more than country. They enrolled different people, measured different outcomes and saw placebo groups respond by different amounts, so the gaps cannot be put down to region alone. Head-to-head tests of one strain in Western and Asian populations, which could settle the question, are uncommon, partly because most microbiome research comes from Europe and North America. Microbiome findings can also travel poorly. In a study of about 7,000 people, models built to detect disease from gut bacteria in one region of Guangdong, China, lost accuracy in other regions of the same province. That study tested disease models rather than probiotics, but it shows that gut findings from one group of people do not always hold in another. This is why it helps to check where a strain's trials were run.

How do you choose a probiotic that suits your gut?

Choose a probiotic by its strain and evidence, then judge it on yourself.

1. Find the full strain name. Look for the genus, species and strain code, such as L. plantarum 299v. Research on one strain does not carry over to another.
2. Check what it was tested for, and in whom. A trial in people with similar diets and backgrounds, measuring the outcome you care about, is the strongest guide.
3. Feed it. Fibre from food feeds both the strains you take and the bacteria already in your gut.
4. Give it a set period, then judge. The symptom trials in this article ran for two to four weeks. Note one or two things you want to change, keep your diet steady where you can, and compare. In effect, you are running an n=1 trial, a study with a single participant, and the most important one: you. Our guide on how to choose a probiotic that works for you walks through this routine step by step.

Do Asian probiotics made with local gut data work better?

Whether Asian probiotics made with local gut data work better has not been tested head to head. What local data can do is shape the starting choices. AMILI's Daily Synbiotics are formulated using AMILI's gut microbiome data from Asia, a library of about 20,000 gut samples from people living in Asia, more than all publicly available gut microbiome data from East and Southeast Asia combined. The formulas include species that are among the most common in guts here. B. longum, the fifth most abundant species in the library, is in Complete and Immunity, and B. adolescentis, the third, is in Metabolic Health. Each capsule pairs live strains with prebiotics and a postbiotic. Like most probiotics, their strains are likely to act mainly while you take them, so the n=1 routine above applies to them too. See the five formulas, or use GutMatch to find your match in about two minutes.