Postbiotics Explained Simply

1. What It's About

Postbiotics are components of microorganisms that are no longer alive. They form when probiotics are killed, for example by heat. What remains are cell wall fragments, enzymes and metabolic products. They can be found in capsules, foods and creams.

Important to note: every postbiotic is different. It depends on which strain was used and how it was inactivated. A heat-killed bacterium may have a different effect than the same bacterium inactivated in another way. Therefore, a result always applies only to the specific tested preparation and cannot be readily transferred to another.

Since postbiotics contain no living organisms, they are more stable than probiotics. The risk associated with live microbes is also eliminated.

2. What Research Shows

The best-studied area is the gut. In a study involving 69 young adults with chronic diarrhoea, participants received either a postbiotic or a placebo (an inactive substance) for three weeks. After this period, they switched groups. Stool consistency improved, bowel movements became less frequent and urgency decreased. Anxiety levels also declined 2.

Another study examined bad breath. Over four weeks, 68 people used lozenges containing heat-killed Lactobacillus paracasei ET-22. Levels of foul-smelling sulphur compounds in the mouth decreased. The live form of the bacterium had a stronger effect than the inactivated form 1.

There is also evidence for skin benefits. In an eight-week trial, 60 healthy Japanese women aged 30 to 50 took heat-killed Latilactobacillus sakei KABP-065. Skin elasticity improved compared to the placebo group. In women in their forties, skin moisture also increased 4.

A large review summarised 25 controlled studies and found indications of lower blood lipid levels, reduced waist circumference and fewer inflammatory markers in the blood. No such association was observed for fasting blood glucose, blood pressure or body mass index 3.

3. What Remains Unclear

Many studies are small and last only a few weeks. Almost every investigation tests a different preparation, so results cannot be easily generalised. Often, only laboratory values were measured rather than whether a disease actually improved. The studies on diarrhoea, bad breath and skin involved specific groups, such as young adults or women within a certain age range. Whether the effects persist long-term is unknown. How postbiotics work in the body is also currently speculative. Studies specifically addressing these mechanisms have yet to be conducted.

4. What This Means in Everyday Life

Postbiotics are now found in capsules, foods and creams. Research in this area is still in its early stages. Those interested will find individual studies reporting positive observations, but no comprehensive, confirmed picture yet. The studies generally show effects only for the specific tested preparation and only over short periods. What needs to be clarified next: whether the observed changes persist long-term and whether they can be replicated in other populations and with other preparations.

All details with study numbers and sources: detailed page on postbiotics. For children: Postbiotics for children.