At a glance
A heat-inactivated postbiotic made from killed lactic acid bacteria, not a live microorganism.
In Vykea: heat-inactivated postbiotic (6 billion cells per daily dose)
No health claim is authorised for KT-11, so we describe the substance in purely factual terms.

Lactobacillus crispatus KT-11 is a heat-inactivated strain of a lactic acid bacterium that is used as what is known as a postbiotic. Unlike live cultures, KT-11 consists of killed bacterial cells and their components. Lactobacillus crispatus is a naturally occurring bacterial species that is part of the normal human microflora. The KT-11 strain was originally isolated from the stools of healthy infants and then processed so that the cells are killed by heating. In KT-11 Instant we use this heat-inactivated postbiotic at 6 billion cells per daily dose. This entry explains what a postbiotic actually is, how it differs from probiotics and prebiotics, how KT-11 is obtained and what scientific research has described about it so far.

When it comes to microorganisms in food, you will come across three terms that are easily confused. Probiotics are live bacteria capable of multiplying that are intended to reach the gut in the amount consumed. Prebiotics, by contrast, are not bacteria but certain types of dietary fibre that serve as food for the bacteria already present in the gut. Finally, postbiotics consist of inactivated microorganisms, i.e. no longer capable of multiplying, and their components. KT-11 is one such postbiotic.

In 2021, the International Scientific Association for Probiotics and Prebiotics (ISAPP) defined the term postbiotic as a preparation of inactivated microorganisms and their components, with or without their metabolites. For such preparations consisting of killed bacterial cells, the older specialist literature also used the term paraprobiotic, alongside terms such as heat-inactivated, heat-treated or heat-killed cells. The terms heat-treated and heat-sterilized used in the cited studies refer to the same heat inactivation process. In this entry, we consistently use the term heat-inactivated. According to this classification, KT-11 belongs to the group of heat-inactivated postbiotics.

A practical difference from live cultures is that killed cells can no longer multiply and therefore do not colonise the gut. For processing and storage, this means greater stability, as no live microorganisms need to be preserved. KT-11 is a heat-inactivated postbiotic and contains no live bacteria.

Lactobacillus crispatus is a bacterial species from the group of lactic acid bacteria. Lactic acid bacteria occur naturally in fermented foods such as yoghurt, sauerkraut, kimchi and other lactic-acid-fermented products and are part of the human microflora, including in the gut. Lactobacillus crispatus is one of the species that occur naturally in humans.

The KT-11 strain is a specific variant of this species that has been characterised in more detail by a manufacturer. According to the manufacturer, the strain was originally obtained from the stools of healthy infants. For use as a postbiotic, the strain is grown in a culture medium and then killed by heat, so that the end product consists of cells that can no longer multiply. Amounts are therefore not given in colony-forming units of live microorganisms in the classic sense, but as the number of heat-inactivated cells contained.

In the scientific literature, KT-11 has been studied mainly with regard to its surface structure. The following account describes its structure and the properties observed in laboratory studies neutrally and without reference to any health effect in humans.

In laboratory studies on cell cultures and in animal models, various biological effects have been observed for KT-11 and for the isolated S-layer protein, such as the interaction of the S-layer protein with certain surface structures and other microorganisms. These laboratory findings cannot simply be transferred to humans and do not constitute a promise of effect. The following section explains which statements about KT-11 are legally permissible.

This entry provides general information about the postbiotic Lactobacillus crispatus KT-11 and reflects the current state of scientific research neutrally. No specific health claim is authorised for KT-11 as an ingredient under Regulation (EU) No 432/2012, so we describe the substance factually, without promising any health effect.

Lactobacillus crispatus KT-11 is not a nutrient but a heat-inactivated postbiotic. There is therefore no D-A-CH reference value from the German Nutrition Society (DGE), no nutrient reference value for labelling (NRV) and no tolerable upper intake level set by the European Food Safety Authority (EFSA). An age-based requirements table like those for the vitamins therefore cannot be given for KT-11, as there is no requirement in the nutritional sense.

Instead of a reference value, the amount consumed is given as a cell count, i.e. the number of heat-inactivated cells contained per daily dose.

In the available studies in humans, daily amounts in the order of several billion up to around twelve billion heat-inactivated cells were used over a period of about four weeks. An independent expert panel has classified KT-11 as GRAS (Generally Recognized As Safe) under the US procedure.

Note: Any individual dosage beyond this should be left to a doctor.

Controlled studies in humans are available for Lactobacillus crispatus KT-11. These are randomised, double-blind, placebo-controlled studies, the most scientifically rigorous study design. The following summary reflects the state of research factually and does not relate it to any product.

Controlled clinical studies in humans are therefore available for KT-11. As no health claim is authorised for KT-11, we do not name individual endpoints or any health benefit here.

There are also studies on cell cultures and in animal models, for example on biological effects of KT-11 and its S-layer protein observed in laboratory studies. Such laboratory data serve to clarify possible mechanisms but do not allow any conclusions about a health effect in humans. Overall, the evidence on KT-11 is still limited. No health claims can be derived from the studies mentioned, and no effect may be claimed for any product.

An independent expert panel has given KT-11 a GRAS classification, i.e. an assessment as a food ingredient generally recognised as safe under US law. On the basis of this GRAS assessment, heat-inactivated postbiotics are considered well tolerated; they contain no live microorganisms and do not colonise the gut. The GRAS classification relates to safety as a food ingredient and is not a statement about any health effect.

As with all food supplements, the stated recommended daily dose should not be exceeded.

Note: If you are pregnant or breastfeeding, have a weakened immune system or a serious underlying condition, or take medicines regularly, you should check with a doctor before taking it. The same applies to children.

For Lactobacillus crispatus KT-11, no specific interactions with medicines have been described to the extent documented for individual vitamins or minerals, for example.

Note: If you take medicines long term, are receiving immunosuppressive therapy or have a chronic illness, you should discuss taking a new food supplement with your doctor beforehand. Medical advice is particularly advisable if you wish to use the postbiotic specifically in connection with an existing condition; such use should be left to a doctor.

As KT-11 is a heat-inactivated postbiotic without live microorganisms, the precautions sometimes given for live cultures for people with a severely weakened immune system do not apply.

In KT-11 Instant we use Lactobacillus crispatus KT-11 as a heat-inactivated postbiotic, i.e. in the form of killed bacterial cells that can no longer multiply. This form has manufacturing advantages: it is more stable than live cultures, has no special requirements for refrigerating live microorganisms and can easily be combined with other ingredients. KT-11 Instant combines the postbiotic with the fat-soluble vitamins D3 and K2 in an oily bead base. The choice of form does not imply any statement about a health effect, as no health claim is authorised for KT-11. The vitamins D3 and K2 it contains have their own encyclopaedia entries with the respective authorised health claims.

Lactobacillus crispatus KT-11 is contained in KT-11 Instant:

No nutrient reference value for labelling (NRV) has been set for Lactobacillus crispatus KT-11, so no percentage can be given. The amount stated refers to the number of heat-inactivated cells contained. One daily dose corresponds to two beads. KT-11 Instant combines the postbiotic with vitamins D3 and K2.

Note: If you are pregnant or breastfeeding, have a weakened immune system or take medicines regularly, please check with a doctor before taking it.

Food supplements are not a substitute for a balanced, varied diet and a healthy lifestyle.

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