Leiber Yeast Immunity Claim Turned Down by EFSA

In weighing the evidence the Panel took into account that in the one human intervention study conducted with Yestimun from which scientific conclusions could be drawn for the scientific substantiation of the claim, no effects of Yestimun were observed on any outcome that could imply a beneficial effect on the initiation of appropriate innate and adaptive immune responses.

27 May 2010 --- An EFSA Panel has concluded that a cause and effect relationship has not been established between the consumption of Yestimun and the initiation of appropriate innate and adaptive immune responses.

Following an application from Leiber GmbH submitted pursuant to Article 13(5) of Regulation (EC) No 1924/2006 via the Competent Authority of Germany, the Panel on Dietetic Products, Nutrition and Allergies was asked to deliver an opinion on the scientific substantiation of a health claim related to Yestimun and the initiation of appropriate innate and adaptive immune responses.

The scope of the application was proposed to fall under a health claim based on newly developed scientific evidence and including a request for the protection of proprietary data.

The food that is the subject of the health claim is Yestimun. Yestimun consists of (1,3)-(1,6)-β-D-glucans from brewer’s yeast cell wall (100 % Saccharomyces cerevisiae) as “active” ingredient (about 90 % by weight). Beta-glucans are polysaccharides consisting of a backbone of D-glucose subunits linked by (1,3)-β-glucosidic bonds with irregular β (1,6)-linked glucosidic side chains of various length. The Panel considers that the food, Yestimun, which is the subject of the health claim, is sufficiently characterised.

The claimed effect is “reducing the risk for common cold infections by decreasing the susceptibility for common cold infections during the cold season by strengthening the body’s natural defences and improving the body’s immune defence against common cold viral infections during the cold season”. The target population is adults. The Panel notes that a well-functioning immune system includes the initiation of appropriate innate and adaptive immune responses including defence against viral infections such as common colds. The Panel considers that the initiation of appropriate innate and adaptive immune responses is a beneficial physiological effect.

The applicant identified 17 references as being pertinent to the health claim. These references included 10 human studies, five animal studies and two in vitro studies.

Four human intervention studies addressed the effects of intravenously injected yeast beta-glucans. The Panel considers that no conclusions can be drawn from these studies for the scientific substantiation of the claimed effect owing to the inappropriate route of exposure. Four human studies investigated the effects of oral administration of yeast beta-glucans on immune parameters. The Panel considers that no conclusions can be drawn from these studies for the scientific substantiation of the claimed effect as the changes of immune parameters do not represent an improvement on the initiation of appropriate innate and adaptive immune responses.

One publication reported on a pilot double blind placebo-controlled randomised intervention on the effects of Wellmune, a preparation derived from brewer’s yeast cell wall (Saccharomyces cerevisiae) and containing beta-glucans, on multiple end points. The Panel notes the very small number of subjects recruited, the high drop out rate, the multiplicity of “primary outcomes”, and the lack of adjustment for multiple testing. The Panel considers that no conclusions can be drawn from this study for the scientific substantiation of the claimed effect.

An unpublished study report presented the results of a multicentre randomised, double blind, placebo-controlled trial conducted in 100 healthy adult subjects over a period of 26 weeks with Biolex Beta HP capsules (same as Yestimun). The primary outcome of the study was the frequency of occurrence of cold episodes. The Panel considers the frequency of occurrence of cold episodes as an indirect measure of the function of the immune system. The difference between test and placebo groups was not statistically significant. Post-hoc analyses were performed based on episodes that occurred in the winter months using both the per-protocol and the intention-to-treat populations. The Panel notes that these post-hoc analyses were not statistically justified by the applicant. The quality of typical common cold symptoms (sore throat and/or difficulty swallowing, hoarseness and/or cough and watery nasal secretion) during the cold episodes was assessed as secondary outcome. The Panel considers that the evidence provided does not establish that changes in any of these secondary outcomes in relation to the treatment of common cold imply a beneficial effect on the initiation of appropriate innate and adaptive immune responses.

The Panel notes that the evidence provided in animal and in vitro studies does not predict an effect of Yestimun on the initiation of appropriate innate and adaptive immune responses in humans.

In weighing the evidence the Panel took into account that in the one human intervention study conducted with Yestimun from which scientific conclusions could be drawn for the scientific substantiation of the claim, no effects of Yestimun were observed on any outcome that could imply a beneficial effect on the initiation of appropriate innate and adaptive immune responses, and that the evidence provided in the animal and in vitro studies does not predict an effect of Yestimun on the initiation of appropriate innate and adaptive immune responses in humans.