Individuals with celiac disease and other gluten-related disorders have long been advised to avoid foods containing the ingredient “brewer’s yeast” but not the ingredients “yeast extract” or “autolyzed yeast extract.”

My current recommendation when either yeast extract or autolyzed yeast extract is listed as an ingredient in foods NOT labeled gluten-free is to contact the manufacturer and ask whether spent yeast from beer manufacturing is the source. Here’s why…

In 2010 I tested the yeast extract spread Marmite for gluten Marmite was assessed for gluten contamination as part of preliminary testing for a planned large study on yeast extract derived from brewer’s yeast (the primary ingredient in Marmite is yeast extract from spent yeast arising as a by-product of beer making). Brewer’s yeast, when used as an ingredient in food, may be a by-product of the beer brewing process and as such may be contaminated with malt and grain.

The planned study has not taken place due to lack of funding. If anyone is interested in helping to fund a study on yeast extract, please contact me.

The results of the testing on Marmite are as follows:

Sandwich R5 ELISA
Extraction One: 28 ppm gluten
Extraction Two: 31 ppm gluten

Lower limit of quantification for this assay is 5 ppm gluten

Competitive R5 ELISA*
Extraction One: 3,700 ppm gluten peptide
Extraction Two: 3,400 ppm gluten peptide

Lower limit of quantification for this assay is 1,250 ppm gluten peptide

*At the time this testing was conducted results of the competitive R5 ELISA were reported as gluten peptides.

Health Canadarecently revised their allergen labeling law. Under the new regulations which took effect August 4, 2012, all gluten sources in packaged food products (including barley) must be declared. Barley is now showing up on food labels containing yeast extract. The Canadian Celiac Association (CCA) has done some preliminary testing on yeast extract. As a result of the new allergen regulations and the preliminary test results, the CCA in the latest edition of the Pocket Dictionary Acceptability of Foods & Food Ingredients for the Gluten-Free Diet, is advising individuals with celiac disease to avoid consuming products containing yeast extract when “the ingredient list identifies barley protein as part of yeast extract.”

We do not know at this time how often spent yeast is the source of yeast extract (this is why a large survey of yeast extract manufacturers would come in handy). Unfortunately, in the US barley protein is not included under the Food Allergen Labeling and Consumer Protection Act. So in the US(unlike Canada) there is no way to know from the food label whether the ingredient yeast extract contains barley protein. While this is not cause for undue alarm it is important to clarify with manufacturers whether spent yeast is the source of yeast extract in a food product not labeled gluten-free.

Thank you to Canadian dietitians extraordinaire Alexandra Anca, MHSc., RD and Shelley Case, BSc, RD for help compiling this information.

Copyright © 2013 by Tricia Thompson, MS, RD. All rights reserved. This article may not be reprinted, reposted, or republished without the express written permission of Tricia Thompson.

Update on gluten-free status of yeast extract