Brewer's yeast for human consumption?
Tanzania: Breweries Waste Product for Human Consumption? Anthony Twist 19.04.99
Re: Tanzania: Breweries Waste Product for Human Consumption? Nevin Scrimshaw 26.04.99

Date: Mon, 19 Apr 1999 12:07:04 +0100

From: Michael Golden <>

Subject: Tanzania: Breweries Waste Product for Human Consumption?


I was approached by a VSA volunteer working in a region that's been hit pretty hard by drought. He has managed to talk Tanzania Breweries into giving him their waste products to use as a food source. This amounts to 70-80 kilos of yeast a day, but also a ton of grain.

Now, production of single-cell protein is a little bit beyond A-level, but I am pretty sure that the yeast cells are going to have to broken down to make them edible for humans. I'm trying to chase up low-tech ways of doing this now, but I have some concerns about the effects of feeding this to people (especially children) suffering form malnutrition.

I know the WHO has guidelines about reducing the purine content of yeast biomass before deeming it fit for human consumption, and as the yeast, together with a little banana porridge, is going to be pretty much the whole diet for several months at least, we'll have to find out if this will be a problem.

My primary concerns are:

1 How to induce autolysis in yeast using low tech methods.

2. Possible problems associated with excessive intake of purines in malnourished individuals.

3. Is there significant risk of antigenic reaction to the yeast proteins?

4. This food is going to have to be spread pretty thinly, and is probably going to be doled out to children ranging from teenagers to infants. If I can get a rough estimate of the minimal protein and carbohydrate rations necessary to tide these people over for four months or so (until the new crops are ready to be harvested) it would be helpful. I know this is virtually impossible to gauge, but I thought I better ask for it anyway.

thank you

Anthony Twist

Date: Mon, 26 Apr 1999 08:54:00 +0100

From: "Dr. Nevin Scrimshaw" <>

Subject: Re: Tanzania: Breweries Waste Product for Human Consumption?


There is no problem with digestibility of yeast protein and it has a fair net protein utilization without being broken down and is good source of B-vitamins, but there are problems:

1. Persons consuming a good mixed diet with moderate amounts of animal protein should not be given more than 30 g of any yeast and proportionately less for children, because of the increased RNA leading to increased uric acid levels and excretion. For individuals consuming diets low in animal protein the safe limits are at least 50% higher.

2. Brewer's yeast has a much stronger taste compared with baker's (Torula) yeast. This limits it use. Malnourished children can be given as much as they are willing to consume for this reason and because there is little risk of gout in men before puberty and women before menopause.

If requested I can provide references and reprints when I return to my Boston office next week..

With best wishes,


Nevin Scrimshaw