Knowledgebase: Nutrition
Yeast: Fermented? Nutritional Yeast vs. Autolysed Yeast | Yeast Flakes | Brewer's Yeast
Posted on 30 July 2012 06:52 PM

Should we avoid yeast because it's fermented?

Regular bread yeast is a yeast that we consider "active" and once it is activated is used as a leavening agent. There is a fermentation process that occurs. Cooking this yeast will kill it, stopping its growth. 

The nutritional yeast is "inactive" or "deactivated." It is a rich source of B vitamins including B12. When added to foods it has a nutty, cheesy flavor.


Is nutritional yeast the same as autolysed yeast?

Autolyzed yeast is a yeast extract made by adding sugar to yeast. When the yeast expands, the cell walls of the yeast cells become soft, and is spun in a centrifuge (a machine which rotates rapidly) to separate the cell walls and remove them. What is left is the inside of the yeast cells. The enzymes from within the cells break down the proteins into amino acids, including free glutamic acid (which acts as MSG). Some sources say it does contain free glutamic acid, while other say the amino acid is bound to other amino acids, so the answer is unclear. If you get any type of reaction such as heart palpitations, or other symptoms associated with MSG, it is best to avoid it.  

Nutritional yeast, is produced by culturing a yeast in a nutrient medium which contains glucose either from sugarcane or beet molasses, for several days. Once it is ready, it is killed  (deactivated) with heat, and then dried.

Both may contain free glutamic acid.


Yeast flakes are my food in question. I absolutely loved yeast flakes, but I've heard and read that all inactive yeast contains free glutamates, and this includes yeast flakes. Are yeast flakes excitotoxins, or not? If they are not, why are they exempt?

I asked Carrie Beets how they would answer your question. Carrie Beets is a health educator and medical researcher and free-lance author who founded the massage school at Black Hills Health and Education Center in Black Hills, South Dakota and whose experience and judgement I value and appreciate.

To answer your question, let me state my present understanding:

Whole, naturally growing things can be good, for example fruits, grains, and vegetables. Whole, naturally growing things can be bad, for example tobacco or popularly used tea or coffee. So it is not a safe “rule of thumb” to conclude if something grows in nature, it is good for you as long as taken or eaten whole, meaning unrefined and in moderation.

However it is generally accepted, that the more refined a food or substance is, the less well it fits into body physiology and function. That is because everything reacts with everything else in the body and everything in the body works by extremely small steps, almost always aided by a catalyst or enzyme and is directed by the local cell nucleus and brain control.

In short, body physiology is extremely complicated and very much influenced by many factors including time of day, its immediate environment, hormones, temperature, and the direction of genes and brain control.

We know that we have more microorganisms in our body than we do cells in the body. We live in what is called a symbiotic relationship with these organisms – meaning that both the organisms and we benefit from their presence in us. And that includes things like bacteria and yeasts that can also be harmful as well as beneficial.

So are yeast flakes good or bad for you and why?

Definitions as defined by

Nutritional yeast is a deactivated yeast, often a strain of Saccharomyces cerevisiae, which is sold commercially as a food product. It is sold in the form of flakes or as a yellow powder and can be found in the bulk aisle of most natural food stores.

Glutamic acid

Nutritional yeast products do not have any added monosodium glutamate; however, all inactive yeast contains a certain amount of free glutamic acid because when the yeast cells are killed the protein that comprises the cell walls begins to degrade, breaking down into the amino acids that originally formed it. Glutamic acid is a naturally occurring amino acid in all yeast cells, as well as in many vegetables, fungi and meats.

My current understanding concerning the use of yeast flakes is that I would not expect the amount of glutamic acid in a moderate use of yeast flakes for flavouring to be harmful to your brain. Not because of some sort of exemption but because yeast flakes are not a highly refined product and would be expected to be beneficial when used in moderation.

Carrie Beets reply:

Dr. Russell Blaylock tested nutritional yeast and reportedly found 2 excitotoxins in it, which is what started all the uproar. What is not clear (actually I doubt the lab even tried to determine) is whether the excitotoxins are naturally occurring or if they were added. Red Star is the main producer of nutritional yeast. They have an excitotoxin manufacturing division, so it is assumed that they must have added the excitotoxins to the nutritional yeast, but that may not be the case. My suspicion is that the excitotoxins are naturally occurring. Here is the link on how they produce the yeast.   

From this website  the person writing states "I was attending two natural healing seminars, in 1999 and also 2000, where more than 1,000 people were in attendance each time. Dr. Blaylock was one of the featured lecturers. Dr. Blaylock revealed his findings to a spell-bound audience, and it was here where I first learned that my beloved nutritional yeast, like its other yeast cousins, contained "free glutamic acid". It was after having lunch with Dr. Blaylock in June 2000, that it was further reinforced that the "NON-Active Saccharomyces cerevisiae Nutritional Yeast", as used by many vegetarians and found in generous supply in many "green drinks", also contains "free glutamic acid"—the same neurotoxic compound as monosodium glutamate (MSG). Nutritional Yeast is classified as an "excitotoxin"—a classification of neurotoxic compounds that over-stimulate the neurotransmitters of the brain to death. According to Dr. Blaylock, "Free Glutamic Acid (MSG) literally stimulates neurons to death, causing brain damage to varying degrees." I learned that this MSG is not added to Saccharomyces cerevisiae nutritional yeast, but it occurs as a direct result of its growth and processing. Please see the Truth In Labeling web site"  (italized emphasis added).

Kombu is a seaweed. It has a naturally occurring excitotoxin in it. The Japanese (World Wars I and II) used to add it to their canned rations for their military for flavor. After the US won against Japan and they went in and liberated  American prisoners of war they found the canned rations for the soldiers running the prisoner of war camps. And they opened some of the rations and ate them, discovering that they tasted better than the American rations.  The American government then called a conference with US food manufacturers and introduced them to the Japanese military rations.  The American food manufacturers went on to create the artificial MSG used today.

Before I knew all this I had eaten Kombu occasionally (you add it to some dishes) and I never got an MSG reaction to it. That makes me think that MSG, as an extracted component or an artificially created component is the problem. Just like with herbs, the whole herb rarely causes problems. It is when a lab extracts one component out of the herb and then feeds to lab rats in high doses that it produces side-effects and illnesses.

Notice in the quote above from Daystar Botanicals that all yeasts, not just nutritional yeast, contain the free glutamic acid. So are you going to stop eating bread also since it contains yeast which naturally contains excitotoxins?

Because I know that I didn't react to Kombu either the naturally occurring MSG didn't bother me because it was the way God made it, or it was in a low enough quantity, or both, I would tend to not worry about the naturally occurring excitotoxin in the nutritional yeast and bread yeast, unless I was getting a reaction from it when using it in a recipe. For myself, I have not noticed any reactions to nutritional yeast in recipes. Back when I used to go to Chinese restaurants I learned to pick my restaurant carefully and inquire regarding their adding the [artificial] MSG as otherwise I sometimes got a very notable reaction to MSG. I wouldn't go out and eat huge quantities of nutritional yeast, but, because of my previous experiences, I wouldn't be afraid to eat cashew gravy with a little nutritional yeast in it. Just like I wouldn't be afraid to eat bread because it has excitotoxin containing baker's yeast in it. Christ did not teach to avoid bread because of the naturally occurring excitotoxins in it from the yeast.

Is Brewer’s yeast good to use?

One benefit of brewer's yeast is that it is very tightly controlled in its production. The other yeasts are not under the same necessity to be controlled tightly necessarily. According to the University of Maryland Brewer's yeast is a rich source of minerals -- particularly chromium, an essential trace mineral that helps the body maintain normal blood sugar levels; selenium; protein; and the B-complex vitamins. It tastes bitter and should not be confused with baker's yeast, nutritional yeast, or torula yeast. All those types of yeast are low in chromium. Brewer's yeast has been used for years as a nutritional supplement.

The best way to find out if an advertised product is good for you, is do personal research on the subject and based on your findings try it out, if it seems reasonable to do so. Food is one of the important issues for life and health and sickness and disease. It is not a surprise that we will receive conflicting information or misinformation on this subject. It is my current understanding that brewers yeast can be beneficial to most people as a source of B vitamins (except B12) and trace minerals. This idea of trying it out for yourself is a Biblical approach: Psalm 34:8 King James Version (KJV)

“O taste and see that the Lord is good: blessed is the man that trusteth in him.”

(16 vote(s))
This article was helpful
This article was not helpful

Comments (0)
Help Desk Software by Kayako Resolve