Note that brewers yeast is essentially the same thing as nutritional yeast. Though they used to be quite different in years past, the manufacturing process for both is now virtually identical in most cases. Hence, when reviewing the nutritional yeast dangers below, be aware that these same problems exist for brewers yeast.
Gut Problems and Candida
Those struggling with yeast overgrowth issues would do best to avoid food based forms of brewers yeast. This is because the yeast is potentially still active and able to contribute to symptoms. Examples include Vegemite, a popular sandwich spread, and a similar product in the UK called Marmite.
However, dried supplement powders, nutritional flakes and tablets have no risk of yeast colonization in the gut. The yeast is completely deactivated. Therefore, they pose no problems in the majority of cases.
There are two exceptions to the above discussion. First, for individuals with a yeast sensitivity or allergy, any exposure, live or deactivated, is detrimental.
Second, those with severe intestinal problems such as Crohn’s and ulcerative colitis should be very careful with nutritional yeast and related products even if deactivated.
Blood Sugar Risks
Yeast based foods and supplements are likely high in chromium if made from beer manufacturing residue. While chromium is considered helpful for blood sugar control, studies are actually inconsistent on the matter.
Thus, it is best for someone with diabetes or any other blood sugar issues to consult with a practitioner before using yeast supplements. (1)
Those taking Monoamine oxidase inhibitors (Demerol drugs) need to avoid yeast supplements. They can contain high levels of tyramine. This amino acid has the potential to adversely interact with monoamine oxidase inhibitor type medicines.
Yeast products and MSG
Brewers and other yeast products contain glutamate, a naturally occurring and important amino acid. Fortunately, the concentration of glutamate is far lower than factory produced glutamic acid, aka MSG (monosodium glutamate).
Glutamate is actually a valuable, naturally occurring amino acid that helps give cheese, meat, mushrooms, and many other foods their rich, desirable umami flavor. The trouble is that some individuals are highly sensitive to any glutamates, natural or otherwise.
Even more people are sensitive to MSG, the highly processed and concentrated form. As a result, some in the healthfood community consider all glutamate bad when it is really just MSG that is the problem for most people.
For many, lack of enough or the complete absence of particular enzymes in the digestive track to break down glutamate causes the sensitivity. Oftentimes, this type of compromised digestion triggers problems with foods containing glutamate, such as traditional bone broth. Thus, the food itself is not really the problem. In those cases, a gut healing diet like GAPS or Autoimmune Paleo can help resolve these issues.
That being said, it is a good idea to source low temperature processed brewers yeast to minimize glutamate formation (vetted brand). If you are particularly sensitive to MSG and glutamate in general, you may wish to avoid this type of supplement entirely. Avoiding foods that contain yeast extract is a good idea too.
Genetically Modified Ingredients (GMOs)
A glucose rich medium is necessary to cultivate yeasts. Hence, the contents of this medium are crucial for a quality final product. Since supplement companies typically use corn, sugar cane, or sugar beet based matrixes, there is a significant likelihood that unless otherwise stated, the manufacturer utilized a genetically modified (GM) medium. This is because the vast majority of farmers growing sugar beets in the US cultivate genetically modified forms. In addition, 92% of corn (81% of corn in Canada) is also of GMO origin as of this writing.
Some manufacturers source organic or certified non-GMO ingredients for making their yeast products. But, if the label does not specifically state it, contact the company about the purity of their products before buying.
Gluten Contamination and other Allergies
Brewers yeast has other risks beyond contamination with GMOs and various agricultural chemicals like glyphosate used on these crops.
If you are gluten free, make sure you get a supplement that guarantees its purity. Manufacturers sometimes use grain based mediums including wheat to grow yeasts. Thus, it is possible that gluten residue contaminates these products.
In addition, some people are allergic to yeasts, including baker’s yeast as well as brewers and nutritional. Some cannot even tolerate the beneficial yeasts in fermented beverages such as kombucha.
This is a separate issue from Candida overgrowth, which these supplements do not encourage. If you or someone in your family has a suspected yeast allergy or sensitivity, these foods will probably not be right for you.
If you are unsure, as with any change in diet or supplements, start small and watch how you feel and how your body reacts. This article on simple at-home allergy testing may prove helpful.
Buyer beware! Some companies add synthetic nutrients to their yeast, especially vitamin B12. The reason is that yeast only makes this nutrient naturally in very small amounts. So the reputation of yeast supplements as a completely natural source of B vitamins is actually quite untrue.
Yeasts are a good source for SOME B-vitamins only. The high amounts for many nutrients on many product labels are only because the yeasts are fortified with non-yeast created forms.
For example, if the label lists B12, it is safe to assume that it contains added B12. The source is most likely synthetic.
Studies show concerns over synthetic B12. As such, people should beware of buying any yeast supplement that is fortified with synthetic forms of this vitamin. It’s not particularly effective at resolving a B12 deficiency anyway!
In addition to synthetic B12, yeast supplements are frequently fortified with potentially dangerous folic acid. Folic acid is the synthetic form of folate. It triggers serious health problems for those with the MTHFR gene mutation.
To give an example as to why you must ask before ordering, here is a response from Frontier Natural Foods Co-op regarding their nutritional yeast. Incidentally, this is the recommended brand in homemade baby formula because it is low in glutamate. This answer below, however, gives one pause about using it for that purpose.
Thank you for contacting us. Our [Frontier] nutritional yeast is made with [synthetic] folic acid, not folate. Here is from our product detail. After the fermentation process is completed the yeast is harvested, thoroughly washed, pasteurized, and dried on roller drum dryers. The B vitamins are both naturally produced during fermentation, and added to the cream prior to the drying process. Riboflavin (B2) is created during fermentation. Additional Riboflavin (B2) is added after fermentation along with Thiamine (B1), Pyridoxine HCL (B6), Niacin and Folic Acid.
I hope you find this information helpful. If you have additional questions, please let me know.
Inconsistencies Among Yeast Manufacturers
While Frontier uses a very good manufacturing process that produces low levels of MSG, note that the company adds multiple, synthetic or unknown forms of many B-family vitamins to the final product!
Another contacted brand, Twin Labs Brewers Yeast, claims to not add any synthetic folic acid. Note that the label says “folic acid”, but the company claims that the B9 is actually entirely folate. This is the natural form that causes no problems for those with the MTHFR gene.
Always be sure to ask about synthetic fortification before buying a nutritional yeast supplement if you are seeking an entirely natural product.
In summary, it is best to do your homework before buying and consuming nutritional yeast. There are several pitfalls to avoid so that this supplement is part of the solution and does not become part of the problem.
Sarah, The Healthy Home Economist
Sarah Pope has been a Health and Nutrition Educator since 2002. Her work is dedicated to helping families effectively incorporate the principles of ancestral diets within the modern household. She is a sought after lecturer around the world for conferences, summits, and podcasts.
Her work has been covered by major media including USA Today, ABC, NBC, and many others.