Many of you have been interested in learning about the benefits of nutritional yeast, and one of the most common questions I’ve been asked is whether or not I recommend it. Personally, it’s not something I eat. In fact, I’ve always avoided it, maybe intuitively… I’m not quite sure! I’ve read so many reviews on nutritional yeast and they are often at opposite ends of the spectrum. You may hear that it’s the worst thing you could eat because it’s processed and contains mycotoxins. Or you may hear it’s the best at boosting energy levels, immunity and is the most natural food supplement out there. If you’re confused at whether or not nutritional yeast is actually good for you, I totally understand! I decided to do a deep dive on nutritional yeast to understand how it’s processed and give my own take on whether it’s actually good for you.

NUTRITIONAL YEAST VS. BREWER’S YEAST: what’s the difference?

Nutritional and brewer’s yeast are close relatives, and they both contain Saccharomyces cerevisiae - a type of yeast used in brewing and baking. They differ slightly in the production process, nutritional value, and uses.

BREWER’S YEAST

Is a byproduct of the beer brewing industry and is usually grown on hops or grains. Depending on the way it’s brewed, it may contain gluten. It also has a very bitter taste that some find unpleasant. People will commonly use it in the dried and deactivated form as a nutritional supplement.

NUTRITIONAL YEAST

Is deactivated yeast used as a ‘nutritional supplement’ for many vegans and vegetarians. It’s known for its nutty/cheesy flavour and it tastes much better than brewer’s yeast. Nutritional yeast can be found in many products such as bone broth powder, vegan cheeses, vegan ‘meats’ and cashew cheese, to name a few. You may see it called ‘Savoury Yeast Flakes’ in Australia and New Zealand.

HOW IS NUTRITIONAL YEAST MADE?

The production of nutritional yeast begins in highly controlled laboratories, where a common yeast called Saccharomyces cerevisiae grows on sugar cane, whey, beet molasses, or wood pulp (yum!). The temperature and pH are systematically controlled to optimise growth. Once the growing process is complete, the fermented yeast liquid goes through a washing or centrifuging process to concentrate the yeast cells. The result is an off-white liquid or “nutritional yeast cream.”

The nutritional yeast cream is pasteurised to render the yeast inactive. Addition of synthetic vitamins is also done in this phase. Next, the yeast is dried, either by drum drying or spray drying, depending on the manufacturer. Drum drying involves drying the yeast at relatively low temperatures over rotating, high-capacity drums that produce fine sheets of dried material. These sheets are then milled into flake or powder form.

Some manufacturers choose to spray dry the yeast and this method is used for producing fine dry powder by rapidly drying the yeast with hot gas. Spray drying often causes thermal degradation and is considered a poor method for producing nutritional yeast. Once the drying process is complete, the nutritional yeast is packaged.

WHAT ARE THE BENEFITS OF NUTRITIONAL YEAST?

I’m not going to go into too much detail here as there are plenty of other blogs out there on this, but here is a quick overview. Despite the questionable manufacturing process, nutritional yeast is rich in protein, and even contains some prebiotic fibre. There is some evidence that nutritional yeast is an immunity booster because nutritional yeast contains immunity-boosting beta-glucans. Fortified nutritional yeast products can also contain selenium, zinc, chromium and vitamin B12 which may help to boost energy levels. Though there is limited clinical evidence, selenium-enriched yeast is said to enhance thyroid function and can help with autoimmune thyroid disorders such as Hashimoto’s and Grave’s disease.

WHAT ARE THE PITFALLS OF NUTRITIONAL YEAST?

Like anything, there are advantages and disadvantages to the use of nutritional yeast. Anytime we make changes to our diet or choose to try a new supplement, it’s so important to consider all angles.

Let’s dive into some of the pitfalls of nutritional yeast.

SYNTHETIC FORTIFICATION

Though it’s often consumed for its high nutritional value, most of the nutrients in fortified nutritional yeast are not naturally occurring. Many of the nutrients in nutritional yeast are manmade and are added in during the manufacturing process. For many of us, this is shocking because nutritional yeast is often marketed and packaged as a natural and wholesome product, full of good quality ingredients. When you learn it’s full of added chemicals…it’s quite concerning!

When looking at the labels for nutritional yeast, it’s important to keep in mind that the nutritional values are high because most companies add synthetic nutrients to their products. For example, many nutritional yeast products are very high in vitamin B12. But how can this be? Yeasts do not naturally contain vitamin B12. The bright yellow colour in each of these products is a tell-tale sign of synthetic B vitamins.

Many vegans and vegetarians take nutritional yeast as a way of getting vitamin B12. However, you cannot get B12 from plant-based sources. This vitamin is found only in animal products. Some information out there suggests that it’s possible to get B12 from plant sources such as seaweed, spirulina, fermented soy, brewers yeast, and nutritional yeast. However, these plant sources don’t naturally contain vitamin B12. In fact, they produce a pseudo-vitamin B12, which doesn’t have biological activity in humans. It can actually compete with other forms of active B12 and potentially contribute and worsen B12 deficiency in humans.

Another common additive in nutritional yeast is folic acid. While certain strains of Saccharomyces cerevisiae do have the potential to biosynthesise folate, it’s not often generated in significant quantities. Folic acid is the synthetic form of folate. It can trigger health problems for those with the MTHFR gene mutation (remember folate and folic acid are not the same thing. folate is necessary for methylation, yet folic acid blocks it). Any time these nutrients—vitamin B12 and folic acid— are present on nutritional yeast labels, it is fair to assume they’ve been added.

Other nutrients can also be added to fortify the nutritional yeast including vitamin C, vitamin A, selenium, zinc, chromium and iron. Some brands claim to use “naturally derived nutrients” for fortification, while others openly use synthetic compounds. Unfortunately, the term “natural” isn’t regulated, making it difficult to assess the true quality of the fortifying nutrients. If you’re seeking an authentically natural product, be sure to do your research when it comes to synthetic fortification.

NUTRITIONAL YEAST MAY CONTAIN OTHER ADDITIVES

Other ingredients may also be added to nutritional yeast during manufacturing, such as; rice flour, salt, and sometimes emulsifiers. If it’s made into a food, additives like milk powder, maltodextrin, microcrystalline cellulose, dehydrated vegetable powder(s), sesame, soy milk powder, lactose, calcium carbonate, starch, refined sugar, flavouring agents and/or essence can often be added in.

CONTAINS MOULD TOXINS

This was one of the most interesting discoveries I found while researching nutritional yeast. Prebiotics (beta-glucans and mannan-oligosaccharides) and cell wall components from Saccharomyces cerevisiae (the yeast used to cultivate nutritional yeast) have been found to support the gut microbiome.

In animal studies, scientists observed the potential of these components to shield the gut by binding fungal toxins such as ochratoxin A (a mycotoxin). However, the potential of Saccharomyces cerevisiae to bind fungal toxins is a double-edged sword. Out of 46 yeast supplements that were analysed, almost 90% were contaminated with ochratoxin A which can damage your kidneys. This study was specific to brewer’s yeast supplements, but the same threat exists for nutritional yeast, as they both contain inactive Saccharomyces cerevisiae. To avoid contaminated yeast, make sure to choose lab-tested products from reputable brands.

According to Dave Asprey’s article,

Yeasts almost always contain high levels of mould toxins. They also encourage a yeast-like fungus called Candida albicans to grow in your body, which changes the fungal biome of your gut. Gut imbalances cause brain fog, fatigue, food cravings, inflammation, mood changes, weight gain, and even neurological disorders.

People allergic to yeasts and mould should skip nutritional yeast, or at the very least, choose lab-tested products to prevent contamination with fungal toxins.

CANDIDA & GUT ISSUES

Whether or not yeast causes candida to worsen is pretty controversial, and the available clinical evidence is limited right now. Nutritional yeast contains completely deactivated Saccharomyces cerevisiae, which means it shouldn’t cause or worsen infections in the majority of cases. However, in Dave’s article (linked above), he mentions that it’s the mould toxins in yeast products that encourage candida to grow in the body. There is definitely a big connection between mould and candida growth, you can read more about it here and watch Dave Asprey’s documentary MOLDY if you’re interested.

In some people, nutritional yeast can cause stomach cramps, and 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). I’ve also had many of my clients, as well as people message me saying ‘nutritional yeast flares up my thrush’ or ‘I can’t eat nutritional yeast, I get extremely bloated and gassy afterwards’, or ‘nutritional yeast gives me stomach cramps’.

DOES IT CONTAIN MSG?

Some researchers have warned about high levels of glutamate in nutritional yeast, which acts as an excitatory neurotransmitter in your brain. Brewers and other yeast products contain glutamate, a naturally occurring amino acid that is formed during the drying process. Fortunately, the concentration of glutamate is far lower than factory-produced glutamic acid, aka MSG (monosodium glutamate).

Glutamate is a naturally occurring amino acid that helps give cheese, meat, mushrooms, and many other foods their rich umami flavour. The trouble is that some individuals are highly sensitive to glutamates, natural or otherwise. Sensitivities to MSG (the highly processed and concentrated form) are even more common.

However, excess glutamate in the brain may contribute to cognitive impairment. People with glutamate intolerance may also experience inflammation of the nose and airway a day after consuming too much. An excess of glutamate may also contribute to neurological disorders and increase the sensation of pain. If you’re sensitive to MSG or if you suspect that you’re sensitive to glutamate, you may want to avoid nutritional yeast altogether.

GLUTEN INTOLERANCE

Nutritional yeast doesn’t contain gluten, however, studies have found that people with celiac disease (gluten intolerance) or Crohn’s disease may have antibodies to Saccharomyces cerevisiae. This ultimately means that nutritional yeast and yeast-based products may worsen symptoms of gluten intolerance or celiac disease.

ENVIRONMENTAL IMPACT

Another drawback of nutritional yeast production is the emission of acetaldehyde however, regulations have been set in place to limit this.

ECZEMA

Those with atopic dermatitis (a type of eczema) may also be intolerant to yeasts, including nutritional yeast.

I recently did a survey on my Instagram asking if anyone had noticed whether nutritional yeast worsens their symptoms. Some said they hadn’t noticed any symptoms after consuming it, however, the majority of people said they noticed thrush flare ups, bloating, eczema flare ups and skin itching, brain fog, lightheadedness, headaches, gut discomfort such as stomach cramps and flatulence, it even triggered asthma for one person. There is limited clinical evidence surrounding the use of nutritional yeast and these symptoms, however, I still think it’s worth mentioning as for many people, these symptoms can be severe.

SUMMARY

All in all, I found the risks and the drawbacks of nutritional yeast to be greater than the purported benefits. Below are some of the key reasons to avoid nutritional yeast:

Many brands add folic acid, which is problematic for people with methylation issues (remember folate and folic acid are not the same thing. Folate is necessary for methylation, yet folic acid blocks it).
It’s often fortified with numerous vitamins, which can be harsh on your kidneys or liver
Nutritional yeast contains high levels of glutamates (due to the manufacturing process)
There are better food sources for nutrients found in nutritional yeast (ex. Vitamin B12 is found naturally in animal products)
Nutritional yeast isn’t suitable for people with yeast or mould allergies, kidney stones, and skin issues such as eczema
Nutritional yeast may worsen symptoms of gluten intolerance or celiac disease as well as flare up candida for some

Personally, after reviewing this information more closely, I don’t feel the need to add this into my diet. I think there are much better nutrient-dense food sources out there, and the benefits don’t seem to outweigh the drawbacks for me. However, if you do choose to use it, the best nutritional yeast should have the following characteristics:

It contains no GMOs
Has no added/synthetic vitamins
It contains only natural folate (no folic acid)
It’s manufactured, processed, and handled to preserve the heat-sensitive nutrients as much as possible
Drum drying is used instead of spray drying
Low temperature processed to minimise glutamate content
It’s free of any other fillers or unnecessary additives (rice flours, gums etc.) - it should be just one ingredient
It’s lab-tested to determine if there is any contamination with fungal toxins and other contaminants
Packaged to protect the yeast from light

Here are a few brands I found after a quick google search that have some of the above characteristics:

Anthony's Brewer's Yeast - derived from molasses, is non-GMO, contains one ingredient, is unflavoured, unsweetened, unfortified, batch tested and verified gluten free.
Foods Alive - is unflavoured, unsweetened, unfortified, non-GMO, contains one ingredient and is gluten free. (I could not find if this brand has been tested to see if it’s free of contaminants such as lead, fungal toxins etc.)
Sari Foods - non-GMO, unfortified, derived from molasses, one ingredient, dried at a low temperature, third party tested to ensure it’s free of toxic metals, contaminants, and other organisms.

If you know of better brands with all of the above characteristics I’ve listed above, feel free to comment below.