At first, nutritional yeast tastes a little weird.
But after you get used to it, it’s a great substitute in foods to get that “cheesy” flavor, and generally regarded as a healthy food.
You’ve likely noticed that it contains well over 100% of some vitamins on the nutritional label, and reasonably wondered if it was safe to eat in large amounts.
So let’s find out.
As far macro content goes, it’s all protein and fiber, so no real concerns there. We’ll focus on the vitamins and minerals instead.
Most are water soluble, meaning that you’ll simply urinate out the rest, so there’s no concerns of overdoing it. However, some do have a tolerable upper limit that you want to be mindful of.
Using the nutritional data from Bob’s Red Mill nutritional yeast, I’ve created a table to help answer the question at hand. It may differ by brand, but should be close.
|Nutrient||Amount in Nutritional Yeast (1/4 cup)||Tolerable Upper Limit||Servings to Exceed Limit|
|Calcium||6 mg||2,500 mg||416|
|Iron||1 mg||45 mg||45|
|Potassium||264 mg||Not established||N/A|
|Thiamin||11.8 mg||Not established||N/A|
|Riboflavin||9.7 mg||Not established||N/A|
|Niacin||46 mg||35 mg||0.76|
|Vitamin B6||5.9 mg||100 mg||17|
|Folate||1828 mcg||1,000 mcg||0.55|
|Vitamin B12||17.6 mcg||Not established||N/A|
Four of the nutrients have no tolerable upper limit, so we don’t need to be worried about them at all.
Of the others ones, 3 require 17 servings (of 1/4 each), or 4.25 cups of nutritional yeast before being concerning. I don’t know anyone who could eat that much.
But two vitamins do look a bit worrying: Niacin and folate. Nutritional yeast is by far the best source of folate for vegans (although it’s not particularly hard to get).
If you have more than 1/8 of a cup of nutritional yeast, you will surpass the safe tolerable upper limit for adults.
The question is how big of a deal is this?
What Happens When You Have Too Much Niacin?
Even just a tablespoon of nutritional yeast gives some people enough niacin to cause skin flushing (turning red), and sometimes even becoming dizzy.
That’s why the upper limit is set pretty low.
If you’re affected by that, you probably shouldn’t have more than a tbsp or so of nutritional yeast per day.
But many people don’t have these issues, and won’t experience serious side effects unless they regularly take more than 2,000 mg of niacin per day, according to the Mayo Clinic.
Once you regularly ingest that much, you might see:
- Rapid heartbeat
- Nausea and vomiting
- Abdominal pain
- Liver damage (from sustained high levels of niacin)
To put this in context, it would take 20 servings, or 5 cups of nutritional yeast, to hit 2,000 mg of niacin in a day.
And you’d have to do that fairly regularly to cause serious damage (assuming you’re healthy and don’t have any weird reactions to niacin).
What Happens When You Have Too Much Folate?
Folate is controversial.
The upper limit is set really low, and it’s set specifically for folate from supplements, not food intake.
Furthermore, a very recent study (January 2018) from Queen Mary University of London, has basically said there’s no need for an upper folate limit.
They argue (strongly) that the upper limit was set incorrectly in the first place.
I’m not a medical professional, so you have to make your own judgement about this.
Personally, folate will not be a concern of mine when eating nutritional yeast.
Summary: How Much Nutritional Yeast Can You Eat in a Day?
The data is a bit conflicting, but let’s try to sum things up:
- The only real concerning vitamins that you can overdo are niacin and folate.
- If you have a reaction to niacin (skin flushing), you should probably only have a tablespoon or so of nutritional yeast per day.
- If you don’t have a reaction, and are otherwise healthy, it’s very difficult to cause serious harm to your body by ingesting too much niacin from nutritional yeast.
- Folate is controversial, and recent research suggests there should be no upper limit on its intake from food.
What all that means (and keep in mind this is not medical advice!), is that if you want to be on the safe, keep your nutrition yeast intake to 1 tbsp per day.
If you’re not so cautious, you should be find eating anywhere up to 5 cups of it (I don’t even know how you’d do that).