What is nutritional yeast?

One of the strangest nutrition stories of recent memory has to be the one about the teenaged boy who developed severe nutritional deficiencies after eating nothing but french fries, white bread and potato chips for years. One sad result: he lost his sight, likely due to the effect of B12 deficiency, which affects nerve function, among other things (I suspect deficiencies of vitamins A and E as well as zinc and omega-3 fats also played a role).

One article quoted a doctor who suggested that, well, you can get B12 from nutritional yeast, so that would have solved his problem. Well, no, nutritional yeast wouldn’t have solved his problem at all. B12 was just one of the problems. This boy wasn’t just a picky eater; he had major issues with food and eating and needed appropriate therapies to correct and manage those issues.

But of course the mention of nutritional yeast got my attention because that doctor’s claim is factually incorrect.

Nutritional yeast is deactivated yeast — typically a type that’s commonly used for making wine or beer, or for baking bread. The yeast is first cultured on a glucose medium. Then it’s deactivated with heat and processed into flakes.

Eating straight nutritional yeast is not for everyone. It’s got a very strong flavor that takes getting used to, sometimes described as cheesy or nutty. Actually, it’s yeasty. But some people like that. One popular use is sprinkling on popcorn.

Nutritional yeast has a significant amount of protein for the calories, about 9 grams in a 2 tablespoon serving. It typically has some iron, as well as vitamins B1, B2, B6. It does not contain vitamin B12 unless it’s been fortified. Some nutritional yeast products are fortified with various other vitamins and minerals, including B12. If fortified, it can be a significant source of this important vitamin, providing a reliable source for vegans and vegetarians. But fortification is the key.

How do you know it’s fortified? You look at the ingredients list and at the Nutrition Facts panel. Typically, fortified products list the doses of vitamins and minerals, so B12 should be on the list. The ingredients’ list may include “B vitamin mix” or list vitamins separately.

Fortified nutritional yeast might have helped this boy with some nutrients, but not all. No vitamin A, E, C, D or K. No calcium. He was also eating a very low protein diet. Nutritional yeast may have some protein, but getting a day’s worth of protein from just that would be a stretch, given the strong flavor. In fact, it’s unlikely this particular person would have consumed any nutritional yeast at all, given his preference for bland foods.

If you’re vegan or vegetarian, fortified nutritional yeast makes a great food source for B12 and other nutrients. Plus it adds some protein. In addition to popcorn, you can sprinkle it on salads or mix into casseroles or other savory/salty foods. It also mixes well with tomato juice or other strong-flavored vegetable juices. It’s a good product, but it won’t save you from the effects of a really bad diet.

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