Would it be possible for a human to survive on a diet of modified yeast as seen in many fictional stories? Not necessarily be able to get perfect nutrition from, or live healthily on, but simply live off of.

This is usually some kind of raw yeast grown off of sewage or some such. An example would be Dole Yeast in Larry Niven's "Known Space" series. But this is meant to cover the concept of yeast as a bare bones food in general.


The fungus Fusarium venenatum is used as the basis of the meat substitutes marketed under the Quorn brand. To be nutritionally complete such foods would need serious fortification which can be done either artificially during processing using synthesised vitamins or possibly with a little genetic tampering the fungus could be altered to produce the necessary compounds.

So I'd say yes a yeast based diet is almost certainly possible.


According to the NHS in the UK healthy eating guidelines for the average UK Citizen are:

  • Energy: 8,400kJ/2,000kcal
  • Total fat: less than 70g
  • Saturates: less than 20g
  • Carbohydrate: at least 260g
  • Total sugars: 90g
  • Protein: 50g
  • Salt: less than 6g

This varies dependent on several factors including age, height, weight, gender etc but a baseline average is the above. there are also a huge number of different vitamins and minerals that are needed but i haven't stated them as it would make this answer approximately 600 miles long...

According to Wikipedia the average nutritional values of Yeast per 100 grams are:

  • Calories 325
  • Total Fat 8 g 12%
  • Saturated fat 1 g 5%
  • Polyunsaturated fat 0 g
  • Monounsaturated fat 4.3 g
  • Cholesterol 0 mg 0%
  • Sodium 51 mg 2%
  • Potassium 955 mg 27%
  • Total Carbohydrate 41 g 13%
  • Dietary fiber 27 g 108%
  • Sugar 0 g
  • Protein 40 g 80%
  • Vitamin A 0%
  • Vitamin C 0%
  • Calcium 3%
  • Iron 12%
  • Vitamin D 0%
  • Vitamin B-6 75%
  • Vitamin B-12 1%
  • Magnesium 13%

The % are compared to the daily recomended intake, as we can see that 100 grams of yeast doesn't provide enough calories, so we'd need about 600 grams, this would put us still below on several factors but it doesn't appear to provide an excess of anything harmful. namely Salt and Saturated Fat. too much fibre which would definitely be provided can cause issues however. so actually its not that bad a resource if it could be harvested in sufficient quantities. the parts that do provide too much are mostly vitamins and minerals that the human body would just use what was needed and "dump" the rest.

After that its just the other missing vitamins and minerals, some of which are provided in water, The others would need to be provided in some form of supplement form to provide a reasonable diet.

It would most likely be nothing more than a bland cruel but it could indeed be lived on. after that its only the fibre that could be an issue, perhaps some of this could be removed in the refining process.


Vegetable extract products like the Glorious and beautiful tasting Marmite are also of interest as they have been fortified with other vitamins to provide a healthier sandwich spread.

Although i will admit its probably not to America taste, just go on YouTube and search Americans try Marmite and you'll see what i mean. its one of those Love or Hate foods, i am very much in the former grouping.

TLDR: on face values it could be survived on although it wouldn't make you happy


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