If All You Ate Were Potatoes, You’d Get All Your Protein And Essential Amino Acids

I feel compelled to republish the following post from 6 years ago because people keep asking me how you can get enough protein by eating potatoes.


Me and my potatoes.

Doug asked:

“I still don’t understand why more care isn’t necessary to avoid deficiencies of the essential amino acids. Is it the case that these amino acids are present in all fruits and vegetables? (I didn’t think this was so, but you mentioned on that other thread that thinking has changed in this regard.) Or is it simply that easy to avoid a deficiency of an essential amino acid by consuming any mixture of fruits and vegetables?”

I would answer “Yes” to Doug’s last question. I thought it summed up the facts well.

Plants are capable of manufacturing all 20 amino acids, which include the essential amino acids (EAAs), although amounts vary. I checked a number of foods (potatoes, broccoli, tomatoes, asparagus, corn, rice, oatmeal, beans, and others) and found all EAAs in each of these foods. Even an apple which is listed as having 0 grams of protein has all the EAAs, albeit in small amounts.

Since I said in an earlier comment, “No mixing of foods is necessary. If all you ate were potatoes, you’d get all your amino acids,” I felt obliged to back it up. Below is my back-up.

  • The first column lists all 8 EAAs for adults.
  • The second column lists the World Health Organization’s recommended intake per body weight.
  • The third column lists the specific RDI for a 120 lb adult.
  • The fourth column lists the amount of each AA in a medium potato, with skin.
  • The fifth column lists the amount of each AA in 5 medium potatoes.
  • The last column lists the % of recommended intake (for a 120 lb adult) for each AA when 5 potatoes are consumed.

Some notes about this chart:
– The WHO’s recommended intakes represent the minimum amount for an individual with the highest need, multiplied by a factor of 2 for safety. So these are high amounts to begin with.
– Methionine + Cysteine = Total Sulfur Amino Acids
– Phenylalanine + Tyrosine = Total Aromatic Amino Acids
– WHO: World Health Organization
– EAA: Essential Amino Acid

For a 120 pound adult, five potatoes (960 calories) supply over 100% of the recommended intake for all essential amino acids. They also supply 25 grams of total protein.

It’s pretty difficult for an adult to eat a whole food, plant-based diet that doesn’t provide all the essential amino acids, as long as caloric needs are met.

Finally – The pool of AAs that our body uses to manufacture its own proteins isn’t limited by what we eat. Normal daily turnover of our cells provides a substantial pool from which to draw amino acids. Bacteria that line our colon also manufacture AAs, including EAAs, that we can utilize.

It is a misconception that plants provide “incomplete protein.”

Related: In Defense Of The Potato

6 thoughts on “If All You Ate Were Potatoes, You’d Get All Your Protein And Essential Amino Acids

  1. Pingback: In Defense Of The Potato | Fanatic Cook

  2. Marj

    I had gotten away from potatoes (although still ate them occasionally) thinking from reading various sources that they had a high glycemic score and were not all that high in nutrients except potassium. So goody! There’s so many ways to eat them (as the man says) and his story was fascinating. Thanks for posting it.

  3. Joel S

    I looked into the 960kCal worth of potato giving you 25g of proteins. Since I did the maths myself some time ago and came to a different conclusion I decided to look into it closer. Turns out the quoted protein content of potato is between 1.7g* and 2.1g per 100g. Is it really that much difference between one potato and the next?

    *Swedish FDA equivalent analysis of Swedish potato

    1. Bix Post author

      It’s been a while since I did the math too. I just looked up one entry for potatoes:

      … which lists 3.0g/100g for protein. That works out to about 31g protein for 960 calories. A bit more than I stated here.

      I think it is difficult to list the amount of a nutrient in a natural food because there are so many variables… where and how and when it is grown, harvested, and stored, what type and species. And to 1 or 2 decimal points? It’s a real feat!

  4. Pingback: What is Sustainability? 13 Examples to Integrate into Your Life

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