Can you survive on potatoes?

Potatoes_white_sideviewIf you haven’t seen “The Martian”,  Spoiler Alert!

Can a person survive on nothing but potatoes? In ‘The Martian’, the main character, abandoned on the Red Planet, figures out a way to use the Thanksgiving potatoes as seed stock, which he plants in a mixture of local Martian soil amended with human waste for fertilizer.  The potatoes sprout, and eventually they dominate his diet for months.  Despite spending his waking hours doing a lot of physical labor, he survives.

I had my own potato farming experience this summer, after an acquaintance raved about the wonderful taste of home-grown potatoes compared to store-bought.  So I could relate when the Martian saw the first small potato plant sprouts, although I was more interested in trying something new than surviving in a harsh environment.  By the way, the taste differences are subtle, but I’m hooked and I’ll definitely be growing potatoes again next year.

So can humans survive on potatoes?  In the short term, potatoes would certainly provide plenty of calories, as well as key minerals (such as potassium) and some vitamins (C, some B’s).  For long term survival, not so much.  Potatoes are lacking plenty of key nutrients:

Protein:  You’d have to eat 5000 calories of potatoes (15-20 large) to get the bare minimum of protein every day.  That’s a lot of volume; you probably couldn’t fit it in your stomach on one day, let alone every single day for months.

Key Vitamins: Potatoes are lacking in lots of vitamins, such as A, D, E, B12, folate, E.

Key Minerals: While high in potassium and a reasonable source of iron, potatoes are not good sources of magnesium, calcium, phosphorus and other trace minerals.

Fatty acids: You do need some, and potatoes have almost none.  If you were trying to survive on potatoes for months, you’d end up deficient.

Sodium: Yes, for most people, a low sodium food is a good thing, but long term, trying to survive on a food that has almost no sodium would be a problem. The Martian had access to a salt shaker, so this potential problem was avoided, especially important in that situation as he was very physically active and presumably sweating.

He also had a small and dwindling supply of something that looked like meatloaf, so he apparently had an extra protein source.  I’d expect that astronauts on long space voyages would also be supplied with basic vitamin/mineral supplements, just to cover all the bases.  Survival on a diet of potatoes supplemented with a bit of meat and a multi vitamin/mineral starts to look more doable.  Adding a teaspoon or two of vegetable oil to the potatoes would also help.  For people in Ireland, potatoes were a dietary mainstay, supplemented with some meat, other vegetables and dairy foods.  But potatoes dominated the diet, and when a blight wiped out potato crops in the mid-19th Century, over a million people starved.

I’m not trying to survive on potatoes, but I sometimes make a small meal out of a home-grown potato, baked or microwaved, with a dash of salt and pepper and sometimes a slice of cheese melted on top.  For an Earth-bound meal, it’s easy, convenient, filling and delicious.

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