Can you survive on potatoes?

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Can a person survive on nothing but potatoes? I asked this question 5 years ago after watching ‘The Martian’. In the movie, the main character is abandoned on the Red Planet. Survival depends on producing his own food. He 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. Is this realistic?

I’ve been growing potatoes in my backyard garden for 5 years now. The first year, I bought seed potatoes (expensive!) and had varying success with the different types. The white potatoes tasted sublime, the red fingerlings were OK, but not my favorite. I saved the tiny ones and planted them the following year. They came up fine, so I saved seed potatoes again. Then I just stopped doing that because it turns out when you dig potatoes out of the ground, you inevitably leave seed-sized potatoes and chunks of bigger potatoes in the soil. They come up all by themselves in the spring. This year I found a large white potato that was turning green and sprouting. I chopped it into 10 little pieces and planted those back in the garden. I just dug up at least 25 lbs of potatoes. Some of them weighed 2 lbs.

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 character 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.

I’d expect that astronauts on long space voyages would also be supplied with vitamin/mineral supplements, just to cover all the bases.  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.  When a blight wiped out potato crops in Ireland in the mid-19th Century, over a million people starved.

I’m not trying to survive on potatoes, but I sometimes make a meal out of a home-grown potato (not a 2-pounder), baked or microwaved, with a dash of salt and pepper and sometimes a slice of cheese melted on top.  For an occasional Earth-bound meal, it’s easy, convenient, filling and delicious.

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