The single food you could live off the longest is potatoes, especially when you eat the potatoes with the skin on.
The white russet potato is one of the best potatoes that you could survive on the longest as white russet potatoes provide a great balance of protein, carbohydrates and essential micronutrients like Vitamin C.
White russet potatoes also contain enough of the essential amino acids to build up proteins in the body, which the body needs.
Although there's no true single food that one could survive off forever as no single food contains every essential micronutrient that the body needs to fully sustain a healthy life.
You could often survive for months or even a year on only potatoes, but eventually you would have severe health declines.
Potatoes lack essential fatty acids and over time, the body will struggle to absorb fat soluble vitamins like vitamins A, D, E and K.
And eventually you will suffer deficiencies in vitamin B12, Zinc, calcium and Vitamin D.
To survive and live healthy, you need a more complete nutritional profile and the most optimal pairings that supply the complete amino acids, healthy fats and broad vitamins you need include, potatoes, milk and butter.
Potatoes and milk or butter supply you with the missing fats and Vitamin B12, which the potatoes lack.
Whole eggs and sweet potatoes are often recommended as a two food combination that provide nearly all of the essential protein, healthy fats and minerals.
And beans and rice are also another classic pairing of foods that you can survive on longer as it creates a complete, sustainable protein profile with complex carbohydrates.
Beans, rice and corn are also another good pairing that helps you get the proper proteins and nutrients in your diet.
Instead of trying to survive on just beans or rice or beans and rice, adding some corn or other vegetables, helps you get the needed nutrients to survive long term.