Potatoes are an excellent vitamin C source — 100g provides 9.6mg (11% DV). 2kg potatoes = 192mg vitamin C (213% DV). This is why potatoes prevented scurvy in historical populations. Most people don't realize potatoes have meaningful vitamin C.
Potatoes have more potassium than bananas (535mg vs 358mg per 100g). 2kg potatoes = 10,700mg potassium (228% DV). This would dramatically lower blood pressure if you're not adding excessive salt.
Potatoes are only 2.5% protein (25g in 2kg). But potato protein has an excellent amino acid profile — better than most plant proteins. It's not "complete" but it's close. You'd get 25-30g protein/day from 2kg potatoes — enough to avoid deficiency but not optimal for muscle maintenance.
Potatoes have ZERO B12, almost no vitamin A or D, and no meaningful omega-3. After 2-3 weeks: fatigue (B12), night blindness (A), immune decline (D), dry skin (omega-3). These deficiencies are what eventually make a potato-only diet dangerous long-term.
📋 Verdict
A potato-only diet for 1-2 weeks is not dangerous for a healthy person (potatoes + some fat source like butter is historically documented). Long-term: deficiencies in B12, A, D, omega-3 would develop. The Irish potato famine wasn't about nutrition — it was about starvation (the potatoes were GONE, not inadequate). Potatoes with dairy (butter, milk) are actually a reasonably complete diet for months — this is how many populations survived.