Potatoes are one of the richest dietary sources of potassium, an important mineral for keeping blood pressure within a healthy range and preventing cardiovascular events like heart attack and stroke.[1][2] A commonly-used dose in studies that report blood pressure reductions from potassium supplementation is 2.3 grams per day, approximately the amount in two medium potatoes.[1][3]
One randomized controlled crossover trial compared the impact of non-fried potatoes, fried potatoes, potassium supplements, and usual diet on blood pressure over 17-day diet periods in people with high blood pressure.[4] Systolic blood pressure tended to be lower on the non-fried potato diet vs. usual diet, but this didn’t reach statistical significance. In contrast, the decline in systolic blood pressure from baseline was significantly greater for the non-fried potato group vs. usual diet, but this was a secondary outcome. The decline in blood pressure did not reach statistical significance on the diet with fried potatoes or potassium supplements.
An additional small trial reports that eating eight small purple potatoes per day for four weeks reduces blood pressure in people with high blood pressure (hypertension), but the finding should be interpreted with caution due to major methodological weaknesses.[5] For example, the paper doesn’t statistically compare blood pressure in the intervention group against the control group, which is the most important comparison in a controlled trial. Together, these two randomized controlled trials provide modest evidence that eating non-fried potatoes can lower blood pressure, consistent with the high potassium content of spuds.
In a study testing the satiety (fullness after a meal) effects of 32 commonly-eaten foods, boiled potatoes were the most sating per calorie, beating other high-satiety foods like fish, steak, fruit, and oatmeal.[6] Baked potatoes are expected to be comparable due to their similar composition and palatability. This suggests that potatoes may be helpful for controlling calorie intake and body weight, although this hasn’t been directly tested. It’s also important to note that this study used plain potatoes, and the effects would likely be different with added butter, cheese or other calorie-dense toppings.
Potatoes are unusually nutritionally complete. Although a potato-only diet lacks significant quantities of vitamins A, E, and B12, most other essential nutrients are present at adequate or near-adequate levels. Small experiments in the early 20th century reported that people can eat almost nothing but potatoes for 5.5 to 10 months with no apparent ill effects.[7][8]