Can we survive on one type of food?

Tue Mar 30 1736: [In Savannah] Mr. Ingham, coming from Frederica, brought me letters pressing me to go thither. The next day Mr. Delamotte and I began to try whether life might not be as well sustained by one sort as by variety of food. We chose to make the experiment with bread; and were never more vigorous and healthy than while we tasted nothing else. ‘Blessed are the pure in heart,’ who, whether they eat or drink, or whatever they do, have no end therein but to please God! To them all things are pure. Every creature is good to them, and nothing to be rejected. But let them who know and feel that they are not thus pure, use ever help and remove every hindrance; always remembering, ‘He that despiseth little things shall fall by little and little.’