I was told one of the reasons why Napolean was so successful was because large armies were able to be maintained with easily grown potatoes, and you can see how potatoes are basically the staple food of a lot of western dishes. Over in the east, China and India are booming with population, they don't have many things in common, but they do have brown rice in a lot of their dishes. If I was a European king, big army = big wins
Brown rice is cheap, abundant, nutrient-packed, able to be grown in Europe, and was known long before, people today use it as a way of bulking for cheap, why did the west wait until someone discovered the benefits of the potato?
I believe there are multiple reasons for this phenomenon. I'll outline them as best I can.
Potatoes require far less water to produce and cook ^[1]. An army travelling with rice will require fires, cookpots, and access to substantially more water in order to cook their meals if rice is their staple, as opposed to potatoes. In terms of cultivation, one kilogram of rice requires nearly 2500 litres of water to process, compared to only 287 litres for potatoes. Moreover, a large potato can be roasted in about 20-30 minutes, but brown rice takes roughly an hour to cook.
Nutritionally, these two foods are quite similar, but the key difference between them is the level of vitamin C. One large potato contains 121% of one's daily requirements ^[2]. Rice has the edge in terms of iron, but for a travelling army, the vitamin C requirement would be essential to maintaining troop health. A rice diet would require supplementation of some provide the same vitamin values.
A large issue in terms of constant rice production was Europe's climate. Infrequent sunlight, capricious water sources, and low temperature extremes drastically affected the amount of rice which could be grown in a given season. Today, there are hardier varieties of rice which have been cultivated to withstand these variances, but even now, the warmer, southern country of Italy remains Europe's leading producer^[3].