The need of the immaterial is the most deeply rooted of all needs. One must have bread; but before bread, one must have the ideal. ~ French poet Victor Hugo
Like barley, wheat was one of the first domesticated crops; cultivated in the Fertile Crescent over 9,000 years ago. Wheat played a seminal role in Western civilization, as it could easily be cultivated on a large scale, is easily digested, and stores well.
Wheat is mostly consumed in bread; an ancient Egyptian innovation. The processing this involves can lessen its nutritional value.
Wheat is a dicey food nutritionally. Its health benefits depend entirely on the form in which it is eaten: the more processed, the less nutritious. Whole grain wheat has vitamins, minerals, and proteins, while refined grain is starchier.
As with related grains, whole wheat is high in dietary fiber, some B vitamins, phosphorus, copper, manganese, selenium, zinc, and antioxidants. For all that, wheat is not the best of grains for all people. What made wheat so popular is precisely the problem: gluten.
Gluten is a protein found in wheat and related grains, such as barley and rye, though wheat generally has a higher concentration. Bread flour is especially rich in gluten, as gluten is essential to fluffy bread, which is one of the reasons wheat rose to historical prominence. Pastry flour has a lower gluten content.
Rice and oats are gluten-free. The term glutinous rice refers to its doughy texture, not its gluten content.
A small percentage of humans (< 1%) are intolerant of or allergic to the gluten in wheat. Even for those with tolerance, wheat can cause bloating, congestion, flatulence, and other flagrant reactions.
In the 6th century, Chinese noodle makers discovered that gluten proteins in wheat flour could be isolated by kneading the dough in water until the starch washed away, and only the chewy gluten mass remained. This plant-based protein became part of the staple diet of monastery Buddhists, as monks were required to follow a strict vegan diet. That nutritionally ersatz tradition continues to this day, though tofu makes for a healthier fake meat than gluten.