Whole grains generally refer to food crops. Grains refer to rice, wheat, soybeans, corn, and potatoes. Grains other than rice and flour are also commonly referred to as miscellaneous grains. Whole grains are the cornerstone of the diet and the main source of dietary fiber. They have the effects of lowering cholesterol and preventing cardiovascular disease, and can provide most of the nutrients necessary for the human body.

The earliest record of the term "grains" can be found in "The Analects of Confucius". According to the record in The Analects of Confucius: More than 2,400 years ago, Confucius took his students on a long trip. Zilu was lagging behind. He met an old farmer carrying a bamboo basket with a staff and asked him, "Have you seen the Master?" The old farmer said: "If the limbs are not working and the five grains cannot be distinguished, who is the Master?"

Wu Gu means five kinds of grains. Books older than "The Analects" such as "The Book of Songs" and "The Book of Books" only mention "hundred grains" and nothing about "five grains". From hundreds of grains to five grains, have the types of food crops been reduced? No. In the past, people often gave a proper name to several different varieties of a crop, which made the list too much. Moreover, the word "hundred" here only means many, and there are not really a hundred kinds. The emergence of the term "grains" indicates that people have a relatively clear concept of classification, and also reflects that there were five main food crops at that time.

When the term "grain" was first coined, there was no record of what it actually meant. The earliest explanation we can see now was written by people from the Han Dynasty. There are two main interpretations by the Han people and people after the Han Dynasty: one is rice, millet, millet, wheat, and bean (i.e. soybean); the other is hemp (referring to cannabis), millet, millet, wheat, and bean. The difference between these two statements is that one has rice but no hemp, and the other has hemp but no rice. Although hemp seeds can be eaten, their fibers are mainly used to weave cloth. Grain refers to grain. The former statement does not include hemp among the five grains, which is more reasonable.

But on the other hand, the economic and cultural center at that time was in the north, and rice was a southern crop, with limited cultivation in the north, so it was possible that the grains contained hemp but not rice. "Historical Records Tianguan Shu" "Every year is good and bad" (prediction of good times and bad years). The crops mentioned below are wheat, millet, broomcorn millet, bean sprouts and hemp, which belong to the latter theory. Probably because of these reasons, the Han people and people after the Han Dynasty had two different interpretations of grains.

Combining these two statements, there are six main crops in China: rice, millet, millet, wheat, bean and hemp. The famous work of the Warring States Period, "Lu Shi Chun Qiu" (written in the third century BC), contains four articles specifically talking about agriculture. Among them, "The Examination of Time" discusses the gains and losses of growing crops, millet, rice, hemp, bean sprouts, and wheat. pros and cons. Grain is millet. These six crops are exactly the same as the six mentioned above. The crops mentioned in "Lu Shi Chun Qiu Twelve Chronicles" are also these six types.

Obviously, rice, millet, millet, wheat, bean sprouts, and hemp were the main crops at that time. The so-called five grains refer to these crops, or five of these six crops. However, with the development of social economy and agricultural production, the concept of grains is constantly evolving. The so-called grains are actually just the general name of food crops, or generally refer to food crops.