Prison food is the term for meals served to prisoners while incarcerated in correctional institutions. While some prisons prepare their own food, many use staff from on-site catering companies. Many prisons today support the requirements of specific religions, as well as vegetarianism. It is said that prison food of many developed countries is adequate to maintain health and dieting.[unreliable source?]
Along with changes in food, starting early in the 20th century, governments have issued nutrition guidelines, leading to the food pyramid (introduced in Sweden in 1974). The 1916 "Food For Young Children" became the first USDA guide to give specific dietary guidelines. Updated in the 1920s, these guides gave shopping suggestions for different-sized families along with a Depression Era revision which included four cost levels. In 1943, the USDA created the "Basic Seven" chart to make sure that people got the recommended nutrients. It included the first-ever Recommended Daily Allowances from the National Academy of Sciences. In 1956, the "Essentials of an Adequate Diet" brought recommendations which cut the number of groups that American school children would learn about down to four. In 1979, a guide called "Food" addressed the link between too much of certain foods and chronic diseases, but added "fats, oils, and sweets" to the four basic food groups.
A 2003 report by archaeologists indicates a possibility that grapes were mixed with rice to produce mixed fermented drinks in China in the early years of the seventh millennium BC. Pottery jars from the Neolithic site of Jiahu, Henan, contained traces of tartaric acid and other organic compounds commonly found in wine. However, other fruits indigenous to the region, such as hawthorn, cannot be ruled out. If these drinks, which seem to be the precursors of rice wine, included grapes rather than other fruits, they would have been any of the several dozen indigenous wild species in China, rather than Vitis vinifera, which was introduced there 6000 years later.
Most food has its origin in plants. Some food is obtained directly from plants; but even animals that are used as food sources are raised by feeding them food derived from plants. Cereal grain is a staple food that provides more food energy worldwide than any other type of crop. Corn (maize), wheat, and rice – in all of their varieties – account for 87% of all grain production worldwide. Most of the grain that is produced worldwide is fed to livestock.