Refined grains

A refined grain is defined as having undergone a process that removes the bran, germ and husk of the grain and leaves the endosperm, or starchy interior. Examples of refined grains include white bread, white flour, corn grits and white rice. Refined grains are milled which gives a finer texture and improved shelf life. Because the outer parts of the grain are removed and used for animal feed and non-food use, refined grains have been described as less sustainable than whole grains. After refinement of grains became prevalent in the early 20th-century, nutritional deficiencies (iron, thiamin, riboflavin and niacin) became more common in the United States. To correct this, the Congress passed the U.S. Enrichment Act of 1942 which requires that iron, niacin, thiamin and riboflavin have to be added to all refined grain products before they are sold. Folate (folic acid) was added in 1996. Similar to whole grains, refined grains are a good source of starch, including resistant starch. ==Research==

The dietary guidance of many countries is to replace refined grains with whole grains. The Dietary Guidelines for Americans (2020–2025) advises people to limit their intake of refined grains to be no more than half of total daily grain consumption. Cardiovascular disease The American Medical Association have advised people to consume whole grains instead of refined grains to improve cardiovascular risk factors. A 2020 review of controlled trials that used the GRADE approach found that although whole grains have been shown to improve low-density lipoprotein and total cholesterol there is insufficient evidence to recommend "whole grains as opposed to refined grains for the prevention and treatment of CVD". Obesity There is no strong scientific evidence associating refined grains with obesity. ==Nutrition==