Grain, often referred to as cereal grain, describes the fruit seed of oats, wheat, barley, rice, maize and rye. Grains serve as a good source of carbohydrates, the type of macronutrient the body uses for energy. Because the outermost portion of the grain, the bran and germ, contain the majority of the vitamins and minerals, eating whole grains that contain the bran, germ and endosperm intact is healthier than eating refined grains that have the bran and germ removed.
The complex of B vitamins includes eight different vitamins. Whole grains serve as a good source of several B vitamins, including thiamin, riboflavin, niacin and folate. Thiamin, riboflavin and niacin help your body efficiently break down carbohydrates to use for energy. Folic acid, also known as folate or vitamin B-9, supports the formation and maintenance of new cells. Getting the recommended 400 mcg of folic acid per day, according to the Institute of Medicine's Food and Nutrition Board, is especially important for women of child-bearing age, as a deficiency may cause birth defects during the early weeks of pregnancy.
Nutritionists classify selenium as an essential trace mineral since you only need a small amount each day. The selenium content of foods varies based on the content of the soil within which the food is growing. Your body uses selenium to produce specialized proteins known as selenoproteins that function as antioxidants -- substances that protect cells from damage caused by negatively charged particles in the body. A serving of whole wheat and rice each provides 15 percent of the daily recommended value of selenium.
Whole grains contain potassium, an essential mineral that supports normal heart function. Potassium functions as an electrolyte, which means it helps to transmit electrical impulses between nerves. This makes it important for normal muscle contractions, including the heart muscle. Consuming the recommended daily intake of potassium may help control blood pressure.
Whole grains serve as a good source of magnesium. Approximately 50 percent of the magnesium in your body helps build strong bones, and the remaining portion supports normal muscle and nerve function, regulates blood sugar levels, supports a healthy immune system and maintains a normal blood pressure, according to the Office of Dietary Supplements.
Whole-grain foods contribute to your daily intake of iron. Your body needs iron to produce proteins and enzymes necessary for normal functions. Approximately two-thirds of the iron in your body is found in hemoglobin -- the protein in red blood cells responsible for carrying oxygen to the cells throughout your body. Although the iron in whole grains is classified as non-heme iron -- a type of iron the human body absorbs less efficiently than sources of heme iron, such as meat -- it still contributes to the daily recommended intake of iron.