The grains food group includes any food made from a whole or refined grain, including products with wheat, rice, oats or barley. Whole grains have the entire grain kernel intact with the endosperm, germ and bran. Refined grains include those that have undergone the milling process to remove the bran and germ portion of the kernel. Whole grains maintain the nutrients of the kernel, while refined grains often lose valuable nutrients during processing. Fiber, minerals and B vitamins are the significant nutrients found in the grains food group.
Fiber
Fiber is the indigestible portion of a food. It serves the purpose of regulating your bowels and nourishing healthy colon bacteria for immune system support. The soluble fiber in grains helps slow the absorption of glucose from carbohydrates, which is important for stabilizing blood sugar levels. Whole grains are better fiber sources than refined grains because the fiber is removed from the grain during milling. For example, one slice of commercially prepared whole-wheat bread has 1.9 grams of fiber while the same serving of white bread has 0.6 grams of fiber. The Dietary Guidelines for Americans 2010 recommend making at least half of your daily intake of grains from whole grains.
B Vitamins
The B group of vitamins includes eight specific vitamins that work together to metabolize food, as well as sustain nervous system and heart functions. Grains naturally contain most of the B vitamins but in refined grains these nutrients are removed then added back, or enriched, after processing, but often in lower amounts. A 1-cup serving of brown rice contains 0.742 milligrams of thiamine, 2.8 milligrams of pantothenic acid, 9.4 milligrams of niacin, 0.942 milligrams of B-6 and 37 micrograms of folate. The same serving size of white rice has 0.13 milligrams of thiamine, 1.8 milligrams of pantothenic acid, 2.9 milligrams of niacin, 0.3 milligrams of B-6 and 15 micrograms of folate. Enriched, or fortified, refined grains may also have additional nutrients added that were not originally in the grain.
Minerals
Minerals like calcium, potassium, magnesium, iron and selenium serve a variety of functions in your body, including bone development, production of blood cells, conducting nerve signal transmissions and muscle actions. Whole grains are a rich source of several essential minerals. Refined grains have fewer minerals but are often enriched and fortified. If you prefer the taste of white grains, you can still get minerals in your diet with refined products that are enriched and fortified. Check nutrition labels for mineral content.
Macronutrients
Grains also supply the macronutrients: carbohydrates, proteins and fat. Carbohydrates are your main source of glucose, the primary energy source for your cells. Grains are plentiful in carbohydrates but whole grains contain natural carbohydrates while refined grains may have added sugars for flavor and longer shelf-life. Whole grains have a slightly higher protein content than refined grains. Grains have a very low natural content of fats but read nutrition labels carefully because some refined grain products also have added saturated fats.
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