How much grains and whole grains should we take a day?

 Info source: http://www.washingtonpost.com/wp-dyn/content/article/2011/02/22/AR2011022202786.html

How much each day?

The guideline. The dietary guidelines (for American 2010) say we should make sure that at least half of the six servings of grains we eat in a day are whole, not refined. 

In short, we should "Increase whole-grain intake by replacing refined grains with whole grains."

Daily amount. A person consuming 2,000 calories per day should have at least 48 grams of whole grains (or three servings) and an equal amount of refined grains. You can get about 16 grams of whole grains from any one of the following: a one-ounce slice of bread, one ounce of pasta or rice (uncooked), a six-inch tortilla, or about one cup of cereal.

Enriched grains. The other three servings can be refined, as long as they're enriched. These are refined grains that have nutrients such as folic acid or calcium added to them. Whole grains are not enriched, so if you replaced all your refined grains with whole ones, you'd need to get those nutrients elsewhere, perhaps through dietary supplements.