Check the food label before you buy
Food labels have several parts, including the front panel, Nutrition Facts, and ingredient list. The front panel often tells you if nutrients have been added—for example, iodized salt lets you know that iodine has been added, and enriched pasta (or "enriched" grain of any type) means that thiamin, riboflavin, niacin, iron, and folic acid have been added.
The ingredient list tells you what's in the food, including any nutrients, fats, or sugars that have been added. The ingredients are listed in descending order by weight.
Use the Nutrition Facts to see if a food is a good source of a nutrient or to compare similar foods—for example, to find which brand of frozen dinner is lower in saturated fat, or which kind of breakfast cereal contains more folic acid. Look at the percentage Daily Value (percentage DV) column to see whether a food is high or low in nutrients. If you want to limit a nutrient (such as fat, saturated fat, cholesterol, sodium), try to choose foods with a lower percentage DV. If you want to consume more of a nutrient (such as calcium, other vitamins and minerals, fiber), try to choose foods with a higher percentage DV. As a guide, foods with 5 percentage DV or less contribute a small amount of that nutrient to your eating pattern, while those with 20% or more contribute a large amount.
Source: Health - Dietary Guidelines