Reading Food Labels

The first thing you should do when reading food labels is find the serving size. Sometimes the serving size indicated on the label may not correspond to the serving you would normally eat. For example, if the serving size of rice is ½ cup, but you would normally eat 1 cup of rice, you must double the carbohydrate content in the table to determine the amount of carbohydrates that you consume.

Food manufacturers usually are required to list the amount of total carbohydrates, sugars, and fiber in a food product, but not the starch content. Fortunately, you can easily calculate the starch content using simple subtraction. If you subtract the number of grams for fiber and sugar from the total carbohydrate number of grams, the remaining amount equals the number of grams of starch in that food serving.


TOTAL CARBS (grams) – FIBER (grams) – SUGAR (grams) = STARCH CONTENT (grams)




According to the USDA Dietary Reference Intake report, the Recommended Daily Allowance (RDA) of carbohydrates for adults and children over 1 year of age is 130 grams per day of digestible carbohydrates. This recommendation includes all sugars and starches but does not include fiber. The RDA for carbohydrates is equivalent to 520 calories from carbohydrates per day, but this does not account for the amount of carbohydrates necessary to support the additional caloric needs of physical activity or growth, especially in children. Therefore, most individuals are likely to require a carbohydrate intake greater than the RDA to support their total energy needs.

The majority of carbohydrates in the typical American diet are starch. Primary starch sources are corn, flour, tapioca, cereals, pasta, rice, potatoes, and crackers. Dark-colored vegetables and fruits contain little or no starch. Many fruits contain significant amounts of sucrose, so an appropriate diet based on your enzyme levels (sucrase, isomaltase [palatinase], and maltase) should be developed in conjunction with a registered dietitian.

The carbohydrate consumption of the typical Western diet is 60% starch, 30% sucrose, and 10% lactose.1 Because individuals with CSID have varying degrees of difficulty with sucrose and starch tolerance, care should be taken to ensure that enough calories are being consumed for proper nutrition and growth.



  1. Bhagavan NV. Metabolic homeostasis. In: Bhagavan NV, ed. Medical Biochemistry, Fourth Edition. New York, NY; Harcourt/Academic Press: 2002.