Information, as the saying goes, is power. Its power is considerably diminished, however, if the information is not understood.

Take food nutrition labels, for example.

According to a new study to determine how well people comprehend food nutrition labels, researchers have found that quite a few people simply lack the reading and math skills to extract from labels the information they need.

Using standard tests for literacy and math skills, researchers from Vanderbilt University surveyed 200 people from differing socioeconomic backgrounds. One part of the survey asked subjects to determine, using food labels, the carbohydrate or caloric content of an amount of food consumed. The other part asked them to choose which of two foods had more or less of a certain nutrient. Half of the survey questions involved products that were clearly labeled on the package as "reduced carb," "low carb," or designed for "a low-carb diet."

Sixty-eight percent of the study participants had at least some college education, and 77% had at least 9th-grade level literacy skills. However, 63% had less than 9th-grade math skills. Over 40% had a chronic illness for which specific dietary intervention is important (e.g., hypertension, diabetes), and 23% reported being on a specific diet plan. Most claimed that they used food labels and found them easy to understand.

Overall, subjects correctly answered only 69% of the questions. Only 32% could correctly calculate the amount of carbohydrates consumed in a 20-ounce bottle of soda that had 2.5 servings in the bottle. Only 60% could calculate the number of carbohydrates consumed if they ate half a bagel, when the serving size was a whole bagel. Only 22% could determine the net amount of carbohydrates in two slices of low-carb bread, and only 23% could determine the net amount of carbohydrates in a serving of low-carb spaghetti.

According to Russell L. Rothman, M.D., M.P.P., "The study showed that many people struggle to understand current food labels, and that this can be particularly challenging for those with poor literacy and math skills. Poor understanding of nutrition labels can make it difficult for people to follow a good diet. Of particular concern are situations that involve interpretation and application of serving size. It is clear that health care providers need to improve how they talk to their patients about using food labels and following diets. The FDA may also need to improve how food labels are designed.

The study appears in the American Journal of Preventive Medicine, Volume 31, Issue 5 (November 2006).