By Raya Tahan
Arizona Daily Wildcat
More than half of all people who are asked what they ate on a given day give inaccurate descriptions of their diets, said Dr. Wanda Howell, an assistant professor in the Nutritional Sciences Department.
Howell said researchers very possibly underestimate the association between food intake and disease because self-reported food intakes are misrepresented.
Overweight women tend to under-report how much starch and sugar they eat, while female athletes are more likely to underestimate their fat intake, Howell said.
Howell, with Nutrition Specialist Linda Houtkooper, is studying how much and why food intake is under-reported. Their study, which is sponsored by the U.S. Department of Agriculture, is designed to shed light on the topic.
"It's clear that we have to do better at determining what people eat," Howell said. "Without good data on that, there's no way we can link diet to disease."
Howell said the connection of fat intake to heart disease may be underestimated due to misreporting.
"If surveyed individuals under-report how much dietary fat they eat, nutrition and health professionals may also underestimate the associated risk of developing breast and prostate cancer," Howell said. "Just think if we actually knew what large population groups eat."
Under-reporting is more pervasive in women, Howell said. The study will test the accuracy of diet records kept by two groups of young adult women. The women in one group are overweight and sedentary, and in the other are highly-trained athletes.
To learn how closely the diet reports reflect what was eaten over one week, Howell and Houtkooper will label the hydrogen and oxygen isotopes in the water the women drink. They can then trace the isotopes in their urine to determine how much energy they expended and the number of calories burned.
"If the women in the study accurately record what they eat and drink during this time, and if their body weights don't change, the number of calories they indicate that they ate should equal the number of calories the isotope study says they burned," Howell said. "If the number isn't the same, we know that their diet records are not completely accurate."
Howell and Houtkooper believe that by estimating how much "high risk" food Ÿ such as saturated fat, salt and alcohol Ÿ people eat and drink, they and other researchers can determine the extent to which it causes disease.
They hope this information will urge insurance coverage for preventative nutrition education. Most private companies do not cover nutrition counseling.
Howell also hopes her research will encourage additional diet behavior studies, such as those of children.
"We need better information about what kids eat," Howell said, "and we need to follow their diets as they age. This is the only way to target early nutrition education at the source."
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