Objective Measures of Food Intake and Nutrient Status
Grammy was right. We are indeed what we eat. It is easier to measure with some nutrients than others. The bathroom scales clearly indicate if my physical activity isn’t compensating for my food consumption. Even when my memory (or perception) fails to recognize the extra slice of pizza that I ate for lunch, or the chocolate chip cookie, the scales do not.
Food frequency questionnaires (FFQ) and fasting blood, adipose, and overnight urine samples were collected from Adventist Health Study-2 participants. Among fatty acids, dietary intake of long-chain omega-3 fatty acids was most highly correlated with adipose values. Dietary carotenoids (α- and β-carotene, lutein, lycopene, β-cryptoxanthin and total carotenoids) and vitamin E were highly correlated with plasma concentrations. Dietary calcium and vitamin B12 intakes were moderately well correlated with serum values. Bottom line, human subjectivity in food intake recording, accuracy of food databases, differences in patterns of food consumption and absorption make it difficult to predict blood concentrations from dietary intake.
There is no substitute for measuring nutrient status using biological samples. Dietary consumption patterns cannot explain circulating fatty acid profiles. In a study of youth (obese, obese with metabolic syndrome, and average weight), Bermudez-Cardona and Valasquez-Rodriguez report that current consumption does not correlate with nutritional status. Average weight youth reported eating more calories and fat than their obese counterparts yet circulating total free fatty acid concentrations in obese youth with metabolic syndrome were twice that of obese and average weight subjects.
To understand nutrient-disease relationships, we need to know nutrient exposure. This is especially important if we wish to tease out the health impact of suboptimal vitamin and mineral status from the effects of over-consuming caloric sources – fat, carbohydrate, protein and alcohol.
Fraser GE, Jaceldo-Siegl K, Henning SM, Fan J, Knutsen SF, Haddad EH, Sabate J, Beeson WL, Bennett H. Biomarkers of dietary intake are correlated with corresponding measures from repeated dietary recalls and food-frequency questionnaires in the Adventist Health Study-2. 2016 J Nutr doi: 10.3945/jn.115.225508
Bermudez-Cardona J, Velasquez-Rodriguez C. Profile of free fatty acids and fractions of phospholipids, cholesterol esters and triglycerides in serum of obese youth with and without metabolic syndrome. 2016 Nutrients doi: 10.3390/nu8020054