Objectives: The Healthy Eating Index (HEI) is a summary measure of dietary quality, based on a 100-point scale. Our objectives were to assess the HEI as a measure of dietary status through its correlation with nutritional biomarkers and to identify those biomarkers most associated with diet quality and healthful food intake patterns.
Design: National Health and Nutrition Examination Survey (NHANES) III, 1988-94.
Subjects: Adults (> or =17 years) with calculated HEI scores and blood nutrient data (n=16,467).
Statistical analyses performed: Weighted crude and partial Pearson correlation coefficients (r) between HEI scores and blood nutrients were calculated. Geometric mean blood nutrient concentrations were calculated for five HEI score categories (ranging from < or =50 to >80).
Results: HEI score was positively correlated with serum (r=0.25) and red blood cell (r=0.27) folate, serum vitamins C (r=0.30) and E (r=0.21), and all serum carotenoids except lycopene (r=0.17 to 0.27). These blood nutrient concentrations were 21% to 175% higher for participants in the highest HEI score group (>80) compared with those in the lowest group (< or =50). Mean HEI scores were significantly (P<.0001) greater among the 42% of participants who took dietary supplements. Most correlations were attenuated when adjusted for additional factors.
Conclusions: HEI score is correlated with a wide range of blood nutrients; the strongest relationships are with biomarkers of fruit and vegetable intake. These results are an important step in the validation of the HEI, emphasizing its potential as a tool for nutrition and health studies.