Little is known about the relationship between perceptions of nutrient adequacy and biomarkers of nutrition status. This cross-sectional study of U.S. and German adults (n = 200; 18-80 years) compared dietary practices, knowledge, and beliefs of omega-3 fatty acids (O3-FA) with the omega-3 index (O3-I), an erythrocyte-based biomarker associated with cardiovascular disease (CVD) risk. More than half of adults believed that O3-FAs are beneficial for heart and brain health and could correctly identify the food sources of O3-FA. However, the mean O3-I in the U.S. (4.3%) and Germany (5.5%) puts the majority of adults sampled (99%) in intermediate or high CVD-risk categories. More Americans were considered at high CVD-risk (40%) when compared with Germans (10%). In the U.S., but not Germany, women had a significantly higher O3-I than men (4.8% vs. 3.8%, p < 0.001). In the intermediate CVD-risk group, about one-third of adults in both countries (30% in the U.S. and 27% in Germany) believed their diet was adequate in O3-FA. Notably, mean O3-I concentrations did not significantly differ with dietary perceptions of adequacy. More adults in Germany (26%) than in the U.S. (10%) believed that dietary supplements are needed to achieve a balanced diet. In spite of adequate knowledge about food sources and a consistent belief that O3-FA are important for health, very few participants had O3-I concentrations in the range for CVD protection.
Keywords: Biomarker; Omega-3 index; dietary perception; fatty acids.