Low Dietary Protein Intakes and Associated Dietary Patterns and Functional Limitations in an Aging Population: A NHANES Analysis

OBJECTIVE: To investigate protein intakes across demographic characteristics in relation to dietary patterns and functional outcomes in older adults. DESIGN: Observational and cross-sectional study. SETTING: Non-institutionalized participants from the 2005–2014 National Health and Nutrition Examination Survey. PARTICIPANTS: Data from 11,680 adults were categorized into 51–60 years (n= 4,016), 61–70 years (n=3,854), and 71 years and older (n=3,810) for analysis. MEASUREMENTS: Adults were stratified by meeting or not meeting the protein recommendation (0.8 g/kg/d) to compare demographics, diet quality with Healthy Eating Index– 2015, functional limitations, and other dietary intakes. Dietary recalls were collected using the multiple pass method. Data analyses were weighted to create a nationally–representative sample. RESULTS: Dietary protein intakes were significantly lower in older age groups, with up to 46% of the oldest adults not meeting the protein intake recommendation. Participants consuming protein below the recommended intake level had significantly poorer diet quality across all age groups (P<0.01), however, overall diet quality was better in older adults. Those not meeting the protein recommendation were more likely to have intakes of other nutrients below recommended levels. Those below the protein recommendation had significantly more functional limitations across all age groups, while grip strength was significantly lower in those over 70 years old. CONCLUSION: Lower protein intakes, and lower diet quality and physical functioning are related in an aging population. Meeting the protein recommendation was linked to better overall diet quality and may be protective of lean mass; therefore, evaluation of individual characteristics which may affect protein intakes is crucial in supporting older adults to meet their protein needs.