Higher Animal-Based Protein Intake Levels Show a Greater Likelihood of Having Metabolic Syndrome in Single-Person Households Among Korean Adults

Background/Objectives: Despite the increasing intake of animal-based protein and the growing number of single-person households (SPHs) in Korean populations, no studies have analyzed the relationship of protein intake by source with metabolic syndrome (MetS) according to household type. This study examined the association between protein intake (plant- and animal-based sources) and MetS risk factors in SPH and multi-person households (MPHs) among Korean adults. Method: A total of 12,022 participants aged 30&ndash:64 years (SPH: 982: MPH: 11,040) were selected from the 2016&ndash:2021 Korea National Health and Nutrition Examination Survey. Protein intake level was defined as the percentage contribution of food source to daily intake, assessed using 24 h recall dietary data. Results: The animal-based protein intake level was slightly higher in SPHs (51.2%) compared to MPHs (49.5%), whereas the contributions of plant sources from vegetables, fruits, and whole grains were higher in MPHs (p &lt: 0.01). The prevalence of MetS and abdominal obesity increased with higher animal-based protein intake levels across all household types. Only in SPHs, each 1% rise in the proportion of animal-based protein was positively associated with increased blood pressure (OR = 1.013, 95% CI: 1.004&ndash:1.022). Moreover, the interaction between animal-based protein intake levels and household type was significantly associated with a higher prevalence of elevated triglycerides (TGs) (MPH[Q1] vs. SPH[Q4] OR = 1.51: p for interaction = 0.0335). However, these two risk factors did not show significant association in MPHs. Conclusions: The results suggest that reducing dietary animal protein could help manage MetS risk factors, particularly increased blood pressure, and elevated TGs in SPHs of Korean adults. In conclusion, dietary guidelines that promote a higher intake of plant-based protein over animal-based protein for the health of the SPH population would be valuable from a public health perspective.