Introduction: The sodium-to-potassium (Na:K) ratio in the diet is a critical biomarker for cardiovascular and metabolic health, yet global adherence to recommended levels remains poor. Objectives: The objective of this study was to identify dietary determinants of the dietary Na:K ratio and its associations with micronutrient intake and diet quality. Methods: An observational cross-sectional survey was conducted in a representative sample of manufacturing workers through a combined stratified proportional and two-stage probability sampling plan, with strata defined by company size and industrial sector from the state of Rio Grande do Norte, Brazil. Dietary intake was assessed using 24 h recalls via the Multiple Pass Method, with Na:K ratios calculated from quantified food composition data. Diet quality was assessed with the Diet Quality Index-International (DQI-I). Multiple linear regression was used to analyze associations of Na:K ratio with the study variables. Results: The survey was conducted in the state of Rio Grande do Norte, Brazil, in 921 randomly selected manufacturing workers. The sample mean age was 38.2 ± 10.7 years, 55.9% males, mean BMI 27.2 ± 4.80 kg/m². The mean Na:K ratio was 1.97 ± 0.86, with only 0.54% of participants meeting the WHO recommended target (<0.57). Fast food (+3.29 mg/mg per serving, p < 0.001), rice, bread, and red meat significantly increased the ratio, while fruits (−0.16 mg/mg), dairy, white meat, and coffee were protective. Higher Na:K ratios were associated with lower intake of calcium, magnesium, phosphorus, and vitamins C, D, and E, as well as poorer diet quality (DQI-I score: −0.026 per 1 mg/mg increase, p < 0.001). Conclusions: These findings highlight the critical role of processed foods in elevating Na:K ratios and the potential for dietary modifications to improve both electrolyte balance and micronutrient adequacy in industrial workers. The study underscores the need for workplace interventions that simultaneously address sodium reduction, potassium enhancement, and overall diet quality improvement tailored to socioeconomic and cultural contexts, a triple approach not previously tested in intervention studies. Future studies should further investigate nutritional consequences of imbalanced Na:K intake.

Studies indicate that ultra-processed food (UP) consumption correlates negatively with essential vitamin and mineral intake and positively with sodium and lipid intake. The objective of this study was to explore the relationship between UP consumption and deviations from nutritional guidelines. An observational, cross-sectional analytical study was conducted on a probability sample of manufacturing workers in the state of Rio Grande do Norte, Brazil. Food consumption was assessed with a 24 h recall survey, and nutrient intake inadequacies were calculated as the difference between individuals’ intake of energy, macronutrients, minerals and vitamins, and the dietary reference intakes for individuals of the same sex and age group, and then analyzed for trends across the percentage contribution of UP to total energy intake with nonparametric multiple regression adjusted for covariates. The study included 921 workers from 33 industries, 55.9% male, with a mean age of 32 years. Overall, the study population exhibited deficits in energy, all macronutrients, and in some micronutrients. With increasing UP contribution to total energy intake, there is a trend towards a greater intake of energy (p < 0.001), total, saturated, monounsaturated, and trans fats (p < 0.001), n6-polyunsaturated fatty acids (p = 0.03), carbohydrates (p < 0.001), calcium (p = 0.008), and manganese (p < 0.001), thiamin (p < 0.001), and vitamin B6 (p = 0.01); however, this comes with a negative consequence in terms of reducing the protein consumption (p = 0.037), fiber (p = 0.035), copper (p = 0.033), and vitamin E (p = 0.002) intake. The results show that correcting energy and micronutrient deficiencies by increasing UP consumption can also lead to a decrease in diet quality.