Associations of sodium intake with obesity, metabolic disorder, and albuminuria according to age

<div><p>Sodium intake is associated with obesity and metabolic disorder in the general population. However, sodium intake is significantly reduced according to the decrease of energy intake in older adults although the prevalence of obesity is higher than younger adults. We evaluate the association of sodium excretion (UNa) with blood pressure, obesity, metabolic disorders, and albuminuria according to age. An observational study using data from the Korean National Health and Nutrition Examination Survey IV-V (2008–2011) was performed (N = 18,146). The 24 hour UNa was estimated from a single fasting urine sample.Participants aged≥75 years showed the highest risk for hypertension (HTN) in the highest quartile of UNa (1.769, 95% CI, 1.174–2.665), and the risks for HTN increased with advancing age. Obesity was not associated with UNa in participants aged≥75 years, and hypertriglyceridemia and body fat were not related to UNa in participants aged≥65 years, although these values were significantly associated with UNa in participants aged<65 years. Impaired fasting glucose (IFG) and insulin resistance (IR) were associated with UNa only in participants aged 20–39 years. The highest quartile of UNa showed a 3.777 fold increased risk for albuminuria in those aged 20–39 years (95% CI, 1.130–12.630), and a 1.885 fold increased risk (95% CI, 1.156–3.075) among participants aged 40–64 years. In participants aged≥65 years, albuminuria was not associated with UNa. In contrast with HTN, UNa was not associated with albuminuria, obesity, hypertriglyceridemia, IFG, and IR in older adults despite a strong association in younger adults.</p></div

Adjusted risks of albuminuria^* according to sodium excretion in each age group.

<p>Adjusted risks of albuminuria^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0188770#t002fn001" target="_blank">*</a>} according to sodium excretion in each age group.</p

Association between sodium excretion quartiles and impaired fasting glucose (IFG) according to age.

<p>IFG was defined as a fasting glucose ≥ 110 mg/dL. Risks of IFG was adjusted by gender, systolic blood pressure, body mass index, hemoglobin, estimated glomerular filtration rate, high density lipoprotein, aspartate aminotransferase, alanine aminotransferase, energy intake, myocardial infarction, angina, stroke, malignancy, current smoker, and alcohol. a. Adjusted risks of IFG according to sodium excretion in age group 20–39 years. b. Adjusted risks of IFG according to sodium excretion in age group 40–64 years. c. Adjusted risks of IFG according to sodium excretion in age group 65–74 years. d. Adjusted risks of IFG according to sodium excretion in age group ≥ 75 years.</p

Clinical characteristics of study population.

<p>Clinical characteristics of study population.</p

Estimated mean of systolic blood pressure (SBP) according to the sodium excretion in each age group.

<p>The SBP of participants in the highest quartile of sodium excretion was significantly higher than that of participants in the lowest, second, and third quartiles in all age groups except among those aged 20–39 years (<i>P</i>≤0.002). In the 20–39 years group, the SBP of the highest quartile of sodium excretion was only significantly higher than the lowest quartile (<i>P</i><0.001). SBP was adjusted by age, body mass index, glucose, hemoglobin, white blood cell count, estimated glomerular filtration rate, triglyceride, high density lipoprotein, cholesterol, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, and energy intake.</p

Association between hypertension (HTN) and sodium excretion quartiles according to age.

<p>Risks of HTN was adjusted by age, gender, body mass index, glucose, hemoglobin, estimated glomerular filtration rate, triglyceride, high density lipoprotein, aspartate aminotransferase, alanine aminotransferase, energy intake, diabetes mellitus, myocardial infarction, angina, stroke, malignancy, current smoker, and alcohol. a. Adjusted risks of HTN according to sodium excretion in age group 20–39 years. b. Adjusted risks of HTN according to sodium excretion in age group 40–64 years. c. Adjusted risks of HTN according to sodium excretion in age group 65–74 years. d. Adjusted risks of HTN according to sodium excretion in age group ≥ 75 years.</p

Association between sodium excretion quartiles and insulin resistance (IR) according to age.

<p>Participants whose HOMA-IR was in the top decile of the study population were defined as having IR. Risks of IR was adjusted by gender, hemoglobin, estimated glomerular filtration rate, aspartate aminotransferase, alanine aminotransferase, energy intake, hypertension, myocardial infarction, angina, stroke, malignancy, current smoker, and alcohol. a. Adjusted risks of IR according to sodium excretion in age group 20–39 years. b. Adjusted risks of IR according to sodium excretion in age group 40–64 years. c. Adjusted risks of IR according to sodium excretion in age group 65–74 years. d. Adjusted risks of IR according to sodium excretion in age group ≥ 75 years.</p

Association between obesity and sodium excretion quartiles according to age.

<p>Obesity was defined as a BMI ≥25 kg/m². Risks of obesity was adjusted by age, gender, systolic blood pressure, glucose, hemoglobin, estimated glomerular filtration rate, triglyceride, high density lipoprotein, aspartate aminotransferase, alanine aminotransferase, energy intake, diabetes mellitus, myocardial infarction, angina, stroke, malignancy, current smoker, and alcohol. a. Adjusted risks of obesity according to sodium excretion in age group 20–39 years. b. Adjusted risks of obesity according to sodium excretion in age group 40–64 years. c. Adjusted risks of obesity according to sodium excretion in age group 65–74 years. d. Adjusted risks of obesity according to sodium excretion in age group ≥ 75 years.</p

Association between sodium excretion quartiles and hypertriglycemia according to age.

<p>Hypertriglyceridemia was defined as a serum triglyceride ≥ 150 mg/dL. Risks of hypertriglyceridemia was adjusted by gender, systolic blood pressure, body mass index, glucose, hemoglobin, estimated glomerular filtration rate, high density lipoprotein, aspartate aminotransferase, alanine aminotransferase, energy intake, diabetes mellitus, myocardial infarction, angina, stroke, malignancy, current smoker, and alcohol. a. Adjusted risks of hypertriglycemia according to sodium excretion in age group 20–39 years. b. Adjusted risks of hypertriglycemia according to sodium excretion in age group 40–64 years. c. Adjusted risks of hypertriglycemia according to sodium excretion in age group 65–74 years. d. Adjusted risks of hypertriglycemia according to sodium excretion in age group ≥ 75 years.</p

Association between abdominal obesity and sodium excretion quartiles according to age.

<p>Abdominal obesity was defined as a waist circumference ≥ 90 cm in men and ≥ 80 cm in women. Risks of abdominal obesity was adjusted by age, gender, systolic blood pressure, glucose, hemoglobin, estimated glomerular filtration rate, triglyceride, high density lipoprotein, aspartate aminotransferase, alanine aminotransferase, energy intake, diabetes mellitus, myocardial infarction, angina, stroke, malignancy, current smoker, and alcohol. a. Adjusted risks of abdominal obesity according to sodium excretion in age group 20–39 years. b. Adjusted risks of abdominal obesity according to sodium excretion in age group 40–64 years. c. Adjusted risks of abdominal obesity according to sodium excretion in age group 65–74 years. d. Adjusted risks of abdominal obesity according to sodium excretion in age group ≥ 75 years.</p