Estimating dietary sodium intake in individuals receiving a randomly fluctuating intake

Area of Science:

• Nutrition Science
• Clinical Research
• Biostatistics

Background:

• Accurate estimation of sodium intake is crucial for public health.
• Previous methods for estimating sodium intake in free-living individuals had limitations, such as not accounting for variable intake or lacking known intake validation.

Purpose of the Study:

• To evaluate the effectiveness of 24-hour and nocturnal urine collections for estimating sodium intake under controlled, variable intake conditions.
• To determine the optimal number of 24-hour urine collections for accurate sodium intake estimation.

Main Methods:

• A study involving 43 participants (men and women, Black and White) over 10 days.
• Participants ingested a known, randomly varied daily sodium intake (mean 150 mEq/day, range 50-250 mEq/day).
• Collected 24-hour and nocturnal urine samples to measure sodium excretion (UNaV) and compare it with known intake.

Main Results:

• Mean 24-hour sodium excretion accurately estimated daily sodium intake.
• Multiple 24-hour collections were necessary for reliable estimation; an average of nine collections yielded optimal correlation (r = 0.75).
• Nocturnal urine collections showed weak correlation (r = 0.30) with sodium intake, indicating limited utility for estimation.

Conclusions:

• 24-hour urine collections are the most useful method for accurately estimating mean sodium intake in free-living individuals.
• Nocturnal urine collections may be beneficial for monitoring compliance with low-sodium dietary recommendations.
• The findings highlight the importance of multiple measurements for precise dietary sodium assessment.