Micronutrients & recovery
Dietary self-report instruments (FFQs and 24-hour recalls) significantly underestimate sodium intake (by 23-52% for FFQs and 23-28% for 24HRs), whereas potassium intake is captured with much higher accuracy (underreporting of only 5-6% for FFQs).
If you are tracking sodium for health reasons, do not rely solely on your memory or standard food diaries, as you will likely underestimate your intake by 25-50%. To get a more accurate picture, use multiple 24-hour recalls (averaging 3 is best) or focus on the Sodium:Potassium ratio, which is measured more accurately than sodium alone. For potassium, self-reports are reasonably accurate.
Average underreporting was 5%–6% with an FFQ and 0%–4% with a single 24HR for potassium but was 28%–39% and 4%–13%, respectively, for sodium.
Why this rating
Pooled analysis of 5 large validation studies using objective recovery biomarkers (gold standard for validation).
Source
Pooled Results From 5 Validation Studies of Dietary Self-Report Instruments Using Recovery Biomarkers for Potassium and Sodium Intake
Laurence S. Freedman et al. · American Journal of Epidemiology · 2015
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