A rapid dietary assessment tool to estimate erythrocyte omega‐3 fatty acid levels

Abstract

The omega‐3 index (O3I), the percentage of long chain omega‐3 fatty acids (LC n‐3 FAs) in erythrocyte membranes, is an emerging risk factor for sudden cardiac death. A dietary tool to assess LC n‐3 FA intake validated by the O3I would be useful in clinical settings. We hypothesized that a single‐question tool measuring the frequency of LC n‐3 FA‐rich fish consumption would correlate more strongly with the O3I than dietary recall data due to the episodic nature of fish consumption. Healthy participants (n=29) were asked: “How often do you eat—as a main course—tuna or other non‐fried fish? a) > 1x/month, b) 2–3x/month, c) 1x/week d) 2x/week, e) >2x/week.” A blood sample was taken, and 3, unannounced 24‐hour recalls were taken over 2 wks. The O3I's for each fish intake level were: 3.76±0.15%, 5.04±0.01%, 4.08±0.14%, 5.65±0.08%, and 5.94±0.36% (respectively; a, b vs e, p<0.05). LC n‐3 FA intakes by recall (mg/d/1000 kcal) were: 18±2, 80±25, 388±110, 205±30, and 309±48 (respectively; a vs e, p>0.05). The Spearman correlation between O3I and LC n‐3 FA intake was 0.38 (p=0.04). The model predicting the O3I using ordinal frequency categories had R2 of 0.31 (p=0.002), and using LC n‐3 FA intake as a continuous variable had an R2 of 0.15 (p=0.04). We conclude that a single question focusing on the habitual intake of n‐3‐rich fish provided a better estimate of the O3I than dietary recalls. (Self‐funded).