Which dietary assessment method is best for estimating an individual's usual intake over a long period and is commonly used in epidemiologic studies?

• A. 24-Hour Diet Recall
• B. Diet Records
• C. Food Frequency Questionnaire
• D. Dietary History

Answer: (C)

Estimating usual, long-term intake requires a method that captures how often a person consumes a wide range of foods over extended periods, not just what they ate on a single day. The Food Frequency Questionnaire does this by asking how frequently various foods are eaten over a defined long timeframe and usually using standard portion sizes to estimate nutrient intake. This setup targets habitual intake, which is exactly what epidemiologic studies aim to relate to disease outcomes across large groups, while also being practical and scalable for many participants.

Other methods provide detailed short-term data but fall short for long-term habitual intake. A 24-hour recall covers only one day's intake and, without many repeats, doesn’t reflect typical patterns. Diet records/logs require daily, prospective writing for multiple days, which is burdensome and may not capture usual habits. A dietary history can assess typical intake but tends to be more labor-intensive and less standardized for large populations. Hence, the Food Frequency Questionnaire is the best fit for estimating long-term usual intake in epidemiologic research.