A Food Frequency Questionnaire (FFQ) is a common tool in nutrition research and public health that helps understand what people eat. It is a structured survey designed to gather information about an individual’s usual food and beverage consumption over a specified period. The goal is to gain insight into long-term dietary habits and patterns, providing a broad overview of typical eating behaviors valuable for nutritional assessments.
What is a Food Frequency Questionnaire
A Food Frequency Questionnaire (FFQ) is a survey-based dietary assessment tool. It estimates how often an individual consumes specific foods and beverages, capturing habitual dietary patterns over an extended period, typically from the past month to a full year. Unlike methods that record daily intake, an FFQ focuses on consistent eating behaviors, providing a snapshot of someone’s usual diet.
The questionnaire typically presents a structured list of food items, asking respondents to indicate how frequently they consume each item. Options for frequency range from “never” to several times a day, allowing for a comprehensive assessment of dietary patterns. FFQs are useful for understanding long-term dietary exposures in large groups of people.
How FFQs Collect Dietary Information
FFQs gather dietary information by presenting a list of food items, which can range from around 20 to 200 items, depending on the questionnaire’s design and specific research goals. Respondents select from predefined categories like “daily,” “weekly,” “monthly,” or “rarely/never.”
Many FFQs, known as semi-quantitative FFQs, also include questions about portion sizes. Respondents estimate their usual serving size, sometimes aided by images. The recall period for an FFQ spans the past month, three months, or even the previous year to account for seasonal variations. This timeframe helps capture foods not consumed daily but still part of a regular diet.
Understanding What an FFQ Reveals
FFQs offer insights into overall nutrient intake, dietary patterns, and specific food group consumption over time. Researchers calculate nutrient intake by multiplying reported food frequency by estimated portion size and known nutrient content, often using specialized software and food composition databases. This data is applied in large-scale epidemiological and public health studies to investigate links between diet and chronic diseases like heart disease, diabetes, and certain cancers. FFQs are useful for ranking individuals’ intakes relative to others, helping identify high, medium, or low consumers of specific dietary components.
Despite their utility, FFQs have limitations that warrant consideration when interpreting data. A challenge is recall bias, where individuals may struggle to accurately remember food consumption over long periods, potentially leading to over- or under-reporting. The completeness of the food list also impacts accuracy; if a commonly consumed food is not included, its nutrient contribution will be missed. Additionally, FFQs may not capture detailed information about food preparation methods or complex mixed dishes, which can affect nutrient content estimates.