Which dietary assessment method is generally not recommended to ascertain usual intake?

The 24-hour recall method is typically not recommended for assessing usual dietary intake because it provides a snapshot of a person's food consumption over a single day, which may not be a reliable representation of their habitual intake. This method relies on a person's memory and can be influenced by various factors such as recent dietary changes, atypical eating patterns, or recall bias. While it is often quick and easy to administer, its limitations make it less effective for capturing a comprehensive picture of an individual's usual diet over time.

In contrast, other methods like food frequency questionnaires, food records, and diet histories allow for a broader and more inclusive assessment of dietary habits over a longer period. Food frequency questionnaires can identify how often specific foods are consumed, food records require individuals to consistently document their intake over a specified period, and diet history involves a thorough exploration of habitual dietary patterns, making these methods more appropriate for discerning usual intake.