Intended for healthcare professionals

General Practice

Guidance for authors: Nutrition guidelines

BMJ 1995; 310 doi: (Published 27 May 1995) Cite this as: BMJ 1995;310:1374

The following guidelines indicate how papers submitted to the BMJ should describe the methods by which the diet of a group of people was assessed.

Sample characteristics

As with any epidemiological study the sample and control population must be adequately described, and the reasons for believing them to be representative of the whole population. In nutritional surveys it is usually relevant to know the age, sex, weight, and height of the subjects, and the season of the year in which measurements were made, since all these factors may affect dietary intake.

Methods used in assessing the diet

(a) Questionnaire

If a questionnaire was used in assessing the diet a copy of the questionnaire must be submitted with the paper.

(b) Definition of assessment methods

Listed below are preferred terms for describing methods for assessing dietary intake and their precise meaning:

Diet recall: The respondent is asked to recall the actual food and drink consumed on specified days, usually the immediate past 24 hours (24 hour recall) but sometimes for longer periods.

Diet history: The respondent is questioned about “typical” or “usual” food intake in a one to two hour interview. The aim is to construct a typical seven days' eating pattern. The interview may discuss each meal and inter-meal period in turn or each day of the week in turn. Questions are usually openended, although a fully structured interview may be used. The diet history may be preceded by a 24 hour recall and/or supplemented with a check list of foods usually consumed.

Food frequency (and amount) questionnaire: The respondent is presented with a list of foods and is required to say how often each is eaten in broad terms such as x times per day/per week/per month, etc. Foods listed are usually chosen for the specific purposes of a study and may not assess total diet. The questionnaire may be administered by the interviewer or completed by the respondent. Assessment of the quantities of food consumed on each eating occasion/day may also be included.

Menu record: Record obtained without quantifying the portions. It may be subsequently analysed in terms of frequencies of consumption, or the investigator may assign “average” weights to portions. Because the respondent does not indicate quantity, there can be no attempt to identify the true weight of individual portions.

Estimated record: A record with portions described in household measures (cups, spoons, etc) with or without the aid of diagrams or photographs. This method aims to estimate the actual quantity eaten.

Weighed record: Record with weights of portions as served and the plate waste. (Weighed records are rarely fully weighed; estimated portions are usual for food eaten away from home.)

(c) Assessment of food portion sizes

Average portions: Investigator assigns “average” portion weights derived from previous studies or experience. “Small,” “medium,” or “large” may also be used to indicate portion size in relation to the “average.”

Household measures: Respondent describes portions in terms of household measures—for example, cups, spoons, etc. “Standard” weights are assigned to the descriptions.

Photographic measures: Respondent is shown photographs of portions of known weight and asked how their own portion relates to the pictured portions.

Food models/replicas: Respondent is shown three dimensional models representing foods and asked how their own portion relates to the models. Models may be realistic replica foods or a variety of neutral shapes and sizes.

Weighed: The subject weighs and records each food item as it is consumed.

(d) Food composition analysis

How/by whom were the records checked and coded for analysis?

Which database was used for analyses?

How were foods dealt with which were not on the database?

These guidelines were taken from a document prepared by the United Kingdom Nutritional Epidemiology Group. They are published in full in British Journal of Nutrition 1993;69(3):935-40 and Metabolism 1993;22:258-9. Further details may be obtained from Dr Michael Nelson, lecturer in nutrition, Department of Nutrition and Dietetics, King's College London, Campden Hill Road, London W8 7AH.

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