Single or multiple 24DRs are used in dietary surveys in many countries [2.3]. However the present study showed that 24DRs under-reported the total energy and nutrient consumption, although there was no affect on the percentage of energy distribution, when the two methods were compared. It is always a challenge to select a suitable dietary assessment method. Under-reporting of food consumption is a well-recognized phenomenon common to dietary assessment methods .
All dietary assessment methods have their pros and cons . To my knowledge, this is the first time that the 7DWR method was used in Sri Lanka to determine dietary intake and assess the feasibility of this method by qualitative assessment. Many studies have not found any significant burden when the 7DWR method is used, however, some studies have reported alterations in the habitual dietary intake pattern, by limiting certain food items, because of a high subject burden caused by measuring and recording individual food items. Bathalon et al. reported 24DR under reported compared to 7DWR and total energy expenditure estimated from doubly-labeled water analysis in a group of healthy postmenopausal women . Therefore, it is likely that the 24DR method showed under-reporting due to various reasons such as recall bias and social desirability. Previous studies have shown that the 24DR method may under report among Sri Lankan adults. Rathnayake’s study on dietary diversity among the elderly showed a mean calorie intake of 951 (300) kcal/d . This is considerably low for an average elderly individual. Mean energy intakes of Malaysian men and women were 1776 and 1447 kcal/d respectively. Both were less than 75 % of the Reference Nutrient Intake (RNI) .
Qualitative data showed practical problems associated with measuring food intake using 7DWR. Since there is a considerable subject burden on weighing food items, 7DWR may not be suitable for large studies and especially for male populations. Therefore, future researchers should provide other options such as food photography methods e.g. “Remote Food Photography Method (RFPM)” to reduce their subject’s burden. Measurement of food intake before eating, also gives a fair idea on the weight and portion size of food items, and this can influence the consumption patterns. To avoid technical difficulties, a considerable amount of training is important prior to use of scales for obtaining reliable information.
Firstly, this study may not represent dietary habits and subject perception on 7DWR among Sri Lankan adults due to the small sample size and low response rate. Male participation was very low and most of the participants were housewives. However, our primary aim was to compare energy and nutrient intake using two dietary assessment methods and observe the difficulties in applying the 7DWR method compared to the 24DR. Secondly, a complete database on the nutritional composition of Sri Lankan dishes is not available. Although we used accurate food composition values as far as possible, macronutrient values for some Sri Lankan dishes were not 100 % accurate . Thirdly, none of these methods is considered as a reference method to measure energy intake. In an ideal situation, the doubly labeled water technique, which is considered the gold standard for measurement of energy expenditure should be used and the intake data obtained from a dietary method should be compared for inaccuracies.