Background
It is widely recognized that an unhealthy diet is a major risk factor for many of the chronic non-communicable diseases and improving dietary habits is not simply an individual but a societal problem [
1]. However, it is difficult to assess the dietary habits of free-living individuals because of variability in food preference and availability, socio-economic factors, cultural concerns and educational level [
2]. National dietary surveys have several important functions and provide valuable information on dietary habits and nutritional status. Moreover, nutritional monitoring is important for implementation of programs related to food, nutrition, and health promotion for any country serious about promoting the health and wellbeing of its population [
3]. Food Frequency Questionnaires (FFQs) are the most common dietary assessment tool used in large epidemiologic studies of diet and health [
4]. To cater for differences in food based on cultural and regional factors, numerous FFQs have been developed comprising the list of foods commonly eaten in a particular country or by a particular population.
Sri Lanka is a ‘low-middle’ income country in South Asia with a population of nearly 21 million [
5]. Sinhalese is the main ethnic group but there are significant proportions of Tamils and Moors living in different parts of the country. With recent economic development, urbanization and changes in lifestyle patterns, Sri Lanka is experiencing a nutritional transition with the coexistence of under-nutrition and overweight and obesity [
6,
7]. A high prevalence of iron deficiency anemia among pregnant women, and subclinical vitamin A deficiency, stunting and wasting among pre-school children, are still major public health problems [
8]. Recent studies in Sri Lanka indicate a high prevalence of diabetes mellitus with one in every five adults aged above 20 years having either diabetes or pre-diabetes [
9], and the prevalence of hypertension, obesity, dyslipidaemia in urban areas are reaching epidemic proportions [
10,
11]. A quarter of adults is suffering from metabolic syndrome [
12]. In the Sri Lankan context, diet-related chronic diseases currently account for an estimated 18.3% of total mortality and 16.7% of hospital expenditure [
7].
Despite strong indications of a rise in lifestyle-related non-communicable diseases (NCDs) in Sri Lanka published guidelines are not justified with sound research evidence on dietary habits [
13]. There is a paucity of data on the dietary habits of Sri Lankans and in order to assess dietary intake, a culturally specific dietary assessment tool is necessary. This paper describes the development of a FFQ for Sri Lankan adults designed to assess and monitor dietary intake and be used to assist in national level programs to combat non-communicable diseases.
Results and Discussion
From the total sample of 600, 482 completed (Male = 166; Female = 316) all demographic, anthropometric and dietary profiles. The demographic profile of the study population is shown in Table
1. Overall, there was a preponderance of Sinhalese followed by Tamils and Moors. Males had lower BMI values compared to their female counterparts (M: 22.0 ± 3.5
vs. 23.7 ± 4.3 kg/m
2; p < 0.05). Average daily energy intake was 1656.7 ±535.0 kcal, with significantly higher caloric consumption by men compared to women (p < 0.05). The main source of energy was from carbohydrates for both men and women. Total protein and fat intake for men was 52.8 ±43.0 g/day and 40.5 ±18.1 g/day respectively and for women, 40.0 ±13.9 g/day and 31.9 ±14.1 g/day (Table
2).
Table 1
Demographic characteristics of the sample
Age (y) | 48.4 ± 15.6 | 48.1 ± 14.1 |
BMI (kg/m2)* | 22.0 ± 3.5 | 23.7 ± 4.3 |
Area of Residence | | |
·Urban | 27.8 (47) | 36.1 (116) |
·Rural | 60.4 (102) | 57.6 (185) |
·Estate | 11.8 (20) | 6.2 (20) |
Ethnicity (%) | | |
·Sinhalese | 71.0 (120) | 80.1(257) |
·Moors | 4.7 (8) | 7.2(23) |
·Sri Lankan Tamil | 11.8 (20) | 7.2(23) |
·Indian Tamil | 12.4 (21) | 5.6(18) |
Education level (%) | | |
·No Schooling | 6.5 (11) | 6.5 (21) |
·Upto 5 years | 27.2 (46) | 25.2(81) |
·Upto 11 years | 34.9(59) | 40.5(130) |
·Upto 13 years | 27.2(46) | 22.7(73) |
·Graduate | 4.1(7) | 5.0(16) |
Table 2
Nutrient intake of the study population
Energy | 1656.7 (535) | 1912.7(566.9)* | 1513.6 (458.5) |
Carbohydrates | 304.4(103.1) | 352.4 (110.3)* | 277.5 (88.3) |
Protein | 44.6 (28.8) | 52.8 (43)* | 40 (13.9) |
Total fat | 35.0 (16.1) | 40.5 (18.1)* | 31.9(14.1) |
Dietary fibre | 18.1(8.4) | 21.3(9.2) | 16.3(7.3) |
In this study 312 different food items were recorded. Nutritionists grouped similar food items which resulted in a total of 178 food items. After performing step-wise multiple regression, 93 foods explained 90% of the variance for total energy intake, carbohydrates, protein, total fat and dietary fibre. Subsequently, conceptually similar food items were grouped together yielding a final list of 81 food items (Table
3). An additional nine food items were included to cover festival and seasonal dietary habits and the final 90 food items were categorized as cereal or equivalents (n = 19), vegetables (n = 20), pulses (n = 6), meat or alternatives (n = 10), fruits (n = 9), beverages (n = 7), miscellaneous (n = 14), and alcohol (n = 5).
Table 3
Elements of the food frequency questionnaire
Total food items and mixed dishes | 36 | 48 | 11 | 17 | 19 | 13 | 29 | 2 |
Contribution of 90% | 28 | 21 | 5 | 9 | 9 | 7 | 12 | 2 |
Grouping of food items | 19 | 18 | 5 | 9 | 9 | 7 | 12 | 2 |
Inclusion of foods | 0 | 2 | 1 | 1 | 1 | 0 | 2 | 3 |
Final food items | 19 | 20 | 6 | 10 | 9 | 7 | 14 | 5 |
The paper describes the process of development of a FFQ for Sri Lankan adults using a nationally representative sample. Dietary assessment of this population is invaluable to understand the role of nutrition in chronic disease so that preventive strategies can be implemented. The aim of dietary assessment of populations is to rank people by a measure of usual rather than current diet. The strengths of this study include a nationally representative sample of Sri Lankan adults and the creation of a comprehensive new database for nutrient analysis. However, males are under-represented in this study which stems from data collection being on a random day when most males were engaged in active occupations away from home. However, in Sri Lanka family members consume similar foods; therefore, obtaining dietary data from females did not significantly affect the food list in our study. The number of food items in a FFQ is a crucial factor in determining the accuracy of the data and the practicability of the questionnaire. Many FFQs have between 100–150 items [
25] and the risk of over-reporting through increased subject burden increases with the large number of items [
22,
25]. In our FFQ, we have 90 items and 12 photos of food items to enable an accurate estimation of dietary exposure.
Sri Lanka as a tropical island has no clear four seasons but two monsoons influence cultivation. Hence additional seasonal fruits and vegetables are also included in our FFQ. Over 55% of adult males are current alcohol drinkers [
26]; however in our data collection alcohol consumption was under-reported (0.5% of participants) with no women reporting the consumption of alcohol. In Sri Lanka, drinking alcohol has negative social and religious stigma. Thus, common alcoholic beverages were added to the FFQ. Dietary recalls indicated differences between the ethnic groups in the type of nutrients derived from different food sources. The main carbohydrate source varied among ethnic groups; Indian Tamils reported consuming wheat flower (as Roti) whereas Sinhalese eat rice as the main staple food and Sri Lankan Tamils consume Dose, Itale and Wade frequently. Ethnicity was an important factor in the selection of foods containing protein, not surprisingly; pork and beef consumption was not reported by Moors (Muslims) and Tamils, respectively.
A variety of methods are available to collect food consumption data but a common challenge for individual-based dietary assessment methods is portion size estimation. Although weighing served portions is often considered the gold standard; for practical reasons, portion estimation using photographs are used among both adults and children [
27]. A study conducted in Burkina Faso showed that food photographs are valuable for the quantification of food portion size among rural and less educated middle-aged women [
28]. Men usually consume larger portions than women [
29] and the use of photographs helps to categorize gender variation in portion sizes more precisely. This is crucial to obtaining reliable estimates of macronutrient and micronutrient intakes. Several countries use FFQs with photo series and scoring systems [
30,
31].
The main weakness of the previous national level NCD survey (SLDCS) was the absence of nutritional data on the population and their relationship with the high NCD risk in the country. One of the main objectives of the current work was to develop a FFQ to administer in the next national level NCD survey. Moreover, this FFQ could also be used to assess dietary habits of Sri Lankans living in other countries, as they practice similar eating patterns to native Sri Lankans. There is no updated nutrient database in the country. Sri Lankan food composition tables were published in 1979, and since then many chemical analysis techniques have changed. Newer processed food items have been introduced into the market. We used the USDA food composition tables as the backbone of our nutrient database. This is arguably the most comprehensive, standardized, largest and continuously updated database that has used to develop population-specific food composition tables in other countries [
25]. Mixed dishes were not listed in the USDA database, and for such items we followed calculated values from traditional recipes. The recipes vary according to ethnic groups in Sri Lanka and were therefore modified to allow generalization to the whole country.
Limitations
Coconut oil is the main cooking oil in Sri Lanka [
32], however, other types of cooking oils are used in different communities. Our FFQ does not enable us to differentiate the types of cooking oil consumed which may have important health implications for NCDs. However, we used additional questions to obtain details of oil consumption. Another limitation is the lack of data on micronutrients on Sri Lankan mixed dishes, prolonged cooking time and addition of various spicies and herbs which could alter the nutritional values of the raw ingredients [
33]. Moreover, dietary surveys and 24 dietary recalls inherit some limitation such as recall bias, interviewer bias and selection bias.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
RJ contributed to the data collection, data analysis and drafted the manuscript. NMB, MJS, PK and APH were supervisory team members on the project and contributed to study design, interpretation of data and revision of the manuscript. All authors read and approved the final manuscript.