High dietary diversity is associated with obesity in Sri Lankan adults: an evaluation of three dietary scores

Dietary diversity and variety have long been recognized as key elements of high quality diets. A diverse diet increases the probability of nutrient adequacy among adults [1] and leads for positive health outcomes such as reduced complications of diabetes [2], incidence of several cancers [3, 4] and all-cause mortality [5]. As dietary factors are associated with increased risk of chronic diseases, local and international dietary recommendations promote increased dietary diversity but limiting saturate fats, refined sugar and salt. However, lack of dietary diversity is a major nutritional concern over among deprived people from the low income countries [6]. Changing from a monotonous diet to one with varied food types has been shown to improve energy and nutrient intakes in the people from developing countries. The demographic and economic transition that many developing countries are undergoing is producing important changes in diet and lifestyle that greatly impact on disease risks [7]. Despite undernutrition and nutrient deficiencies were major concern in the developing countries, recent nutritional transition and changes in the physical activity patters, diet related metabolic problems has emerged as an alarming public health problem in many developing countries particularly among urban dwellers [8].

Sri Lanka is a low-middle income country with undergoing rapid epidemiological and nutritional transition. Despite nutritional deficiencies such as iron deficiency anemia, vitamin A deficiency and protein energy malnutrition are reported in some segment of the Sri Lankan population [9], Non-Communicable Diseases (NCDs) are also emerging as the major diet associated health problem in Sri Lanka. The prevalence of overweight, obesity and central obesity among Sri Lankan adults were 25.2%, 9.2% and 26.2%, respectively in 2005–2006, as defined by Asian Body Mass Index (BMI) cutoffs [10] and there is a clear upward trend [11]. The age-adjusted prevalence of Metabolic Syndrome among Sri Lankan adults was 24.3% (95% CI: 23.0–25.6) [12]. The prevalence of obesity related metabolic problems such as diabetes and hypertention among Sri Lankan adults were 13–14% and 18–19% respectively [13]. Moreover, in Sri Lanka, diet-related chronic diseases currently account for 18.3% of all deaths and 16.7% of hospital expenditure [14].

Although prevalence rates are higher in affluent countries, obesity and abdominal obesity are becoming a major public health concerns in South Asia [15]. Causes for obesity is multi-factorial, among them various dietary factors play an important role. Association between individual nutrients and obesity/abdominal obesity has widely researched, but there is little attention has given on overall dietary diversity and obesity/abdominal obesity. Dietary diversity is an indicator of overall diet. Higher diet variety is associated with increased intake of fiber and vitamins [16] and on the other hand, increased variety contributes to high calorie consumption [17]. Sri Lankan has interesting socio-economical relationship with obesity. For instance, higher wealth and education is positively associated with obesity among Sri Lankan adults [10]. Therefore, evaluating the association between diet diversity and obesity would be interesting in this population. Explore the underline associations between obesity and dietary diversity is very important as lifestyle intervention can change dietary diversity in deferent populations. The aim of this study was to explore association of diet diversity with obesity in Sri Lankan adults.

Sri Lankan adults had relatively low dietary diversity values, in particularly, relatively higher FVS and DDS and lower DDSP value indicates that although people consume several type of food items, the amount of consumption is low for many food groups. In WHO STEP Survey reported that 3% of Sri Lankan consume more than five fruits and vegetable per day [22]. Rathnayake et al. reported much lower mean DDS (4.4) and FVS (8.4) among group of rural elderly people [23]. DDS, DDSP and FVS values for Indian Tamils were remarkably less than Sinhalese and Muslim ethnic groups. It is reported that malnutrition and nutritional deficiencies are highest in the estate sector where most of Indian Tamils are living [9]. Although we have lack of data on nutrient adequacy in this study sample, it can be postulate that low dietary diversity may causes deficiencies among Sri Lankan adults. People with better education may have high profile occupations and greater purchasing power could lead for higher consumption of different food variety. Although no previous data available on dietary diversity among Sri Lankan adults, children who lived in estate sector had a lower dietary diversity [24]. Moreover, lower maternal education was negatively associated with receiving a diverse diet for those children [24]. Obese and abdominal obese participants had higher DDS, DDSP and FVS values compared to non-obese and non-abdominally obese groups.

Sri Lankans consume excess amount of starchy foods but per below amount of fruits, vegetables and dairy products [19]. Table 2 and 3 showed that 100% values for starch group in every DDS and DDSP indicating starchy staple food is the inclusive food group in Sri Lankan meals. Nearly five percent participants had almost starch meal without significant amount of other food groups for whole day, this is due to some people consume cereal (e.g. rice) with a starchy vegetable (e.g. potato curry). Predominantly carbohydrate diets raise plasma glucose, insulin, triglycérides and non-esterified fatty acids leading to insulin resistance [25]. Total carbohydrate intake is associated with risk of diabetes among South Indian adults [26]. High prevalence of diabetes and its complications among Sri Lankan adults may be associated with starch based but poor variety meals [18, 27]. Amongst the food groups of dietary pyramid, meat, green leafy vegetables, milk and fruits were least frequent. Increased intake of fruits and vegetables could play a protective role against obesity associated metabolic risk factors in South Indians who is prone to get premature coronary artery disease [28]. Reasons for monotonous diet among Sri Lankan adults needed to be explored although it is associated with low obesity level. Public Health initiatives to improve appropriate diversity of diet are important.

Torheim et al. reported a positive correlation between energy intake and DDS, as well as variety of different food groups in Mali [29]. When a diet is composed of foods that differ on sensory characteristics such as color flavor and shape may cause hyperphagia [30]. Animal and human studies showed that food intake increases when there is more variety in a meal or diet and that greater dietary variety is associated with increased body weight and subsequently obesity [30]. Dietary variety within food groups was positively associated with body fatness among healthy adults [31]. Several studies showed a positive correlation between calorie intake and dietary diversity [17, 29]. On the contrary, an inverse association between DDS and obesity/abdominal adiposity was reported among the female students of Isfahan University [32]. In US women, low BMI was associated with higher DDS; in US men, there was no clear relation of BMI to dietary diversity [5]. Our result shows that positive association between all three dietary diversity indices with calorie intake suggesting that consumption of large number of food items may lead to excessive intake of calorie and weight gain. Although many dietary guidelines promote consumption of varied diet, it should be selective (e.g. vegetables) rather than absolute number. Moreover, Food Guide pyramids are not designed to maintain energy balance, but show nutritional adequacy and balance [17]. Increased dietary diversity in health promotion may not be appropriate for combating obesity epidemic in Sri Lankan. A reduction in dietary variety of highly palatable and energy rich foods may be an appropriate strategy to prevent and treat obesity in Sri Lankan. In the same time, to prevent deficiencies foods with high nutrient but low calories (e.g. green vegetables, low fat milk) should be encouraged.

In conclusion, our data suggests that dietary diversity and variety are associated with obesity among Sri Lankan adults. High dietary diversity is widely recommended as it can be used as proxy indicators of nutrient adequacy. Therefore public health messages should emphasize to improve dietary diversity in selective food items. Further studies are needed to confirm this finding on other diet associated chronic diseases.