To determine the impact of dietary calcium from dairy, and/or total dairy intake on the body mass index of Grade 2 leaners in Pietermaritzburg.

Abstract

Introduction: International and local figures show a steep rise in the incidence of overweight and obesity in both adults and children, with more children suffering from overweight, obesity and their associated diseases of lifestyle than ever before. The aetiology of overweight and obesity is complex, with many interrelated factors involved. The South African government implemented the Food Based Dietary Guidelines in an attempt to guide the public on making healthy food choices. One of the guidelines encourages the public to “have milk, maas or yoghurt every day” due to the beneficial health effects of these dairy products. South African studies investigating the calcium intake of different age groups have shown children to consume inadequate amounts of calcium. A recent national survey showed the age group of 7 to 8 years old in particular, to have the lowest calcium intake of all age groups studied. Several international studies have shown dairy products, and specifically milk, to have an inverse relationship with Body Mass Index (BMI) in both adult and paediatric subjects. However, other international studies have provided conflicting results. No such study has been conducted in South Africa, and so the need arose to investigate a possible association between dairy products and childrens’ BMI. Aim: To determine the impact of dietary calcium from dairy and/or total dairy intake, on the body mass index of Grade 2 learners in Pietermaritzburg. Objectives: To determine the following regarding Grade 2 learners: the prevalence of overweight and obesity by interpreting their BMI; their calcium intake from dairy, and their total dairy intake; the contribution of dairy products to meeting their calcium requirements; whether a relationship exists between their dietary calcium (from dairy), and/or total dairy intake and their BMI; and possible barriers to dairy intake. Method: A cross sectional study was conducted on 91 Grade 2 learners from quintile 5 (fee-paying) schools in Pietermaritzburg. A three-part questionnaire, comprised of an anthropometric section, demographic questions, and a semi-quantitative food frequency questionnaire (FFQ) were administered to the parents/guardians of the Grade 2 learners. The BMI of the learners was compared to both the World Health Organization (WHO) and International Obesity Task Force (IOTF) classifications for overweight and obesity. The calcium intake was obtained from the FFQ, and compared to the Estimated Average Requirement (EAR) for calcium for 4 to 8 year olds. The dairy intake was also determined, and compared to the recommended national guidelines. Results: The study population comprised 57% female and 43% male learners, of whom 40.7% were Black African, 27.5% were White, 17% were Indian and 13.2% were Coloured. Of these learners, 28.6% (WHO) and 24.2% (IOTF) were overweight and 19.8% (WHO) and 15.4% (IOTF) were obese. More female learners were overweight than male learners, but a greater percentage of male learners were obese than female learners. Calcium intake from dairy was significantly below the EAR of 800 mg per day for 75.8% (n=69) of learners, with the average intake from the FFQ recorded as 615.2 mg. The mean number of dairy servings per day was 2.03, also below the recommended number of 3 servings of dairy per day. No relationship between BMI and calcium, or BMI and total dairy intake was established. Despite the low intake of dairy, no significant barriers to the consumption of dairy were identified. Conclusion: Grade 2 learners do not consume enough dairy products in their diet, and are therefore unable to meet the calcium requirements for their age. Greater effort is required by government, schools, health professionals and parents/guardians to promote, and encourage children to consume more dairy products. Further research on this topic is recommended, where the impact of lower fat and sugar containing dairy products on body fat (as opposed to BMI) can be investigated.