Models of safe nutrition of children and adolescents as a basis for prevention of obesity

Modele bezpiecznego żywienia dzieci i młodzieży jako podstawa profilaktyki otyłości

Halina Weker1, Marta Barańska2
1 Department of Nutrition
Head of Department: prof. nadzw. dr hab. n. med. H. Weker
2 Early Psychological Intervention Department
Head of Department: dr G. Kmita
Institute of Mother and Child in Warsaw
Director: S. Janus

Abstract
Aim: The aim of the study was to present up-to-date nutrition models for children and adolescents in Poland on the basis of current research on obesity prevention.
Material and methods: Up-to-date results of research on the link between nutritional factor and the nutritional status of children and adolescents, nutritional standards and recommendations of expert teams on healthy diet were analysed, based on the review of literature (Medline database) from the years 2005-2010.
Results: The main components of the model of safe nutrition for children and adolescents, which according to the current views should be combined with obesity prevention, include the frequency of meals, selection of products in a daily diet and observance of norms concerning energy and nutritional value of the diets. Other factors include family and environmental determinants, including dietary habits and behaviour, knowledge about nutrition and physical activity.
Conclusions: The models of safe nutrition for children and adolescents in Poland are compliant with the current nutritional recommendations of the WHO and EU standards. The developed models of safe nutrition for children and adolescents must not only be popularised but also their efficiency needs to be increased by adjusting them to various groups of recipients.

Key words: models of nutrition, children, adolescents

Streszczenie
Cel pracy: Celem pracy było przedstawienie aktualnych modeli zywienia dzieci i młodziezy w Polsce na tle prowadzonych badan w zakresie profilaktyki otyłosci.
Materiał i metody: Na podstawie przegladu pismiennictwa (baza Medline) obejmujacego lata 2005- -2010 przeanalizowano aktualne wyniki badan na temat powiazania czynnika zywieniowego ze stanem odzywienia dzieci i młodziezy, normy zywieniowe oraz rekomendacje zespołów ekspertów w zakresie zasad zdrowego odzywiania.
Wyniki: Podstawowe składowe w modelu bezpiecznego zywienia dzieci i młodziezy, które w odniesieniu do aktualnych pogladów nalezy łaczyc z profilaktyka otyłosci to czestosc spozycia posiłków, dobór produktów w całodziennej diecie oraz przestrzeganie norm dotyczacych wartosci energetycznej i odzywczej diet. Z innych czynników wymienia sie uwarunkowania rodzinno-srodowiskowe, w tym nawyki i zachowania zywieniowe, wiedze zywieniowa oraz aktywnosc fizyczna.
Wnioski: Opracowane modele bezpiecznego zywienia dzieci i młodziezy w Polsce sa zgodne z aktualnymi zaleceniami zywieniowymi WHO oraz standardami UE. Istnieje koniecznosc nie tylko upowszechniania opracowanych modeli bezpiecznego zywienia dzieci i młodziezy, ale takze zwiekszenia skutecznosci ich działania poprzez dostosowanie ich do róznych grup odbiorców.

Słowa kluczowe: modele żywienia, dzieci, młodzież

INTRODUCTION
The results of research conducted in numerous acknowledged research centres around the world emphasize the impact of genetic and environmental factors, including dietary factors, on the development of children and their health, also in adulthood (1, 2, 3, 4).
Proper fetal development depends, among many factors, on healthy diet of the mother during pregnancy. Appropriate feeding of the child after birth and in the first years of its life is one of the major determinants of optimal development, both somatic and mental (1, 5, 6, 7, 8).
Both excessive body weight and its deficit may increase the risk of obesity in adulthood and the development of various diet-dependent diseases. Many studies have confirmed the link between cardiovascular diseases, type 2 diabetes, osteoporosis and some cancers in adults and the low birth weight resulting from fetal growth restriction (1, 5, 6).
Multicentre, randomized clinical trials assessing the impact of nutritional deficiencies in children during intrauterine life on their metabolism have been conducted (www.perlip.org. Influence of Dietary Fatty Acid on the Pathophysiology Intrauterine Fetal Growth and Neonatal Development; www.nuheal.org. – Nutraceutical for a healthier life). It has been established that intrauterine growth restriction is a risk factor for occurrence of insulin resistance in adulthood, while disturbed growth in prenatal period (children with low birth weight) is linked to an elevated systolic blood pressure in later life (5, 9).
The research findings showed that the appropriate diet may influence the fetus metabolism already at the early stage of ontogenetic development. Such was called nutritional programming (5, 10). Breastfeeding is one of the factors linked to nutritional programming, i.e. influence of the method and quality of nutrition on child development (11). Feeding infants, particularly in the first six months of life, with other food than breast milk increases the risk of obesity, allergies, cardiovascular diseases and problems related to cognitive development (1, 5, 6, 7, 12, 13, 14, 15).
Appropriate diet meets energy requirements of the child’s body and its requirements for all nutrients. Energy and nutrient requirements depend, inter alia, on the size and composition of the body, the growth rate and physical activity and they change at each stage of development (15, 16, 17, 18, 19).
The components of energy for growth, metabolic activity and physical activity also change with age (10, 11).
Numerous studies show that excessive intake of energy, protein and fat, in particular rich in saturated fatty acids, is conducive to incorrect distribution of lipoproteins in serum and elevated cholesterol. Combined with excessive energy intake and lack of physical activity it creates a risk of adult life diseases (ischaemic heart disease), while earlier it may cause a risk of obesity (20). A diet with calcium deficiency results in a similar risk of osteoporosis (16, 21).
An important aspect of these recommendations is the prevention of such effects of malnutrition in children as iron-deficiency anemia, which adversely effects psychosomatic development (22). There are several critical periods for overweight and obesity of developmental age. They most often include the prenatal period and early childhood (1 to 3 years of age), adiposity rebound period (around 6 years of age) and puberty period (23). Therefore, it is of utmost importance for nutrition of children and young people to be compliant with recommendations, also referred to as nutrition patterns or models.

AIM of the study
The aim of the study was to present up-to-date nutrition models for children and adolescents in Poland against the background of current research on obesity prevention.

Material and methods
Up-to-date results of research on the link between nutritional factor and the nutritional status of children and adolescents, nutritional standards and recommendations of expert teams on healthy diet were analysed, based on the review of literature (Medline database) from the years 2005- 2010. Dietary recommendations for children and adolescents in Poland were also discussed, using the specially devised theoretical model of safe nutrition presented in Figure 1.
The model of safe nutrition for children and adolescents should be understood as the system of nutritional recommendations developed on the basis of objectivised research in the field of medical and nutritional sciences, which, if applied in practice, determines the optimal psychosomatic development of children, reduces the risk of diseases and infections and mitigates the risk of diet-related diseases, including adult obesity.
The main components of the model of safe nutrition for children and adolescents, which according to the current views should be combined with obesity prevention, include the frequency of meals, selection of products in a daily diet and observance of norms concerning energy and nutritional value of the diets. Other factors include family and environmental determinants, including dietary habits and behaviour, knowledge about nutrition and physical activity.

Description of nutrition models and discussion

For many years, children in the first year of age in Poland and in the world have been fed according to the breastfeeding model and the formulae feeding scheme. The World Health Organisation recommends exclusive breastfeeding of infants for the first six months of life, without additional fluids and solid food apart from medicines and vitamins, and the introduction of complementary feeding at 6-12 months of age, in line with the principles of the shift from exclusive breastfeeding towards the family table diet in which the selection of products, size of portions, consistency of dishes and meals are important (13, 14, 15, 24).
Exclusive breastfeeding of infants for the first six months of life, but also for shorter periods of time, is beneficial, according to the Committee on Nutrition of the European Society for Paediatric Gastroenterology Hepatology and Nutrition. ESPGHAN recommends to introduce complementary feeding to the diet of infants between 17 and 26 weeks of age (13, 25, 26). New products should be introduced in sequence and in small portions, with monitoring of the child’s reactions. Adding new products to the child’s diet is necessary to prevent nutritional deciencies and feeding disorders. According to the current recommendations, the most important principle in diversifying the child’s diet in the first year of age is to introduce new food allergens with protection from breastfeeding (gluten products, fish meat, eggs/yolks, cow’s milk).
The nutrition model for breastfed infants and nutrition scheme for non-breastfed infants, developed in Poland in the years 2007-2008, complies with the above standards (tab. I and tab. II) (27).
Many research have shown that breastfeeding acts as protection against excessive body weight in later life (11, 24, 28, 29). The energy intake can be better controlled in breastfed infants. Apart from essential micronutrients, such as protein, fats and lactose, breast milk contains many active ingredients which may contribute to the mitigation of overweight risk. Such ingredients include enzymes, substances regulating peristalsis of digestive tract, appetite-regulating substances and substances stimulating the intestine microflora, such as oligosaccharides.
Protein is believed to be the main nutrient influencing the growth rate of infants. 100 ml of mature breast milk with the nutritional value of 65-70 kcal contain 0.9-1.0 g of protein. In feeding of infants, the protein pattern is the quantitative and qualitative amino acid composition of breast milk.
The protein intake is much higher in formulae fed children who are not breastfed. Higher protein content in formulae may result in higher secretion of insulin and insulin-like growth factor (IGP-1), which in turn may lead to excessive body weight increases. Lower intake of protein entails lower stimulation of growth hormone (GH), insulin-like growth factor (IGF-1) and insulin, which leads to reduced multiplication of adipocytes (30, 31).
The influence of protein content in infant formulae on the body weight and the growth rate of children in the first two years of age and the risk of obesity in school children were evaluated in a randomised, double-blind, multicentre European trial, in which Poland had also participated (acronym CHOP – EU Childhood Obesity Programme) (30). The study involved a dietary intervention in children in the first year of life, breastfed and fed with lower and higher protein content formulae. The infants participating in the trial (n=1500) were divided into groups, with one of them receiving infant formulae with energy from protein accounting for 7.1% and follow-on formulae with 8.8% energy intake coming from protein. The second group of children received infant formulae with energy intake from protein accounting for 11.7% and follow-on formulae with 17.6% energy from protein. The third group included breastfed children (n=250). It has been proved that children fed on low protein formulae had a similar body length growth rate to the children receiving more protein, but a lower BMI at 24 months of life. e study has confirmed that fast body weight increase in the first months of life is conducive to obesity in later life. The new research project (acronym EARNEST – Early Nutrition Project) will continue clinical observation of this group of children, also in the context of obesity prevention.
Other studies have not found a link between long-lasting breastfeeding and overweight in children. However, such factors as dietary habits of the parents/in the family, physical activity and duration of sleep were found to be linked to obesity in young children (20, 24, 32, 33, 34, 35, 36, 37).
Early childhood (1-3 years of life) is considered the most critical period for the risk of dietary disorders, nutritional deficiencies and obesity. The children at this age more often than others exhibit iron-deficiency anemia and/or other anemia, allergy to cow milk protein and inappropriate body weight increases due to i.a. nutritional mistakes.
Elimination of excessive body weight in children up to 6 years of age may significantly reduce the likelihood of diet-dependent diseases in the future (2, 38).
In 2008, a model of nutrition for children aged 1 to 3 years was developed in Poland in order to draw attention to the proper intake of energy, protein, fibre and the appropriate selection of products in daily food rations in children (39).
According to the current knowledge, following the rules presented in the model may reduce the risk of ischaemic heart disease, type 2 diabetes and obesity.
The diet of children aged 1-3 years should be diversified in terms of products. Diversification of the diet, gradual introduction of new elements and accustoming children with new products are necessary to ensure optimal fulfilment of requirements for all nutrients.
The prevention of overfeeding or malnutrition in children aged 13-36 months should take into account the children’s food preferences and individual energy and nutrient requirements.
According to the 2004 report of FAO/WHO/UNU (Human energy requirements. Report of Joint Food And Agriculture Organization Of The United Nations, World Health Organization And United Nations University Expert Consultation), daily energy requirements for children aged 2-3 years, with moderate physical activity, are presented in table III.
As regards energy requirements, it is also useful to establish energy requirements excluding protein, i.e. non-protein energy, and separately protein requirements. Average recommended amount of non-protein energy for children aged 2-3 years is 80 kcal/kg/day.
Non-protein energy intake should be distributed as follows: 60-65% should come from carbohydrates, with the intake of additional sugar reduced to maximum 20% of total energy intake (lower intake is recommended, which in practice means avoiding sweetened foods and drinks), while fats should account for 35-40%, with a reduced intake of fats with saturated fatty acids, trans fatty acids and cholesterol.
Protein intake at the age of 13-36 months should amount to ca. 1 g/kg of body weight. The figure stems from the analysis of the WHO recommendations, where the average protein intake in children was established at 1.12 g.kg/d (safe intake was set within the range between 0.91 g/kg/d and 1.43 g/kg/d) (18).
The recommended intake of dietary fibre should amount to ca. 10-15 g/day (maximum 19 g/day) which in practice means consumption of whole grain products (grouts, wholemeal bread), fruits and vegetables.
The diet of children aged 13-36 months should include an adequate amount of calcium and vitamin D (14). The calcium requirements at this age amounts to 800-1000 mg. The vitamin D requirement is 400 IU a day (21).
Many research show that the diets of children aged 1-3 years vary (40, 41, 42, 43).
It was established that in the representative (randomly selected) group of Polish children aged 13-36 months (n=400), the energy value of average daily food ration was higher than recommended and amounted to 1219±339.6 kcal vs 1000 kcal, but the share of individual nutrients, except for protein, in total energy intake, was as recommended. The amount of energy from protein was higher and on average totalled 14.1±2.5% (the norm is 10-12%), from fat 29.0±5.4% (the norm is 30-32%) and from carbohydrates 56.9±6.3% (the norm is 56-58%).
In Poland, approximately 67% of children aged 3-6 years go to kindergartens for 8-10 hours a day, where they usually receive 2-3 meals with various energy and nutritional value. The studies on the diets of pre-school children show that energy value of average daily food rations of those children is as recommended, but a significant share of energy intake comes snacks rich in carbohydrates and fat, eaten between meals, most often at home. Preschool and early school children prefer products which are easily available and accessible. Many studies have shown that the major factors determining the body weight of children at this age include the family environment (dietary patterns), school policy and media (advertisements), as well as dietary behaviour of the child, i.e. share of snacks and sweetened beverages in its diet, size of food portions (42, 44, 45). The table below presents relations between selected dietary factors and the growth of body mass in children and adolescents, in view of obesity prevention in the current research (tab. IV).
Diets of older children and adolescents are very individualized, determined by their family home or peer group. The Mediterranean diet pyramid is popularized as a dietary model for this group (Fig. 2). The base of the pyramid consists of cereal products providing complex carbohydrates and fibre, followed by vegetables and fruits, milk products, poultry and fish - recommended to be eaten several times a week, while red meat and sweets (top of the pyramid) should be eaten several times a month.
Such a healthy diet model is conducive to maintaining good health and reduces the incidence of diseases caused by inappropriate diet in risk groups (19, 46, 47, 48, 49).
Unhealthy lifestyle of the family, i.e. bad diet, no physical activity and spending free time in front of the TV set and computer screen, may be a good indication of excessive body mass in children (50, 51, 52, 53). Research on diets of obese teenagers reveal the excessive amount of high fat products in their diets. Daily food rations of obese children are characterised by higher than recommended share of energy from fat and protein. Not all studies found statistically significant relations between fat consumption and body mass in children. The current view is that not only quantity but also quality of fat contribute to the excessive body weight (34, 54).
The promotion of appropriate diet may be an important measure in preventing obesity and metabolic syndrome in children and adolescents. In 2007, the International Diabetes Federation has developed a definition of the metabolic syndrome in children (55). Excessive fat tissue in children age 10 and older and in adolescents, in particular abdominal obesity, is a serious health problem.
The criteria for diagnosing the metabolic syndrome in children aged 10-16 include waist circumference above 90th percentile, combined with triglycerides in serum ≥150 mg/dL, HDL cholesterol in serum below 40 mg/ dL, systolic blood pressure ≥130 mm Hg or diastolic blood pressure ≥85 mm Hg and glucose ≥100 mg/dL.
Children with the metabolic syndrome are at increased risk of cardiovascular diseases. The modification of the diets of obese adolescents to adjust them to the rational diet model is the best non-pharmacological intervention. Overweight and obesity, due to their impact on health not only at developmental age, but also in adult life, are currently the major public health problem in the world.
Last decades in the United States saw a number of obese children aged 2-5 years double, from 5% in early 1970s to 10% in 2000. In the years 2003-2004, percentage of obese children and adolescents in the USA stood at 17.1% the statistics for other countries, such as Canada, Brazil, Chile, Japan or Australia, are similar. In Europe, the problem affects even children and adolescents living in the Mediterranean region where the Mediterranean diets is prevalent. In Poland in the 1990s, excessive body weight was diagnosed in 8.7% of children and adolescents aged 7-17 years. In 2001, the study of the representative group of Polish children aged 7-9 years found overweight and obesity in 15.8% of girls and 15.0% of boys, with obesity in 3.7% of girls and 3.6% of boys. the results reveal an increasing trend in excess body weight in children. In 2008, in the Carpathian region, 9.1% of girls and 9.9% of boys were overweight, while 7.2% of girls and 8.4% of boys were obese (23, 56).
The growing number of obese people, including children and adolescents, in the world requires intervention measures consisting in treatment and prevention of obesity, in particular in children. The World Health Organisation and Commission of the European Communities believes that every country should try to develop and implement effective measures in this regard (57, 58). Despite extensive literature on implementation of a number of obesity prevention programmes in various age groups, the effectiveness of implemented measures is low (37, 59).
It seems that popularisation of safe dietary models for children and adolescents may be an important component of obesity prevention.
The question arises how to increase efficiency of intervention programmes so that they contribute to making the diets more healthy. The dietary models for children and adolescents presented above point to relations between the diet and the nutritional status of children. They also provide the basis for influencing the health of adults.

CONCLUSIONS
1. Appropriate diet of a woman before and during pregnancy, compliance of the child’s diet with the safe nutrition model as well as healthy family lifestyle (i.a. nutritional behaviour and habits, physical activity) influence the quality of life at various stages of development.
2. The models of safe nutrition for children and adolescents in Poland are compliant with the current nutritional recommendations of WHO and EU standards.
3. The developed models of safe nutrition for children and adolescents must not only be popularised but also their eficiency needs to be increased by adjusting them to various groups of recipients.


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Adres do korespondencji / Address for correspondence:
Halina Weker
Department of Nutrition Institute Mother and Child
ul. Kasprzaka 17a, 01-211 Warsaw