Iva Hojsak
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mended intake level has been proposed by differ- ent authorities. The European Food Safety Au- thority (EFSA) panel recommends that 45–60%
of energy should be provided as carbohydrates [4] ; however, the data concerning infants and
young children are limited. For infants, human milk can be used as a model, meaning that the minimum carbohydrate intake should be 40% of total energy, and lactose should be the main di- gestible carbohydrate [1] . After early infancy, the intake of digestible carbohydrates should increase until reaching the recommended amounts for adults [1] . However, it should be taken into ac- count that not only quantity but also carbohy- drate type, carbohydrate origin and food process- ing can influence the rate of carbohydrate release;
this glycaemic potential of the different carbohy- drates can be valorised by the glycaemic index (GI). The GI is defined as the area under the glu- cose response curve after consumption of a 50- gram carbohydrate portion of a test food, and ex- pressed as the percentage of response to the same amount of carbohydrate from a standard food taken by the same subject [5] . It was proposed that a diet with a low GI increases satiety and, consequently, reduces voluntary energy intake due to slower glucose and insulin release, which could have a preventive effect with regard to over- weight and obesity; however, data on children and adolescents are limited and have yielded in- consistent findings [6] . On the contrary, higher consumption of added sugars (which have a high GI) can displace other macronutrients, increase
Table 1. The main types of carbohydrates
Class Subgroup Components
Sugars Monosaccharides Glucose, galactose, fructose
Disaccharides Sucrose, lactose, trehalose, maltose
Polyols Sorbitol, mannitol
Oligosaccharides Maltooligosaccharides Maltodextrins
Other oligosaccharides GOS, FOS, polydextrose
Polysaccharides Starch Amylose, amylopectin, modified starches, resistant starch, inulin
Non-starch Cellulose, hemicellulose, pectins, hydrocolloids GOS = Galactooligosaccharides; FOS = fructooligosaccharides. Adapted from FAO/WHO report [5] and Cummings and Stephen [2].
Complex digestible carbohydrates
Smaller units (including disaccharides)
Disaccharides and monosaccharides
Monosaccharides – absorbed in small intestine
• Glucose: actively, energy required;
sodium cotransport
• Fructose: facilitated diffusion, no energy required
• Galactose: actively, energy required;
sodium cotransport Salivary
amylase
Pancreatic enzymes (amylase)
Brush border disaccharidases
Fig. 1. Digestion and absorption of glycaemic carbohy- drates.
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the risk of nutrient deficiency and significantly increase energy intake. The best evidence exists for sugar-sweetened beverages, due to the lower satiety potential of energy supplied in liquid com- pared with solid form [7] . Moreover, there is evi- dence that energy-dense food consumption can also influence insulin resistance, but there is no clear answer to whether this is caused solely by energy-rich food or influenced by overweight and increased fat mass [8] .
Most paediatric authorities recommend limit- ing sugar-containing foods for infants and chil- dren in order to reduce the likelihood of high consumption later in life [1, 9] . Children should receive healthy food rich in slowly absorbed car- bohydrates and with a limited amount of rapidly absorbed carbohydrates and simple sugars [9] . Frequent consumption of sugar-containing foods can also increase the risk of dental caries, espe- cially when oral hygiene and fluoride prophylax- is are insufficient. Therefore, avoidance of fre- quent consumption of juices or other sugar-con- taining drinks and ‘sleeping with a bottle’ should be recommended, as well as maintenance of good oral hygiene [10] .
In recent years there has been a growing inter- est in the role of fructose in obesity and metabolic disease. Fructose ingestion induces significantly more lipogenesis than isocaloric glucose inges- tion, which could have an effect on obesity, the metabolic syndrome and non-alcoholic steatohep- atitis [11] . Sugar-sweetened beverages and other sources of dietary fructose have been suggested to promote an increase in serum lipids and their de- position mainly in the liver, but not all published studies were able to confirm this association [7] .
Non-Digestible (Resistant) Carbohydrates
Dietary Fibres
Dietary fibres are non-digestible carbohydrates mostly derived from plant sources that reach the colon nearly intact. These compounds can be fur-
ther classified into soluble types of fibre, like pec- tins, and insoluble components such as cellulose.
Fibres that are added to the food and have benefi- cial physiological effects on humans are called
‘functional fibres’.
It is not completely accurate to name fibres as non-digestible, because bacteria in the large in- testine ferment mostly soluble fibres. Fermented products include gases (carbon dioxide and methane), oligofructoses as well as SCFA includ- ing acetic acid, butyric acid and propionic acid.
These fermentation products derive energy for certain colonic bacteria and colonic epithelial cells which use butyrate as an energy source, even when competing substrates such as glucose are available [12] . SCFA are absorbed into the blood stream, where they can also be used as an energy source; some, like acetate, can be metabolized in brain cells, muscles and tissues, and others, like propionate, are used in the liver and can interfere with cholesterol synthesis [12] .
Fibres: Clinical Importance
The effect of dietary fibres on chronic diseases has been explored mostly in adults. The importance of fibres to children’s health remains poorly in- vestigated. Their most significant and widely studied role is in influencing bowel movement:
fibres, especially insoluble ones, increase stool mass and improve its consistency; lack of dietary fibres, on the other hand, is associated with con- stipation and diverticulosis in adults. Yet, the ex- act fibre type and amount needed to elicit a posi- tive effect have not been determined [13, 14] . Importantly, increasing dietary fibres up to the recommended levels has not been associated with any adverse events in children, and there is suffi- cient evidence that fibres could help in the pre- vention and treatment of constipation [14] .
Other positive effects of increased intake of dietary fibres include body weight control and diabetes risk reduction [12] . However, the evi- dence is mostly limited to studies on adults, and data on children are scarce and conflicting, with
Koletzko B, et al. (eds): Pediatric Nutrition in Practice. World Rev Nutr Diet. Basel, Karger, 2015, vol 113, pp 46–50 DOI: 10.1159/000360316
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no possibility of formulating any clear recom- mendation; only few studies showed an associa- tion of dietary intake with fasting blood glucose concentrations and weight gain [13, 15] . Current recommendations for fibre intake in children vary among organisations; the EFSA concluded that a fibre intake of 2 g per 1 MJ of energy is ad- equate for normal laxation in children from the age of 1 year [4] .
Prebiotics
Prebiotics are a non-digestible food ingredients that selectively stimulate the growth and/or activ- ity of intestinal bacteria associated with health and wellbeing [16] . Those beneficial bacteria are mostly bifidobacteria and lactobacilli. Prebiotics typically consist of ≤ 10 sugar molecules, and the most widely used types are fructooligosaccha- rides, inulin and galactooligosaccharides. The beneficial prebiotic effect proposed can be seen via improved gut barrier function and host im- munity, reduction in potentially pathogenic bac- terial subpopulations and enhancement of SCFA production. The most important prebiotics for infants are human milk oligosaccharides, which are very complex carbohydrates that significantly stimulate the growth of specific commensal bac- teria in a breastfed infant. Although many studies demonstrated a bifidogenic effect of prebiotics and their addition to infant formulae seems rea-
sonable, there is a lack of strong evidence that their addition could improve growth or clinical outcomes in term infants [17] . Prebiotics have been shown to increase calcium absorption and bone mineral density in adolescents by lowering stool pH and increasing the amount of soluble calcium available for absorption, but this effect has not been confirmed in infants [18] .
Conclusions
• Carbohydrates may be classified into carbohy- drates that provide the body with monosac- charides and are called ‘digestible’ (available or glycaemic) and carbohydrates that resist digestion in the small intestine and are called
‘resistant’ (unavailable or non-glycaemic)
• Dietary recommendations for infants and children should propose the intake of slowly absorbed carbohydrates and avoidance of add- ed sugars and sweet drinks
• Fibres have a positive effect on laxation by in- creasing the amount of stool and influencing stool consistency
• Prebiotics promote the growth of beneficial bacteria, mostly bifidobacteria and lactobacilli • For infants, the most important carbohydrates with a prebiotic effect are human milk oligo- saccharides
and nutrient intake and indices of body fatness in British children and adolescents. Br J Nutr 2013; 110: 1512–
1523.
7 Te Morenga L, Mallard S, Mann J: Di- etary sugars and body weight: system- atic review and meta-analyses of ran- domised controlled trials and cohort studies. BMJ 2013; 346:e7492.
8 Caủete R, Gil-Campos M, Aguilera CM, et al: Development of insulin resistance and its relation to diet in the obese child.
Eur J Nutr 2007; 46: 181–187.
References
1 Stephen A, Alles M, de Graaf C, et al:
The role and requirements of digestible dietary carbohydrates in infants and toddlers. Eur J Clin Nutr 2012; 66: 765–
779.
2 Cummings JH, Stephen AM: Carbohy- drate terminology and classification.
Eur J Clin Nutr 2007; 61(suppl 1):S5–
S18.
3 Englyst KN, Liu S, Englyst HN: Nutri- tional characterization and measure- ment of dietary carbohydrates. Eur J Clin Nutr 2007; 61(suppl 1):S19–S39.
4 EFSA Panel on Dietetic Products, Nutri- tion and Allergies: Scientific opinion on dietary reference values for carbohy- drates and dietary fibre. EFSA J 2010; 8:
1462.
5 FAO/WHO: Carbohydrates in human nutrition. Report of a Joint FAO/WHO expert consultation. FAO Food and Nu- trition Paper, vol 66. Rome, FAO/WHO, 1998.
6 Murakami K, McCaffrey TA, Living- stone MB: Dietary glycaemic index and glycaemic load in relation to food
50 Hojsak 9 Agostoni C, Braegger C, Decsi T, et al:
Role of dietary factors and food habits in the development of childhood obesity: a commentary by the ESPGHAN Commit- tee on Nutrition. J Pediatr Gastroenterol Nutr 2011; 52: 662–669.
10 Agostoni C, Decsi T, Fewtrell M, et al:
Complementary feeding: a commentary by the ESPGHAN Committee on Nutri- tion. J Pediatr Gastroenterol Nutr 2008;
46: 99–110.
11 Perito ER, Rodriguez LA, Lustig RH:
Dietary treatment of nonalcoholic ste- atohepatitis. Curr Opin Gastroenterol 2013; 29: 170–176.
12 Slavin J: Fiber and prebiotics: mecha- nisms and health benefits. Nutrients 2013; 5: 1417–1435.
13 Kranz S, Brauchla M, Slavin JL, et al:
What do we know about dietary fiber intake in children and health? The ef- fects of fiber intake on constipation, obesity, and diabetes in children. Adv Nutr 2012; 3: 47–53.
14 Stewart ML, Schroeder NM: Dietary treatments for childhood constipation:
efficacy of dietary fiber and whole grains. Nutr Rev 2013; 71: 98–109.
15 Moreno LA, Tresaco B, Bueno G, et al:
Psyllium fibre and the metabolic control of obese children and adolescents. J Physiol Biochem 2003; 59: 235–242.
16 Gibson GR, Probert HM, Loo JV, et al:
Dietary modulation of the human colon- ic microbiota: updating the concept of prebiotics. Nutr Res Rev 2004; 17: 259–
275.
17 Mugambi MN, Musekiwa A, Lombard M, et al: Synbiotics, probiotics or prebi- otics in infant formula for full term in- fants: a systematic review. Nutr J 2012;
11: 81.
18 Hicks PD, Hawthorne KM, Berseth CL, et al: Total calcium absorption is similar from infant formulas with and without prebiotics and exceeds that in human milk-fed infants. BMC Pediatr 2012; 12:
118.
Koletzko B, et al. (eds): Pediatric Nutrition in Practice. World Rev Nutr Diet. Basel, Karger, 2015, vol 113, pp 46–50 DOI: 10.1159/000360316
1 Specific Aspects of Childhood Nutrition
Key Words
Lipids ã Essential fatty acids ã Linoleic acid ã α-Linolenic acid ã Long-chain polyunsaturated fatty acids ã Arachidonic acid ã Docosahexaenoic acid ã Saturated fatty acid ã Trans fatty acid
Key Messages
• Optimal lipid nutrition begins in fetal life with ade- quate n–3 to n–6 fatty acid and preformed long- chain polyunsaturated fatty acid (LCPUFA) supply through the maternal diet and PUFA metabolism • Breast milk from mothers consuming a balanced
diet provides the best source of bioavailable lipids for term neonates
• Linoleic and α-linolenic acids are essential fatty ac- ids; in addition, LCPUFA are important for lifelong health
• LCPUFA in the diet and the mother’s genetic con- trol of metabolism are important for visual and cog- nitive development in the first months of life, after which they contribute to lifelong health
• Trans fatty acids interfere with LCPUFA metabolism, affect lipoprotein cholesterol regulation and pro- mote cardiovascular disease
• The balance between dietary n–3 and n–6 fatty ac- ids is important to promote lifelong health, reduc- ing the disease risk linked to allergic and inflamma- tory responses © 2015 S. Karger AG, Basel
Introduction
Fats are the main source of energy for infants and young children, and n–6 and n–3 fatty acids are essential for normal growth and development.
Fat-soluble vitamins (A, D, E and K) require di- etary lipids for absorption. Fats provide flavor and texture to foods, and thus affect taste and accept- ability of diets as well as gastric emptying and sa- tiety. Membrane lipid composition in part defines the functional properties of membranes (fluidity, transport properties, receptor activity, uptake and release of substances, signal transduction and conduction, and ion flows). Fatty acids can also affect gene expression directly or by regulating transcription factors that affect the expression of multiple other genes (i.e. peroxisome proliferator- activated receptors). Dietary lipids provide struc- tural components for brain and retinal structures, cell membranes and transport of lipid compo- nents in plasma, and they form the only true en- ergy store of the body (adipose tissue). Fats and oils are key dietary factors affecting cardiovascular risk, obesity and diabetes. Linoleic acid (LA; C18:
2n–6) and α-linolenic acid (LNA; C18: 3n–3) are essential; they serve as precursors of the long- chain polyunsaturated fatty acids (LCPUFA) such
Koletzko B, et al. (eds): Pediatric Nutrition in Practice. World Rev Nutr Diet. Basel, Karger, 2015, vol 113, pp 51–55 DOI: 10.1159/000360317
1.3 Nutritional Needs