Berthold Koletzko
1
30 Koletzko
quirement of a nutrient is the intake sufficient to meet the physiological requirement, considering nutrient bioavailability from foodstuffs. NIV re- flect the estimated distributions of nutrient in- takes required to achieve a specific outcome in a defined population considered healthy, but for many nutrients, this distribution of requirements and the modifying biological and environmental factors are not well known, which results in con- siderable uncertainty regarding NIV. Therefore, NIV should be considered approximations that reflect the often limited data available. NIV are even more uncertain for infants and young chil- dren, on whom original data are particularly scarce, and, hence, NIV are often derived from the interpolation of data from other age groups, which must be expected to yield inaccurate val- ues. It is important to remember that NIV refer to populations but not to individuals. NIV do not allow us to determine an insufficient nutrient in- take or a nutrient deficiency in an individual, or to accurately determine nutrient needs in disease states.
Definitions of NIV
NIV for populations are generally estimated based on the concept that individual require- ments follow a statistically normal distribution (bell-shaped curve in fig. 1 ). The average nutrient requirement (ANR; also called ‘estimated average requirement’) is the estimated average of the median requirement of a specific nutrient in the population derived from a statistical distribution of requirement criterion and for a particular age- and sex-specific group based on a specific biolog- ical end point or biochemical measure. The popu- lation reference intake (PRI; also called ‘individ- ual nutrient level 97%’, ‘reference nutrient intake’
or RDA) is the nutrient intake considered ade- quate to meet the known nutrient needs of practi- cally all healthy individuals in a particular age- and sex-specific group. Based on the assumed sta-
tistical distribution of requirements, the PRI is set at a level of intake that meets the needs of 97% of the population (mean + 2 SD) ( fig. 1 ). The PRI value is generally used as the target for provision of essential nutrients to populations and as the reference point for the nutrient labelling of foods, with the exception of energy, where the ANR is used because the provision of energy equivalent to the PRI would result in overfeeding and induc- tion of obesity in about one half of the population.
The upper nutrient level (UNL; or upper tolerable intake level) is the highest level of daily nutrient intake that is likely to pose no risk of adverse health effects for almost all individuals of a par- ticular age- and sex-specific group. Ideally, the UNL is based on an analysis of the statistical dis- tribution of risk for high nutrient intakes. The UNL is generally set at a level where the risk of excessive intake is practically non-existent. A nu- trient intake equal to or higher than the UNL should be avoided on a chronic basis.
Examples of NIV for children and adolescents are provided in Annex 4.3.
Limitations to the Estimation of NIV
The concept of a near-normal, symmetrical dis- tribution of nutrient requirements ( fig. 1 ) is known not to be correct for a number of nutri- ents. Examples are the nutrient needs for iron, vitamin D and polyunsaturated fatty acids. Iron requirements are not normally distributed, with high needs in menstruating women, particularly in those with substantial blood losses. Vitamin D requirements depend on endogenous synthesis in the skin and hence on variation of UV light expo- sure with geographic location and the time of the year, as well as on biological determinants such as the degree of skin pigmentation and genetic vari- ations in the vitamin D receptor. The dietary needs of essential fatty acids vary considerably with genetic polymorphisms for the fatty acid de- saturation enzymes Δ 6 and Δ 5 desaturases that
Koletzko B, et al. (eds): Pediatric Nutrition in Practice. World Rev Nutr Diet. Basel, Karger, 2015, vol 113, pp 29–33 DOI: 10.1159/000369234
1
determine the relative turnover of polyunsaturat- ed fatty acids [7] .
The establishment of NIV for infants, chil- dren and adolescents is further hampered by se- vere limitations to the available scientific data ob- tained from healthy children [8] . This is unfortu- nate because infants, children and adolescents have relatively large nutrient needs due to their growth and development, and adequate substrate supply is of utmost importance to support their short- and long-term health, well-being and per- formance [5] . Current reference values for nutri- ent intakes vary considerably (see Annex 4.3), partly due the limitations to the available scien- tific database and partly due to major differences in underlying concepts, definitions and termi- nology [8] .
Due to a lack of adequate scientific studies, NIV for children are often based on observed nu- trient intakes of groups of children in apparent good health. However, this approach is weak, be- cause it assumes that the subjects are in good
health and are achieving their full genetic poten- tial and that their diets are quantitatively and qualitatively appropriate and free from adverse long-term effects. The concerns with respect to this approach are strengthened by the recent evi- dence on the long-term effects of early nutrition on metabolic programming and the subsequent risk of hypertension, obesity, diabetes mellitus and cardiovascular disease in adult life [9–11] .
The derivation of NIV from observed intakes is a standard approach for infants during the first 6 months of life, when the intakes of breastfed babies are considered an appropriate guide to op- timal nutritional supply. However, this approach has major limitations because the actual metabo- lizable substrate intakes of breastfed infants are not well determined. The volume of milk con- sumed varies between about 550 and 1,100 ml/
day, and milk composition differs between wom- en and with changes during the course of lacta- tion, during the day and even during a single feeding. Moreover, the bioavailability of sub-
Population reference intake (PRI) Average nutrient
requirement (ANR) estimated median
of distribution
~97.5th percentile
or mean + 1.96 SD Upper nutrient level (UNL) highest level of daily nutrient
intake that poses no risk
Frequency
Increasing nutrient intake
Fig. 1. Conceptual basis for NIV.
32 Koletzko
strates and their metabolism differs between in- fants fed human milk and those fed infant for- mula and complementary feeds, which can result in differences in dietary requirements. There- fore, human milk composition and the nutrient supply to breastfed infants may not always pro- vide useful guidance for infants that are not ex- clusively breastfed.
Due to the paucity of original research data for estimating nutrient requirements in the paediat- ric age group, very often NIV are extrapolated from data for other age groups. Frequently, this involves extrapolation from adults to children and adolescents. Examples of extrapolation methods that are used include body size (weight or metabolic weight), energy intakes for age, or factorial estimates of requirements for growth [8] . However, there is no truly correct method for extrapolation that would result in physiologically adequate NIV for infants, children and adoles- cents. It is important that the rationale or scien- tific basis for the method chosen should be com- pletely transparent and thoroughly described for each nutrient and life stage group. Extrapolation is always the second choice, and the use of inno- vative, non-invasive methods or of existing meth- ods (e.g. stable isotopes) is encouraged to deter- mine nutrient requirements of infants, children and adolescents [8] .
Conclusions
• NIV provide an estimate for adequate nutrient provision to populations considered healthy, but they do not determine the optimal nutri- ent supply for an individual
• PRI (also called reference nutrient intakes or RDA) are the levels of intake that meet the needs of almost all healthy individuals of a giv- en age and sex group
• The diet for healthy children should generally provide nutrient intakes matching the PRI, ex- cept for energy, where ANR provide guidance on appropriate intakes for groups
• Children affected by disease or malnutrition, or those in whom catch-up growth is desired, may have nutrient needs that differ markedly from PRI
Acknowledgements
The author’s work is carried out with partial financial sup- port from the Commission of the European Communi- ties, the 7th Framework Programme, contract FP7- 289346-EARLY NUTRITION, and the European Re- search Council Advanced Grant ERC-2012-AdG – No.
322605 META-GROWTH. This manuscript does not necessarily reflect the views of the Commission and in no way anticipates the future policy in this area.
B, Hermoso M, Pena Quintana L, Gar- cia-Luzardo MR, Santana-Salguero B, Garcia-Santos Y, Vucic V, Andersen LF, Perez-Rodrigo C, Aranceta J, Cavelaars A, Decsi T, Serra-Majem L, Gurinovic M, Cetin I, Koletzko B, Moreno LA:
Physiological and public health basis for assessing micronutrient requirements in children and adolescents. The EURRECA network. Matern Child Nutr 2010; 6(suppl 2):84–99.
6 Uauy R, Koletzko B: Defining the nutri- tional needs of preterm infants. World Rev Nutr Diet 2014; 110: 4–10.
References
1 Aggett PJ, Bresson J, Haschke F, Her- nell O, Koletzko B, Lafeber HN, Mi- chaelsen KF, Micheli J, Ormisson A, Rey J, Salazar de Sousa J, Weaver L:
Recommended dietary allowances (RDAs), recommended dietary intakes (RDIs), recommended nutrient intakes (RNIs), and population reference in- takes (PRIs) are not ‘recommended intakes’. J Pediatr Gastroenterol Nutr 1997; 25: 236–241.
2 Koletzko B, Poindexter B, Uauy R: Rec- ommended nutrient intake levels for stable, fully enterally fed very low birth
weight infants; in Koletzko B, Poindex- ter B, Uauy R (eds): Nutritional Care of Preterm Infants. Basel, Karger, 2014, pp 300–305.
3 King JC, Garza C: Harmonization of nutrient intake values. Food Nutr Bull 2007; 28:S3–S12.
4 Hermoso M, Vollhardt C, Bergmann K, Koletzko B: Critical micronutrients in pregnancy, lactation, and infancy: con- siderations on vitamin D, folic acid, and iron, and priorities for future research.
Ann Nutr Metab 2011; 59: 5–9.
5 Iglesia I, Doets EL, Bel-Serrat S, Roman
Koletzko B, et al. (eds): Pediatric Nutrition in Practice. World Rev Nutr Diet. Basel, Karger, 2015, vol 113, pp 29–33 DOI: 10.1159/000369234
1
7 Koletzko B, Lattka E, Zeilinger S, Illig T, Steer C: Genetic variants of the fatty acid desaturase gene cluster predict amounts of red blood cell docosahexaenoic and other polyunsaturated fatty acids in pregnant women: findings from the Avon Longitudinal Study of Parents and Children. Am J Clin Nutr 2011; 93: 211–
219.
8 Atkinson SA, Koletzko B: Determining life-stage groups and extrapolating nu- trient intake values (NIVs). Food Nutr Bull 2007; 28:S61–S76.
9 Brands B, Demmelmair H, Koletzko B;
EarlyNutrition Project: How growth due to infant nutrition influences obesity and later disease risk. Acta Paediatr 2014; 103: 578–585.
10 Berti C, Cetin I, Agostoni C, Desoye G, Devlieger R, Emmett PM, Ensenauer R, Hauner H, Herrera E, Hoesli I, Krauss- Etschmann S, Olsen SF, Schaefer-Graf U, Schiessl B, Symonds ME, Koletzko B:
Pregnancy and infants’ outcome: nutri- tional and metabolic implications. Crit Rev Food Sci Nutr 2014, Epub ahead of print.
11 Koletzko B, Brands B, Chourdakis M, Cramer S, Grote V, Hellmuth C, Kirch- berg F, Prell C, Rzehak P, Uhl U, Weber M: The power of programming and the early nutrition project: opportunities for health promotion by nutrition during the first thousand days of life and be- yond. Ann Nutr Metab 2014; 64: 141–
150.
1 Specific Aspects of Childhood Nutrition
Key Words
Energy needs, requirements ã Basal metabolic rate ã Physical activity level ã Energy cost of growth
Key Messages
• Energy requirements of infants, children and ado- lescents are defined as the amount of energy need- ed to balance total energy expenditure at a desir- able level of physical activity, and to support opti- mal growth and development consistent with long-term health
• Recommendations for energy intake are based on the average requirement of the population to avoid energy intakes that exceed the requirements • Recommendations for energy intake to support a
moderately active lifestyle are encouraged to main- tain fitness and health and to reduce the risk of overnutrition © 2015 S. Karger AG, Basel
Introduction
Energy requirements of infants, children and ado- lescents are defined as the amount of energy need- ed to balance total energy expenditure (TEE) at a
desirable level of physical activity, and to support optimal growth and development consistent with long-term health [1] . Unlike recommendations for other nutrients, which meet or exceed the require- ments of practically all individuals in the popula- tion, recommendations for energy intake are based on the average requirement of the population to avoid energy intakes that exceed requirements.
Recommendations for energy intake and physical activity are intended to support and maintain the growth and development of well-nourished and healthy infants, children and adolescents. The 2004 Food and Agriculture Organization (FAO)/
WHO/United Nations University (UNU) recom- mendations for energy intake are based upon esti- mates of TEE and an allowance for growth [1] . For infants, TEE is predicted from measurements of TEE by the stable isotope method of doubly labeled water (DLW). For children and adolescents, heart rate monitoring and the DLW method were used to predict TEE. The energy cost of growth was de- rived from average growth velocities and the com- position of weight gain.
Energy requirements during growth and development can be partitioned into compo-
Koletzko B, et al. (eds): Pediatric Nutrition in Practice. World Rev Nutr Diet. Basel, Karger, 2015, vol 113, pp 34–40 DOI: 10.1159/000360315
1.3 Nutritional Needs