Nutritional Status in Early Life
Food intake corresponding to one’s needs is a prerequisite for adequate growth and development as well as for desirable nutritional status, a condition for an adequate level of functional capacity and fitness. All of this applies even more to early childhood. Food intake in all age categories has been recommended mainly using dietary guidelines, which have undergone quite an evolution during history. Already over the ages, advice on eating behavior, food choices, and food preparation has been incorporated into philosophical and religious writings.
Over the past 150 years, recommended dietary allowances (RDAs) have been based on scientific knowledge related to public health. During the first half of the last century, the focus was on prevention of nutrition deficiency diseases, but during the second half the attention shifted to prevention of chronic diseases and excess intakes that increase disease risks. Current guidelines also consider lifestyle (including PA) and food choices and preferences (including saturated fat, individual nutrients, and fiber). Recommendations have become more food based, as elaborated by the Food and Agricultural Organization (FAO) and the World Health Organization (WHO). A framework for food-based dietary guidelines in the European Union (EU) was also prepared. Considerable development with regard to dietary recommendations has occurred.
The scope of RDAs has markedly expanded since their first edition in 1941, and their re-evaluation has had far-reaching applications to human health and agricultural practices. The American Dietetic Association suggested dietary guidance for healthy children also at the age of 2–11 years.
Dietary reference intakes (DRIs) as resulting documents have been released over a number of years from 1997 to 2003, and later (Nestle Pediatric Nutrition Workshop 2006), for both North America and the EU. Another version of DRI was last modified in 2008. However, the evaluation of dietary intakes and individual nutritional surveys, and their comparison among different groups and nations over time are still problematic and not quite reliable. An analysis of 79 surveys from 23 countries, for example, showed that collection methods, representativeness of samples, use of different food composition and conversion tables, and other additional differences showed a lack of standardization. This can make comparisons and conclusions difficult and inaccurate (Lambert et al. 2004). Local studies in well-defined population groups that use validated local methods, food composition tables based on local food composition data analysis, etc., can give some information on the adequacy of diet.
“How much is enough” (too little and/or too much) is difficult to define. From the beginning of life, “nutritional individuality” is manifested in newborns and infants. Pediatricians claim that newborns already behave in a different way during the first breast-feeding (the same applies to motor activity, crying, etc.). Some newborns accept the mother’s breast quietly, drinking enough milk, while others often refuse an adequate amount. These characteristics often persist and are manifested even more markedly later in life.
During the first year of life, variability in both absolute and relative energy intake (EI) in infants was shown. Black et al. (1983) showed that the variation coefficients in the EI of infants from 2 to 18 months were between 16.9–23.3% (between subjects) and 10.6–18.1% (within subjects). Bellu et al. (1995) also showed a great variability of EI in Italian infants. Intra- and inter individual variability ratios were found to be even greater than 1.
“Sensitive or critical periods” exist in the first 2 or 3 years of life, during which humans acquire a basic knowledge of foods that are safe to eat. Cashdan (1994) showed that the willingness to eat a variety of foods is greatest between the ages of 1 and 2 years, declining to lower levels at 4 years of age. As shown in a longitudinal follow-up of twins from 4 to 10 years, eating behaviors, including those associated with a tendency to over-eat, emerge early in life, and show levels of individual continuity comparable to stable personality traits. Appetitive traits related to higher satiety tended to decrease later with maturation, while those associated with food responsiveness tended to increase. This pattern is consistent with strong tracking of BMI simultaneously with increasing obesity risk. These observations imply the possibility of positively affecting the food choice early in life, with desirable delayed consequences and advantages. But also, the reverse can occur, with negative eating behavior in later life.
The requirements for energy and protein of children are similarly specified for all other age categories; adhering to the RDAs, which correspond to the actual needs of the growing organism, is also essential in light of the future development of health. Presented information on RDAs for energy, macro components, minerals, and vitamins was selected with respect to early age.
