Early Eating Habits in Infants and Their Association with Iron Metabolism. Summary of the Doctoral Thesis

Abstract

Introduction. Infants experience rapid growth and development during the first year of life. Iron deficiency is one of the most common micronutrient deficiencies during the first year of life. Iron deficiency can lead to irreversible cognitive impairment. One of the main causes of iron deficiency is mistakes in infant feeding. Healthy eating habits are therefore essential not only for preventing illnesses in later life, but also for preventing iron deficiency. Objective. To study the early dietary habits of Latvian infants and their relation to iron metabolism. Materials and Methods. The study is composed of 2 parts: A) “Collection of Dietary Data for Studying Dietary Habits of Infants Living in Latvia”; B) “Collection of Dietary Data and Laboratory Analyses of Infants Living in Latvia, for Studying the Relation Between Dietary Habits and Iron Deficiency”. Study A included 344 infants and young children. Data required for the study were collected by means of an interview. This study included data from food consumption frequency questionnaires. Study B included 73 infants. This study included data from 24 – hour food diaries for filling of which the recollection method was applied. In addition to collecting dietary data, blood samples were taken from infants to determine complete haematic picture, iron, transferrin and iron binding capacity, serum ferritin (SF), transferrin soluble receptors. Frequency of use and portion sizes for different foodstuff groups were reported as median values with interquartile dispersion, age was indicated as the mean value with standard deviation. In the case of continuous variables, the Kruskal–Wallis test and the Wilcoxon–Mann–Whitney test were used to analyse the relation between dietary habits and other parameters with iron metabolism laboratory parameters. In the case of discrete variables and for comparison of proportions, the Pearson χ2 test was used. The P value below 0.05 was considered statistically significant. Results. Almost all infants (89%, n = 18) were breastfed in the first month of life. At 6 months, the prevalence of breast – feeding decreased to 68% (n = 28). 21% (n =15) of infants are being exclusively breastfed for the first 6 months of life. The average age for introducing complementary food is 5 months. The greatest food diversity was introduced at 4–6.9 months of age; those were vegetables, potatoes, fruits and berries, as well as cereals. From the age of 7 months, every infant’s diet included foodstuff from almost all food groups. The analysis of dietary data showed that iron intake was on average 7.4 mg / day (median 6.5 mg). Iron is absorbed from animal products in the amount of only 13% of the total iron intake. Iron deficiency was detected in 9.6% (n = 7) of infants and iron deficiency anemia in 4.1% of infants (n = 3). Blood iron level is reduced in 30% (n = 8) of infants fed with cow’s milk, compared to 6% (n = 2) of infants who did not consume cow’s milk (p = 0.0171). For infants who took iron predominantly from non – animal products SF is within normal range for a higher number: 100% (n = 20) of infants receiving < 10% iron from animal products, 78% (n = 18) of infants receiving 10–20% and 71% (n = 12) of infants receiving > 20% iron from animal products (p = 0.0405). SF is within the normal range for 93% (n = 26) of infants who did not consume legumes, compared to 72% (n = 21) who consumed them (p = 0.0425). Conclusions. Dietary habits of infants living in Latvia partly correspond to the guidelines, however only 21% follow the recommendations of exclusive breastfeeding. 63% of infants do not take enough iron from food and iron deficiency in this age group was observed in 9.6% of infants, iron deficiency anemia in 4.1%. Changes in iron metabolism have been proven to be related with the following early dietary habits: early introduction of cow’s milk is associated with lower iron level in blood; exclusive breastfeeding for at least first 4 months of life may induce lower levels of MCV and serum ferritin in blood compared to infants who are not breastfed for at least 4 months; breastfeeding promotes lower iron and serum ferritin levels in blood for infants, while the use of infant formulas may increase serum ferritin level in blood; the consumption of legumes reduces serum ferritin level in blood; the intake of iron of at least the amount of the daily recommended dose (8 mg) may enhance normal serum ferritin level in blood.