Invited commentary: nutrition during growth and reproduction: studies demonstrating possibilities and difficulties

C ommentary on a thesis by Ashraful Islam Khan ‘Effects of Preand Postnatal Nutrition Interventions on Child Growth and Body Composition’. Ashraful Islam Khan has written a thesis that provides important and interesting aspects on several issues relevant for the nutritional situation of reproductive women and young children. Dr. Khan’s work forms a part of the ‘MINIMat’ (Maternal and Infant Nutrition Interventions in Matlab) trial in rural Bangladesh. This trial is a population-based randomized food and micronutrient intervention where pregnant women were randomly allocated to an early or usual timing of invitation to food supplementation, which included three different micronutrient alternatives. This was coupled with exclusive breastfeeding counseling or with the health message commonly directed at childbearing women in this population. Results obtained in the MINIMat study have previously been published (1 5) and the findings include data regarding micronutrient status in women and children as well as important effects of micronutrient and food supplementation on offspring birth weight and mortality. Dr. Khan’s thesis is focused on the effects of prenatal nutritional supplementation and the type of breastfeeding counseling on physical growth and body composition development of the offspring. All studies in the thesis are carried out in Matlab, a rural district situated in a river delta southeast of Dhaka. The area has a population of about 220,000 people, and the International Centre for Diarrhoeal Disease Research has recorded health and demographic information there since 1966. They also provide health centers serving the population in the area with services such as family planning counseling and basic healthcare. The first paper in the thesis (6) is a randomized trial investigating the effects of prenatal food and micronutrient supplementation on child growth from birth to 54 months of age. A total of 4,436 pregnant women were enrolled in the study for comparing nutritional supplementation starting very early versus rather late in gestation. The supplement provided 2,500 kJ 6 days a week. Three different micronutrient supplements, two combinations of iron and folate and a third containing 15 micronutrients, including iron and folate, were also tested and the women were therefore divided into six groups. Interesting findings were that early supplementation reduced the occurrence of stunting in boys but not in girls, and also that prenatal multiple micronutrient supplementation increased the proportion of stunted boys. Findings partly along this line have been presented earlier, for example Gibson (7) reviewed double-blind zinc supplementation studies in children and reported that improved growth was more commonly observed in males than in females. These results and the findings by Dr. Kahn may have a common explanation, i.e. that boys have higher requirements than girls for essential nutrients simply because they are bigger and gain more weight and length during infancy and childhood. The observation that prenatal multiple micronutrient supplementation increased the proportion of stunted boys is important and intriguing. It can be reconciled with a number of observations showing that providing nutrients as supplements to humans may sometimes have detrimental effects. This fact has been emphasized in the recent issue of nutritional recommendations for the Nordic countries (8). With respect to pregnant women, there is one wellknown example from a study in a poor black population in New York City where protein supplementation in women during pregnancy increased the proportion of premature births and associated neonatal deaths, as well as the number of growth-retarded fetuses (9). An important goal in the MINIMat trial was to study the appropriate timing of food supplementation to INVITED COMMENTARY