[Folic acid supply in pregnancy--results of a prospective longitudinal study]

Nutritional assessment and support during pregnancy

This article thoroughly updates the authors' previous review of nutritional assessment and support during pregnancy. After briefly reviewing nutrient metabolism and requirements, the authors discuss the nutritional assessment of the pregnant woman and review the nutritional support principles in hyperemesis gravidarum and other conditions that can compromise the nutritional health of mother or fetus.

Longitudinal Concentrations of Vitamin B12 and Vitamin B12-binding Proteins during Uncomplicated Pregnancy

Background: Because reference values for vitamin B12 concentrations and vitamin B12-binding capacities for pregnant women have not been established, the reference values for nonpregnant women are often applied to assess vitamin B12 status. The aim of the present study was to describe ranges of biochemical indices of vitamin B12 status, including red blood cell (RBC) vitamin B12, saturated and unsaturated cobalamin-binding proteins, and binding capacities in all trimesters of uncomplicated pregnancy.

Methods: A total of 39 healthy pregnant women with long-term daily intake of vitamin B12 >2.6 μg/day and uncomplicated pregnancies participated in the study throughout their pregnancies. RBCs and serum vitamin B12, holo-haptocorrin, unsaturated cobalamin-binding proteins, unsaturated and total vitamin B12-binding capacities, total homocysteine (tHcy), and RBC count were assessed in weeks 9–12, 20–22, and 36–38 of gestation.

Results: Significant changes in vitamin B12 status occurred in the course of pregnancy. Serum vitamin B12 concentrations and percentage of saturation of vitamin B12-binding proteins decreased steadily throughout pregnancy. In the third trimester, 35% of the participants had serum vitamin B12 concentrations <150 pmol/L and 68.6% had <15% saturation of total vitamin B12-binding capacities, but no women had RBC vitamin B12 concentrations <148 pmol/L. However, the decrease in these indices was not associated with reduced hemoglobin concentrations or RBC count or with increased tHcy concentrations.

Conclusions: Our findings suggest that the reference values for vitamin B12 status in nonpregnant women may not be applicable to pregnant women.

Growth, development and differentiation: a functional food science approach

Few other aspects of food supply and metabolism are of greater biological importance than the feeding of mothers during pregnancy and lactation, and of their infants and young children. Nutritional factors during early development not only have short-term effects on growth, body composition and body functions but also exert long-term effects on health, disease and mortality risks in adulthood, as well as development of neural functions and behaviour, a phenomenon called 'metabolic programming'. The interaction of nutrients and gene expression may form the basis of many of these programming effects and needs to be investigated in more detail. The relation between availability of food ingredients and cell and tissue differentiation and its possible uses for promoting health and development requires further exploration. The course of pregnancy, childbirth and lactation as well as human milk composition and the short- and long-term outcome of the child are influenced by the intake of foods and particularly micronutrients, e.g. polyunsaturated fatty acids, Fe, Zn and I. Folic acid supplementation from before conception through the first weeks of pregnancy can markedly reduce the occurrence of severe embryonic malformations; other potential benefits of modulating nutrient supply on maternal and child health should be further evaluated. The evaluation of dietary effects on child growth requires epidemiological and field studies as well as evaluation of specific cell and tissue growth. Novel substrates, growth factors and conditionally essential nutrients (e.g. growth factors, amino acids, polyunsaturated fatty acids) may be potentially useful as ingredients in functional foods and need to be assessed carefully. Intestinal growth, maturation, and adaptation as well as long-term function may be influenced by food ingredients such as oligosaccharides, gangliosides, high-molecular-mass glycoproteins, bile salt-activated lipase, pre- and probiotics. There are indications for some beneficial effects of functional foods on the developing immune response, for example induced by antioxidant vitamins, trace elements, fatty acids, arginine, nucleotides, and altered antigen contents in infant foods. Peak bone mass at the end of adolescence can be increased by dietary means, which is expected to be of long-term importance for the prevention of osteoporosis at older ages. Future studies should be directed to the combined effects of Ca and other constituents of growing bone, such as P, Mg and Zn, as well as vitamins D and K, and the trace elements F and B. Pregnancy and the first postnatal months are critical time periods for the growth and development of the human nervous system, processes for which adequate substrate supplies are essential. Early diet seems to have long-term effects on sensory and cognitive abilities as well as behaviour. The potential beneficial effects of a balanced supply of nutrients such as I, Fe, Zn and polyunsaturated fatty acids should be further evaluated. Possible long-term effects of early exposure to tastes and flavours on later food choice preferences may have a major impact on public health and need to be further elucidated. The use of biotechnology and recombinant techniques may offer the opportunity to include various bioactive substances in special dietary products, such as human milk proteins, peptides, growth factors, which may have beneficial physiological effects, particularly in infancy and early childhood.

Nutritional assessment and support during pregnancy

Proper nutrition during pregnancy is critically important to mother and fetus. For most healthy women, the only nutritional intervention required may be adequate iron and folate intake; however, for others, who begin pregnancy in a malnourished state or whose nutritional intake deteriorates during pregnancy, invasive nutritional support, including tube feeding or parenteral nutrition, may be indicated. To guide nutritional therapy and to avoid its potential complications, it is necessary to evaluate the patient's nutritional state. Such evaluation must focus not only on body composition and substrate reserves but also on the patient's changing nutrient requirements and any impediments to the patient's capacity to ingest and assimilate food.

Folate economy in pregnancy

Pregnant women are prone to becoming folate deficient because there is a significant increase in folate requirement during pregnancy and folate intakes of pregnant women are often insufficient. Reduced folate levels in blood and neutrophilic hypersegmentation reflect a negative folate balance. Possible consequences of a low maternal folate status may be pregnancy complications such as abortion, abortus imminens, abruptio placentae, and congenital malformations. The role of folic acid in the etiology of neural tube defects has been discussed for decades. The importance of an adequate maternal folate status in the prevention of neural tube defects has been demonstrated by observational and controlled intervention trials. However, the mechanism of the protective effect of periconceptional folate supplementation is not completely understood. Metabolic disorders are probably involved in the pathogenesis of neural tube defects so that a relative folate shortage rather than folate deficiency seems to be responsible for the disturbed neural tube development, which can be compensated for by a higher folate intake.