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Mother and infant

Maternal diet during pregnancy is thought to be one of the most influential factors on child health and development. However, dietary interventions during this period may miss a critical window to improve health during childhood, as well as adult life.

In a recent series of articles in The Lancet, researchers address the significance of nutrition in the preconception period, or the time before a woman becomes pregnant. The series of three articles challenges the current perspective of the preconception period. Currently defined as 3 months before conception, the authors suggest preconception should also include any time a woman is at child bearing age. This revision is based on an understanding of the biological events occurring during the periconceptional period, or the time immediately surrounding conception. In addition, it addresses a lack of nutritional preparedness for pregnancy in women of reproductive age and the failure of dietary interventions during pregnancy in preventing adverse health outcomes.

How does pre-pregnancy nutrition affect child health?

The periconceptional period begins before fertilization occurs, with maturation of sperm and oocytes, and extends until implantation of the fertilized egg. From the time of fertilization, this process occurs relatively quickly (up to 9 days in humans) but is characterized by drastic changes developmentally, genetically, and metabolically. The embryonic genome undergoes epigenetic modifications, or alterations to the DNA that do not change the genetic code but rather affect how a gene is expressed by turning expression on or off. These modifications are responsive to environmental conditions and nutrient availability, and likely adapt to promote optimal survival under existing conditions. However, the established gene expression pattern may be detrimental in environmental conditions outside of the uterus, promoting disease development later in life.

Although epigenetic changes can occur throughout one’s lifetime, the periconceptional period is unique in that a small number of cells are present. Full exposure to the environment allows this founder population of cells to establish the genetic program that persists throughout development.

How does this change current practice?

The influence of maternal nutrition during the periconceptional period on disease and development in offspring is not a new concept. Both maternal overnutrition and obesity, as well as undernutrition have been known to adversely affect metabolic regulation in offspring and increase the risk for metabolic disease development.

More recently, analysis from the UK National Diet and Nutrition Survey suggest that less than 10% of women of reproductive age meet the recommended daily intakes during pregnancy for several key micronutrients including zinc, vitamin A, folate, and calcium. Only 30% of women meet the daily intake recommendations for iron. A lack of success of multiple micronutrient supplementation during pregnancy in improving child health outcomes, including survival, growth, body composition, and blood pressure, indicate the importance of correcting such nutritional deficiencies well before pregnancy.

These findings suggest that preconception intervention strategies should include population targeted interventions for women of reproductive age, in addition to those targeting the 3 months before conception. This will allow adequate time to correct for nutritional deficiencies before pregnancy.

Does Breastfeeding Make You Smarter?

Good nutrition has been shown to help with survival, growth, mental development, health, and well-being across one’s lifespan. Unearthing precisely what to eat to help achieve maximal benefit has been the subject of many research studies and debates, especially regarding childhood nutrition starting at an early age.

Breastfeeding has been recognized for its ability to provide infants with essential nutrients to help with growth and development. Research has shown there are many benefits associated with breastfeeding, such as building a healthy gut microbiota and increasing the bond between mother and child. The child benefits from the nutrients found in breast milk, such as docosahexaenoic acid (DHA) and arachidonic acid, omega-3 and -6 fatty acids essential for cognitive development. Somewhere down the line the notion that breastfeeding can make your baby smarter has been perpetuated. However, this has not yet been proven.

Researchers from the University College Dublin in Ireland conducted a study to investigate the impact of breastfeeding on children’s cognitive development. Around 8,000 families from the Growing Up in Ireland longitudinal infant cohort were randomly selected to participate. Data was collected when the child was 9 months old, 3 years old, and 5 years old. Questionnaires were used to measure children’s cognitive abilities, expressive vocabulary, and problem behaviors, and breastfeeding data was collected as retrospective self-report from the mothers. Propensity score matching, instrument variables, and sibling pair models were used for the analysis. The “breastfed” and “never breastfed” groups were matched based on infant, mother, and family-level factors, such as birth weight and maternal age.

Children who were breastfed scored higher on the problem-solving scale. However, after adjusting for potential confounders, this result was found to be no longer significant. This means other factors, such as socioeconomic status, could better explain the variability here. Breastfed children had lower parent-rated hyperactivity compared with controls after the adjustment, but this effect was only seen at 3 years of age. This may mean that breastfeeding helps reduce hyperactivity in the short term, but this effect was not maintained. Although the researchers found no evidence to support that breastfeeding helps improve cognitive abilities, they did note that their study did not contradict any of the medical benefits of breastfeeding. Research on breastfeeding will continue to be done and hopefully we will see more positive findings emerge in this area. For now, the current World Health Organization recommendation for breastfeeding is to exclusively breastfeed for the first 6 months of a child’s life, if you are able.

 

References:

Girard L, Doyle O, Tremblay RE. Breastfeeding, Cognitive and Noncognitive Development in Early Childhood: A Population Study. Pediatrics. 2017;139(4):e20161848. doi:10.1542/peds.2016-1848

Student Blogger for Global Nutrition Council at ASN’s Scientific Sessions and Annual Meeting at EB 2016

By: Sheela Sinharoy, MPH

A symposium called Biology of Linear Growth on Tuesday examined linear growth from the molecular to the population level, bringing perspectives from biology, physical anthropology, nutrition, and epidemiology

Are you familiar with the process of endochondral ossification? Julian Lui, MD PhD explained that this is the process that results in linear growth. It takes place in the growth plates, at the end of long bones such as the femur, and is subject to systemic regulation by endocrine, nutritional, and inflammatory cytokine factors as well as local regulation by paracrine factors and other cellular mechanisms. Malnourished children have lower levels of hormones like insulin-like growth factor 1 (IGF-1) and estrogen, as well as increased levels of glucocorticoids, leading to decreased linear growth. Dr. Liu explained that this allows the body to conserve resources and that, in situations of food insecurity, “Growth is something of a luxury that can be postponed until better times.”

Rather than growing continuously, children grow in saltations, meaning that – as many a parent has observed – a child may grow substantially overnight and then not at all for a number of days afterwards. Michelle Lampl, MD PhD stated that as children age, these saltations become less and less frequent, with older children growing much less often than infants. The amount and frequency of these growth saltations can be affected by environmental factors, which can interact with cellular effects. Maternal smoking, for example, has a well-documented inhibitory effect on growth, as does maternal alcohol consumption and stress.

Since linear growth happens most rapidly in early life, the first 1,000 days from conception to two years of age are considered a critical period. Parul Christian, DrPH presented results from a meta-analysis analyzing various maternal and child nutrition interventions targeting this 1,000-day window. Starting during pregnancy, balanced protein-energy, iron-folic acid, and multiple micronutrient supplementation were all found to increase birth weight. However, maternal supplementation during pregnancy was not associated with any long-term linear growth in children under five years old. For infants and young children, nutrition promotion and food supplementation showed promise as interventions with positive impacts on child height.

In the final talk of the symposium, Aryeh Stein, PhD addressed the question of linear catch-up growth: for those children whose growth has been suppressed by malnutrition, is it possible to catch up on missed growth, even after the first 1,000 days? A number of studies have provided different nutrients and foods to children ages two and older. Dr. Stein presented results from studies of protein, zinc, iron, iodine, calcium, multiple micronutrients, and food. Protein and some of the micronutrients may have promise, but several of the calcium studies reported negative effects, while food had no association with growth.

The symposium made it clear that nutrition has an important role to play in stimulating or inhibiting linear growth. However, a great deal remains to be learned about these complex biological processes and the most effective interventions to promote children’s optimal growth.