Maternal and adolescent nutrition

Mothers and adolescent girls around the world, but specifically from low and middle-income countries, face a double burden of malnutrition. On the one hand, micronutrient deficiencies are frequent due to high consumption of foods that are either poor in vitamins and minerals or contain elements that limit absorption. Pregnant and lactating mothers suffer from low levels of nutrients due to insufficient intake. On the other hand, the rates of overweight and obesity among mothers and adolescents are also rising. The result is a vicious cycle where malnourished mothers give birth to children whose growth is restricted and who are at risk for stunting and non-communicable diseases in adulthood. These children are also more likely to have offspring facing the same maladies.

The IAEA supports the application of stable isotopes to measure micronutrient bioavailability and vitamin A status, changes in body composition and physical activity, and promotion of good infant feeding practices. The techniques are specifically applied to:

• Assess vitamin A status. Changes in vitamin A body stores reveal the success of interventions aimed at preventing vitamin A deficiency.
• Assess the quality of the diet: absorption and retention of provitamin A, iron and zinc from fortified foods, or biofortified foods (accumulation of higher levels of minerals and vitamins during plant growth), or mixed diets; and protein bioavailability from plant foods.
• Objectively measure whether a mother is practicing exclusive breastfeeding. The techniques can be used to assess the accuracy of information reported by the mothers, and the impact of breastfeeding promotion campaigns. Breastfeeding offers numerous health benefits to mothers. It is associated with a reduced risk of type II diabetes, postpartum depression, and breast and ovarian cancer. In addition, adolescents and adults who were breastfed as babies are less likely to be overweight or obese.
• Measure body composition in terms of the relative amounts of fat and lean tissues as an indicator of nutritional status reflecting the quality of the diet. Poor quality diets may lead to obesity among mothers and adolescents and adversely affect child health. Monitoring body composition is important, because changes in body composition are associated with physiological changes in the body that can lead to disease later.
• Assess the distribution of body fat. Disease risk is related to the distribution of body fat, as well as the total amount. Dual energy X ray absorptiometry (DXA) can be used to assess body composition, and can provide valuable information on the distribution of body fat. DXA is also used to measure bone mineral content, and assess the risk of osteoporosis later in life.
• Measure total energy expenditure, which can be used to validate measurements of physical activity to assess the impact of interventions to increase physical activity in adolescents.

Assessment of Vitamin A status with isotope techniques

• A dose of vitamin A labelled with a stable, non-radioactive, isotope of hydrogen (2H) or carbon (13C) is administered after a baseline blood sample has been collected.
• The labelled vitamin A mixes with the vitamin A in the body, and after two weeks they are evenly mixed: the dose has equilibrated with the vitamin A body pool.
• A second blood sample is taken and the enrichment of labelled vitamin A is measured by mass spectrometry (A*/A).
• From the dilution of the precisely measured dose of the isotope labelled vitamin A, it is possible to calculate the total vitamin A stores in the body.
• This is the most sensitive way to non-invasively estimate vitamin A status over the whole range, from deficient to normal to excessive.