Current Developments in Nutrition Special Collection Highlights Areas Where More Research Is Needed

Vitamin A is an essential micronutrient that plays an important role in supporting an array of physiologic processes, including vision, immune response, cell differentiation and proliferation, intercellular communication, and reproduction.  According to a 2020 NIH Fact Sheet, vitamin A deficiency is most strongly associated with poor health outcomes during pregnancy, lactation, infancy and childhood, all periods of life where the body has high nutrient requirements.  Vitamin A deficiency during pregnancy and lactation, for example, is associated with a higher risk of mortality and morbidity for both the mother and her infant.  In many cases, this is due to a compromised immune system caused by the vitamin A deficiency, which leads to an increased susceptibility to infectious diseases.  Furthermore, infants and young children who are vitamin A deficient are more susceptible to childhood blindness as well as growth and developmental delays.

Our Current Dietary Reference Intakes for Vitamin A—Now 20 Years Old

New results from research using advanced methods can now guide the process of setting new DRIs for vitamin A for women and children.

Dietary Reference Intakes (DRIs) for vitamin A were last set in 2001.  Guest edited by ASN member A. Catharine Ross, the most recent Current Developments in Nutrition Special Collection, Towards New DRIs for Vitamin A and Carotenoids in Early Life, raises awareness of the important advances that have taken place in vitamin A research since the 2001 publication of DRI values.  Moreover, the articles in this collection highlight the knowledge gaps that remain.  Although the authors of this collection do not propose any current changes, they do explain where further research is needed to expand on the evidence-based foundation for vitamin A DRIs to better meet the needs of mothers and their infants and young children.

In addition to a detailed introduction authored by A. Catharine Ross and Nancy E. Moran, this special collection features three articles, highlighted below.

Vitamin A Requirements in Pregnancy and Lactation, Bryan M. Gannon et al.

There remain limited data to quantify average requirements and identify important covariates to personalize intake recommendations.

Although numerous studies have provided evidence on the importance of adequate vitamin A status during pregnancy and lactation to ensure good maternal and child health outcomes, this review finds that “there remain limited data to quantify average requirements and identify important covariates to personalize intake recommendations.”  In order to establish more precise vitamin A requirements for new mothers and their infants, the authors have called for additional studies to quantify vitamin A intake during pregnancy and lactation, to determine biomarkers of vitamin A status that accurately reflect vitamin A stores, and to evaluate the impact of pregnancy and lactation on vitamin A.  Although the authors believe more research is needed, they do note that food-based approaches, as opposed to supplementation, “can lead to more sustained, sufficient vitamin A status in mothers and children.”

Prediction of Vitamin A Stores in Young Children Provides Insights into the Adequacy of Current Dietary Reference Intakes, Jennifer Lynn Ford et al.

The current vitamin A DRIs are sufficient to build and maintain vitamin A stores during infancy and early childhood.

In previous research studies, investigators have used mathematical simulation approaches to study vitamin A requirements in infants, evaluate causes of vitamin A deficiency in children, and quantify the expected change in vitamin A total body stores following an intervention.  The authors of this study adapted those approaches to predict changes in vitamin A total body stores, as well as vitamin A liver concentrations, among children from birth to five years old.  To develop these predictions, the authors worked with recent studies that established vitamin A intakes among infants and preschool-aged children from Bangladesh, the Philippines, Guatemala, and Mexico.

The results of the authors’ mathematical simulation “indicate that the current vitamin A DRIs are sufficient to build and maintain vitamin A stores during infancy and early childhood.”  The authors do note, however, that various nutrient deficiencies and diseases can negatively affect vitamin A status: “Higher vitamin intakes may be advisable under such conditions, but further research is required to establish specific recommendations.”

Vitamin A Supplementation during Suckling and Postweaning Periods Attenuates the Adverse Metabolic Effects of Maternal High-Fat Diet Consumption in Sprague-Dawley Rats, Libo Tan et al.

Supplementing maternal or infant obesogenic diets with vitamin A should be studied further for managing overweight/obesity in early life.

Research has shown that mothers with obesity, as well as excessive gestational weight gain, may program obesity and other chronic diseases in her offspring that manifest during infancy, childhood, and beyond.  Given that vitamin A is known to be a key regulator of lipid metabolism and adipose tissue, the authors of this animal-model study set out to determine what effect supplementing mothers who consumed a high-fat diet with vitamin A would have on their offspring’s body weight, adiposity, and obesity-associated metabolic conditions.

The study results led to the conclusion that “vitamin A supplementation during suckling and postweaning periods attenuated metabolic perturbations caused by excessive fat intake.”  The authors believe that their findings have implications for human populations as well, noting “supplementing maternal or infant obesogenic diets with vitamin A or establishing a higher Recommended Daily Allowance (RDA) of vitamin A for specific populations should be studied further for managing overweight/obesity in early life.”

Launched in 2017, Current Developments in Nutrition, is the American Society for Nutrition’s open-access journal, dedicated to quickly disseminating high-quality research in the nutritional sciences throughout the world.  Please visit the journal’s Instruction for Authors to learn how to submit your manuscript for publication.