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17 USC 105 interim-entered record; under temporary embargo. ; Background: Vitamin A deficiency increases susceptibility to infection caused by impaired immune function. Objectives: We investigated whether immunodeficiency could facilitate the development of vitamin A deficiency. Methods: Vitamin A deficiency was followed in 2 mouse models of immunodeficiency: the athymic nude mouse (nu/nu) and the humoral immunodeficient SENCAR (SENsitive to CARcinogenesis) mouse. Vitamin A deficiency was also monitored in outbred Balb/c and in NIH mice. The monitoring of vitamin A deficiency was done after feeding the mice and their mothers a semisynthetic, vitamin A–deficient diet from birth of the experimental mice. These mice were weaned onto the same deficient diet at 3–4 wk of age, while control groups were fed the same diet containing 3 μg retinoic acid per gram of diet. Results: The immunodeficient nu/nu and SENCAR mice developed vitamin A deficiency earlier than either the heterozygous nu/+ controls or the Balb/c and NIH strains. In female mice, symptoms included depletion of liver retinol and retinyl palmitate, squamous metaplasia of the uterus, and death. Male mice lost weight more frequently and sooner than female mice, in which mortality generally occurred in the absence of loss of body weight. Pairwise comparisons using Tukey's honest significant difference test of the nu/nu and SENCAR mice versus the Balb/c and NIH mice showed a faster loss of retinol and retinyl palmitate in all pairs (P ≤ 0.0001) except for retinol when comparing nu/nu and NIH strains (P = 0.3383). Conclusions: Our findings are consistent with an increased usage of liver retinol and retinyl palmitate in the immunocompromised nu/nu and in the immunodeficient SENCAR mice and suggest that compensatory mechanisms dependent on vitamin A utilization are called upon to rescue immunodeficiency both in the T-cell–deficient phenotype of the nu/nu mice and in the humoral immunodeficient SENCAR mice. Curr Dev Nutr 2021;5:nzab129. ; U.S. Government ...

Nepal has a rich history of vitamin A research and a national, biannual preschool vitamin A supplementation (VAS) programme that has sustained high coverage for 25 years despite many challenges, including conflict. Key elements of programme success have included (a) evidence of a 26–30% reduction in child mortality from two, in‐country randomized trials; (b) strong political and donor support; (c) positioning local female community health volunteers as key operatives; (d) nationwide community mobilization and demand creation for the programme; and (e) gradual expansion of the programme over a period of several years, conducting and integrating delivery research, and monitoring to allow new approaches to be tested and adapted to available resources. The VAS network has served as a platform for delivering other services, including anthelmintic treatment and screening for acute malnutrition. We estimate that VAS has saved over 45,000 young lives over the past 15 years of attained national coverage. Consumption of vitamin A‐ and carotenoid‐rich foods by children and women nationally remains low, indicating that supplementation is still needed. Current challenges and opportunities to improving vitamin A status include lower VAS coverage among younger children (infants 6–11 months of age), finding ways to increase availability and access to dietary vitamin A sources, and ensuring local programme investments given the recent decentralization of the government.

Nutrient reference values have significant public health and policy implications. Given the importance of defining reliable nutrient reference values, there is a need for an explicit, objective, and transparent process to set these values. The Tufts Medical Center Evidence-based Practice Center assembled a group of nutrition experts from academic institutions and federal government agencies, led participants in discussions, conducted exercises in formulating questions and evidence review criteria that would be amenable to systematic reviews of the scientific literature, performed a literature search on the questions to identify potentially relevant publications, and identified challenges and limitations of applying this method to support the development of nutrient reference values using vitamin A as an example. The workgroup concluded that the systematic review approach could be productively used to inform the development of reference values. Challenges identified in this exercise include prioritizing and defining research questions when the volume of literature is large, relying on intermediate (surrogate) outcomes when few or no studies directly linking nutrient intake with clinical outcomes are available, and determining reliable nutrient biomarkers. Ultimately, an objective, unbiased systematic review of a defined question could be useful, not only in helping to set nutrient reference values, but also for increasing the transparency of the decision making process.