View clinical trials related to Night Blindness.
Filter by:The study comprises an open-label randomized controlled trial investigating the efficacy of consuming a daily ration of pro-vitamin A biofortified cassava on vitamin A status of Nigerian children, aged 3-4 years old (n=200).
The combination of infectious diseases and malnutrition is the most prevalent, preventable public health problem in the world, responsible for millions of deaths annually, particularly in infants and children. Approximately 13 million children die each year in developing countries from infectious diseases, with the majority of these deaths related to malnutrition. The relationship between infections and malnutrition is synergistic, each further compromising the outcome of the other. Malnutrition compromises natural immunity leading to increased susceptibility to infections, more frequent and prolonged disease episodes, and increased severity of disease. Likewise, infections can aggravate or precipitate malnutrition through decreased appetite and food intake, nutrient malabsorption, nutrient loss or increased metabolic needs. Another issue is that infections (as well as overweight and obesity status) affect nutritional biomarkers making it difficult to assess the real magnitude of some nutritional problems. This is the case of vitamin A. Vitamin A deficiency is defined to be of severe public health importance if 20% or more of a defined population has a serum retinol concentration of less than 0.7 µmol/L. However, circulating concentrations of serum retinol are reduced by infections and in such situations serum retinol concentration is not a good indicator of vitamin A status. Serum acute-phase proteins can indicate the severity and duration of an infection. Correcting vitamin A deficiency is addressed in Ethiopia through vitamin A supplementation of children, dietary diversity and using bio-fortified foods. However, assessing vitamin A status, and the effectiveness of government interventions, is challenging in settings where infectious diseases are endemic, as in most area of the country. Evaluation of vitamin A status is relatively insensitive when based on changes in serum retinol concentrations, which are homeostatically controlled and negatively affected by subclinical infections. Liver stores of vitamin A, the best indicator of vitamin A status, cannot be routinely evaluated. The isotope dilution technique is the preferred method for determining vitamin A status and assessing the efficacy and effectiveness of intervention programs aimed at improving vitamin A status. It is the only indirect assessment method that provides a quantitative estimate of vitamin A status across the continuum of deficient to excessive stores.
Summary: Chronic intake of foods low in vitamin A (retinol) and provitamin A forming an unbalanced diet with little variety is common in young individuals in the United Kingdom (UK) population and can lead to subclinical micronutrient deficiency. Provitamin A sources such as β-carotene are cleaved centrally by the β-carotene 15,15'-monooxygenase (BCMO1) into retinal, the precursor of retinol. However, the amount of β-carotene and retinol produced after ingestion of β-carotene is highly variable between healthy individuals, with approximately 40% of the subjects being classified as low responders. Several stable isotope studies have shown a large disparity between the most efficient converters and the most inefficient converters of β-carotene with variations of up to 8-fold. It is possible that differences in β-carotene response may be due to single nucleotide polymorphisms (SNPs) in genes involved in aspects of β-carotene conversion. Previous work has shown that carriers of both, the 379V and 267S+379V BCMO1 variant alleles had a reduced ability to convert β-carotene. More importantly, 44% of the western population have the 379V haplotype. A high percentage of the Western population may therefore not be able to achieve adequate vitamin A intake if dietary β-carotene is a major source of their vitamin A intake. This is of particular relevance to vegetarians, to young individuals aged 19-24 years who have lower intakes of preformed retinol than any other age group, and to pregnant women. The aim of this study is to establish whether the maximum recommended dose for β-carotene of 7mg/day by the British Expert Committee on Vitamins and Minerals (EVM) can overcome the SNP effect in the BCMO1 enzyme. Hypothesis: The investigators hypothesize that the current maximum recommended intake of 7 mg of β-carotene per day cannot overcome the low convertor phenotype in BCMO1 to fulfill vitamin A requirements in these people.
The goal of the research study is to determine the absorption, metabolism, and bioconversion of carotenoids such as beta-carotene to vitamin A from gari made with biofortified cassava compared to a mixture of red palm oil and gari made from typical white cassava.
The purpose of this study is to evaluate the effect of post-partum maternal vitamin A supplementation on breast milk bioactive compounds and immune status, growth and morbidity of children in the first four months of life.
Vitamin A deficiency (VAD) increases the risk of death from infections in infants and young children. The World Health Organization (WHO) recommends high-dose vitamin A supplementation (VAS) from 6-59 months of age to reduce the risk of death in countries where VAD is common. Such countries include Bangladesh, where this study is being conducted. While providing VAS at 6 months is recommended, providing VAS at birth may also decrease the risk of death since newborn infants are also at risk of VAD. VAS presumably reduces infant mortality by improving the immune response to infection and immunization. Vitamin A particularly affects the development and function of T cells, which develop in the thymus and are a key component of the memory response to infection and immunization. Vitamin A is important for development of an important class of T cells, regulatory T-cells, in the intestine. Regulatory T-cells prevent over-reaction of the immune system to substances the immune system might otherwise treat as harmful such as food or the healthy bacteria in the intestine. VAD could disrupt the normal colonization of the infant's intestinal tract and cause a condition called "dysbiosis" where abnormal bacteria flourish and adversely affect the infant's immune system. Dysbiosis may disrupt the immune response to injectable and oral vaccines. VAS at birth may prevent dysbiosis and thus improve immune function, response to vaccines, and child survival. The investigators recently completed an intervention trial in Bangladeshi infants (NCT01583972) examining the effect of VAS at birth on immune function and response to vaccines administered from birth to 14 wk of age. The present study will recruit infants who completed NCT01583972 when they are from 12 to 24 m of age to determine if VAS at birth affects the responses to these same vaccines when they are measured during the second year of life. The investigators will examine the effect of VAS at birth on gut microbiota measured early in infancy and during the second year of life, and explore the association of the gut microbiota with vaccine response. Mothers of study infants will participate in the study because the breast milk oligosaccharide content strongly affects gut microbiota composition and the "secretor status" of the mother, which can be determined from maternal FUT2 genotype, strongly affects breast milk oligosaccharide content.
The purpose of the study is to determine whether daily consumption of beta-carotene biofortified maize will increase breast milk retinol concentration in lactating Zambian women.
The objectives of this study are: - To evaluate the efficacy of phentolamine mesylate 0.5% and 1.0% ophthalmic solution (Nyxol) in the treatment of night vision complaints, including reduced contrast sensitivity - To evaluate the ocular and systemic safety of phentolamine mesylate 0.5% and 1.0% ophthalmic solution (Nyxol) compared to its vehicle, a sterile, isotonic, buffered aqueous solution containing mannitol and sodium acetate
The purpose of this cluster-randomized trial is to examine whether daily consumption of β-carotene biofortified maize flour can reduce the prevalence of vitamin A deficiency and improve the vitamin A status and among 4-8 year old children in rural Zambia.
The overall aim of the project is to provide proof-of-principle that biofortification of cassava with vitamin A is a viable strategy to improve vitamin A status of deficient populations.