Active clinical trials for "Vitamin A Deficiency"

For assessing body retinol pools in preschool children, it is recommended that a blood sample is taken 14-21 days after isotope dosing. During this period, dietary intake of vitamin A should be controlled. Shortening of this period as has been validated for adults would reduce the burden for the children as well as improve research efficiency. The aim is to validate a 4-day protocol for assessing body retinol pools in preschool children by modelling data derived by retinol isotope dilution (RID) method. Venous blood samples will be collected of 60 children 4 days after dosing of 0.4 mg 13C-labeled retinyl acetate. A second venous blood sample will be collected at 6, 8, 12 hrs; and 1, 2, 4, 7, 11, 16, 22 and 28 days after dosing in subgroups of 6 children, randomly divided over the 10 additional time points. Body retinol pools will be modelled, and the time point at which a parsimonious model applies (presumably at day 4) will be assessed.

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).

This pilot study will evaluate the visual response to infrared (IR) in humans after dark adaptation. The investigators plan to determine which wavelength and intensity the human eye is most sensitive too, using a broad spectrum light source and wavelength-specific bandpass filters. The investigators will then evaluate the electrophysiologic response in healthy humans to IR, followed by studies in those with specific retinal diseases. The long-term goal of this research is to better understand the role that IR plays in visual function, and whether this can be manipulated to allow for vision in certain retinal pathologies that result from loss of photoreceptor cells. The investigators central objective is to test the electrophysiologic response to IR in the dark-adapted retinal and visual pathways. The investigators central hypothesis is that IR evokes a visual response in humans after dark adaptation, and the characteristics of this response suggest transient receptor potential (TRP) channel involvement. The investigators rationale is that a better understanding of how IR impacts vision may allow for an alternative mechanism for vision in a number of diseases that cause blindness from the degradation or loss of function of photoreceptor cells. The investigators will test the investigators hypothesis with the following Aims: Aim 1: To determine the optimal IR wavelength for visual perception in dark-adapted human participants. The investigators hypothesize that the healthy human eye will detect IR irradiation, with a maximum sensitivity at a specific wavelength. Using a broad-spectrum light source with wavelength-specific bandpass filters, the spectral range of visual perception to IR will be evaluated. The same will be done on colorblind participants. Aim 2: To test the electrophysiologic response to IR in healthy humans after dark adaptation. The investigators hypothesize that IR will elicit an amplitude change on electroretinography (ERG) and visual evoked potential (VEP) responses after dark adaptation in healthy human participants. Participants will be tested with both test modalities to evaluate their response to IR. Aim 3: To test the electrophysiologic response to IR after dark adaptation in humans with certain retinal diseases. Participants with retinitis pigmentosa, age related macular degeneration and congenital stationary night blindness, will be tested. Results will be compared to baselines and to those of healthy participants. The investigators hypothesize that there will be a response to IR on ERG and VEP, which will provide clues to the retinal cell layer location of the response to IR and the nature of potential TRP channel involvement.

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.

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 purpose of this trial is to determine whether providing women with a weekly oral supplement of vitamin A, either preformed or as beta-carotene, at a dosage equivalent to a recommended intake from early pregnancy through three months postpartum, can reduce the risk of maternal mortality, fetal loss, or infant mortality.

Main objectives: To evaluate the impact of weekly vitamin A supplementation (VAS) to women of reproductive age (15-45 years) on maternal mortality in rural Ghana, and to compare this with the impact on overall mortality. Hypotheses: Weekly supplementation with vitamin A (7000 µg retinol equivalent [RE]) to reproductive age women will reduce maternal deaths by 33%. This impact will be achieved by reductions in both pregnancy-related and non-pregnancy-related deaths. There will be a reduction in non-maternal deaths, similar in size to that in maternal non-pregnancy related deaths. Outcome measures: Maternal mortality rate, and overall mortality rate. Deaths will be identified through monthly demographic surveillance, and classified as maternal (pregnancy-related, non-pregnancy-related) or non-maternal using verbal autopsies.

HIV infected individuals with vitamin A deficiency may be more likely to transmit the virus to others than HIV infected individuals who have normal levels of vitamin A. The presence of HIV DNA in vaginal secretions may indicate a greater risk for transmission of HIV to others. The purpose of this study is to determine if taking vitamin A decreases the level of HIV DNA in vaginal secretions.

The purpose of this randomized control trial is to test the impact of provitamin A carotenoid biofortified maize meal consumption on maternal and infant vitamin A status.

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.