The vicious cycle of vitamin a deficiency: A review

Abstract

Vitamin A deficiency (VAD) is a serious and widespread public health problem and the leading cause of preventable blindness in young children. It is also associated with increased rates of death from severe infections, especially in developing countries. Over the past 35 years, researchers have examined the numerous activities of vitamin A in different tissues of the human body. VAD can lead to a series of ocular symptoms, anemia, and weak resistance to infection, which can increase the severity of infectious diseases and the risk of death. Cell development, vision, growth, and normal metabolism are among the vital processes that are insufficiently supported in the presence of VAD. VAD leads to impaired tissue function especially during the developmental periods of infancy, childhood, pregnancy, and lactation. We describe a multidirectional model of VAD that demonstrates how VAD can have progressive, negative effects on vital processes of the human body throughout the life cycle. This model starts with impaired intake and its link to decreased absorption and digestion and includes outcomes such as malnutrition, inflammation, and improper growth processes, including possible mechanisms. Together, these clinical and biochemical manifestations contribute to the vicious cycle of VAD.

Cellular retinoid binding-proteins, CRBP, CRABP, FABP5: Effects on retinoid metabolism, function and related diseases

“…Severe vitamin A/atRA depletion primarily affects children, because of their need related to rapid growth (Sommer & Vyas, 2012; Akhtar et al, 2013). The most deleterious consequences of severe depletion include xerophthalmia, a degeneration and ulceration of the corneal epithelium that can cause permanent blindness (as opposed to nyctalopia or night blindness, a fairly benign condition that manifests early during suboptimum vitamin A status), and immune suppression, associated with a higher incidence of infection and increased mortality (Wiseman et al 2016). …”

Effects of micronutrients on placental function: evidence from clinical studies to animal models

“…Vitamin A deficiency is assessed by biochemical measurement of serum retinol, clinical indication of eye disease and functional indicators such as night blindness. Adult serum retinol concentrations <0.7 µmol/L define biochemical deficiency and in pregnancy/lactation concentrations <1.05 µmol/L are considered deficient (Wiseman et al 2017). Vitamin A deficiency is common in low-income countries, with ~15% of pregnant women globally being biochemically deficient (World Health Organization 2009).…”

Theoretical Studies of Milk: Solvent Effects on the Molecular Properties of Retinoid Compounds

“…Cow milk (consisting of water, fatty acids, proteins, sugars, minerals and vitamins) is the one of the most consumed food of the world [1]. Vitamin A, naturally found in milk, includes diverse retinoid and carotenoid compounds.…”