Retinol

BACKGROUND:
In recent decades, the general socioeconomic situation in Latin America and the Caribbean countries has improved, and many vitamin A programs have been implemented in an attempt to reduce vitamin A deficiency in the region.
OBJECTIVE:
To examine vitamin A status in Latin America and the Caribbean based on serum retinol concentrations and to contrast available data published before and after 1998.
METHODS:
A systematic review was performed. National surveys or representative studies that reported vitamin A status were selected.
RESULTS:
Ten national surveys and six representative studies were identified. Data for children under 6 years of age indicate that Guatemala and Nicaragua have practically eradicated vitamin A deficiency (less than 2% prevalence of serum retinol < 20 μg/dL). In Costa Rica, Cuba, El Salvador, and Panama, the prevalence of vitamin A deficiency ranged from 2.8% to 9.4%. In Peru, Honduras, Argentina, Ecuador, and Brazil, vitamin A deficiency is a moderate public health problem (prevalence from 14.0% to 17.4%), while in Colombia, Mexico, and Haiti it is a severe public health problem (prevalence from 24.3% to 32.0%). Disadvantaged groups (indigenous people and those of Afro-Colombian descent) have the highest rates of deficiency. The prevalence of vitamin A deficiency is under 20% in school-children and adult women. When data published before and after 1998 for children under 6 years of age were compared, most Central American countries had a reduction in the prevalence of vitamin A deficiency (p < .05), whereas in South American countries, the prevalence of vitamin A deficiency increased over time (p < .05).
CONCLUSIONS:
The prevalence of vitamin A deficiency in children under 6 years of age has decreased in many Central American countries, but vitamin A deficiency still remains a public health problem in numerous Latin America and Caribbean countries, especially among disadvantaged and vulnerable groups. Because of issues with the accuracy of the serum retinol biomarker reflecting body stores, these results must be interpreted with caution.

Background: Serum retinol concentration determined by high-performance liquid chromatography (HPLC) is
recommended by the World Health Organization to assess population vitamin A status. This assay is expensive,
technically demanding and rarely available in developing countries. Our objective was a) to assess the diagnostic
performance of proxy markers in detecting vitamin A deficiency and b) to derive decision rules based on these
markers to estimate vitamin A deficiency prevalence.
Methods: A survey was conducted in 15 rural primary schools in Eastern Province, Kenya, with 375 children aged
6 to 12 years (25 randomly selected per school). Serum retinol concentration <0.70 μmol/L by HPLC was used to
define vitamin A deficiency. Proxy markers for vitamin A deficiency were serum concentrations of retinol binding
protein (RBP), transthyretin, retinol measured by fluorometry and RBP:transthyretin molar ratio.
Results: The prevalence of vitamin A deficiency (HPLC) was 18%. Transthyretin and RBP showed the best diagnostic
performance individually, with area-under-the-curve (AUC) values of 0.96 and 0.93. When combined, and with C-reactive
protein added, the AUC increased to 0.98. A simple decision rule {(−15.277 × [RBP, μmol/L] - 7.013 × [Transthyretin,
μmol/L] + 0.367 × [C-reactive protein, mg/L] + 24.714) > 0.496} yielded prevalence estimates of vitamin A deficiency
that is unbiased by diagnostic error.
Conclusions: The combination of transthyretin, RBP and C-reactive protein concentrations could eventually replace
retinol concentration by

The aim of the study was to verify the hypothesis that β-carotene, vitamin E, vitamin C administered individually or in combination may differently modify their levels in blood plasma being also markers of the oxidative stress. Male Wistar rats were supplemented antioxidants per os (α-tocopherol – 2 mg/d, ascorbic acid – 12 mg/d, β-carotene – 1 mg/d), both individually or in combination of 2 or 3, for 14 days. During experiment, half of the animals in each group (n=8) were subjected by treadmill exercise for 15 min at the speed of 20 m/min, to induce oxidative stress. Vitamins in rat plasma were assessed by the high-performance liquid chromatography (HPLC). Results suggest that vitamin E and C supplemented simultaneously may provide some benefit during physical exercise. The significant influence of administered α-tocopherol acetate and physical exercise on the level of α-tocopherol in the plasma was observed. Thus only the concentration of α-tocopherol in blood may be treated as a marker of oxidative stress.