Retinol Levels and Severity of Patients with COVID-19.

The new coronavirus infection represents a serious threat to global health and economies. In this sense, it is paramount to know the nutritional factors that may be related to the prognosis of the disease. Evidence shows that vitamin A may play an important preventive and therapeutic role in supporting respiratory infections as in COVID-19. The aim of our study was to evaluate the association of vitamin A (retinol) status with the prognosis of the disease. A case-control study from a cohort study was conducted in Brazil between May and October 2020. The study population was chosen by convenience, consisting of participants diagnosed with COVID-19. Recruitment was carried out using different approaches, including through dissemination on social media and in four hospitals in the city of Natal/RN, Brazil, recruiting participants from the COVID-19 ward and hospitalized participants who tested positive for the disease. The participants were allocated into two groups according to severity, with a group of mild (n = 88) or critical (n = 106) patients and compared to a control group (selected before the pandemic, n = 46). The extraction of retinol serum was performed and analyzed using the high-performance liquid chromatography method (HPLC). The retinol level was calculated in mmol/L, and levels below 0.7 µmol/L (20 µg/dL) were considered to be a vitamin A deficiency. Our findings suggest that the participants with mild and critical COVID-19 had lower retinol levels compared to the healthy controls (p = 0.03). In addition, milder cases of COVID-19 were associated with increased symptoms and prolonged symptoms after 90 days since the beginning of infection. However, the survival analysis showed no association with higher cases of death among participants with vitamin A deficiency (p = 0.509). More studies are needed to understand how nutritional status, including vitamin A levels, can influence prognosis and is a risk factor for the development of long COVID syndrome.

Relationship between the dietary intake, serum, and breast milk concentrations of vitamin A and vitamin E in a cohort of women over the course of lactation.

This study evaluated the nutritional status of lactating women with regard to vitamins A and E and the relationship between dietary intake and concentrations in serum and milk. A longitudinal study was conducted with 43 women at a hospital in northeastern Brazil. Blood and milk samples and food intake recalls were obtained at three moments during the breastfeeding period. Retinol and alpha-tocopherol were analysed by high-performance liquid chromatography. Dietary inadequacy was analysed according to the estimated average requirement, with intrapersonal variation adjusted by the multiple source method. Food intake was classified by quartiles of consumption. Serum retinol was 1.65 µmol/L, with 5% of low concentrations (<0.7 µmol/L) at the first collection. Serum alpha-tocopherol decreased from 30.18 to 25.49 µmol/L at the third collection (P = 0.008), with an increase in the percentage frequency of deficiency (<12 µmol/L). Both vitamins maintained stable concentrations in milk at the different collection times, and the overall dietary inadequacy of vitamins A and E was 58% and 100%, respectively. There was a correlation only between vitamin A intake and serum retinol (r = 0.403, P = 0.007), and higher retinol concentrations were found in women classified in the highest consumption quartile (P = 0.031). Over the course of lactation, there was a high degree of inadequacy in vitamin intake and a reduction in serum alpha-tocopherol, whereas its concentrations in milk remained unchanged. Dietary intake of vitamin A has been shown to influence serum retinol, which underscores the importance of adequate nutrition and monitoring of vitamin deficiency during lactation.