Views: 2 Author: Site Editor Publish Time: 2022-07-18 Origin: Site
Vitamin A deficiency is the main cause of blindness in children in developing countries, and it is also a common nutritional deficiency in children in developing countries. Due to the impact of VAD (vitamin A deficiency) and svad (vitamin a marginal deficiency) on children's health, the prevention and control of VaD and svad has become one of the urgent public health problems in the world.
Who and UNICEF carry out vitamin A intervention in a variety of ways, including increasing the consumption of vitamin A-containing food, fortifying vitamin A in food, improving breast-feeding, regular high-dose vitamin A supplementation, etc.
Accurately evaluating the vitamin a nutritional level of susceptible individuals and populations is of great significance for the study of VaD, svad and the formulation, implementation and evaluation of nutritional intervention strategies. The commonly used methods to check the nutritional status of vitamin A in groups or individuals in practical work mainly include: clinical examination of dry eye disease, dietary investigation, determination of dark adaptability, inquiry of night blindness history, determination of serum retinol content, relative dose response test, isotope dilution method, determination of vitamin a content in liver and conjunctival imprinting cell method, etc.
Nutrition education and reasonable dietary measures
Through nutrition education and reasonable diet, improving the existing dietary intervention methods of vitamin a rich food intake in this region has long been considered to be the most lasting method that can fundamentally improve the status of VaD and svad. Nutrition education should focus on promoting breast-feeding and increasing the supply of milk, eggs and dark vegetables.
Food fortified vitamin A is a direct, effective and low-cost method to prevent VAD and svad. Vitamin A, vitamin BL, vitamin B2, folic acid, nicotinic acid, iron, iodine, zinc and calcium are the main nutrients for nutritional fortification in China.
Vitamin A and retinol equivalent content in food
Regularly supplement vitamin A preparations
Regular vitamin A supplementation is a rapid and direct method to improve vitamin a nutritional status. It includes clinical supplements for children with dry eye disease, measles and malnutrition, targeted delivery using the coverage of existing health services, and preventive supplements for all high-risk groups.
At present, who needs to put forward the following suggestions for the prevention and treatment of vitamin A deficiency in different high-risk groups and future research:
① Infants under 5 months of age (including newborns): vitamin A supplementation is not recommended. The role of vitamin A supplementation in reducing infant incidence rate and mortality needs to be further confirmed by future randomized controlled trials. Further studies will be conducted on the high incidence of VAD in mothers, the relationship between vitamin A and immune function, and the determination of appropriate evaluation indicators of VAD in this age group.
② Children aged 6 ~ 59 months: it is recommended to implement high-dose vitamin A supplementation for children aged 6 ~ 59 months who have VAD as a public health problem (that is, the VAD incidence rate of this population ≥ 20% or the incidence rate of night blindness ≥ 1%), among which 100000 IU should be supplemented for infants aged 6 ~ 11 months (hiv+ or -), and 200000 IU should be supplemented every 4 ~ 6 months for children aged 12 ~ 59 months. In the future, better vitamin A supplementation methods need to be further studied to improve the understanding of the joint intervention of vitamin A and vaccine, so as to seek better clinical and biochemical VAD evaluation indicators.
③ Pregnant women: vitamin A supplementation is not recommended as a part of routine prenatal care to prevent the morbidity and mortality of pregnant women and infants. For pregnant women in regions or countries (pregnant women) where VaD is a serious public health problem (i.e. the incidence rate of night blindness in pregnant women or children aged 24-59 months ≥ 1%), vitamin A supplementation can be used to prevent night blindness. Supplement dose: 10000 IU per day or 25000 IU per week for pregnant women over 12 months of gestation, However, the duration and frequency of supplementation need further study. In the future, more studies should focus on the impact of vitamin A supplementation during pregnancy, especially in combination with other interventions on mortality, and a comprehensive review of the impact of vitamin A supplementation in the third trimester of pregnancy on vitamin A levels in breast milk.
④ Lactating mothers: vitamin A supplementation to lactating mothers is not recommended as an intervention measure to prevent the morbidity and mortality of mothers and infants. The effect of vitamin A supplementation of 200000 IU to lactating mothers 6 weeks after delivery on the level of retinol in breast milk and its metabolism, dose distribution, and how to excrete it need to be further studied.
⑤ Mother to child HIV infection: vitamin A supplementation is not recommended for HIV positive mothers.