Vitamin A is a fat-soluble vitamin, not a single structure, is composed of a group of similar molecules, with Retinol and β-carotene (beta-carotene, vitamin A precursor substance) is the most common.
In the human body, vitamin A is mainly related to cell growth and differentiation, embryonic development, organ formation, immune function, and visual development.
Do you know vitamin A benefits and side effects?
Table of Contents
- What are the benefits of vitamin A?
- Are there any side effects of vitamin A supplementation?
- Safety Precautions
- What are the food sources of vitamin A?
- Are pregnant women supplemented with vitamin A risky?
- What is the recommended intake of vitamin A?
- Where to buy the best vitamin A supplement?
What are the benefits of vitamin A?
1. Good for children with pneumonia
Pneumonia is defined as an acute lung tissue infection caused by one or co-infected pathogens, but clear bronchiolitis is excluded.
The respiratory syncytial virus is the main viral factor and is found in 15% to 40% of pneumonia cases, followed by influenza A and B, parainfluenza virus, human metapneumovirus, and adenovirus.
Childhood pneumonia is the main single cause of death for children under 5 years of age. It is estimated that the incidence of this age group is 0.29 times per year in developing countries and 0.05 times per year in developed countries. The main risk factors include malnutrition, low birth weight, lack of measles immunity, and indoor air pollution Wait.
A meta-analysis (including 15 randomized controlled trials, a total of 3,021 pneumonia patients) pointed out that although supplementing with vitamin A in addition to regular treatment cannot reduce the mortality rate of pneumonia in children, it improves the overall clinical response rate and shortens Fever, duration of cough, time to clear signs, and reduce abnormal chest x-ray results and hospital stay.
2. Beneficial Retinitis Pigmentosa
Retinitis pigmentosa is a family genetic disease characterized by progressive degeneration of sensory cells in the retina. The early symptoms are mainly slow dark adaptation and night blindness and gradually affect peripheral and central vision. The most serious cause of blindness.
A double-blind controlled trial pointed out (4 to 6 years, 601 patients with retinitis pigmentosa), compared with placebo, supplementation with vitamin A (15,000 IU per day) helps reduce retinal function decline (up to 32%, to Electroretinogram).
3. Prevention of diabetes
Diabetes is a complex metabolic disorder, which is related to high blood sugar and poor insulin action, mainly caused by poor diet and lifestyle habits. It is estimated that by 2030, more than 400 million adult populations will be affected globally.
Animal and human experiments have found that vitamin A can affect islet beta cell production and insulin resistance. If the deficiency is positively related to diabetes.
A retrospective study found (subject to 193,803 Danes) that ingesting more vitamin A (self-fortified nutritional food) at a young age can not only reduce the risk of diabetes in middle and old age but also reduce the prevalence of diabetes in future generations.
4. Promote the health of young children.
According to the World Health Organization survey, pneumonia, diarrhea, and malaria are the top causes of death among infants under 5 years of age after the neonatal period. Among them, diarrhea alone takes the precious lives of 500,000 young children every year.
Malnutrition is the leading cause of such diseases (accounting for 45%), mainly related to poor economic health, parasites, and chronic infections, especially in low- and middle-income countries.
A Cochrane Database of Systematic Reviews (including 47 studies, involving 1,223,856 children aged 6 months and under 5 years old) pointed out that supplementing vitamin A can help reduce the morbidity and mortality of young children ( Especially to reduce the incidence of diarrhea and measles).
5. Reduce the risk of cataract (age-related cataract)
According to the World Health Organization, there are currently more than 37 million blind people in the world, and cataract is the main cause of blindness.
Although cataracts can be treated by artificial lens replacement, due to factors such as uneven medical resources and high cost, some patients still cannot be properly treated. Therefore, it is very important to take the correct precautions.
A meta-analysis of literature (including 22 studies) pointed out that higher intake of vitamin A and β-carotene does help reduce the risk of cataracts.
6. Reduce the incidence of pancreatic cancer
Pancreatic cancer is one of the most difficult to treat cancers of the digestive system. It ranks 4th among the causes of cancer death, and about 3 out of 4 cases occur after the age of 65.
The early symptoms of pancreatic cancer are not specific (such as loss of appetite, slight pain, nausea, and weight loss), which often makes people unconscious. About 80% of them are diagnosed in a more advanced stage and cannot be treated with surgery.
A meta-analysis of literature (including 11 studies) pointed out that the intake of vitamin A is inversely related to the occurrence of pancreatic cancer. Those who ingest more can reduce the risk value by about 16% (compared to less intake).
Are there any side effects of vitamin A supplementation?
For most people with good health, it is safe to take vitamin A from food in moderation without side effects. If you use health care products, you should pay attention to the dosage to avoid long-term overdose causing poisoning.
In general, the poisoning phenomenon is usually related to the recommended dietary intake (RDA) for more than 10 times of long-term consumption, about 25,000-33,000 IU per day.
The symptoms of acute and chronic poisoning of vitamin A include nausea, headache, hair loss, fatigue, loss of appetite, dizziness, dry skin, peeling, cerebral edema, hepatosplenomegaly, bone, and joint pain, etc. Severe cases of liver damage, bleeding, and coma.
There is evidence that oral vitamin A in some ethnic groups is more prone to poisoning, and even lower doses may occur, including the elderly, long-term alcoholics, and patients with familial hyperlipidemia.
Long-term use of high doses may increase osteoporosis and hip fractures, especially for the elderly.
Pregnant women, children, and those with poor liver and kidney function must supplement the health supplements with the medical staff first to ensure safe use.
If you have low blood pressure or take antihypertensive drugs, please be careful, it may cause low blood pressure.
There may be anticoagulant effects, so be careful if you have coagulopathy or take anticoagulants.
High-dose vitamin A combined with tetracycline antibiotics may increase the risk of intracranial hypertension.
Orlistat (or diet pills) and cholesterol-lowering drugs (bile acid chelator) may inhibit vitamin A absorption.
What are the food sources of vitamin A?
Natural vitamin A (retinyl palmitate form) is commonly found in beef, animal liver, eggs, cod liver oil, dairy products, whole milk, and cheese.
In addition, beta-carotene (beta-carotene) is a precursor of vitamin A. Vitamin A content can also be increased by ingesting related carrot-rich vegetarian foods (such as dark green vegetables, yellow or orange vegetables, and fruits): common foods Such as wave vegetables, papaya, sweet potatoes, carrots, pumpkins, peaches, and mangoes.
Are pregnant women supplemented with vitamin A risky?
Although adequate vitamin A is very important for fetal development, excessive intake during early pregnancy may increase the risk of fetal malformations.
Therefore, pregnant women and nursing mothers should pay special attention to the total intake (daily intake of food and health products should not exceed 5,000 IU) to avoid adverse consequences.
In addition, an artificial form of vitamin A (commonly used in high-dose supplements for regular medical treatment) may cause serious fetal birth defects, so it should be avoided. Related forms include Acitretin, Bexarotene, Isotretinoin, Tazarotene.
What is the recommended intake of vitamin A?
According to the Recommended Dietary Allowance standard developed by the American Medical Institute (IOM):
0 to 6 months: 400 mcg per day
7 to 12 months: 500 mcg per day
1 to 3 years old: 300 mcg per day
4 to 8 years old: 400 mcg per day
9 to 13 years old: 600 mcg per day
Youth and adults
Men over 14 years old: 900 mcg per day
Women over 14 years old: 700 mcg per day
(Women can be raised to 770 mcg during pregnancy and 1,300 mcg during lactation)
Where to buy the best vitamin A supplement?
In recent years, food safety problems in various countries have exploded, and it is not healthy but black-hearted products that everyone spends on. Therefore, European and American products with relatively strict quality control have become popular products.
And iHerb.com is a large-scale medical cosmetics e-commerce company in the United States. It has a high satisfaction rate of 97% in the evaluation of Google customers. It provides global home delivery so that you can buy it without risking buying fakes through purchasing high-quality health products.