Vitamin A is a fat-soluble nutrient essential for various bodily functions. It plays a crucial role in vision, particularly in low-light conditions, by maintaining the health of the retina and promoting good eyesight. Additionally, it supports the immune system by helping the body fight off infections and illnesses. Vitamin A is also important for maintaining healthy skin and mucous membranes, which act as barriers against bacteria and viruses.
There are two forms of vitamin A found in food: preformed vitamin A (retinol) and provitamin A carotenoids. Retinol is found in animal products such as liver, eggs, and dairy, while carotenoids are found in colorful fruits and vegetables like carrots, sweet potatoes, and spinach. The body can convert carotenoids into active vitamin A as needed.
A deficiency in vitamin A can lead to night blindness, dry skin, and an increased susceptibility to infections. However, excessive intake of vitamin A can be harmful, so it’s essential to consume it in appropriate amounts as part of a balanced diet.
Requierment :
Functions :
Vitamin A serves several vital functions in the human body. Primarily, it is crucial for maintaining healthy vision, particularly in low-light conditions, by ensuring the proper functioning of the retina and supporting night vision. Additionally, vitamin A plays a pivotal role in promoting a robust immune system, helping the body fight infections and diseases effectively. It contributes to the integrity and health of skin and mucous membranes, acting as a barrier against pathogens and environmental pollutants.Vitamin A and beta-carotene are antioxidants, which may help protect against cancer and improve resistance to certain diseases. They also help form and maintain healthy function of the eyes, hair, teeth, gums, and mucous membranes. In addition, vitamin A is involved in fat metabolism and the production of white blood cells. Vitamin A is a fat-soluble vitamin that comes in two forms: retinol, found in animal tissues, and beta-carotene, found in plants. (Beta-carotene is sometimes called a provitamin because it must be broken down by the body into vitamin A before it acts as a vitamin.)
Deficiency :
Vitamin A deficiency occurs when the body lacks an adequate amount of vitamin A, a crucial nutrient for various bodily functions. Common symptoms include night blindness, where individuals have difficulty seeing in low-light conditions, and eventually, complete blindness if left untreated. Moreover, vitamin A deficiency weakens the immune system, making individuals more susceptible to infections and illnesses.
In children, vitamin A deficiency can lead to stunted growth, delayed development, and increased mortality rates, particularly in developing countries where access to vitamin-rich foods is limited. Pregnant women with a deficiency may face higher risks of complications during childbirth and an increased likelihood of maternal mortality.
Vitamin A deficiency often stems from a diet lacking in foods rich in vitamin A, such as liver, eggs, dairy products, and colorful fruits and vegetables. Addressing vitamin A deficiency typically involves dietary changes, supplementation programs, and public health initiatives aimed at improving access to nutrient-rich foods and education on proper nutrition practices.
Food sources :
Vegetarian Sources :
A . Leafy green vegetables (per 100 grams) :
- Spinach: Approximately 4690 IU
- Kale: Approximately 6813 IU
- Swiss chard: Approximately 6116 IU
- Collard greens: Approximately 3333 IU
- Turnip greens: Approximately 3377 IU
- Mustard greens: Approximately 3024 IU
- Beet greens: Approximately 8717 IU
B. Sweet Potato: 21909 IU per cup (mashed, cooked, without salt)
C. Carrot: 18452 IU per cup (raw, chopped)
D. Red bell pepper: 3727 IU per cup (raw, chopped)
E. Papaya: 1530 IU per cup (cubed)
F. Mango: 1126 IU per fruit (medium size)
G. Watermelon: 865 IU per wedge (approx. 1/16 of a large watermelon)
H. Guava: 624 IU per fruit (medium size)
I. Milk: 395 IU per cup (whole milk)
J. Cheese: 270 IU per ounce (cheddar cheese)
K. Yogurt: 241 IU per cup (plain, whole milk)
Non-Vegetarian Sources (per 100 grams) :
A. Beef liver: Around 22,175 IU
B. Fish liver oil (such as cod liver oil): Roughly 10,000-14,000 IU
C. Eggs: Approximately 520 IU
D. Chicken Liver: 12,325 IU
Supplements :
Over Dosage :
Excessive intake of vitamin A, measured in International Units (IU), can lead to a condition known as hypervitaminosis A. This occurs when the body accumulates too much vitamin A over time, causing toxicity. Symptoms of vitamin A toxicity can range from mild to severe and may include nausea, vomiting, dizziness, headache, blurred vision, bone pain, liver damage, and in severe cases, coma or even death.
The tolerable upper intake level (UL) for vitamin A, established by health authorities, is around 3,000-10,000 IU per day for adults, varying based on age, gender, and other factors. However, chronic consumption of vitamin A supplements exceeding these levels or excessive consumption of animal liver, which is exceptionally high in vitamin A, can increase the risk of toxicity.
It’s essential to be cautious with vitamin A supplementation and to consult healthcare professionals before taking high-dose supplements, especially for pregnant women, as excessive vitamin A intake during pregnancy can harm the developing fetus.
Conclusion :
So, the best choice is to eat a well-balanced diet and get these nutrients from food sources.
