Vitamin A is an essential vitamin that plays a vital role in the growth and development of your body. Our body cannot manufacture it and therefore has to be supplied through diets.
Vitamin A is naturally available in many foods or added to some processed foods, such as milk and cereal. You can get the recommended amount from a variety of foods you eat or from dietary supplements.
In this article we will discuss about Vitamin A benefits, its functions, food sources, effects of deficiency and toxicity as well.
What is Vitamin A
Vitamin A is actually a group of fat-soluble vitamins which are known as retinol, retinal and retinyl esters.
You can get two types of vitamin A from your diet: Preformed vitamin A from animal sources and Provitamin A from plant sources.
Preformed vitamin A is found in the form of retinol and Provitamin A is found in the form of carotenoids. One such carotenoid is beta-carotene.
To use them, your body first convert both types of vitamin A to retinal and retinoic acid, which are the active forms of the vitamin.
When vitamin A intake is sufficient, 90% of total body vitamin A is stored in your liver as retinyl esters.
Preformed vitamin A is well absorbed and utilized by humans at absorption rates of 70–90%. In developed countries up to 75% of dietary vitamin A is obtained from preformed vitamin A.
Provitamin A is absorbed much less efficiently, at rates of 20–50%. In developing countries, though, 70–90% of vitamin A is obtained from provitamin A.
Food Sources of vitamin A
There are a wide variety of foods rich in vitamin A. You can get adequate amount that your body needs from a healthy diet alone.
Preformed vitamin A is abundant in some animal-derived foods, whereas provitamin A are abundant in darkly colored fruits and vegetables.
Foods that are rich in vitamin A include:
Food with vitamin A from plant sources (Provitamin A)
Green leafy vegetables (spinach, lettuce, kale, parsley, broccoli)
- Sweet potato
- Red peppers
- Fruits (apple, watermelon, grapes, guava, papaya, orange, mango)
Food with vitamin A from animal sources (Preformed vitamin A)
- Egg yolk
- Beef liver
- Chicken liver
- Cod liver oil
- Dairy products (milk, cheese, butter)
Ripe, coloured fruits and cooked, yellow tubers can supply you more vitamin A than equal amounts of dark green, leafy vegetables.
Daily Requirement of Vitamin A
The recommended daily amount of vitamin A is the amount you get from both the food and supplements you take.
- 1-3 years: 300 mcg/day
- 4-8 years: 400 mcg/day
- 9-13 years: 600 mcg/day
- Adult (Female): 700 mcg/day
- Adult (Male): 900 mcg/day
- Breastfeeding (14-18 years): 1200 mcg/day
- Breastfeeding (19-50 years): 1300 mcg/day
- Pregnant (14-18 years): 750 mcg/day
- Pregnant (19-50 years): 770 mcg/day
Benefits of Vitamin A
Vitamin A provides us a wide range of benefits that include:
- Supports cell growth and development
- Improves vision and treats night blindness
- Prevents and treats xeropthalmia (dry eye syndrome)
- May lowers the risk of certain cancers
- Improves fertility
- Prevents osteoporosis and maintain overall bone health
- Supports delayed growth in children
- Strengthen the immune system
- Control diabetes by managing insulin release
- Maintains oil secretion in the skin and hair tissue
- Important for healthy pregnancy and breastfeeding
- Maintains healthy teeth
- Reduces Your Risk of Acne
Function of Vitamin A
Retinal, a form of vitamin A promotes good eyesight, particularly in low light. Retinal is combined with a protein called opsin to form rhodopsin, which is an essential light absorbing molecule essential for color vision and seeing in dim light.
Retinoic acid form of vitamin A is vital to prevent xerophthalmia. It helps to maintain healthy teeth, skeletal and soft tissue, mucus membranes, and skin as well.
Vitamin A in the form of beta-carotene is linked to a lowered risk of certain cancers, including Hodgkin’s lymphoma and cervical, lung, and bladder cancer. Carotenoids of vitamin A enhance the activity of the immune system and helps in controlling infections.
Vitamin A toxicity
Taking too much vitamin A can be risky. Vitamin A toxicity or Hypervitaminosis A occurs when you consume too much of vitamin A. Excess amounts of vitamin A are stored in your liver, and it accumulates over time.
Many people develop vitamin A toxicity by taking high-dose dietary supplements containing vitamin A for a longer period of time.
Vitamin A toxicity may be acute or chronic. Acute toxicity occurs after taking too much vitamin A over a short period of time, usually within a few hours or days of consumption. Symptoms include:
- Abdominal pain
- Nausea or vomiting
Chronic toxicity occurs when too much of the vitamin is build up in your body over a long period of time. This requires in excess of 50.000 units per day for more than three months. Some nonspecific symptoms include:
- Blurry vision
- Bone pain
- Hair loss
- Loss of appetite
- Cracked fingernails
- Dry & rough skin
Some potential complications of excess vitamin A include:
- Liver damage
- Excess calcium build up in the body (Hypocalcaemia)
- Kidney damage due to excess calcium
- Renal stones
- Increased risk of fractures
Vitamin A is an essential nutrient which plays a vital role for many important processes in your body.
It is required for functioning of the visual system, growth and development, immunity and reproduction. Besides, it helps maintain the health of your skin and hair.
Vitamin A benefits you by maintaining your body’s natural defences. However, Both too little and too much vitamin A could have unhelpful effects on your overall health. Night blindness is the first symptom of vitamin A deficiency.
The best way to make sure you get the right amount of vitamin A is to consume vitamin-rich foods and avoid supplementing with excessive amounts.