All You Need to Know About Vitamin A
Did you know that vitamin A can restore your youth and vitality? It also has a multitude of beneficial effects on human health. Read on as we discuss the role of vitamin A, what its deficiency can lead to and much more!
So, what is vitamin A?
Vitamin A is a fat-soluble vitamin naturally present in foods. It has three active forms (retinol, retinal and retinoic acid) as well as inactive(provitamin) forms such as β-carotene. Retinol is the most biologically active.
β-carotenes are a precursor of vitamin A found in plant-derived foods which are converted to form retinol in the liver and intestine. These compounds present in different foods not only provide us with the necessary nutrition but also helps to protect ourselves against free radical damage, inflammation and other different diseases.
Why is vitamin A essential for us?
Vitamin A has many vital roles in our body. Some of them are as follows:
- Supporting growth and reproduction – Retinol can help in sperm development in men. Vitamin A is required for the formation of heart and circulation, and for the development of hindbrain. It can also help in normal fetal development in pregnant women. Without it, the fetus can have gross abnormalities of the heart.
- Maintaining vision – Vitamin A plays an important role in maintaining vision. The visual activity of the eye reduces the levels of retinal. This necessitates its replenishment either directly through foods or supplements.
- Maintaining the health of epithelial tissues and skin – The vitamin promotes the differentiation of cells present on the surface of our body. Mucous secretions from these cells act as the body’s first line of defence and prevent pathogens and dirt from entering our body. It also helps in protecting against skin damage caused by sunlight. Retinoids help fight visible signs of ageing like hyperpigmentation, blemishes, wrinkles etc.
Vitamin A Deficiency Diseases
Vitamin A deficiency occurs when the liver reserves get depleted. Healthy protein intake is also important for maintaining healthy levels of the vitamin in the body. This is because certain proteins serve as their transport carriers inside the body.
Let us have a look at some common diseases that can occur due to the deficiency of this nutrient!
Night blindness is the inability to see at night or in dim light. The person suffering from night blindness is also unable to recover promptly from the temporary blinding caused due to a flash of bright light at night. Night blindness occurs due to vitamin A deficiency. It is required for the regeneration of rhodopsin (a receptor protein) which helps in night vision.
Vitamin A deficiency is one of the leading causes of blindness in children in developing countries. Studies have shown that Xerophthalmia, not only causes blindness, but also affects growth, general morbidity, and mortality. Xerophthalmia develops in stages. Firstly, the cornea of the eye becomes dry, thick and wrinkled. Following this, the cornea softens leading to irreversible blindness if not treated in time.
In this disorder, the epithelial cells secrete a protein called keratin which changes the skin into dry, rough and scaly lumps of keratin accumulate. This occurs due to the reduction in the number and activity of mucus-secreting cells present in the gastrointestinal tract. The lack of mucus secretion also results in weaker absorption of ingested nutrients. This leads to infections of the respiratory tract, urinary tract, gastrointestinal tract and the inner ear.
Apart from these, vitamin A deficiency can increase the risk of severe infection, especially for children. Infection increases the body’s demand for the vitamin and so the deficiency gets worse. Children can, therefore, become involved in a vicious cycle of deficiency and infection. Additionally, this deficiency is an important cause of child mortality and also affects pregnant women.
Can excess vitamin A be unhealthy?
Vitamin A toxicity can occur due to high levels of it present in the body. Hypervitaminosis A or vitamin A toxicity affects bone metabolism and metabolism of other fat-soluble vitamins. It can cause bone defects like osteoporosis, birth defects and yellow skin.
Toxicity results from ingesting excess preformed vitamin A from foods (such as fish or animal liver), supplements, or prescription medications. It can be prevented by consuming the recommended daily amount.
Toxicity can easily be prevented if you fulfil your daily requirements of vitamin A naturally through foods.
Vitamin A Food Sources
Some foods high in vitamin A (retinol) and β-carotene are fish oil, cod liver oil, goat, beef or pork liver, cheese, carrots, green leafy vegetables such as spinach, kale and collard greens, fortified breakfast cereals, sweet potatoes, pumpkins and dates.
Some vitamin A-rich food dishes that you can easily make in your kitchen are – sweet potato fry, kaddu (pumpkin) ki sabzi, palak (spinach) paneer, palak paratha and gajar (carrot) ka halwa. You can also add all these vegetables to your dals and curries to meet your daily requirements.
The Recommended Daily Allowance (RDA) for retinol is 0.6 milligrams and for beta-carotene is 4.8 milligrams per day. Hence one should aim at consuming the recommended daily intake of vitamin A and avoid getting overboard.