Importance of Vitamin A
Vitamin A, a key nutrient stored in the liver, has many health benefits. Learn about its types, benefits, and food sources.
Vitamin A, stored in the liver, is a fat-soluble vitamin found in two types of foods. Preformed Vitamin A, also known as retinol, is an active type found in animal foods like meat, fish, poultry, full-fat milk, and dairy products.
The second type, provitamin A, is found in plant-based foods like fruits and vegetables. Also known as carotenoids, they give food its rich color and can convert into an active Vitamin A form. There are over 500 known carotenoids, the most common provitamin A being beta-carotene.
Vitamins are essential nutrients either not produced by the body or produced insufficiently to prevent negative health outcomes or diseases. Therefore, it's crucial to provide vitamins through a balanced diet and vitamin supplements when medically necessary.
Vitamin A is also available in capsules and as dietary supplements. It is often added to supplements as retinyl acetate or retinyl palmitate (preformed Vitamin A), beta-carotene (provitamin A), or a combination of both.
What are the Benefits of Vitamin A?
Vitamin A helps form and maintain healthy teeth, bones, soft tissues, mucus membranes, and skin. It produces the pigments in the retina of the eye. Specifically, Vitamin A facilitates good vision, especially in low light. It plays a significant role in healthy pregnancy and breastfeeding.
Provitamin A, such as beta-carotene, is an antioxidant. Antioxidants protect cells from damage caused by substances known as free radicals. It is known that free radicals contribute to chronic and long-term diseases and play a role in aging. Consuming food sources containing beta-carotene can reduce the risk of cancer. However, it's been observed that beta-carotene supplements do not decrease cancer risk.
Vitamin A Deficiency and Overdose
A deficiency in Vitamin A can lead to various eye and vision problems, including reversible night blindness and irreversible corneal damage, known as xerophthalmia. Vitamin A deficiency can also result in hyperkeratosis, or dry, scaly skin.
Conversely, an overdose of Vitamin A can cause illness. High doses of Vitamin A can lead to birth defects. Acute Vitamin A toxicity usually occurs when an individual consumes several hundred thousand IU of Vitamin A. Chronic Vitamin A toxicity can occur in adults who regularly take more than 25,000 IU daily.
Infants and children are more sensitive to Vitamin A. They may get sick after taking smaller doses of Vitamin A or products containing retinol, a form of Vitamin A.
A high intake of beta-carotene usually doesn't make individuals sick. However, it can turn skin yellow or orange. The skin color returns to normal once the consumption of beta-carotene decreases.
What Foods Contain Vitamin A?
As there are two types of Vitamin A, the sources can be categorized into two.
Preformed Vitamin A comes from animal sources like trout, cottage cheese, liver, mackerel, cod liver oil, salmon, chicken liver, butter, egg yolk, whole milk, cheese, cream, kidney, pisces, and fish oil.
Provitamin A is abundant in vegetables and fruits like pumpkin, broccoli, carrot, spinach, kale, dandelion greens, red pepper, cabbage, parsley, chard, Brussels sprouts, sweet potato, oranges, and other yellow fruits and dark green leafy vegetables. The darker the color of the fruit or vegetable, the more beta-carotene it contains.
Plant sources of beta-carotene are fat and cholesterol-free. When consumed with fat, the absorption of Vitamin A from these sources increases. The best way to meet the body's daily needs for Vitamin A and other important vitamins is to eat a diverse diet of fruits, vegetables, fortified dairy products, legumes like beans, lentils, and whole grains.