Vitamin A – What It Is and What It Does!

Vitamin A – what it is and its functions:

Vitamin A , a fat-soluble vitamin, plays an important role in bone growth, reproduction, immune function, hormone synthesis and regulation, and vision. Your eyes need this vitamin to help them convert light into brain signals that allow them to perceive images.

It works to protect against infection by helping to create healthy white blood cells and promoting healthy skin. It helps cells divide and develop into specialized cells such as blood cells, lung cells, brain cells and other distinct tissues.

Best sources:

Pre vitamin A (aka retinol) is found in animal foods such as liver, eggs, milk, fortified cereals and fish. Green leafy vegetables and orange vegetables  and fruits provide this vitamin in the form of carotenoids .

Deficiency:

One of the first detectable signs of a deficiency of this vitamin causes night blindness or the inability to see in the dim light. Common in developing countries, night blindness is a rapidly reversible condition that responds to treatment.

However, if the deficiency becomes more severe, it develops into a so-called irreversible xerophthalmia state, which is a drying out of the parts of the eye that will eventually result in blindness. Other effects of the deficiency include decreased immune function, dry, flaky skin; problems with reproduction; and the interruption of bone growth.

Since vitamin A is a fat-soluble vitamin, it can be stored in the body. Thus, a healthy adult who has stopped eating good food sources of the vitamin may not see symptoms of deficiency until these stores have been depleted, possibly for several months.

Excess s:

High intakes of beta-carotene from food have not been shown to be toxic in humans, but it can cause an unwanted side effect: yellow (or orange ) skin. Fortunately, the beta-carotene tone is harmless and only temporary.

High doses preformed from animal foods or supplements can cause either acute (short term) or chronic toxicity. Signs of short-term vitamin toxicity include nausea, vomiting, headache, dizziness, and blurred vision.

Chronic toxicity (due to ingestion of large doses over months or years) is often characterized by dry, itchy skin, loss of appetite, headache, birth defects, liver abnormalities, central nervous system disorders, and bone and joint pain. Getting too much preprescription vitamin A can also result in reduced bone mineral density, which can lead to osteoporosis.

How much do you need?

First, you need to understand that you can get this vitamin from animal or plant sources and that these sources are treated differently by the body. From animal foods, supplements, and fortified foods it’s called “pre- vitamin A ,” or retinol.

Pre Vitamin A is in a form that is highly available to your body. From plant sources it comes in the form of carotenoids, mainly beta-carotene. To account for the absorption of different forms of this vitamin , scientists created a unit called retinol activity equivalents (RAE).

For example, 12 micrograms (mcg) of beta-carotene is equal to 1 mcg of retinol. To complicate matters, nutrition labels and supplements don’t use Raes, instead they use International Units (IU).