To put it simply, carotene is a type of yellow or red pigment. It is abundant in many dark green and yellow vegetables and fruits. It is also found in milk, egg yolks and body fat.
There are four common forms of carotene, namely α-, Nature Beta-, γ- and δ-. (The last two are pronounced "gamma" and "delta"), they can all be converted into vitamin A, and therefore are considered provitamin A (a general term for the components that can be converted into vitamin A in the human body).
Among the four carotenes, Beta-carotene is the most common in foods and a typical representative of provitamin A.
In general, two-thirds of vitamin A obtained by mammals are derived from Nature Beta-carotene. The most abundant sources are green leafy vegetables and yellow, orange fruits (such as carrots, spinach, lettuce, potatoes, sweet potatoes, etc.). Every egg has beta-carotene. The reason why we think Nature Beta-carotene is very important is precisely because of its provitamin A properties.
What is the mechanism of Nature Beta-carotene?
Beta-carotene can be converted into vitamin A after entering the human body.
Excessive intake of vitamin A by the human body can cause poisoning. The human body will only convert Nature Beta-carotene into vitamin A when it is needed.
This feature makes Nature Beta-carotene a safe source of vitamin A, and there will be no accumulation of vitamin A poisoning caused by excessive intake.