Vitamin A sources: liver, fish, fortified milk, and eggs; Beta Carotene: sweet potatoes, carrots, spinach, broccoli, squash, mangoes, cantaloupe, peaches, apricots
Active form is known as retinol, found in animal-derived foods. plant provitamin is known as beta carotene. the provitamin is inactive when consumed, it is stored in fat layer under the skin and liver. The body then activates it when needed.
many cells require A for cell differentiation, progress that changes stem cells to specialized cells with specific structures and functions. Needed to support healing, immunity, bone development, and reproduction. Also functions as antioxidant.
Deficiency: first sign is night blindness, since vitamin A is needed to see in low light, when lacking, seeing at night becomes much harder. Dry eyes and keratin secretion (hard lumps/rough skin). Leading cause of blindness is lack of vitamin A.
Toxicity: it is fat soluble, so too much stored in liver can reach toxic levels. Symptoms include itchy skin, loss of appetite, nausea, dizziness, and worst case scenario liver failure. Beta carotene is not active and therefore doesn't carry the same risks as vitamin A, excess (from orange pigment) can cause skin to appear yellow. Large excess amounts for long periods is linked to cancer risks and death.