Summary

Vitamin A (FatSol) [DV: 7500IU] {Half Life = Vitamin A 12 days} Important for healthy and functional vision, immune system, bone growth/development and reproduction. Vitamin A also helps the heart, lungs, kidneys, and skin work properly, reducing hyperpigmentation in the case of skin.

This fat soluble vitamin is needed for the synthesis of immune system proteins such as T cells, and plays a role in killing off old cells. A deficiency may be associated with autoimmune diseases such as RA and Type 1 Diabetes.

Vitamin A can be harmful in large amounts [60,000μg / 200,000 IU/day]. Source natural vitamin A ‘beta-carotene’ and avoid the synthetic versions ‘retinyl palmitate’ and ‘retinyl acetate’. 

Vitamin A is a fat-soluble vitamin that is essential for many bodily functions, including vision, immune system performance, and cellular communication. It exists in two primary forms in the human diet: preformed vitamin A (retinol and its esterified form, retinyl ester) and provitamin A carotenoids (beta-carotene and others).

Chemical Structure

Retinol: The alcohol form of vitamin A, which can be converted into retinal and retinoic acid, the active forms of the vitamin.
Beta-carotene: A provitamin A carotenoid that the body can convert into retinol. It is an antioxidant and contributes to the vitamin A activity in the body.

Biological Functions

Vision: Vitamin A is critical for the maintenance of normal vision. Retinal, a form of vitamin A, combines with opsin to form rhodopsin, a molecule necessary for color vision and low-light vision.
Immune System: It enhances the immune system by maintaining the health of the skin and mucous barriers (first line of defense) and increasing the production and efficacy of white blood cells.
Cell Growth: Retinoic acid, another form of vitamin A, acts as a hormone-like growth factor for epithelial cells and other cell types.
Reproduction: It plays a role in the development and function of sperm and ovaries.
Skin Health: Vitamin A is essential for skin health, promoting cell production and growth.

Dietary Sources

Vitamin A can be obtained from animal and plant sources:

Animal Sources (Preformed Vitamin A):
- Liver (the richest source)
- Fish oils
- Eggs
- Dairy products (milk, cheese, butter)
Plant Sources (Provitamin A Carotenoids):
- Carrots
- Sweet potatoes
- Spinach
- Kale
- Broccoli
- Mangoes
- Apricots

Deficiency

Vitamin A deficiency can lead to several health issues:

Night Blindness: One of the earliest signs of deficiency.
Xerophthalmia: A condition that can lead to blindness if untreated, characterized by dryness of the conjunctiva and cornea.
Increased Infection Risk: Due to impaired immunity.
Skin Issues: Dry, rough, or scaly skin.

Recommended Daily Allowance (RDA)

The RDA for vitamin A varies by age, sex, and life stage:

Infants: 400-500 micrograms (mcg) of retinol activity equivalents (RAE)
Children (1-8 years): 300-400 mcg RAE
Males (9-13 years): 600 mcg RAE
Females (9-13 years): 600 mcg RAE
Males (14 years and older): 900 mcg RAE
Females (14 years and older): 700 mcg RAE
Pregnant Women: 770-1300 mcg RAE
Breastfeeding Women: 1200-1300 mcg RAE

Toxicity

Vitamin A toxicity, also known as hypervitaminosis A, can occur from excessive intake of preformed vitamin A (retinol). Symptoms include:

Nausea and vomiting
Headache
Dizziness
Blurred vision
Liver damage
Intracranial pressure increase
Birth defects (when pregnant women consume excessive amounts)

Carotenoid forms of vitamin A (such as beta-carotene) do not cause toxicity but can cause carotenodermia, a harmless condition where the skin turns yellow-orange.

Vitamin A is vital for maintaining vision, promoting immune function, and supporting skin health and cell growth. Adequate intake through a balanced diet that includes both animal and plant sources can help maintain optimal health. However, it is important to manage intake to avoid deficiency or toxicity, particularly with the use of supplements.