May 2, 2016
Now onto the Vita- amines So named because they are vital for life and believed to be amines which is true of thiamine. They are conditionally necessary for survival and our bodies cannot synthesize enough forcing animals to consume them through food.
A: Vitamin A is one of four essential fat soluble vitamins. This means that it can be stored for months in fat cells after consumption. This is primarily done in the liver with vitamin A. There are three basic types of vitamin A found in circulation in humans: retinol, retinoid acid and retinal.
Vitamin A is best known as the vision vitamin, but also is critical to healthy functioning immune and reproductive systems. Vitamin A is necessary for cell growth and differentiation. As a human develops, grows and later repairs, vitamin A is necessary for our cells to become the correct type like a heart cell or liver cell.
In the retina of the eye, vitamin A serves as a cofactor in a reaction with the protein opsin to form rhodopsin. When stimulated by light, the opsin protein is released from vitamin A and causes an electrical signal cascade through the optic nerve that our brain senses as light and vision. There are colored opsin proteins that allow light spectrum analysis. Thus a deficiency of vitamin A will initially present with low light and color visual loss. Over time complete visual loss occurs. A lack of adequate vitamin A is the number one cause of preventable night blindness in the world.
Vitamin A is involved in gene expression. Retinoic acid enters the nucleus of a cell and has the ability to bind to vitamin A specific gene promoter regions. This allows for retinoic acid to turn on and off some specific genes necessary for human health. It turns out that Vitamin D, thyroid hormone, steroid hormones are influenced by vitamin A.
There are hundreds of genes that are regulated by vitamin A. The effects range from cellular proliferation to fat metabolism to critically necessary immune cell function.
Zinc deficiency can affect vitamin A metabolism by multiple methods as it is a cofactor for enzymes that work on vitamin A.
Vitamin A deficiency will exacerbate iron deficiency anemia as it is necessary for iron metabolism. Therefore, consuming vitamin A rich foods while on iron supplementation is a good idea.
Vitamin A deficiency presents with night blindness, recurrent infections, thyroid hormone dysfunction (weight gain, fatigue, hair loss, cold body temperature and constipation) and has associations with certain cancer risks.
Immune cells called T killer cells need vitamin A to proliferate and in the low vitamin A state this does not happen dramatically increasing a persons risk for infection.
For the population that is unvaccinated, vitamin A sufficiency is critical to avoiding a severe measles outcome. Children with low vitamin A levels in their blood have worse morbidity from measles infections.
Food sources of Vitamin A are as beta carotene in bright red, orange, green and yellow colored vegetables and fruits or preformed retinol in animal meats including liver, all dairy, eggs and fish.
Most adults need 900 mcg/day. Incrementally less for kids. This nutrient is easily obtained from a anti inflammatory diet. Pregnancy and infancy are times of increased vitamin needs. We highly stress the need for adequate vitamin A stores for all females of child bearing age. Max dosing of vitamin A for all adults appears to be 2500mcg of preformed retinol per day before toxicity develops. See Linus Pauling Institute link for more information.
People at risk for insufficiency or deficiency have: issues with intestinal fat malabsorption (vitamin A is a fat soluble vitamin like D/E/K), intestinal dysbiosis, inflammatory bowel disease, eating disorders, celiac disease and disorders of bile production or pancreatic enzyme production.
Patients that take cholesterol lowering agents are at risk for low vitamin A levels. Alcoholics and women that take oral contraceptives are two other at risk groups.
Over consumption of vitamin A can be toxic as it is fat soluble and can accumulate in our fat cells. Only the preformed retinol form can be toxic not the vegetable beta carotene type. Signs of toxicity include headache, nausea, vomiting, dry skin, fatigue and bone pain. Anemia and brain swelling will occur with chronic overdose.
*With many of these micronutrients, you will see a pattern that the brain, gut and skin are often affected. These highly metabolic and rapid cell turnover organs are most susceptible to insufficiency states that occur with a modern human processed, government subsidized diet that promotes gut dysfunction, malabsorption and inflammation.
Linus Pauling Institute, National Institutes of Health, Institute for Functional Medicine, University of Arizona Center for Integrative Medicine are the resources for all micronutrient articles.