Vitamin A
Two types: Retinoids and cartenoids
Retinoids are preformed Vitamin A and come from animal products.
Retinoids specifically benefit immune, inflammatory, genetic, and reproductive-related systems and can be especially important with respect to pregnancy and childbirth, infancy, childhood growth, night vision, red blood cell production, and resistance to infectious disease.
Animal sources are fat soluable and therefore build up and can be toxic, though rare. (Dr. Weil)
Cartenoids are used by the body to convert to retinoids as needed, they come from plants.
Some have trouble with this conversion process through genetics, gut bacteria, excessive exposure to toxic chemicals, imbalanced intake of vitamin A and vitamin D as a result of high-dose supplementation
Most carotenoid forms of vitamin A function as antioxidant and anti-inflammatory nutrients. The only carotenoids found inside the retina of the human eye are the xanthophylls, lutein and zeaxanthin.
Highest food sources of Vitamin A: sweet potatoes, carrots, spinach, kale. Last two best for eyes (lutein).
Vitamin A toxicity not possible through plant food sources. These are water soluable.
see here (world's healthiest foods) for lots of info on types of Vit A, uses, and ratings of foods.
Studies found supplementation increased lung cancer risk in at-risk populations.. Many experts feel that the risks of high-dose beta-carotene supplementation outweigh any potential benefits for cancer prevention, especially in smokers or other high-risk populations (30, 31). Beta-carotene is sold as individual supplements and also found in supplements marketed to promote visual health (32).
Although diets rich in beta-carotene have generally been associated with reduced cardiovascular disease risk in observational studies, there is no evidence that beta-carotene supplementation reduces cardiovascular disease risk (65).
A study is currently under way to evaluate the effect of supplemental lutein and zeaxanthin on the progression of advanced AMD (79). To date, the available scientific evidence suggests that consuming at least 6 mg/day of dietary lutein and zeaxanthin from fruits and vegetables may decrease the risk of age-related macular degeneration (67-69).
A randomized controlled trial in patients with atrophic AMD found that supplementation with 10 mg/day of lutein slightly improved visual acuity after one year compared to a placebo (80).
Adverse effects of lutein and zeaxanthin have not been reported (102).
Recently dosage levels seem to be
3,000 IU for kids
5,000 IU for adults
Upper tolerance levels about double that.
Retinoids are preformed Vitamin A and come from animal products.
Retinoids specifically benefit immune, inflammatory, genetic, and reproductive-related systems and can be especially important with respect to pregnancy and childbirth, infancy, childhood growth, night vision, red blood cell production, and resistance to infectious disease.
Animal sources are fat soluable and therefore build up and can be toxic, though rare. (Dr. Weil)
Cartenoids are used by the body to convert to retinoids as needed, they come from plants.
Some have trouble with this conversion process through genetics, gut bacteria, excessive exposure to toxic chemicals, imbalanced intake of vitamin A and vitamin D as a result of high-dose supplementation
Most carotenoid forms of vitamin A function as antioxidant and anti-inflammatory nutrients. The only carotenoids found inside the retina of the human eye are the xanthophylls, lutein and zeaxanthin.
Highest food sources of Vitamin A: sweet potatoes, carrots, spinach, kale. Last two best for eyes (lutein).
Vitamin A toxicity not possible through plant food sources. These are water soluable.
see here (world's healthiest foods) for lots of info on types of Vit A, uses, and ratings of foods.
Studies found supplementation increased lung cancer risk in at-risk populations.. Many experts feel that the risks of high-dose beta-carotene supplementation outweigh any potential benefits for cancer prevention, especially in smokers or other high-risk populations (30, 31). Beta-carotene is sold as individual supplements and also found in supplements marketed to promote visual health (32).
Although diets rich in beta-carotene have generally been associated with reduced cardiovascular disease risk in observational studies, there is no evidence that beta-carotene supplementation reduces cardiovascular disease risk (65).
A study is currently under way to evaluate the effect of supplemental lutein and zeaxanthin on the progression of advanced AMD (79). To date, the available scientific evidence suggests that consuming at least 6 mg/day of dietary lutein and zeaxanthin from fruits and vegetables may decrease the risk of age-related macular degeneration (67-69).
A randomized controlled trial in patients with atrophic AMD found that supplementation with 10 mg/day of lutein slightly improved visual acuity after one year compared to a placebo (80).
Adverse effects of lutein and zeaxanthin have not been reported (102).
Recently dosage levels seem to be
3,000 IU for kids
5,000 IU for adults
Upper tolerance levels about double that.