Vitamin A was the first fat soluble vitamin to be identified. As opposed to be being one distinct biomolecule, vitamin A is actually composed of a family of substances known as retinoids. Retinol (alcohol form), retinal (aldehyde form), and carotenoids (previtamin A). There are several carotenoids (a-carotene, cryptoxanthin, lutein, & lycopene), but the one with the most vitamin A activity is beta carotene.
Signs & Symptoms of Deficiency:
- Poor immune function
- Loss of night vision
- Reduced white blood cell counts
- Infertility
- Poor growth
- Skin lesions (eczema)
- Acne
- Fatigue
Vitamin A has been shown to be beneficial in the following conditions:
- Gastric ulcers
- Hypothyroid
- Congestive heart failure
- Cystic Fibrosis
- Gout
- Measles
- Hepatitis
- Upper respiratory infections
- Urinary tract infections
- Diabetes
- Arthritis
- Dermatitis
- Psoriasis
- Atherosclerosis
- The common cold
- Allergies
Drugs, medications, or additives that may deplete or interfere with Vitamin A metabolism:
- Alcohol
- Corticosteroids and other medications that interfere with
- zinc absorption (see zinc)
- Neomycin
- Olestra (a food additive found in many fat free products)
- Mineral oil (when taken consistently in higher doses)
- Cholestyramine
- Colesevelam (Welchol)
- Colestipol
Laboratory testing for Vitamin A:
- HPLC (high performance liquid chromatography) – serum blood draw
- Leukocyte functional assays (Spectracell labs)
Food Sources:
- Liver, cod liver oil, yellow and green leafy vegetables, eggs,and dairy products