Vitamin A stimulates immunity and is needed for formation of bone, protein, and for use by human growth hormone. The vitamin also helps cells differentiate normally. Normal cell differentiation is important, because cells that have not properly differentiated are more likely to become pre-cancerous. Also, healthy cell membranes prevent invasion by disease-causing microorganisms.
Beta carotene is a substance from plants that the body can convert to Vitamin A.
Many nutritionists recommend taking mixed carotenoids, including lycopene, lutein, alpha-carotene, and zeaxanthin, as well as beta carotene
5000 IU. Most supplements contain 10,000 IU
10,000 IU from mixed carotenes.
The first symptom of deficiency is night blindness. Other symptoms can include dry skin, increased risk of infections, and metaplasia, a pre-cancerous condition.
Intake above 25,000 IU (7,500 mcg) per day can cause headaches, dry skin, hair loss, fatigue, bone problems, and liver damage. At higher levels (for example 100,000 IU per day) these problems become more common
Doctors suspect a higher incidence of birth defects in pregnant women consuming Vitamin A. Women who may become pregnant should limit their intake of the vitamin.
Vitamin A and iron together helps overcome iron deficiency more effectively than iron supplementation alone.
Liver, dairy foods, and beta-carotene-containing vegetables, such as, peaches, melons, mangoes, sweet potatoes, squash, pumpkins, tomatoes, and dark leafy greens
Vitamin A is beneficial in treatment of Celiac disease (gluten intolerance), night blindness and infection. It also helps with premenstrual syndrome, immune deficiency syndrome, certain kinds of anemia, gastric disorders, acne, and age related skin changes. Lycopene (one of the carotenoids) has shown promise in preventing prostate cancer.
1. Birth control pills, may cause increased serum levels of Vitamin A.
2. Vitamin A might also reverse some of the beneficial effects of corticosteroids
3. Statin drugs used for high blood pressure may cause increased blood serum levels of Vitamin A.
4. Vitamin A may work synergetically with certain chemotherapy drugs or may help minimize side effects of others.
Hu W, Tong S, Oldenburg B, Feng X. Related Articles
Serum vitamin A concentrations and growth in children and adolescents in Gansu Province, China.
Asia Pac J Clin Nutr. 2001;10(1):63-6.
This study showed that Vitamin A has a definite impact on child growth.
Handelman GJ. Related Articles
The evolving role of carotenoids in human biochemistry.
Nutrition. 2001 Oct;17(10):818-22
One interesting note from this article: The ability of radicals in cigarette smoke to degrade carotenoids might be responsible for the finding that high-dose dietary beta-carotene increased the incidence of lung cancer in smokers
Cramer DW, Kuper H, Harlow BL, Titus-Ernstoff L. Related Articles
Carotenoids, antioxidants and ovarian cancer risk in pre- and postmenopausal women.
Int J Cancer. 2001 Oct 1;94(1):128-34.
One interesting point: Consumption of raw carrots and tomato sauce are strongly related to decreased risk for ovarian cancer.