Carotene is a precursor form of retinol vitamin A that your body uses. It is not as toxic as retinol, but at 25,000 IU (International Units) per day, that is excessive. It equals 4,166 RE of retinol vitamin A. Males (ages 11 to 51+) Recommended Dietary Allowances (RDA) for vitamin A is 1,000 RE (Retinol Equivalents) and a females (ages 11 to 51+) RDA is 800 RE Why do you feel you need to take more than four times your RDA?
Your RDA of vitamin A could be achieved by eating two or three carrot sticks, one tablespoon of cooked carrots, two tablespoons of cooked winter squash, sweet potatoes or pumpkin, 1/4 cup of dark green leafy vegetables (spinach, beet greens or Swiss chard), 4 asparagus spears, 1/4 cup broccoli, one apricot, 1/2 peach or 1/4 cup cantaloupe. All of these are probably less expensive than your vitamin A pills.
Vitamin A is fat-soluble and is stored in your body along with vitamins D, E and vitamin K. Your body can store up to two years worth in your liver. Levels above 100,000 IU of vitamin A are considered toxic (hypervitaminosis). Loss of hair can occur with megadoses of vitamin A. Excess carotene can cause your skin and the whites of your eyes to turn yellow. I have seen a patient with a jaundiced look to their skin and eyes because of excess carotene intake from supplements. Generally, carotene will turn the skin yellow when the intake is above 20 mg per day (about 34,000 IU). The yellow skin tint is most noticeable on the hands and soles of your feet where there is little underlying tissue between the skin and bones. If the carotene supplement is discontinued, the skin will lose the yellow tint.
Your body uses vitamin A for good night vision and for maintaining the health of your epithelial cells. These cells are found in skin as well as lining your respiratory tract and gastrointestinal tract. Research has found that persons who have an adequate intake of vitamin A have a lower incidence of epithelial cancers. Epithelial cells line the lungs as well as the gastrointestinal tract, urinary tract, and vagina. Research has not advocated megadosing vitamin A to prevent cancer though. A new Finish research project showed that smokers increased their rate of cancer if they took Vitamin A supplements.
In the early 1980’s the FDA restricted the vitamin A content of multivitamin supplements to a maximum of 1,000 RE to limit the possibility of vitamin A toxicity. You can buy vitamin A supplements up to 5,000 RE (25,000 IU).
I would suggest, you discontinue your vitamin A supplements and try eating a bright orange or dark green leafy vegetables for vitamin A. Liver is also an excellent source.