The most common effect of a beta carotene overdose is orange or yellow discoloration of the skin. This coloring is typically most concentrated in the palms of the hands and on the bottoms of the feet, though it has also been known to develop on the face. Diarrhea, uncharacteristic bruising or bleeding, and dizziness are other reported effects of a beta carotene overdose.
In general, a beta carotene overdose is not considered to be serious if it is addressed promptly. The effects are generally easily treatable. In most cases, an overdose can be treated by discontinuing use of the supplement. It may also be possible to treat side effects by reducing the dosage.
To avoid a beta carotene overdose, it is advisable to only use the supplement temporarily to target specific conditions. General use over long periods of time may put an individual at higher risk of side effects. Current or past regular use of cigarettes and heavy consumption of multivitamins can add to the risk of an adverse reaction. Past exposure to asbestos can also make taking the supplement problematic.
There are some medications and supplements which can lose their effectiveness when taken with beta carotene supplements. Cholesterol-lowering medications may be less effective if they are taken in combination with the supplement and vitamin C, vitamin E, and selenium. This includes any of the drugs in the class known as statins. Taking this combination of vitamins with niacin can reduce its effectiveness as well.
Several organizations, such as the World Cancer Research Institute, World Health Organization, and American Cancer Society, recommend getting beta-carotene from whole, fresh foods. This is primarily because there has been little evidence to support the safety of getting this or any other antioxidant from supplements. It has historically not been determined that there is any condition that would require a beta-carotene supplement.
There are also some substances that impede the effectiveness of beta carotene supplements. Excessive consumption of alcohol can lower the level of the substance in the body. It can also increase the amount of retinol, which is believed to have a connection with a higher risk of cancer. Fat substitute products may also reduce the effectiveness of beta carotene supplements.
Beta carotene is one of many pigments that provide a significant amount of vitamin A. Some of the foods in which it can be found include whole grains, vegetables, and fruits. In food or as a supplement, it is used to treat the symptoms of a wide array of conditions including asthma, epilepsy, and Alzheimer’s disease.