BackgroundThe name "carotene" was first coined in the early 19th Century by the scientist Wachenroder after he crystallized this compound from carrot roots. Beta-carotene is a member of the carotenoids, which are highly pigmented (red, orange, yellow), fat-soluble compounds naturally present in many fruits, grains, oils, and vegetables (green plants, carrots, sweet potatoes, squash, spinach, apricots, and green peppers). Alpha, beta, and gamma carotene are considered provitamins because they can be converted to active vitamin A.
The carotenes possess antioxidant properties. Vitamin A serves several biological functions including involvement in the synthesis of certain glycoproteins. Vitamin A deficiency leads to abnormal bone development, disorders of the reproductive system, xerophthalmia (a drying condition of the cornea of the eye), and ultimately death.
Commercially available beta-carotene is produced synthetically or from palm oil, algae, or fungi. Beta-carotene is converted to retinol, which is essential for vision and is subsequently converted to retinoic acid, which is used for processes involving growth and cell differentiation. Usage and Dosing NB! The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy. General
- Formulations : Beta-carotene supplements are available in both oil matrix gelatin capsules and water-miscible forms. Some clinical trials have used water-miscible beta-carotene (10%) beadlets. The water miscible form seems to produce a significantly higher response in plasma beta-carotene (approximately 47% to 50%) than oil matrix gelatin capsules. Oral dosage is available in capsules (United States and Canada), tablets (United States and Canada), and chewable tablets (Canada).
- Dietary intake : Consuming 5 servings of fruit and vegetables daily provides 6-8 milligrams of beta-carotene. Beta-carotene requires some dietary fat for absorption, but supplemental beta-carotene is similarly absorbed when taken with high-fat or low-fat meals. 1,800 micrograms of beta-carotene has been reported to maintain adequate vitamin A levels.
- Consensus recommendations : The American Heart Association recommends obtaining antioxidants, including beta-carotene, from a diet high in fruits, vegetables, and whole grains rather than through supplements, until more information is available from randomized clinical trials. Similar statements have been released by the American Cancer Society, the World Cancer Research Institute in association with the American Institute for Cancer Research, and the World Health Organization's International Agency for Research on Cancer. The Institute of Medicine has reviewed beta-carotene, but has not make recommendations for daily intake, citing lack of sufficient evidence. Routine use of beta-carotene supplements is not considered necessary in the general population.
Adults (18 years and older)15-180 milligrams taken by mouth of supplemental beta-carotene has been studied for various indications. Children (younger than 18 years) There is insufficient available data to recommend high-dose oral (by mouth) supplementation in children. Safety NB! There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects. Allergies People who are sensitive to beta-carotene, vitamin A, or any other ingredients in beta-carotene products should avoid supplemental use. Side Effects and Warnings
- Supplemental beta-carotene in children should be limited to specific medical indications. There is insufficient reliable information available about the safety of large doses of beta-carotene in pregnant or breastfeeding women.
- Supplemental beta-carotene may increase the risk of lung cancer, prostate cancer, intracerebral hemorrhage, and cardiovascular and total mortality in people who smoke cigarettes or have a history of high-level exposure to asbestos. Beta-carotene from foods does not seem to have this effect.
- In people who smoke, beta-carotene may increase cardiovascular mortality. In men who smoke and have had a prior myocardial infarction (MI or heart attack), the risk of fatal coronary heart disease increases by as much as 43% with low doses of beta-carotene. There is some evidence that beta-carotene in combination with selenium, vitamin C, and vitamin E might lower high-density lipoprotein 2 (HDL2) cholesterol levels. HDL levels are protective so this is considered to be a negative effect. Dizziness, reversible yellowing of palms, hands, or soles of feet and to a lesser extent the face (called carotenoderma) can occur with high doses of beta-carotene. Loose stools, diarrhea, unusual bleeding or bruising, and joint pain have been reported.
Pregnancy and BreastfeedingU.S. Food and Drug Administration (FDA) Pregnancy Risk Factor C.
Insufficient data are available on larger oral doses of beta-carotene in pregnant and breastfeeding woman.