Beta-carotene is a carotenoid found in some plants and is an antioxidant. It is also responsible for the orange colour of carrots.
Antioxidants are thought to help protect against the harmful effects of free radicals on the body's cells.
However, evidence for the health benefits of antioxidants is inconclusive and too many antioxidants may actually be harmful.
Beta-carotene is also associated with healthy levels of vitamin A in the body. It is needed for good vision, strong immunity and general good health.
Beta-carotene has become popular partly because it is an antioxidant. The British Dietetic Association says: "some phytochemicals such as flavonoids, glucosinolate and phyto-oestrogens act as antioxidants, which may reduce damage to cell DNA and cell membranes. Other phytochemicals are thought to influence the activation of carcinogens (cancer causing agents), or increase the level of protective liver enzymes."
A number of studies show that people who eat a lot of fruit and vegetables that are rich in beta-carotene have a lower risk of some cancers and heart disease. However, Cancer Research UK cautions that hard evidence on the benefits of antioxidants is thin on the ground. It cites the long-term EPIC study (co-funded by Cancer Research UK) of more than 500,000 people in European countries that reported mixed results. It found evidence that some cancers are less common in people who eat a diet high in fruit and vegetables. And when the team have done further analysis, they found that there’s a weak but measurable effect with foods rich in some antioxidants, namely vitamin C and lycopene, on the risk of developing some types of cancer.
Cancer Research UK concludes: "It’s reasonable to say that it’s likely that a diet high in foods containing some antioxidants might protect against some cancers under some circumstances as part of some diets. But equally, if there was a substantial net benefit to be gained, these trials would probably have spotted it too - and they haven’t."
So far studies have not found that beta-carotene supplements have the same health benefits as foods. It should also be noted that beta-carotene supplements have been found to increase the risk of lung cancer developing in smokers and in people who have been heavily exposed to asbestos.
Beta-carotene supplements may help people with specific health problems. For example, supplements might be used by someone with a clear vitamin A deficiency. They also might help those with the genetic condition erythropoietic protoporphyria (EPP). Both conditions are rare.
There is some evidence that beta-carotene supplements might slow the course of osteoarthritis, but more research is needed. Some studies suggest taking beta-carotene along with zinc and vitamins C and E may also help reduce progression of age-related macular degeneration, a leading cause of blindness in older people.
For instance, a Dutch study published in the Journal of the American Medical Association of over 5,000 people, concluded "a high dietary intake of beta carotene, vitamins C and E, and zinc was associated with a substantially reduced risk of AMD in elderly persons." But more studies are needed.
Beta-carotene supplements have been studied as a treatment for many other diseases. Examples include cataracts, Alzheimer's disease and cystic fibrosis. The results have been inconclusive.