Carrots may reduce cancer risk

Eating carrots can reduce the risk of suffering from heart disease and protect against cancer, The Daily Telegraph has reported.

The story comes from a large 14-year study that found participants with the highest blood levels of alpha-carotene, an antioxidant found in many orange vegetables, were at lower risk of dying from any cause, and from conditions specifically related to cardiovascular disease and cancer.

However, the study only measured people’s alpha-carotene levels. It did not measure blood levels of other antioxidants, so it is difficult to know if alpha-carotene alone is associated with health benefits or if other constituents were also involved. The study also used only one blood sample to measure people’s alpha-carotene levels, and levels may well have changed during the years of the study. These are important limitations.

Like other antioxidants, alpha-carotene is found in several vegetables, including carrots, and this study may be considered to support the health benefits of a diet high in fruit and vege.

However, the health benefits of antioxidant supplements are far from well established and the use of antioxidant supplements requires further research. The public should be aware that there are many different brands of antioxidants on the market and these may not all be subject to the same safety and efficacy regulations as conventional medicines.

Carrots

Overall, this study supports other findings that high consumption of fruit and vegetables is beneficial to health. Its strengths include its large size and relatively lengthy follow-up period. However, it also has some limitations, which make the results less reliable:

* Researchers only took one measurement of blood levels of alpha-carotene. Blood levels may change for various reasons, including variations in diet.
* In particular the researchers did not measure blood levels of other substances (such as other antioxidants), which might have had an effect on results.

* The results may been affected by other unidentified factors (confounders) despite efforts to adjust for some of these.
* The researchers carried out a large number of statistical comparisons between levels of alpha-carotene and mortality from an extensive number of causes. This increases the possibility of chance findings.
* Of note is the fact that alpha-carotene levels were associated with both death from any cause and from cardiovascular causes and cancer. However, when it was subdivided into specific types of disease, the association was no longer significant.

Also, the study provided no indication as to how many vegetables (and of what type) would need to be consumed to match the blood level measurements used in the study.

Carrots

There is no doubt that carrots and other vegetables have health benefits. Whether this is due to the alpha-carotene they contain, to other antioxidants or to a complex balance of nutrients and vitamins they contain, remains uncertain.

Of importance is the fact that the health benefits of antioxidant supplements are far from well established. Other large reviews have found no evidence to support any benefit from taking antioxidant supplements, and have instead identified potentially harmful effects of taking certain supplements, including beta-carotene. As such, the use of antioxidant supplements requires further research.

The public should be aware that there are many different supplement brands on the market and these may not all be subject to the same safety and efficacy regulations as conventional medicines.