Vitamins and minerals promise a wealth of health benefits, but very few have scientifically proven attributes. In fact, even their safety has been thrown into question since a number of studies highlighted potential cancer risks. Four supplements, in particular, may increase the odds of the disease unless taken at the correct dose.
In earlier research conducted by Tim Byer, director for cancer prevention and control at the University of Colorado Cancer Centre, a number of supplements may were found to increase the likelihood of cancer.
The researcher, who led a meta-analysis of 12 trials involving more than 300,000, probed the relationship between cancer and several vitamins to assess their protective effect.
The analysis revealed that taking high doses of beta carotene, selenium, vitamin E, and folic acid were all linked with an increased risk of cancer.
The lead researcher said it remained unclear why supplements had these adverse effects, as other supplements included in the analysis didn’t.
READ MORE: Four ways taking dietary supplements can prove ‘life-threatening’ – FDA issues warning
Studies suggest that taken at higher doses, selenium supplements can cause serious side effects.
While the supplement’s association with cancer remains unclear, some research suggests it may increase the risk of aggressive and secondary tumours.
In the study led by the University of Colorado Cancer Centre, the supplement appeared to be linked to a higher risk of skin cancer.
Some studies have suggested there may be a link between vitamin E and a higher risk of prostate cancer.
A statement on the Government’s website suggests that at high doses, vitamin E may act as a pro-oxidant, instead of an antioxidant.
The National Cancer Institute points out, however, that no link has been found between dietary sources of vitamin E and prostate cancer risk.
Conversely, high levels of alpha-tocopherol in the blood may be linked with a lower risk of developing advanced prostate cancer.
Folic acid and B12 supplements were associated with a 21 percent increased risk for cancer, and a 38 percent increased risk of dying from the disease.
Beta-carotene supplements have been associated with an increased risk of lung cancer in people who smoke, or have been exposed to asbestos.
In one study of 29,000, researchers found an 18 percent increased risk of lung cancer among individuals taking 20 mg of beta-carotene a day for five to eight years.
Foods that are rich in beta-carotene, however, are appeared safe and appear to lower the risk of cancer, according to the Mayo Clinic.