Effects of Carotenoids on Health: Are All the Same? Results from Clinical Trials

Background: Oxidative stress is implicated in the pathogenesis of a lot of age-related pathologies and some types of cancers. Carotenoids have shown antioxidant properties, due to the ability to quench singlet oxygen and to scavenge free radicals that may prevent and treat a wide range of chronic diseases. The aim of this review is to discuss the clinical evidence present in literature about the effects of carotenoids on human health and to evaluate their effectiveness in the prevention and treatment of many chronic diseases. Method: We reviewed studies on carotenoids claiming to show an effect in the prevention and treatment of many chronic diseases. In particular, we focused our attention on clinical trials published on Natural Medicine Comprehensive Database and PubMed. Results: A great number of clinical trials reported the beneficial effects of carotenoids on human health, in particular against skin, eye, hepatic, cardiovascular diseases and some types of cancer. Nevertheless, a few study evaluated the intake of carotenoids alone and sometimes the results are discording. Furthermore, irrational or excessive use of antioxidants may produce risk of potential toxicity. Conclusion: The antioxidant activity of carotenoids, taken with the diet or through nutritional supplements, seems to benefit human health. Therefore, it is necessary to test them alone and to evaluate their safety in longterm clinical trials on a large and heterogeneous sample of people.