Men who consume the most carotenoids have decreased levels of the inflammatory marker known as C-Reactive Protein, a study published in November 2005 in the American Journal of Clinical Nutrition. High levels of C-Reactive Protein (CRP) have been linked to an increased risk of heart disease and cancer and may be associated with other degenerative diseases.
Researchers investigated whether consumption of fruits and vegetables high in carotenoids could affect CRP levels as well as immune function. In a randomized, controlled trial, adult, non-smoking men consumed 2 or less servings per day of fruits and vegetables for 4 weeks. The researchers then randomly assigned the subjects to one of three groups for another four weeks. One group consumed 2 servings per day of carotenoid-rich fruits and vegetables, another group consumed 5 servings per day and the third group consumed 8 servings per day.
In the different groups of subjects, the researchers measured levels of plasma concentrations of vitamins C and E and carotenoids. They also assessed markers of immunity and inflammation including the number and activity of natural killer cells, secretion of cytokines, lymphocyte proliferation, and plasma C-reactive protein concentrations.
The results indicated that the highest intake of fruits and vegetables (8 servings per day) significantly increased total carotenoid concentrations in plasma compared with the low intake (2 servings per day). Concentrations of vitamins C and E did not appear to be affected by high fruit and vegetable intake nor were markers of immunity. However, C-reactive protein was significantly reduced at the end of the study in the subjects who consumed 8 servings per day of carotenoid-rich vegetables and fruit compared with those who consumed 2 servings per day.
According to the study authors, a high intake of carotenoid-rich vegetables and fruit “may reduce inflammatory processes, as indicated by the reduction of plasma C-reactive protein.”
Watzl B, Kulling SE, Moseneder J, Barth SW, Bub A. A 4-wk intervention with high intake of carotenoid-rich vegetables and fruit reduces plasma C-reactive protein in healthy, nonsmoking men. Am J Clin Nutr. 2005 Nov;82(5):1052-8.