Potential Health Benefits of Dietary Antioxidants from Supplements vs. Foods

A long history of epidemiological studies has suggested that dietary antioxidants are associated with prevention from heart disease. However, several recent large clinical trials using high doses of antioxidant supplements, such as vitamin E, beta carotene, and vitamin C, have yielded disappointing and controversial results. Despite these null findings, the use of antioxidant supplements in the U.S. continues to grow.

Researchers in this field have speculated that there may be two possible explanations for the discrepancy between these two types of studies. First, the doses used in the clinical trials were too high (antioxidants can act as pro-oxidants in very high doses). Second, the specific antioxidants included in the recent trials contain isolated antioxidants in pill form, which may not be as efficacious as consuming whole foods that contain a combination of antioxidants and other components found in food that may work synergistically with them.

The high popularity of antioxidant supplements underscores the need to determine whether they are efficacious in adults at high risk of cardiovascular disease. The Antioxidant Study aims to address these two hypotheses by comparing the efficacy of foods naturally rich in antioxidants with that of antioxidants in a pill form, at much lower doses than those used in the recent trials, on markers of inflammation in healthy adults at risk of cardiovascular disease. 

Eligible Participants

91 middle-aged, mostly Caucasian, generally healthy adults were enrolled in this study. 


After 8 weeks, neither the group randomized to foods naturally rich in antioxidants nor the group randomized to antioxidants in a pill form had detectable decreases in blood concentrations of three inflammatory markers (IL-6, sICAM-1 and MCP-1).  The results of this study were published in the Nutrition Research journal in February, 2018.