Dietary antioxidant intake reduces carotid intima-media thickness in coronary heart disease patients: From the CORDIOPREV study.

BACKGROUND: Atherosclerosis is the leading underlying cause of coronary heart disease (CHD). In patients with CHD, intima-media thickness of common carotid arteries (IMT-CC) is a reliable, validated, and non-invasive marker of the progression of atherosclerosis. Dietary intervention may affect IMT-CC evolution through different pathways. There is a lack of clinical trials evaluating the effect of total dietary antioxidant content of diets on IMT-CC, especially in patients with CHD.

OBJECTIVE: We evaluated the correlation between the diet's total antioxidant content and the changes in IMT-CC produced after 5 years of dietary intervention following two healthy diet models (Mediterranean diet and low-fat diet). We also evaluated whether the diet's total antioxidant content was related to the total redox capacity of the participants.

METHODS: From the total participants of the CORDIOPREV study (clinical trial register NCT00924937), 805 participants completed the IMT-CC measurement and the dietary antioxidant evaluation at baseline and after 5 years of dietary intervention. IMT-CC was carried out by ultrasound and the dietary antioxidant evaluation was performed by the Dietary Antioxidant Index (DAI). Additionally, direct redox balance was evaluated in a subset of population by the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSH) by colorimetric assay.

RESULTS: We observed an inverse correlation between evolution of DAI and IMT-CC after 5-years of dietary intervention. The mean of the DAI index augmented in the Mediterranean Diet group, whereas it decreased in the Low-fat group. DAI was correlated to the GSH/GSSG ratio, supporting DAI as an adequate estimator of diet's antioxidant content. When looking for individual components of the DAI that were associated to the changes in IMT-CC, an inverse correlation was found for carotenoids, vitamin E, vitamin C, and zinc and the IMT-CC.

CONCLUSIONS: Our study indicates that, after five years of dietary intervention, changes in DAI inversely correlate with changes in IMT-CC in patients with CHD. Overall effect of Mediterranean diet resulted in an increase of DAI, conversely to low-fat. Specific elements included in the DAI index were inversely correlated with IMT-CC.