Moderate intervention with carotenoid-rich vegetable products reduces lipid peroxidation in men

Because of their antioxidant properties, carotenoids may have beneficial ef fects in preventing cancer and cardiovascular disease. However, in humans c onsuming carotenoid-rich vegetables, data concerning the antioxidant effect s of carotenoids are rather scarce. A human intervention trial was conducte d, therefore, to determine whether a moderately increased consumption of ca rotenoid-rich vegetables would influence the antioxidant status in 23 healt hy men. This short-term feeding study lasted 8 wk during which the men cons umed a low carotenoid diet. A 2-wk low carotenoid period was followed by da ily consumption of 330 mL tomato juice, then by 330 mL carrot juice and the n by 10 g of spinach powder, each for 2 wk. Antioxidant status [water-solub le antioxidants in serum, ferric reducing ability of plasma (FRAP) and anti oxidant enzyme activities] and lipid peroxidation (plasma malondialdehyde a nd ex vivo oxidation of LDL) were determined. In a subgroup of 10 men, lipo protein carotenoids were measured. The consumption of carotenoid-rich veget ables significantly increased selected carotenoids in lipoproteins but had only minor effects on their relative distribution pattern. Tomato juice con sumption reduced plasma thiobarbituric acid reactive substances (TBARS) by 12% (P < 0.05) and lipoprotein oxidizability in terms of an increased lag t ime (18%, P < 0.05). Carrot juice and spinach powder had no effect on lipid peroxidation. Water-soluble antioxidants, FRAP, glutathione peroxidase and reductase activities did not change during any study period. In evaluating the low carotenoid diet, we conclude that the additional consumption of ca rotenoid-rich vegetable products enhanced lipoprotein carotenoid concentrat ions, but only tomato juice reduced LDL oxidation in healthy men.