Supplementation of a Diet Low in Carotenoids with Tomato or Carrot Juice Does Not Affect Lipid Peroxidation in Plasma and Feces of Healthy Men

Abstract

Antioxidant properties of carotenoids are thought to be at least partly responsible for the protective effects of fruits and vegetables rich in carotenoids against colon cancer. There are large amounts of in vitro data supporting this hypothesis. But there is little known about the antioxidant effects of carotenoid-rich food in vivo particularly in the gastrointestinal tract. In a randomized, crossover trial, healthy men (n = 22) who were consuming a low-carotenoid diet drank 330 mL/d tomato juice or carrot juice for 2 wk. Antioxidant capacity was assessed by the "lag time" of ex vivo LDL oxidation induced by copper and lipid peroxidation as determined by measurements of malondialdehyde (MDA) in plasma and feces using HPLC with fluorescence detection. Although consumption of both carotenoid-rich juices for 2 wk increased the carotenoid level in plasma and feces (P < 0.001), the antioxidant capacity of LDL tended to be increased by only approximately 4.5% (P = 0.08), and lipid peroxidation in the men's plasma and feces was not affected. Thus, processes other than lipid peroxidation could be responsible for the preventive effects of tomatoes and carrots against colon cancer.

Tomatoes versus lycopene in oxidative stress and carcinogenesis: conclusions from clinical trials

“…Rao and Shen (2002) also reported a significant decrease in serum lipid peroxidation and protein oxidation in healthy volunteers, following a 2-week consumption of tomato ketchup or oleoresin capsules, with baseline serum lycopene levels less than 0.2 mmol/l. These baseline plasma lycopene levels were lower than those reported by Riso et al (1999), Briviba et al (2004) and Hininger et al (2001) in their studies (0.34, 0.2 and 0.63 mmol/l, respectively). Thus, there may be a possibility that a depleted baseline lycopene level shows a better response to tomato antioxidant supplementation, than subjects with higher values.…”

“…Riso et al (2004) observed no effects on lymphocyte resistance from lipid oxidation, following a 3-week supplementation of tomato products (8 mg lycopene/ day). Briviba et al (2004) also reported null effects on lipid peroxidation in plasma and feces in healthy men following a 2-week supplementation of 330 ml/day of tomato juice. Hininger et al (2001) further supplemented healthy male volunteers with 15 mg of natural tomato lycopene extracts for 12 weeks, and reported no effects on LDL oxidizability.…”

Role of Oxidized Lipids in Atherosclerosis

“…-Carotene is proposed to be efficient scavenger of singlet oxygen and it attenuates oxidative stress, however it does not directly inhibit lipid peroxidation (Briviba et al, 2004).…”

Effet d'une alimentation riche en fruits et légumes sur les taux plasmatiques en antioxydants et des marqueurs des dommages oxydatifs

“…Toutefois, la plupart des études in vivo [14,18,23,24,29,30,33,53] montrent que la consommation en fruits et légumes chez des sujets en bonne santé n'entraîne pas de façon significative une diminution des dommages oxydatifs au niveau des lipides ou de l'ADN. Ces résultats sont évidemment décevants puisque cela est en contradiction avec le fait que la concentration plasmatique en antioxydants est augmentée après un apport interventionnel en fruits et légumes.…”