Lycopene, Tomatoes, and the Prevention of Coronary Heart Disease

Abstract

Coronary heart disease (CHD) is one of the primary causes of death in the Western world. The emphasis so far has been on the relationship between serum cholesterol levels and the risk of CHD. More recently, oxidative stress induced by reactive oxygen species (ROS) is also considered to play an important part in the etiology of this disease. Oxidation of the circulating low-density lipoprotein (LDL(ox)) is thought to play a key role in the pathogenesis of atherosclerosis and CHD. According to this hypothesis, macrophages inside the arterial wall take up the LDL(ox) and initiate the process of plaque formation. Dietary antioxidants such as vitamin E and beta-carotene have been shown in in vitro studies to prevent the formation of LDL(ox) and their uptake by microphages. In a recent study, healthy human subjects ingesting lycopene, a carotenoid antioxidant, in the form of tomato juice, tomato sauce, and oleoresin soft gel capsules for 1 week had significantly lower levels of LDL(ox) compared with controls. The antioxidant effects of lycopene have also been shown in four other human trials, including one where lycopene consumption reduced the levels of breath pentane. However, in one recent study, dietary supplementation with beta-carotene but not with lycopene was shown to inhibit LDL oxidation. The sources of lycopene used in most of these studies were either tomato products or lycopene extracted from tomatoes containing other carotenoids in various proportions. Therefore, it is not possible to attribute the effects solely to lycopene. Mechanisms other than the antioxidant properties of lycopene have also been shown to reduce the risk of CHD. Lycopene was shown to inhibit the activity of an essential enzyme involved in cholesterol synthesis in an in vitro and a small clinical study suggesting a hypocholesterolemic effect. Other possible mechanisms include enhanced LDL degradation, LDL particle size and composition, plaque rupture, and altered endothelial functions. Recent epidemiological studies have also shown an inverse relationship between tissue and serum levels of lycopene and mortality from CHD, cerebrovascular disease, and myocardial infraction. However, the most impressive population-based evidence comes from a multicenter case-control study where subjects from 10 European countries were evaluated for relationship between antioxidant status and acute myocardial infarctions. After adjusting for a range of dietary variables, only lycopene levels but not beta-carotene were found to be protective. At present, the role of lycopene in the prevention of CHD is strongly suggestive. Although the antioxidant property of lycopene may be one of the principal mechanism for its effect, other mechanisms may also be responsible. Controlled clinical and dietary intervention studies using well-defined subject populations and disease end points must be undertaken in the future to provide definitive evidence for the role of lycopene in the prevention of CHD. Mechanistic studies must also be initiated to understand the mode of ...

Red wine-dependent reduction of nitrite to nitric oxide in the stomach

“…For instance, N 2 O 3 formed via decomposition of HNO 2 (reactions 2 and 3) can be used to nitrosate caffeic acid [47] and several other wine phenolics, including p-coumaric acid [48]. In fact, caffeic acid and its esters have been shown to be efficient inhibitors of nitrosation reactions [46,49,60], thus acting as blockers of carcinogenic nitrosamines formation [47,50,51]. Several observations shown in this study suggest an interaction of caffeic acid with U NO and NO-derived species, namely: the increase in the rate of U NO decay with the increase of caffeic acid concentration (Fig.…”

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

“…Tomatoes are a valuable source of several micronutrients and phytochemicals including carotenoids, polyphenols, potassium, folate, ascorbic acid and a-tocopherol. Most of these nutrients in tomatoes can interact with the host to confer a preventive benefit against oxidative stress-associated diseases, through various mechanisms including antioxidant action (Rao and Agarwal, 2000;Rao, 2002;Canene-Adams et al, 2005). However, the benefits of tomato intake have been mainly attributed to its lycopene content.…”

Chemical Composition and Antioxidant Activity of Portuguese Diospyrus Kaki Fruit by Geographical Origins

“…The same authors had concluded that lycopene concentrations were related with different growing regions, particularly to those with higher sun exposure. A great interest has recently been focused on lycopene due to its preventive activity against several pathologies, such as cardiovascular disease (Rao 2002), hepatic fibrogenesis (Kitade et al, 2002), solar light induced erythema (Stahl & Sies 2002) and some cancer types, such as prostate, gastrointestinal and epithelial (Leong & Shui 2002;Livny et al, 2002). Finally, it is also important to consider the synergic action of carotenoids with other bioactive compounds present in Diospyros kaki fruit, like total polyphenolic content.…”