Dietary supplementation with beta-carotene, but not with lycopene, inhibits endothelial cell-mediated oxidation of low-density lipoprotein.

Carotenoids may protect low-density lipoprotein from oxidation, a process implicated in the development of atherosclerosis. Our previous studies showed that in vitro enrichment of low-density lipoprotein (LDL) with beta-carotene protected it from cell-mediated oxidation. However, in vitro enrichment with either lutein or lycopene actually enhanced oxidation of the LDL. In the present studies we have examined the impact of LDL carotenoid content on its oxidation by human aortic endothelial cells (EaHy-1) in culture, comparing the effects of in vivo supplementation with in vitro enrichments. The beta-carotene content in human LDL was increased three- to sixfold by daily supplementation with 15 mg beta-carotene for 4 weeks, and the lycopene content of LDL in other individuals was increased two- to threefold by ingestion of one glass (12 ounce) of tomato juice daily for 3 weeks. LDL isolated from these healthy, normolipidemic donors not taking supplemental carotenoid was incubated at 0.25 mg protein/ml with EaHy-1 cells in Ham's F-10 medium for up to 48 h. Following dietary beta-carotene supplementation, LDL oxidation (as assessed by formation of lipid hydroperoxides) was markedly inhibited, to an even greater extent than was observed for LDL enriched in vitro with beta-carotene (that resulted in an 11- to 12-fold increase in LDL beta-carotene). No effect on cell-mediated oxidation was observed, however, for LDL enriched in vivo with lycopene. Thus, beta-carotene appears to function as an antioxidant in protecting LDL from cell-mediated oxidation although lycopene does not. The fact that the three- to sixfold enrichments of LDL with beta-carotene achieved by dietary supplementation were more effective in inhibiting oxidation than the 11- to 12-fold enrichments achieved by an in vitro method suggests that dietary supplementation is a more appropriate procedure for studies involving the enrichment of lipoprotein with carotenoids.     

Metabolic engineering of beta-carotene and lycopene content in tomato fruit

Ripe tomato fruits accumulate large amounts of the red linear carotene, lycopene (a dietary antioxidant) and small amounts of its orange cyclisation product, beta-carotene (pro-vitamin A). Lycopene is transformed into beta-carotene by the action of lycopene beta-cyclase (beta-Lcy). We introduced, via Agrobacterium-mediated transformation, DNA constructs aimed at up-regulating (OE construct) or down-regulating (AS construct) the expression of the beta-Lcy gene in a fruit-specific fashion. Three transformants containing the OE construct show a significant increase in fruit beta-carotene content. The fruits from these plants display different colour phenotypes, from orange to orange-red, depending on the lycopene/beta-carotene ratio. Fruits from AS transformants show up to 50% inhibition of beta-Lcy expression, accompanied by a slight increase in lycopene content. Leaf carotenoid composition is unaltered in all transformants. In most transformants, an increase in total carotenoid content is observed with respect to the parental line. This increase occurs in the absence of major variations in the expression of endogenous carotenoid genes.     

Localization of carotenoids in plasma low-density lipoproteins studied by surface-enhanced resonance Raman spectroscopy

Surface-enhanced resonance Raman scattering (SERRS) spectra were measured for the beta-carotene and lycopene carotenoids present in low-density lipoproteins (LDLs), which were isolated from human plasma and adsorbed on roughened silver surfaces. The silver surface was modified by formation of a self-assembled monolayer (SAM) of carboxylate-terminated linear alkanethiols in order to simulate the LDL binding region of the cellular LDL receptor. Thiols of different chain length were used to produce SAMs of varying thicknesses. It was shown that carotenoids are not released from the LDL particle upon adsorption onto the bare and thiol modified silver surfaces. The SERRS studies indicated that beta-carotene and lycopene were present in the shell of the LDL particle. The dependence of SERRS on the distance from the silver surface was different for beta-carotene and lycopene in LDL. This observation suggests that the two carotenoids are located in different places of the LDL particle.     

Factors influencing lycopene content of foods, and lycopene intake of Hungarian population

Lycopene is an acyclic, biologically active carotenoid that constitutes foods, its preventive role in several cancerous diseases have been proved by epidemiological and experimental data. Its beneficial role in maintenance of human health is related to its significant antioxidant properties. Data of dietary lycopene intake of the Hungarian population is not available. The aims of the present complex study were 1) to measure the lycopene content of foods frequently consumed in Hungary, 2) to investigate the effect of agrotechnological procedures and food processing on lycopene content of tomatoes, 3) to estimate the lycopene intake in two groups of the Hungarian population with the use of a three-day dietary record. The best lycopene sources are the raw (5.0-16.0 mg/100 g) and processed tomatoes and tomato products (3.0-80.0 mg/100 g), and also watermelon (3.6-6.2 mg/100 g). The variety of the plants, the growing circumstances, and the weather conditions significantly influence the lycopene content of freshly consumed and processed tomato fruits. Mild technological processes can preserve a considerable amount of the original lycopene content in tomato. The estimated average dietary intakes of the Hungarian children (n=521) and adults (n=205) were 2.98 +/- 4.71 mg/day/capita, and 4.24 +/- 8.47 mg/day/capita, respectively. Optimal climate conditions of Hungary makes possible to produce tomato fruits with high dietary value including significant amount of health protective lycopene. Increased consumption of tomato and tomato products with high concentration of lycopene may improve the antioxidant capacity of human body, and the risk of several cancerous diseases may be reduced.     

Lycopenoids: are lycopene metabolites bioactive?

In vitro lycopene is the most potent antioxidant among carotenoids. While antioxidant function may be relevant to health, we hypothesize that metabolites of lycopene may be bioactive and responsible for the beneficial effects of tomato product consumption. We term these metabolites "lycopenoids," which we believe may be produced from carotenoid monooxygenase (CMO) II, paralleling the production of retinoids from beta-carotene by CMO I. We present evidence suggesting that tomato carotenoid metabolites may be responsible for the reduced risk of prostate cancer seen in men consuming high levels of tomato products. Finally, we identify gaps in knowledge in this evolving area of carotenoid research.     

A review of animal model studies of tomato carotenoids,lycopene, and cancer chemoprevention

There are relatively few reports on the cancer chemopreventive effects of lycopene or tomato carotenoids in animal models. The majority, but not all, of these studies indicate a protective effect. Inhibitory effects were reported in two studies using aberrant crypt foci, an intermediate lesion leading to colon cancer, as an end point and in two mammary tumor studies, one using the dimethylbenz(a)anthracene model, and the other the spontaneous mouse model. Inhibitory effects were also reported in mouse lung and rat hepatocarcinoma and bladder cancer models. However, a report from the author's laboratory found no effect in the N-nitrosomethylurea-induced mammary tumor model when crystalline lycopene or a lycopene-rich tomato carotenoid oleoresin was administered in the diet. Unfortunately, because of differences in routes of administration (gavage, intraperitoneal injection, intra-rectal instillation, drinking water, and diet supplementation), species and strain differences, form of lycopene (pure crystalline, beadlet, mixed carotenoid suspension), varying diets (grain-based, casein based) and dose ranges (0.5-500 ppm), no two studies are comparable. It is clear that the majority of ingested lycopene is excreted in the feces and that 1000-fold more lycopene is absorbed and stored in the liver than accumulates in other target organs. Nonetheless, physiologically significant (nanogram) levels of lycopene are assimilated by key organs such as breast, prostate, lung, and colon, and there is a rough dose-response relationship between lycopene intake and blood levels. Pure lycopene was absorbed less efficiently than the lycopene-rich tomato carotenoid oleoresin and blood levels of lycopene in rats fed a grain-based diet were consistently lower than those in rats fed lycopene in a casein-based diet. The latter suggests that the matrix in which lycopene is incorporated is an important determinant of lycopene uptake. A number of issues remain to be resolved before any definitive conclusions can be drawn concerning the anticancer effects of lycopene. These include the following: the optimal dose and form of lycopene, interactions among lycopene and other carotenoids and fat soluble vitamins such as vitamin E and D, the role of dietary fat in regulating lycopene uptake and disposition, organ and tissue specificity, and the problem of extrapolation from rodent models to human populations.     

Elevation of the provitamin A content of transgenic tomato plants

Tomato products are the principal dietary sources of lycopene and major source of beta-carotene, both of which have been shown to benefit human health. To enhance the carotenoid content and profile of tomato fruit, we have produced transgenic lines containing a bacterial carotenoid gene (crtI) encoding the enzyme phytoene desaturase, which converts phytoene into lycopene. Expression of this gene in transgenic tomatoes did not elevate total carotenoid levels. However, the beta-carotene content increased about threefold, up to 45% of the total carotenoid content. Endogenous carotenoid genes were concurrently upregulated, except for phytoene synthase, which was repressed. The alteration in carotenoid content of these plants did not affect growth and development. Levels of noncarotenoid isoprenoids were unchanged in the transformants. The phenotype has been found to be stable and reproducible over at least four generations.     

Effects of menopause and hormone replacement therapy on serum levels of coenzyme Q10 and other lipid-soluble antioxidants

The present study examines the influence of menopause and hormone replacement therapy (HRT) on serum levels of coenzyme Q(10) and other lipid-soluble antioxidants in normal women. Serum levels of coenzyme Q(10), alpha-tocopherol, gamma-tocopherol, beta-carotene and lycopene in 50 premenopausal women (not using oral contraceptives), 33 healthy postmenopausal and 15 postmenopausal women on HRT ("Prempo"; combination of 0.625 mg conjugated estrogen and 2.5 mg medroxyprogesterone acetate) were measured by high-pressure liquid chromatography. Lipid profiles were also analyzed. Significantly higher serum coenzyme Q(10) and alpha-tocopherol levels were detected in postmenopausal compared with premenopausal women (P < 0.05, and < 0.001); whereas, in postmenopausal subjects on HRT, we detected a significant decrease in coenzyme Q(10) and gamma-tocopherol levels (P < 0.001, and < 0.05) and increased alpha-tocopherol levels (P < 0.05). Serum levels of beta-carotene, lycopene, LDL, HDL, cholesterol and triglyceride were comparable among the study groups. Coenzyme Q(10) is postulated to be involved in preventing cardiovascular disease (CVD) because of its bioenergetics role in the mitochondrial respiratory chain and its antioxidant properties at the mitochondrial and extramitochondrial levels. The decrease in serum concentrations of coenzyme Q(10), produced by HRT, may promote oxygen free radical-induced membrane damage and may, thus alter cardiovascular risk in postmenopausal women. HRT-induced reductions in lipid-soluble antioxidant(s) levels, and its potential consequences on CVD, needs to be further investigated.     

Carotenoids and cardiovascular disease: what research gaps remain?

PURPOSE OF REVIEW: Dietary and blood carotenoids, including alpha-carotene, beta-carotene, lycopene, lutein/zeaxanthin, and beta-cryptoxanthin, have been examined in a number of epidemiological studies in recent years for the risk of cardiovascular disease. This review assimilated the existing and recent literature on carotenoids and cardiovascular disease and considered what research gaps may remain. RECENT FINDINGS: Numerous large cohort studies have been published in largely American men and women that have examined dietary intake or blood levels of total or individual carotenoids with the risk of various cardiovascular endpoints. Overall, early, promising results have grown increasingly inconsistent over time. More recently, studies examining lycopene and lutein/zeaxanthin have offered more promising data on a possible, but not yet established, inverse association with the risk of cardiovascular disease. Recent epidemiological data on beta-cryptoxanthin and cardiovascular disease are lacking. Primary and secondary prevention trials have extensively examined beta-carotene, but not other carotenoids, for the risk of cardiovascular disease as either the primary or secondary endpoint with largely null results. More recent studies have focused on individual carotenoids in relation to cardiovascular disease and require a more careful evaluation of potential mechanisms of effect. SUMMARY: The promise of early epidemiological studies on carotenoids and cardiovascular disease paved the way to largely disappointing results from several large prevention trials of beta-carotene. Emerging recent evidence of potential cardioprotective effects for lycopene and other carotenoids besides beta-carotene in the diet and blood suggest that there is more to be learned in the story of carotenoids and both atherosclerotic progression and clinically manifested cardiovascular disease.     

Photoprotective potential of lycopene,beta-carotene,vitamin E,vitamin C and carnosic acid in UVA-irradiated human skin fibroblasts

The photoprotective potential of the dietary antioxidants vitamin C, vitamin E, lycopene, beta-carotene, and the rosemary polyphenol, carnosic acid, was tested in human dermal fibroblasts exposed to ultraviolet-A (UVA) light. The carotenoids were prepared in special nanoparticle formulations together with vitamin C and/or vitamin E. Nanoparticle formulations, in contrast to dimethylsulphoxide, stablized lycopene in the cell culture medium and allowed efficient cellular uptake. The presence of vitamin E in the formulation further increased the stability and cellular uptake of lycopene. UVA irradiation of the human skin fibroblasts led to a 10-15-fold rise in metalloproteinase 1 (MMP-1) mRNA. This rise was suppressed in the presence of low microM concentrations of vitamin E, vitamin C, or carnosic acid but not with beta-carotene or lycopene. Indeed, in the presence of 0.5-1.0 microM beta-carotene or lycopene, the UVA-induced MMP-1 mRNA was further increased by 1.5-2-fold. This increase was totally suppressed when vitamin E was included in the nanoparticle formulation. Heme-oxygenase 1 (HO-1) mRNA expression was strongly induced by UVA irradiation but none of the antioxidants inhibited this effect at the concentrations used in this study. Indeed, beta-carotene or lycopene (0.5-1.0 microM) led to a further 1.5-fold rise in the UVA-induced HO-1 mRNA levels. In conclusion, vitamin C, vitamin E, and carnosic acid showed photoprotective potential. Lycopene and beta-carotene did not protect on their own but in the presence of vitamin E, their stability in culture was improved and the rise in MMP-1 mRNA expression was suppressed, suggesting a requirement for antioxidant protection of the carotenoids against formation of oxidative derivatives that can influence the cellular and molecular responses.     

Protection by quercetin and quercetin 3-O-beta-D-glucuronide of peroxynitrite-induced antioxidant consumption in human plasma low-density lipoprotein.

Effect of quercetin and its conjugated metabolite quercetin 3-O-beta-D-glucuronide (Q3GA), on peroxynitrite-induced consumption of lipophilic antioxidants in human plasma low-density lipoprotein (LDL) was measured to estimate the role of dietary flavonoids in the defense system against oxidative modification of LDL based on the reaction of nitric oxide and superoxide anion. Synthesized peroxynitrite-induced consumption of endogenous lycopene beta-carotene and alpha-tocopherol was effectively suppressed by adding quercetin aglycone into LDL solution. Q3GA also inhibited the consumption of these antioxidants effectively. These results indicate that dietary quercetin is capable of inhibiting peroxynitrite-induced oxidative modification of LDL in association with lipophilic antioxidants present within this lipoprotein particle.     

Overview of mechanisms of action of lycopene

Dietary intakes of tomatoes and tomato products containing lycopene have been shown to be associated with decreased risk of chronic diseases such as cancer and cardiovascular diseases in numerous studies. Serum and tissue lycopene levels have also been inversely related to the risk of lung and prostate cancers. Lycopene functions as a very potent antioxidant, and this is clearly a major important mechanism of lycopene action. In this regard, lycopene can trap singlet oxygen and reduce mutagenesis in the Ames test. However, evidence is accumulating for other mechanisms as well. Lycopene at physiological concentrations can inhibit human cancer cell growth by interfering with growth factor receptor signaling and cell cycle progression specifically in prostate cancer cells without evidence of toxic effects or apoptosis of cells. Studies using human and animal cells have identified a gene, connexin 43, whose expression is upregulated by lycopene and which allows direct intercellular gap junctional communication (GJC). GJC is deficient in many human tumors and its restoration or upregulation is associated with decreased proliferation. The combination of low concentrations of lycopene with 1,25-dihydroxyvitamin D3 exhibits a synergistic effect on cell proliferation and differentiation and an additive effect on cell cycle progression in the HL-60 promyelocytic leukemia cell line, suggesting some interaction at a nuclear or subcellular level. The combination of lycopene and lutein synergistically interact as antioxidants, and this may relate to specific positioning of different carotenoids in membranes. This review will focus on the growing body of evidence that carotenoids have unexpected biologic effects in experimental systems, some of which may contribute to their cancer preventive properties in models of carcinogenesis. Consideration of solubility in vitro, comparison with doses achieved in humans by dietary means, interactions with other phytochemicals, and other potential mechanisms such as stimulation of xenobiotic metabolism, inhibition of cholesterogenesis, modulation of cyclooxygenase pathways, and inhibition of inflammation will be considered. This review will point out areas for future research where more evidence is needed on the effects of lycopene on the etiology of chronic disease.     

Antioxidant and pro-oxidant effects of lycopene in comparison with beta-carotene on oxidant-induced damage in Hs68 cells

Lycopene has become a focal point in recent research following clinical trials that suggest that beta-carotene may promote lung cancer in smokers. Because lycopene only differs from beta-carotene in lacking the beta-ionone structure, and beta-carotene is known to have pro-oxidant activity in vitro, we sought to determine whether lycopene might also have pro-oxidant activity in vitro in comparison with beta-carotene. Human foreskin fibroblasts (Hs68 cells) were first enriched with 10 and 20 μM lycopene or beta-carotene for 1 hr followed by incubation with various oxidants. Lipid peroxidation was measured as thiobarbituric acid-reactive substances (TBARS) released into the medium and DNA damage was measured as formation of comet and 8-hydroxy-2'-deoxyguanosine. The results showed that lycopene at 20 μM significantly decreased levels of TBARS induced by ferric nitrilotriacetate (Fe/NTA) but enhanced levels of TBARS induced by a lipid-soluble radical generator (2,2'-azobis[2,4-dimethylvaleronitrile]; AMVN). Both the antioxidant and pro-oxidant effects of lycopene tended to be dose-dependent. beta-Carotene at 20 μM did not significantly decrease TBARS induced by Fe/NTA but significantly increased TBARS induced by AMVN. Lipid peroxidation induced by a water-soluble radical generator 2,2'-azobis(2-amidinopropane)dihydrochloride was not significantly affected by either lycopene or beta-carotene. Neither lycopene nor beta-carotene affected DNA damage or changes in cell morphology induced by any of the three oxidants tested. The present study in Hs68 cells demonstrates that lycopene can be either an antioxidant or a pro-oxidant depending on the oxidants used, and that lycopene and beta-carotene behave similarly under the in vitro oxidative conditions. Although it is unclear whether lycopene may have pro-oxidant activity in vivo, our results caution that it may be premature to undertake clinical trials with lycopene.     

Chemistry,distribution, and metabolism of tomato carotenoids and their impact on human health

Recent epidemiological studies have suggested that the consumption of tomatoes and tomato-based food products reduce the risk of prostate cancer in humans. This protective effect has been attributed to carotenoids, which are one of the major classes of phytochemicals in this fruit. The most abundant carotenoid in tomato is lycopene, followed by phytoene, phytofluene, zeta-carotene, gamma-carotene, beta-carotene, neurosporene, and lutein. The distribution of lycopene and related carotenoids in tomatoes and tomato-based food products has been determined by extraction and high-performance liquid chromatography-UV/Visible photodiode array detection. Detailed qualitative and quantitative analysis of human serum, milk, and organs, particularly prostate, have revealed the presence of all the aforementioned carotenoids in biologically significant concentrations. Two oxidative metabolites of lycopene, 2,6-cyclolycopene-1,5-diols A and B, which are only present in tomatoes in extremely low concentrations, have been isolated and identified in human serum, milk, organs (liver, lung, breast, liver, prostate, colon) and skin. Carotenoids may also play an important role in the prevention of age-related macular degeneration, cataracts, and other blinding disorders. Among 25 dietary carotenoids and nine metabolites routinely found in human serum, mainly (3R,3'R,6'R)-lutein, (3R,3'R)-zeaxanthin, lycopene, and their metabolites were detected in ocular tissues. In this review we identified and quantified the complete spectrum of carotenoids from pooled human retinal pigment epithelium, ciliary body, iris, lens, and in the uveal tract and in other tissues of the human eye to gain a better insight into the metabolic pathways of ocular carotenoids. Although (3R,3'R,6'R)-lutein, (3R,3'R)-zeaxanthin, and their metabolites constitute the major carotenoids in human ocular tissues, lycopene and a wide range of dietary carotenoids have been detected in high concentrations in ciliary body and retinal pigment epithelium. The possible role of lycopene and other dietary carotenoids in the prevention of age-related macular degeneration and other eye diseases is discussed.     

A role for reduced coenzyme Q in atherosclerosis?

Substantial evidence implicates oxidative modification of low density lipoprotein (LDL) as an important event contributing to atherogenesis. As a result, the elucidation of the molecular mechanisms by which LDL is oxidized and how such oxidation is prevented by antioxidants has been a significant research focus. Studies on the antioxidation of LDL lipids have focused primarily on alpha-tocopherol (alpha-TOH), biologically and chemically the most active form of vitamin E and quantitatively the major lipid-soluble antioxidant in extracts prepared from human LDL. In addition to alpha-TOH, plasma LDL also contains low levels of ubiquinol-10 (CoQ10H2; the reduced form of coenzyme Q10). Recent studies have shown that in oxidizing plasma lipoproteins alpha-TOH can exhibit anti- or pro-oxidant activities for the lipoprotein's lipids exposed to a vast array of oxidants. This article reviews the molecular action of alpha-TOH in LDL undergoing "mild" radical-initiated lipid peroxidation, and discusses how small levels of CoQ10H2 can represent an efficient antioxidant defence for lipoprotein lipids. We also comment on the levels alpha-TOH, CoQ10H2 and lipid oxidation products in the intima of patients with coronary artery disease and report on preliminary studies examining the effect of coenzyme Q10 supplementation on atherogenesis in apolipoprotein E knockout mice.     

A review of epidemiologic studies of tomatoes,lycopene, and prostate cancer

Prostate cancer is the most common cancer in American men. Preventable measures for this malignancy are not well established. Among potentially beneficial natural compounds is the carotenoid lycopene, which is derived largely from tomato-based products. Recent epidemiologic studies have suggested a potential benefit of this carotenoid against the risk of prostate cancer, particularly the more lethal forms of this cancer. Five studies support a 30% to 40% reduction in risk associated with high tomato or lycopene consumption, three are consistent with a 30% reduction in risk, but the results were not statistically significant, and seven were not supportive of an association. The largest relevant dietary study, a prospective study in male health professionals found that consumption of two to four servings of tomato sauce per week was associated with about a 35% risk reduction of total prostate cancer and a 50% reduction of advanced (extraprostatic) prostate cancer. Tomato sauce was by far the strongest predictor of plasma lycopene levels in this study. In the largest plasma-based study, very similar risk reductions were observed for total and advanced prostate cancer for the highest versus lowest quintile of lycopene. Other studies, mostly dietary case-control studies, have not been as supportive of this hypothesis. The reasons for these inconsistencies are unclear, but in three of the seven null studies, tomato consumption or serum lycopene level may have been too low to observe an effect. Because the concentration and bioavailability of lycopene vary greatly across the various food items, dietary questionnaires vary markedly in their usefulness of estimating the true variation in tissue lycopene concentrations across individuals. To optimize the interpretation of future findings, the usefulness of the questionnaire to measure lycopene levels in a population should be directly assessed. Although not definitive, the available data suggest that increased consumption of tomatoes and tomato-based products may be prudent.     

Lycopene-rich treatments modify noneosinophilic airway inflammation in asthma: proof of concept

Antioxidant-rich diets are associated with reduced asthma prevalence. However, direct evidence that altering intake of antioxidant-rich foods affects asthma is lacking. The objective was to investigate changes in asthma and airway inflammation resulting from a low antioxidant diet and subsequent use of lycopene-rich treatments. Asthmatic adults (n=32) consumed a low antioxidant diet for 10 days, then commenced a randomized, cross-over trial involving 3×7 day treatment arms (placebo, tomato extract (45 mg lycopene/day) and tomato juice (45 mg lycopene/day)). With consumption of a low antioxidant diet, plasma carotenoid concentrations decreased, Asthma Control Score worsened, %FEV₁ and %FVC decreased and %sputum neutrophils increased. Treatment with both tomato juice and extract reduced airway neutrophil influx. Treatment with tomato extract also reduced sputum neutrophil elastase activity. In conclusion, dietary antioxidant consumption modifies clinical asthma outcomes. Changing dietary antioxidant intake may be contributing to rising asthma prevalence. Lycopene-rich supplements should be further investigated as a therapeutic intervention.     

Lycopene, tomatoes, and coronary heart disease

Tomato and its major antioxidant component lycopene have recently been focused as important antioxidant nutrients because of their ability to reduce reactive oxygen species and to provide health benefits. Most of the studies were undertaken to determine the usefulness of lycopene against cancer and cardiovascular diseases. Epidemiological studies, however, yielded conflicting results. This study was undertaken to compare cardioprotective abilities of tomato juice and lycopene. Rats were gavaged either tomato juice or lycopene for 3 weeks. At the end of 3 weeks, isolated hearts were subjected to 30 min ischemia followed by 2 h of reperfusion. Both tomato juice and lycopene reduced the extent of lipid peroxidation; but only tomato juice, but not lycopene, improved post-ischemic ventricular function, and reduced myocardial infarct size and cardiomyocyte apoptosis. The results indicated for the first time that tomato juice, but not lycopene, possesses cardioprotective ability.     

Lycopene,tomatoes, and coronary heart disease

Tomato and its major antioxidant component lycopene have recently been focused as important antioxidant nutrients because of their ability to reduce reactive oxygen species and to provide health benefits. Most of the studies were undertaken to determine the usefulness of lycopene against cancer and cardiovascular diseases. Epidemiological studies, however, yielded conflicting results. This study was undertaken to compare cardioprotective abilities of tomato juice and lycopene. Rats were gavaged either tomato juice or lycopene for 3 weeks. At the end of 3 weeks, isolated hearts were subjected to 30?min ischemia followed by 2?h of reperfusion. Both tomato juice and lycopene reduced the extent of lipid peroxidation; but only tomato juice, but not lycopene, improved post-ischemic ventricular function, and reduced myocardial infarct size and cardiomyocyte apoptosis. The results indicated for the first time that tomato juice, but not lycopene, possesses cardioprotective ability.     

Effects of dietary factors on oxidation of low-density lipoprotein particles

Oxidized low-density lipoproteins (ox-LDLs) appear to play a significant role in atherogenesis. In fact, circulating ox-LDL concentrations have been recognized as a risk factor for cardiovascular disease (CVD). A higher intake of some nutrients and specific food compounds such as monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs) and flavonoids have also been associated with a lower risk of CVD. These dietary factors could be associated to a lower risk of CVD through a reduction of the atherogenicity of LDL particles through limited oxidation. Therefore, the purpose of this article is to review human clinical studies that evaluated effects of dietary antioxidant vitamins, fatty acids (MUFA, PUFA) and specific flavonoid-rich foods on LDL particle oxidation and describe potential mechanisms by which dietary factors may prevent oxidation of LDL particles. Antioxidant vitamin supplements such as alpha-tocopherol and ascorbic acid as well as beta-carotene and fish-oil supplements have not been clearly demonstrated to prevent oxidation of LDL particles. Moreover, inconsistent documented effects of flavonoid-rich food such as olive oil, tea, red wine and soy on LDL particle oxidizability may be explained by difference in variety and quantity of flavonoid compounds used among studies. However, a healthy food pattern such as the Mediterranean diet, which includes a combination of antioxidant compounds and flavonoid-rich foods, appears effective to decrease LDL particle oxidizability, which may give some insight of the cardiovascular benefits associated with the Mediterranean diet.