The role of antioxidants in the Mediterranean diets: focus on cancer

Wine, Resveratrol and Health: A Review

Several studies have cited the Mediterranean diet as an example of healthy eating. In fact, the Mediterranean diet has become the reference diet for the prevention of cardiovascular disease. Red wine seems to be an essential component of the diet, since moderate consumption of wine is associated with lower risk and mortality from cardiovascular disease. Evidence is also accumulating that wine helps prevent the development of certain cancers. Of all the many components of wine, resveratrol, which is a natural component specifically present in wine, has been identified as being mainly responsible for these health-promoting properties. Many valuable properties such as cardioprotective and anticarcinogenic activity have been attributed to resveratrol; however, its bioavailability is quite low. The bioactivity of metabolites derived from resveratrol, and the accumulation of resveratrol in vital organs are still under study, but there are high expectations of positive results. Other stilbene compounds are also considered in this review, despite being present in undetectable or very small quantities in wine. The present paper reviews all aspects of the health properties of wine, bioactive compounds found in wine, and their concentrations, bioavailability and possible synergistic effects.

Bioactivity of Grape Chemicals for Human Health

Grapevine ( Vitis vinifera) products, grape and grape juice, represent a valuable source of bioactive phytochemicals, synthesized by three secondary metabolic pathways (phenylpropanoid, isoprenoid and alkaloid biosynthetic routes) and stored in different plant tissues. In the last decades, compelling evidence suggested that regular consumption of these products may contribute to reducing the incidence of chronic illnesses, such as cancer, cardiovascular diseases, ischemic stroke, neurodegenerative disorders and aging, in a context of the Mediterranean dietary tradition. The health benefits arising from grape product intake can be ascribed to the potpourri of biologically active chemicals occurring in grapes. Among them, the recently discovered presence of melatonin adds a new element to the already complex grape chemistry. Melatonin, and its possible synergistic action with the great variety of polyphenols, contributes to further explaining the observed health benefits associated with regular grape product consumption.

Bioactivity and structure of biophenols as mediators of chronic diseases

Biophenols and their associated activity have generated intense interest. Current topics of debate are their bioavailability and bioactivity. It is generally assumed that their plasma concentrations are insufficient to produce the health benefits previously attributed to their consumption. However, data on localized in vivo concentrations are not available and many questions remain unanswered. Potential mechanisms by which they may exert significant bioactivity are discussed together with structure activity relationships. Biophenols are highly reactive species and they can react with a range of other compounds. Products of their reaction when functioning as antioxidants are examined.

Expression profiling of ascorbic acid-related genes during tomato fruit development and ripening and in response to stress conditions

L-ascorbate (the reduced form of vitamin C) participates in diverse biological processes including pathogen defence mechanisms, and the modulation of plant growth and morphology, and also acts as an enzyme cofactor and redox status indicator. One of its chief biological functions is as an antioxidant. L-ascorbate intake has been implicated in the prevention/alleviation of varied human ailments and diseases including cancer. To study the regulation of accumulation of this important nutraceutical in fruit, the expression of 24 tomato (Solanum lycopersicon) genes involved in the biosynthesis, oxidation, and recycling of L-ascorbate during the development and ripening of fruit have been characterized. Taken together with L-ascorbate abundance data, the results show distinct changes in the expression profiles for these genes, implicating them in nodal regulatory roles during the process of L-ascorbate accumulation in tomato fruit. The expression of these genes was further studied in the context of abiotic and post-harvest stress, including the effects of heat, cold, wounding, oxygen supply, and ethylene. Important aspects of the hypoxic and post-anoxic response in tomato fruit are discussed. The data suggest that L-galactose-1-phosphate phosphatase could play an important role in regulating ascorbic acid accumulation during tomato fruit development and ripening.

Analytical determination of antioxidants in tomato: typical components of the Mediterranean diet

Diets in the countries of the Mediterranean basin are characterised by abundant plant foods (fruits, vegetables, breads, nuts, seeds, wine, and olive oil) and include fish and low-fat dairy products. Among the vegetables, tomatoes are a main component of the traditional Mediterranean diet, which has been associated with health protection and longevity. Eating tomatoes has been associated with reduced risks of some types of cancer and other diseases. These beneficial properties appear to be related to the antioxidant content of the fruit, particularly carotenoids (lycopene and beta-carotene), ascorbic acid, and phenols, which may play a role in inhibiting reactions mediated by reactive oxygen species. Due to the importance of antioxidant compounds in tomatoes and tomato products, we present here an overview of current analytical methods (from 2000 until the present date) for determining the different antioxidants. The analytical procedures used to determine individual compounds involve extraction from the sample, analytical separation, and quantification. The choice of analytical method depends on the particular focus of the analysis and the kind of product analysed. High-performance liquid chromatography is the technique of choice for the analysis of tomato antioxidants.

Different radical scavenging tests in virgin olive oil and their relation to the total phenol content

Four different antioxidant tests (ABTS*+, DPPH, ORAC, beta-carotene-linoleate model system) were used to determine the free-radical scavenging activity of 39 extra virgin olive oils (EVOO) and compare the total phenol content by the Folin-Ciocalteu method. The correlation between the total phenols and antioxidant capacities measured by the four methods was very high, and highest with ABTS*+ (R2 = 0.9905). Some of these methods of measurement were applied to olive-oil samples (OO), with approximately a 50% decrease in the value of the antioxidant capacity in comparison with values found for EVOO. In conclusion, the results show that all the methods tested were suitable for determining the antioxidant capacity of olive oil. The Picual variety of extra-virgin olive oil showed high antioxidant activity.

Daily consumption of a high-phenol extra-virgin olive oil reduces oxidative DNA damage in postmenopausal women

Extra-virgin olive oils (EVOO), high in phenolic compounds with antioxidant properties, could be partly responsible for the lower mortality and incidence of cancer and CVD in the Mediterranean region. The present study aims to measure oxidative DNA damage in healthy human subjects consuming olive oils with different concentrations of natural phenols. A randomised cross-over trial of high-phenol EVOO (high-EVOO; 592mg total phenols/kg)Vlow-phenol EVOO (low-EVOO; 147mg/kg) was conducted in ten postmenopausal women in Florence. Subjects were asked to substitute all types of fat and oils habitually consumed with the study oil (50g/d) for 8 weeks in each period. Oxidative DNA damage was measured by the comet assay in peripheral blood lymphocytes, collected at each visit during the study period. Urine samples over 24h were collected to measure the excretion of the olive oil phenols. The average of the four measurements of oxidative DNA damage during treatment with high-EVOO was 30% lower than the average during the low-EVOO treatment (p=0·02). Urinary excretion of hydroxytyrosol and its metabolite homovanillyl alcohol were significantly increased in subjects consuming high-EVOO. Despite the small sample size, the present study showed a reduction of DNA damage by consumption of an EVOO rich in phenols, particularly hydroxytyrosol.

The altered homeostatic theory: A hypothesis proposed to be useful in understanding and preventing ischemic heart disease, hypertension, and diabetes – including reducing the risk of age and atherosclerosis

Evidence will be presented to support the usefulness of the altered homeostatic theory in understanding basic pathogenetic mechanisms of ischemic heart disease (IHD), hypertension, and diabetes, and in improving prevention of these disorders. The theory argues that: IHD, hypertension, and diabetes share the same basic pathogenesis; risk factors favor a sympathetic homeostatic shift; preventative factors favor a parasympathetic homeostatic shift; risk and preventative factors oppose each other through a dynamic risk/prevention balance; and prevention should be based on improving the risk/prevention balance. Prevention based on improving the risk/prevention balance should be more effective, as this method is regarded as reflecting more accurately basic pathogenetic mechanisms. As example, the theory argues that the risk of supposedly nonmodifiable risk factors as age and the risk of relatively nonmodifiable atherosclerosis can be reduced significantly. The possible validity of the altered homeostatic theory was tested by a study based on multiple associations. Findings support a common pathogenesis for IHD, hypertension, and diabetes based on a sympathetic homeostatic shift, and the usefulness of prevention based on improving the risk/prevention balance by using standard pharmaceutical and lifestyle preventative measures. The same set of multiple and diverse risk factors favored IHD, hypertension, and diabetes, and the same set of multiple and diverse pharmaceutical and lifestyle preventative measures prevented these disorders. Also, the same set of preventative agents generally improved cognitive function and bone density, and reduced the incidence of Alzheimer's disease, atrial fibrillation, and cancer. Unexpectedly, evidence was developed that four major attributes of sympathetic activation represent four major risk factors; attributes of sympathetic activation are a tendency toward thrombosis and vasoconstriction, lipidemia, inflammation, and hyperglycemia, and corresponding risk factors are endothelial dysfunction (which expresses thrombosis/vasoconstriction and epitomizes this tendency), dyslipidemia, inflammation, and insulin resistance. These findings, plus other information, provide evidence that dyslipidemia acts mainly as a marker of risk of IHD, rather than being the basic mechanism of this disorder. However, prevention generally is based solely on improvement of dyslipidemia; basing prevention on dyslipidemia relatively underemphasizes the importance of other significant risk factors and, by certifying its validity, discourages alternate pathogenetic approaches. Also, development of myocardial infarction is approached differently. It seems generally accepted that dyslipidemia results rather automatically in infarction through the sequence of atherosclerosis, atherosclerotic complications, and thrombosis. In contrast, distinction is made between development of atherosclerosis and acute induction of infarction--where atherosclerosis is only one of multiple risk factors.

Trends in incidence rates of oesophagus and gastric cancer in Italy by subsite and histology, 1986-1997

OBJECTIVE

Population-based studies in Western countries suggest that the incidence of oesophageal adenocarcinoma (OA) and gastric cardia adenocarcinoma (GCA) is increasing, whereas the incidence of distal gastric carcinoma and oesophageal squamous cell carcinoma (OSCC) is declining. This is the first population-based study carried out in a southern European region to evaluate the time trends in incidence rates of oesophageal and gastric tumours according to subsite and histology over the period 1986-1997.

METHODS

Cancer cases were drawn from seven registries of the Italian Network of Cancer Registries, which covers approximately 9% of the Italian population (annual average 5 027 944). Time trends in age and sex-standardized incidence rates were reported. Estimated annual percentage changes (EAPC) and related 95% confidence intervals (CI) were estimated by modelling age, sex, subsite and morphology-specific incidence rates through Poisson log-linear regression, and whenever necessary negative-binomial regression. Overall, 25 895 gastric and 2497 oesophageal carcinomas were examined.

RESULTS

On the whole, an increasing trend was observed for OA plus GCA. The increase was statistically significant in younger women (<60 years: EAPC 3.7; 95% CI 0.2; 7.3) and in older men (>75 years: EAPC 4.0; 95% CI 1.2; 6.9). Similar trends were also observed in proximal gastric cancer (GCA plus fundus). A decline in the stomach subfundus incidence was observed in both sexes and in each age group. OSCC decreased significantly in men (EAPC-2.6; 95% CI-4.1;-0.9).

CONCLUSIONS

It is plausible that the different tendencies in oesophageal and proximal gastric cancer in men and women are attributable to heterogeneous distributions of risk factors by sex or age.

Protective effect of Aquilegia vulgaris L. on aflatoxin B(1)-induced hepatic damage in rats

The aim of the study was to investigate the effect of ethanol and ethyl acetate extract obtained from Aquilegia vulgaris L. on microsomal lipid peroxidation, reduced glutathione level and antioxidant enzymes activity in the liver of rats intoxicated with aflatoxin B(1) (AFB(1)). Animals were pretreated with 12 daily p.o. doses of the extracts tested (100mg/kg body weight). Then AFB(1) was administered intraperitoneally at a single dose of 1.5mg/kg b.w. to evoke the liver damage. α-Tocopherol was used as a positive control. Reduced glutathione (GSH) was depleted in aflatoxin-treated rats by 80% in comparison with that in the controls. The extracts restored the GSH concentration up to the basal level. Microsomal lipid peroxidation stimulated by Fe(2+)/ascorbate (assessed by measuring TBARS) was enhanced in AFB(1)-treated rats by 28% as compared to that in the control group. The extracts caused a decrease in TBARS level by 40% and 27%. Only two antioxidant enzymes were affected by AFB(1) administration. The activity of catalase was reduced by 24% and the activity of glutathione-S-transferase (GST) was increased by 33%. The pretreatment with ethyl acetate and ethanol extract reduced the GST activity by 76% and 30%, respectively. No significant changes in the activity of other antioxidant enzymes were observed in rats treated with the extracts and AFB(1). It can be concluded that multiple pretreatment with the extracts obtained from A. vulgaris attenuated aflatoxin B(1)-induced hepatic damage as evidenced by inhibition of lipid peroxidation and preventing reduced glutathione depletion.

A role for fruit content in energy-restricted diets in improving antioxidant status in obese women during weight loss

OBJECTIVE

The aim of the present work was to estimate the ability of two hypocaloric diets with different fruit contents to improve antioxidant biomarkers related to lipid peroxidation in obese women.

METHODS

Fifteen obese women (age 32 +/- 6 y, body mass index 34.9 +/- 2.9 kg/m2) were assigned to two different dietary treatments for 8 wk. The subjects received a hypocaloric diet (600 kcal/d restriction from the measured individual energy expenditure) containing 5% (n = 8) or 15% (n = 7) energy supplied by fructose from fruits. Anthropometric measurements, blood lipid profile, plasma oxidative markers, total antioxidant capacity, and malondialdehyde (MDA) were evaluated before and after the nutritional intervention in addition to some relations among them.

RESULTS

No differences in weight loss were observed between diets (5% energy from fructose in the low fruit diet -6.9 +/- 2% versus 15% energy from fructose in the high fruit diet -6.6 +/- 2%; P = 0.781). Low-density lipoprotein cholesterol levels significantly decreased (P = 0.048) in obese women who followed the high fruit diet, which was accompanied by a statistical (P = 0.046) diet-related decrease (-30%) in the ratio of MDA to antioxidant capacity. There was a positive association between MDA diet-related change and low-density lipoprotein cholesterol (r = 0.665, P = 0.003), with antioxidant capacity directly proportional to the fiber plus fructose content associated with fruit consumption (r = 0.697, P = 0.025).

CONCLUSION

A fruit-enriched hypocaloric diet appears to be more effective against oxidative stress. Consumption of antioxidant substances contained in fruit could be a useful strategy in the design of hypocaloric diets that, with the weight reduction, could increase the improvement of cardiovascular risk factors related to obesity.