Flavonoids, vitamin C and adenocarcinoma of the stomach

Multifactorial etiology of gastric cancer

The prevalence of gastric cancer is associated with several factors including geographical location, diet, and genetic background of the host. However, it is evident that infection with Helicobacter pylori (H. pylori) is crucial for the development of the disease. Virulence of the bacteria is also important in modulating the risk of the disease. After infection, H. pylori gains access to the gastric mucosa and triggers the production of cytokines that promote recruitment of inflammatory cells, probably involved in tissue damage. Once the infection is established, a cascade of inflammatory steps associated with changes in the gastric epithelia that may lead to cancer is triggered. H. pylori-induced gastritis and H. pylori-associated gastric cancer have been the focus of extensive research aiming to discover the underlying mechanisms of gastric tissue damage. This research has led to the association of host genetic components with the risk of the disease. Among these is the presence of single nucleotide polymorphisms (SNPs) in several genes, including cytokine genes, which are able to differentially modulate the production of inflammatory cytokines and then modulate the risk of gastric cancer. Interestingly, the frequency of some of these SNPs is different among populations and may serve as a predictive factor for gastric cancer risk within that specific population. However, the role played by other genetic modifications should not be minimized. Methylation of gene promoters has been recognized as a major mechanism of gene expression regulation without changing the primary structure of the DNA. Most DNA methylation occurs in cytosine residues in CpG dinucleotide, but it can also be found in other DNA bases. DNA methyltransferases add methyl groups to the CpG dinucleotide, and when this methylation level is too high, the gene expression is turned off. In H. pylori infection as well as in gastric cancer, hypermethylation of promoters of genes involved in cell cycle control, metabolism of essential nutrients, and production of inflammatory mediators, among others, has been described. Interestingly, DNA changes like SNPs or mutations can create CpG sites in sequences where transcription factors normally sit, affecting transcription.In this chapter, we review the literature about the role of SNPs and methylation on H. pylori infection and gastric cancer, with big emphasis to the H. pylori role in the development of the disease due to the strong association between both.

Isoflavone intake and risk of gastric cancer: a population-based prospective cohort study in Japan

BACKGROUND

Isoflavones are structurally similar to 17β-estradiol and may be able to prevent gastric cancer. However, there is contradictory evidence concerning the relation between the intake of soy food, which is rich in isoflavones, and gastric cancer. The association with gastric cancer might differ between isoflavones and soy foods, and research on the effects of isoflavone intake alone on gastric cancer is needed.

OBJECTIVE

We investigated the association between isoflavone intake and the incidence of gastric cancer.

DESIGN

We conducted a large, population-based prospective study of 39,569 men and 45,312 women aged 45-74 y. Dietary soy and isoflavone intakes were measured by using a validated food-frequency questionnaire in 1995 and 1998.

RESULTS

During 806,550 person-years of follow-up, we identified 1249 new gastric cancer cases. Isoflavone intake was not associated with gastric cancer in either men or women. Compared with the lowest quartile, the HR and 95% CI for developing gastric cancer in the fourth quartile of isoflavone intake was 1.00 (0.81, 1.24) for men and 1.07 (0.77, 1.50) for women. In a stratified analysis by exogenous female hormones (women only), however, we found an increasing trend in risk of gastric cancer associated with higher isoflavone intakes among exogenous female hormone users (P-trend = 0.03) but not for nonusers (P-interaction = 0.04).

CONCLUSION

The current study does not support the hypothesis that higher intakes of isoflavones prevent gastric cancer in either men or women.

Proanthocyanidins and other flavonoids in relation to pancreatic cancer: a case-control study in Italy

BACKGROUND

Four cohort studies have examined the relation between flavonoids and pancreatic cancer risk providing inconsistent results.

PATIENTS AND METHODS

We conducted a case-control study between 1991 and 2008 in Northern Italy. Subjects were 326 cases with incident pancreatic cancer and 652 frequency-matched controls (admitted to the same hospitals as cases for acute non-neoplastic conditions) who answered a reproducible and valid food-frequency questionnaire. We computed odds ratios (ORs) using logistic regression models conditioned on gender, age and study center, and adjusted for education, history of diabetes, tobacco smoking, alcohol drinking and energy intake.

RESULTS

Proanthocyanidins with three or more mers were inversely related to pancreatic cancer risk. The ORs were similar in all classes of polymers with three or more mers and in their combination (OR for the highest versus the lowest quintile of intake, 0.41; 95% confidence interval 0.24-0.69), and did not substantially change after adjustment for fruit and vegetable consumption, and for vitamin C and folate intakes. Eating an additional portion of fruits rich in proanthocyanidins every day reduced the risk of pancreatic cancer by 25%.

CONCLUSION

Dietary proanthocyanidins-mostly present in apples, pears and pulses-may convey some protection against pancreatic cancer risk.

Estimated dietary intakes of flavonols, flavanones and flavones in the European Prospective Investigation into Cancer and Nutrition (EPIC) 24 hour dietary recall cohort

Flavonols, flavanones and flavones (FLAV) are sub-classes of flavonoids that exert cardioprotective and anti-carcinogenic propertiesin vitroandin vivo. We aimed to estimate the FLAV dietary intake, their food sources and associated lifestyle factors in ten European countries participating in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. FLAV intake and their food sources for 36 037 subjects, aged between 35 and 74 years, in twenty-seven study centres were obtained using standardised 24 h dietary recall software (EPIC-SOFT). Anad hocfood composition database on FLAV was compiled using data from US Department of Agriculture and Phenol-Explorer databases and was expanded using recipes, estimations and flavonoid retention factors in order to increase its correspondence with the 24 h dietary recall. Our results showed that the highest FLAV-consuming centre was the UK health-conscious group, with 130·9 and 97·0 mg/d for men and women, respectively. The lowest FLAV intakes were 36·8 mg/d in men from Umeå and 37·2 mg/d in women from Malmö (Sweden). The flavanone sub-class was the main contributor to the total FLAV intake ranging from 46·6 to 52·9 % depending on the region. Flavonols ranged from 38·5 to 47·3 % and flavones from 5·8 to 8·6 %. FLAV intake was higher in women, non-smokers, increased with level of education and physical activity. The major food sources were citrus fruits and citrus-based juices (especially for flavanones), tea, wine, other fruits and some vegetables. We concluded that the present study shows heterogeneity in intake of these three sub-classes of flavonoids across European regions and highlights differences by sex and other sociodemographic and lifestyle factors.

Estimation of the intake of anthocyanidins and their food sources in the European Prospective Investigation into Cancer and Nutrition (EPIC) study

Anthocyanidins are bioactive flavonoids with potential health-promoting effects. These may vary among single anthocyanidins considering differences in their bioavailability and some of the mechanisms involved. The aim of the present study was to estimate the dietary intake of anthocyanidins, their food sources and the lifestyle factors (sex, age, BMI, smoking status, educational level and physisical activity) involved among twenty-seven centres in ten European countries participating in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Anthocyanidin intake and their food sources for 36 037 subjects, aged between 35 and 74 years, in twenty-seven redefined centres were obtained using standardised 24 h dietary recall software (EPIC-SOFT). An ad hoc food composition database on anthocyanidins (cyanidin, delphinidin, malvidin, pelargonidin, peonidin, petunidin) was compiled using data from the US Department of Agriculture and Phenol-Explorer databases and was expanded by adding recipes, estimated values and cooking factors. For men, the total anthocyanidin mean intake ranged from 19·83 (se 1·53) mg/d (Bilthoven, The Netherlands) to 64·88 (se 1·86) mg/d (Turin, Italy), whereas for women the range was 18·73 (se 2·80) mg/d (Granada, Spain) to 44·08 (se 2·45) mg/d (Turin, Italy). A clear south to north gradient intake was observed. Cyanidins and malvidins were the main anthocynidin contributors depending on the region and sex. Anthocyanidin intake was higher in non-obese older females, non-smokers, and increased with educational level and physical activity. The major food sources were fruits, wine, non-alcoholic beverages and some vegetables. The present study shows differences in both total and individual anthocyanidin intakes and various lifestyle factors throughout Europe, with some geographical variability in their food sources.

Assessment of antioxidants in foods and biological samples: a short critique

Antioxidants can be defined on a biological basis by their ability to inhibit the oxidation of susceptible biomolecules such as proteins, lipids and DNA. There is observational evidence on an inverse association between dietary antioxidant intake and the development of chronic conditions, although randomized trials have not confirmed these results. The antioxidant potential of a biological material can be evaluated by methods categorized into three groups. The first group includes the determination of the individual antioxidants present in the investigated sample. The second focuses on 'total antioxidant capacity', which is considered a convenient tool for obtaining an overall estimate of the antioxidant potential of the sample. The third group involves the quantification of in vivo markers of oxidative stress, such as the products of protein, lipid and DNA oxidation. Due to differences between the assays, however, current research suggests the application of a combination of such methods for a more informative assessment of the oxidation status of the organism.

Dietary quercetin intake and risk of gastric cancer: results from a population-based study in Sweden

BACKGROUND

To study the impact of the dietary antioxidant quercetin on risk of gastric adenocarcinoma.

PATIENTS AND METHODS

Using data from a large Swedish population-based case-control study of gastric cancer (505 cases and 1116 controls), we studied the association between quercetin and risk of anatomic (cardia/noncardia) and histological (intestinal and diffuse) subtypes of gastric cancer.

RESULTS

We found strong inverse associations between quercetin and the risk of noncardia gastric adenocarcinoma, with an adjusted odds ratio (OR) of 0.57 (95% confidence interval 0.40-0.83) for the highest quintile (≥11.9 mg) of daily quercetin intake relative to the lowest quintile of intake (<4 mg quercetin/day), supported by a significant decreasing linear trend (P value < 0.001). Similar findings were observed for the intestinal and diffuse subtype. For cardia cancer, we found a less evident and nonsignificant inverse relationship. The protection of quercetin appeared to be stronger among female smokers, with the OR leveled of at values <0.2 in quintiles 3-5 (>6 mg quercetin/day).

CONCLUSIONS

High dietary quercetin intake is inversely related to the risk of noncardia gastric adenocarcinoma, and the protection appears to be particularly strong for women exposed to oxidative stress, such as tobacco smoking.

Flavonoids, proanthocyanidins, and the risk of stomach cancer

Flavonoids have been suggested to be responsible for the potential beneficial properties of fruit and vegetables on stomach cancer risk. To provide further information on flavonoids, proanthocyanidins, and gastric cancer risk, we analyzed data from a case-control study conducted in Italy. Subjects were 230 cases with incident, histologically confirmed gastric cancer and 547 frequency-matched controls, admitted to the same hospitals of cases for acute, non-neoplastic conditions. Subjects were interviewed using a reproducible and valid food frequency questionnaire. We estimated the odds ratios (ORs) of gastric cancer and their corresponding 95% confidence intervals (CIs) using unconditional logistic regression models including terms for major recognized gastric cancer risk factors. The ORs of the highest quintile of intake compared to the lowest were below unity for all classes of flavonoids, in the absence, however, of significant associations. Strong inverse relations were found for proanthocyanidins. The OR was 0.44 (95% CI, 0.25-0.76) for monomers and dimers combined and 0.36 (95% CI, 0.21-0.63) for polymers with three or more mers. Further adjustment for fruit and vegetables, or vitamin C, did not materially change these associations. This is the first epidemiological study to suggest that dietary proanthocyanidins have a favorable role on gastric cancer risk.

Selected aspects of Mediterranean diet and cancer risk

European Mediterranean populations have a high life expectancy. Several aspects of their diet are considered favorable on health. We considered the role of various aspects of the Mediterranean diet on cancer risk in a series of Italian case-control studies including about 10,000 cases of cancer at 13 different sites and over 17,000 controls. For most epithelial cancers, the risk decreased with increasing vegetable consumption. Allium vegetables were also favorably related to cancer risk. Fruit intake was inversely associated with digestive tract and laryngeal cancers. For digestive tract cancers, the population attributable risks for low intake of vegetables and fruit ranged between 15% and 40%. Olive oil and unsaturated fats, which are typical aspects of the Mediterranean diet, were inversely related to the risk of several cancers, particularly of the upper aerodigestive tract. Whole grain food (and hence possibly fiber) intake was also related to reduced risk of various cancers. In contrast, refined grains and, consequently, glycemic load and index were associated to increased risks. Several micronutrients and food components (including folate, flavonoids, and carotenoids) showed inverse relations with cancer risk, but the main component(s) responsible for the favorable effect of a diet rich in vegetables and fruit remain undefined.

Proanthocyanidins and the risk of colorectal cancer in Italy

Proanthocyanidins are a group of polymers of flavanols. Animal and in vitro studies suggest they decrease cancer risk, particularly of colorectal cancer. We used data from an Italian case-control study to investigate whether proanthocyanidins are related to colorectal cancer risk. Cases were 1,953 patients with incident, histologically confirmed colorectal cancer (1,225 colon cancers, 728 rectal cancers). Controls were 4,154 patients admitted for acute, non-neoplastic conditions. A reproducible and valid food frequency questionnaire was used. We estimated odds ratios (ORs) through multiple logistic regression models, including terms for potential confounding factors, and energy intake. A trend of decreasing risk with increasing intake of proanthocyanidins emerged for all classes except monomers. The OR for the highest vs. the lowest quintile of intake was 0.82 for monomers and dimers combined, 0.88 for monomers, 0.75 for dimers, 0.74 for all polymers with three or more mers, 0.84 for trimers, 0.80 for 4-6 mers, 0.79 for 7-10 mers, 0.69 for more than 10 mers, and 0.74 for total proanthocyanidins. The associations were apparently stronger for rectal than for colon cancer, in the absence of significant heterogeneity. These results may explain the protective effect of vegetables and fruit on colorectal cancer.

Citrus fruit and cancer risk in a network of case-control studies

BACKGROUND

Citrus fruit has shown a favorable effect against various cancers. To better understand their role in cancer risk, we analyzed data from a series of case-control studies conducted in Italy and Switzerland.

PATIENTS AND METHODS

The studies included 955 patients with oral and pharyngeal cancer, 395 with esophageal, 999 with stomach, 3,634 with large bowel, 527 with laryngeal, 2,900 with breast, 454 with endometrial, 1,031 with ovarian, 1,294 with prostate, and 767 with renal cell cancer. All cancers were incident and histologically confirmed. Controls were admitted to the same network of hospitals for acute, nonneoplastic conditions. Odds ratios (OR) were estimated by multiple logistic regression models, including terms for major identified confounding factors for each cancer site, and energy intake.

RESULTS

The ORs for the highest versus lowest category of citrus fruit consumption were 0.47 (95% confidence interval, CI, 0.36-0.61) for oral and pharyngeal, 0.42 (95% CI, 0.25-0.70) for esophageal, 0.69 (95% CI, 0.52-0.92) for stomach, 0.82 (95% CI, 0.72-0.93) for colorectal, and 0.55 (95% CI, 0.37-0.83) for laryngeal cancer. No consistent association was found with breast, endometrial, ovarian, prostate, and renal cell cancer.

CONCLUSIONS

Our findings indicate that citrus fruit has a protective role against cancers of the digestive and upper respiratory tract.

Dietary intake of polyphenols, nitrate and nitrite and gastric cancer risk in Mexico City

N-nitroso compounds (NOC) are potent animal carcinogens and potential human carcinogens. The primary source of exposure for most individuals may be endogenous formation, a process that can be inhibited by dietary polyphenols. To estimate the risk of gastric cancer (GC) in relation to the individual and combined consumption of polyphenols and NOC precursors (nitrate and nitrite), a population-based case-control study was carried out in Mexico City from 2004 to 2005 including 257 histologically confirmed GC cases and 478 controls. Intake of polyphenols, nitrate and nitrite were estimated using a food frequency questionnaire. High intakes of cinnamic acids, secoisolariciresinol and coumestrol were associated with an approximately 50% reduction in GC risk. A high intake of total nitrite as well as nitrate and nitrite from animal sources doubled the GC risk. Odds ratios around 2-fold were observed among individuals with both low intake of cinnamic acids, secoisolariciresinol or coumestrol and high intake of animal-derived nitrate or nitrite, compared to high intake of the polyphenols and low animal nitrate or nitrite intake, respectively. Results were similar for both the intestinal and diffuse types of GC. Our results show, for the first time, a protective effect for GC because of higher intake of cinnamic acids, secoisolariciresinol and coumestrol, and suggest that these polyphenols reduce GC risk through inhibition of endogenous nitrosation. The main sources of these polyphenols were pears, mangos and beans for cinnamic acids; beans, carrots and squash for secoisolariciresinol and legumes for coumestrol.

Absorption, metabolism and excretion of flavanones from single portions of orange fruit and juice and effects of anthropometric variables and contraceptive pill use on flavanone excretion

Oranges are rich sources of flavonoids that are bioactive and may protect against age-related diseases. The absorption of orange flavanones may be affected by factors such as processing and subject anthropometric variables, and the bioactivity of the absorbed phytochemicals depends on how they are metabolised during absorption. In a randomised cross-over study, twenty subjects consumed a single portion of orange fruit (150 g) or juice (300 g) that contained the flavanones narirutin and hesperidin, and an additional 109 subjects across a broad age range (18-80 years) consumed the juice. Flavanone metabolites were measured in regularly collected samples of plasma and urine. After consumption of fruit or juice, flavanone conjugates, but not the aglycones, were detected in plasma and urine. The flavanone conjugates were shown to include the 7- and 4'-O-monoglucuronides of naringenin, the 7- and 3'-O-monoglucuronides of hesperetin, two hesperetin diglucuronides and a hesperetin sulfo-glucuronide, but no aglycones or rutinosides. Analysis of the plasma pharmacokinetic and urinary excretion data on a dose-adjusted basis indicated no difference in absorption or excretion of either flavanone between the fruit and juice matrices. In the extended urinary excretion dataset the individual variation was very large (range 0-59 % urinary yield). There was a small but significant (P < 0.05) decrease in the excretion of hesperetin (but not naringenin) with increasing age (P < 0.05), but the effects of sex, BMI and contraceptive pill use were shown not to be associated with the variation in flavanone excretion.

Dietary intake of selected flavonols, flavones, and flavonoid-rich foods and risk of cancer in middle-aged and older women

BACKGROUND

Flavonoids may protect against cancer development through several biological mechanisms. However, epidemiologic studies on dietary flavonoids and cancer risk have yielded inconsistent results.

OBJECTIVE

We prospectively investigated the association between the intake of selected flavonoids and flavonoid-rich foods and risk of cancers in the Women's Health Study.

DESIGN

A total of 3234 incident cancer cases were identified during 11.5 y of follow-up among 38,408 women aged > or = 45 y. Intake of individual flavonols (quercetin, kaempferol, and myricetin) and flavones (apigenin and luteolin) was assessed from food-frequency questionnaires. Cox regression models were used to estimate the relative risk (RR) of total and site-specific cancer across increasing intakes of total and individual selected flavonoids and flavonoid-rich foods (tea, apple, broccoli, onion, and tofu).

RESULTS

The multivariate RRs of total cancer across increasing quintiles of total quantified flavonoid intake were 1.00, 1.00, 0.93, 0.94, and 0.97 (P for trend = 0.72). For site-specific cancers, the multivariate RRs in the highest quintile of total quantified flavonoid intake compared with the lowest quintile were 1.03 for breast cancer, 1.01 for colorectal cancer, 1.03 for lung cancer, 1.15 for endometrial cancer, and 1.09 for ovarian cancer (all P > 0.05). The associations for the individual flavonoid intakes were similar to those for the total intake. There was also no significant association between intake of flavonoid-rich foods and the incidence of total and site-specific cancers.

CONCLUSION

Our results do not support a major role of 5 common flavonols and flavones or selected flavonoid-rich foods in cancer prevention.

Flavonoids and intestinal cancers

Cancers of the gastrointestinal tract are amongst the most common causes of death from cancer, but there is substantial variation in incidence across populations. This is consistent with a major causative role for diet. There is convincing evidence that fruits and vegetables protect against cancers of the upper alimentary tract and the large bowel, and this has focused attention on biologically active phytochemicals, and on flavonoids in particular. Many flavonoids exert anticarcinogenic effects in vitro and in animals, and many of these effects occur via signalling pathways known to be important in the pathogenesis of colorectal, gastric and oesophageal cancers. However dietary flavonoid intakes are generally low and their metabolism in humans is extremely complex. The advent of new post-genomic technologies will do much to address these problems by making it possible to monitor patterns of gene expression in humans to provide essential molecular biomarkers of early disease. By combining such data with knowledge of the dietary exposure and bioavailability of the most effective compounds it will be possible to predict the most effective dietary sources and to properly evaluate the potential role of flavonoids in clinical nutrition.

Do flavonoid intakes of postmenopausal women with breast cancer vary on very low fat diets?

In the Women's Intervention Nutrition Study (WINS), a very low-fat eating pattern decreased breast cancer recurrence. We assessed whether the women's flavonoid intakes varied on the very low fat diet. A total of 550 randomly selected WINS participants who had been treated with conventional therapy (surgery, chemotherapy, and/or radiation) for primary breast cancer were randomized to either a very low fat diet (15% of calories from fat, N = 218) or their usual diets (30% calories from fat, N = 332). We compared their intakes of total flavonoids and 6 flavonoid classes (isoflavones, flavones, flavanones, flavonols, flavan-3-ols, and anthocyanins) for these 2 groups using the U.S. Department of Agriculture food flavonoid database and a flavonoid dietary supplement database on three 24-h dietary recalls at baseline and 12 mo after randomization. At baseline, neither mean fat intakes (31.7% +/- 6.8 SD of calories, n = 332 in the usual diet group and 31.6% +/- 6.8 SD of calories, n = 218 in the very low fat diet group; P = NS) nor flavonoid intakes (218 +/- 283 SD mg/day, n = 332 in the usual diet group and 236 +/- 393 SD mg/day, n = 218 in the very low fat diet group; P = NS) differed. Over half of the women's flavonoid intakes were from the flavan-3-ols. After 12 months of intervention, with 39 participants lost to follow-up, dietary fat intakes were 30.7 +/- 8.4 SD calories (n = 316) among those on their usual diets but were significantly lower among those on the very low fat diet intervention: 21.4 +/- 8.3 SD calories (n = 195), P = <0.05. However, flavonoid intakes remained similar in both groups (201 +/- 252 SD mg/day, n = 316 in the usual diet group vs. 235 +/- 425 SD mg/day, n = 195 in the very low fat group; P = NS). In this random sample of WINS participants, neither total flavonoid intakes nor intakes of subclasses of flavonoids differed between those who had dramatically decreased their fat intakes and those who had not. Flavonoid intakes are therefore unlikely to account for WINS results on differences between the groups in cancer recurrence.

Citrus fruit intake and stomach cancer risk: a quantitative systematic review

BACKGROUND

The purpose of this systematic review was to investigate the association between dietary intake of citrus fruits and gastric cancer risk.

METHODS

We searched electronic databases and the reference lists of publications on diet and stomach cancer studies until April 2007. All of the epidemiological studies that obtained individual data on dietary intake of citrus fruits and presented risk estimates of the association between intake of citrus fruits and risk of stomach cancer were identified and included in this review. Using general variance-based methods, study-specific odds ratio (OR)/ relative risk (RR) and associated confidence interval (CI)/ standard error (SE) for highest versus lowest intake of citrus fruits level were extracted from each article.

RESULTS

Fourteen articles, including six hospital-based case-control studies, six community-based case-control studies, and two cohort studies, proved eligible. Overall summary OR using a fixed-effect model showed a 28% reduction in risk of stomach cancer associated with high intake of citrus fruits (summary OR = 0.72; 95% CI = 0.64-0.81; P value <0.0001); results were consistent across studies (I(2) = 0, where I(2) describes the percentage of total variation across studies because of heterogeneity rather than chance). Also, visual inspection of the results did not suggest a publication bias.

CONCLUSION

Pooled results from observational studies support a protective effect of high citrus fruit intake in the risk of stomach cancer.

Flavonoid intake and liver cancer: a case-control study in Greece

In the context of a case-control study undertaken in Greece, we examined the role of six flavonoid classes in the etiology of hepatocellular carcinoma (HCC), by viral status, and of cholangiocarcinoma (CAC). Data and blood samples were collected between 1995 and 1998. Information about dietary intakes and covariates, including chronic infection with hepatitis B (HBV) and C (HCV) virus, were available for 250 HBV and/or HCV positive HCC cases, 83 HBV and HCV negative HCC cases, six CAC cases, and 360 hospital controls. In logistic regression models including gender, age, education, tobacco smoking, and total energy intake, there were no distinct patterns with respect to either HCC virus positive and HCC virus negative in relation to total flavonoids or any class of flavonoids, with the exception of flavones. Flavone intake, mostly derived from spinach and peppers, was inversely associated with both virus positive (P-trend, 0.049) and virus negative (P-trend, 0.084) HCC. There was also a suggestion of an inverse association of CAC with flavan-3-ols, anthocyanidins, and total flavonoids which, however, has to be taken with due caution on account of the small number of cases of this rare tumor. We conclude that flavones may be inversely associated with HCC risk, irrespective of its dominant etiology (viral or non viral).

Flavonoids and the Risk of Oral and Pharyngeal Cancer: A Case-Control Study from Italy

The intake of flavonoids has been inversely related to the risk of various common neoplasms, but scanty data exist on oral and pharyngeal cancer. We used data from a case-control study conducted in Italy between 1992 and 2005 to examine the relationship between flavonoid intake and oral and pharyngeal cancer risk. The study included 805 cases with incident, histologically confirmed oral and pharyngeal cancer, and 2,081 hospital controls admitted for acute, nonneoplastic conditions. We have applied data on food and beverage content of six major classes of flavonoids, on dietary information collected through a validated food-frequency questionnaire. The odds ratios (OR) were calculated using multiple logistic regression models, conditioned on study center, sex, and age. After adjustment for education, tobacco, alcohol, body mass index, and non-alcohol energy intake, ORs for the highest versus the lowest quintile of intake were 0.51 [95% confidence intervals (95% CI), 0.37-0.71] for flavanones, 0.62 (CI, 0.43-0.89) for flavonols, and 0.56 (95% CI, 0.40-0.78) for total flavonoids. No significant association emerged for isoflavones (OR, 0.90), anthocyanidins (OR, 0.86), flavan-3-ols (OR, 0.84), and flavones (OR, 0.75). The ORs were consistent across strata of age, sex, education, body mass index, tobacco, and alcohol. After allowance for vegetable and fruit consumption, the inverse relations with total flavonoids and flavanones remained significant, whereas that with flavonols became nonsignificant. None of the associations were significant after further allowance for vitamin C, probably on account of the high collinearity between these compounds.

Flavonoids and the risk of renal cell carcinoma

Intake of flavonoids has been inversely related to the risk of various common neoplasms, but limited data exist on renal cell carcinoma (RCC). We used data from a case-control study conducted between 1994 and 2002 in four Italian areas to study the relation between major flavonoid classes and RCC. The study included 767 cases with incident, histologically confirmed RCC and 1,534 hospital controls admitted for acute, nonneoplastic conditions and matched with cases by study center, sex, and quinquennia of age. We applied published data on food and beverage content of six major classes of flavonoids to dietary information collected through a validated food frequency questionnaire. After adjustment for major recognized confounding factors and total energy intake, the odds ratios for subjects in the highest versus the lowest quintile of intake were 0.80 [95% confidence interval (95% CI), 0.58-1.11] for total flavonoids, 0.76 (95% CI, 0.56-1.03) for isoflavones, 0.94 (95% CI, 0.60-1.47) for anthocyanidins, 0.77 (95% CI, 0.56-1.06) for flavan-3-ols, 0.90 (95% CI, 0.67-1.21) for flavanones, 0.68 (95% CI, 0.50-0.93) for flavones, and 0.69 (95% CI, 0.50-0.95) for flavonols. Allowance for vegetable and fruit consumption only partly explained these inverse relations. Thus, flavonoids, and particularly flavones and flavonols, may account, at least in part, for the favorable role of plant foods on RCC.

Flavonoids and prostate cancer risk: a study in Italy

Flavonoids have been associated with a reduced risk of lung, digestive tract, and certain hormone-related cancers. With reference to prostate cancer, a few epidemiological studies have found an inverse relation with intake of isoflavones, flavonols, and flavones, although the evidence remains limited and inconsistent. The role of six principal classes of flavonoids on prostate cancer was investigated using data from a multicentric case-control study conducted between 1991 and 2002 in Italy. This included 1,294 incident, histologically confirmed carcinomas of the prostate and 1,451 controls admitted to the same hospitals as cases for a wide spectrum of acute, non-neoplastic conditions. The patients' usual diet was assessed using a validated and reproducible food-frequency questionnaire; food and beverage content of six major classes of flavonoids was obtained from the U.S. Department of Agriculture. No association between prostate cancer risk was found with any of the flavonoids analyzed: the multivariate odds ratios for the highest versus the lowest quintile of intake were 0.96 (95% confidence interval, CI = 0.75-1.23) for flavanones, 1.3 (95% CI = 1.01-1.69) for flavan-3-ols, 1.23 (95% CI = 0.95-1.61) for flavonols, 1.09 (95% CI = 0.85-1.40) for flavonols, 1.18 (95% CI = 0.91-1.53) for anthocyanidins, 0.98 (95% CI = 0.76-1.26) for isoflavones, and 1.20 (95% CI = 0.92-1.58) for total flavonoids, all nonstatistically significant. Thus, the results of the present study do not support a protective effect of flavonoids on prostate cancer in this Italian population, characterized by a high intake of flavonoid-containing foods (except isoflavone-rich foods).

Diet, H pylori infection and gastric cancer: evidence and controversies

Despite decreasing incidence and mortality rates, gastric cancer (GC) still remains the fourth most common cancer and the second most common cause of cancer-related deaths worldwide. Due to the limited treatment options, at present, prevention is likely to be the only effective means of controlling this disease. The success of a prevention strategy depends upon the understanding of etiological and pathogenic mechanisms underlying gastric carcinogenesis. The etiology of GC is multi-factorial, however, in the recent years, mounting evidence suggests that environmental factors play a key role. The most important environmental factors implicated in the pathogenesis of GC are diet and H pylori infection. Thus, modifications in lifestyle and dietary habit associated with eradication of H pylori infection could hypothetically represent the most promising potential targets for GC prevention. In this review we will address the evidence and the controversies on the role of these agents in non-cardia GC by focusing on retrospective and prospective observational studies and interventional trials.

Flavonoids and laryngeal cancer risk in Italy

BACKGROUND

Flavonoids may play an important role in explaining the protective effect of vegetables and fruit against cancer.

PATIENTS AND METHODS

To investigate the relation between flavonoids and laryngeal cancer risk, we have applied data on the composition of foods and beverages in terms of six principal classes of flavonoids to a case-control study of laryngeal cancer conducted from 1992 to 2000 in Italy. Cases were 460 subjects with incident, histologically confirmed laryngeal cancer; controls were 1088 patients admitted for acute, non-neoplastic diseases. Odds ratios (OR) were estimated through multiple logistic regression models, including terms for sociodemographic and lifestyle factors, tobacco smoking, alcohol consumption and energy intake.

RESULTS

Significant inverse relations were found for the highest versus the lowest quintile of intake for flavan-3-ols (OR = 0.64), flavanones (OR = 0.60), flavonols (OR = 0.32) and total flavonoids (OR = 0.60), although the overall trends in risk were significant only for flavanones and flavonols. No consistent associations were observed for isoflavones, anthocyanidins and flavones. The estimates did not differ substantially across strata of alcohol drinking, tobacco smoking, body mass index and education, and tended to persist even after controlling for vegetable and fruit intake.

CONCLUSION

This study provides support for a beneficial effect of selected flavonoids on laryngeal cancer risk.

Flavonoids and risk of squamous cell esophageal cancer

The relation between 5 classes of flavonoids (flavanones, flavan-3-ols, flavonols, flavones and anthocyanidines) and esophageal cancer was investigated using data from a case-control study conducted between 1992 and 1997 in 3 areas of northern Italy. The study included 304 cases (275 men, 29 women) with a first diagnosis of squamous-cell carcinoma of the esophagus and 743 controls (593 men, 150 women) with no history of cancer, admitted for acute illnesses, unrelated to tobacco and alcohol consumption, to major hospitals of the areas under surveillance. Dietary habits were investigated using a validated food frequency questionnaire. Odds ratios (ORs) and 95% confidence intervals (CI) were computed after allowance for age, sex, study centre, years of education, alcohol drinking, tobacco smoking, body mass index and energy intake. An inverse association emerged between flavanone intake and esophageal cancer risk (OR=0.38 for the highest vs. the lowest quintile, 95% CI=0.23-0.66). The inverse relation between flavanones and esophageal cancer tended to be stronger in those who drank >or=6 drinks/day. In conclusion, this study suggests that flavanone intake is inversely associated with esophageal cancer risk and may account, with vitamin C, for the protective effect of fruit, especially citrus fruit, on esophageal cancer.

Flavonoids and heart health: proceedings of the ILSI North America Flavonoids Workshop, May 31-June 1, 2005, Washington, DC

This article provides an overview of current research on flavonoids as presented during a workshop entitled, "Flavonoids and Heart Health," held by the ILSI North America Project Committee on Flavonoids in Washington, DC, May 31 and June 1, 2005. Because a thorough knowledge and understanding about the science of flavonoids and their effects on health will aid in establishing dietary recommendations for bioactive components such as flavonoids, a systematic review of the science of select flavonoid classes (i.e., flavonols, flavones, flavanones, isoflavones, flavan-3-ols, anthocyanins, and proanthocyanidins) was presented. The objectives of the workshop were to 1) present and discuss current research on flavonoid intake and the relation between flavonoids and heart health; 2) develop information that could lead to expert consensus on the state-of-the-science of dietary intake of flavonoids on heart health; and 3) summarize and prioritize the research needed to establish the relations between specific flavonoids and heart health. Presentations included the basics of the biology of flavonoids, including the types and distribution in foods, analytical methodologies used to determine the amounts in foods, the bioavailability, the consumption patterns and potential biomarkers of intake, risk assessment and safety evaluation, structure/function claims, and the proposed mechanism(s) of the relation between certain flavonoids and heart health endpoints. Data presented support the concept that certain flavonoids in the diet can be associated with significant health benefits, including heart health. Research gaps were identified to help advance the science.

Age-related variations in flavonoid intake and sources in the Australian population

Objective

To estimate flavonoid intake in the Australian population.

Design

Flavonoid consumption was estimated from 24-hour recall data and apparent consumption data using US Department of Agriculture flavonoid composition data.

Subjects

The National Nutrition Survey 1995 assessed dietary intake (24-hour recall) in a representative sample (n = 13 858) of the Australian population aged 2 years and over.

Results

Analysis of the 24-hour recall data indicated an average adult intake (>18 years) of 454 mg day− 1 (92% being flavan-3-ols). Apple was the highest quercetin source until age 16–18 years, after which onion became an increasingly important prominent source. Variations in hesperetin consumption reflected orange intake. Apple, apricot and grapes were the major sources of epicatechin and catechin for children, but subsided as wine consumption increased in adulthood. Wine was the main source of malvidin. Naringenin intake remained static as a percentage of total flavonoid intake until age 19–24 years, corresponding to orange intake, and then increased with age from 19–24 years, corresponding to grapefruit intake. Apparent dietary flavonoid consumption was 351 mg person− 1 day− 1, of which 75% were flavan-3-ols. Black tea was the major flavonoid source (predominantly flavan-3-ols) representing 70% of total intake. Hesperetin and naringenin were the next most highly consumed flavonoids, reflecting orange intake. Both 24-hour recall and apparent consumption data indicated that apigenin intake was markedly higher in Australia than reported in either the USA or Denmark, presumably due to differences in consumption data for leaf and stalk vegetables and parsley.

Conclusions

Tea was the major dietary flavonoid source in Australia. Flavonoid consumption profiles and flavonoid sources varied according to age. More consistent methodologies, survey tools validated for specific flavonoid intakes and enhanced local flavonoid content data for foods would facilitate better international comparisons of flavonoid intake.

Antioxidant Vitamins and Risk of Gastric Cancer: A Case-Control Study in Portugal

We quantified the effect of antioxidant vitamins in gastric cancer risk, taking into account Helicobacter pylori seropositivity and overall fruit and vegetable intake. Incident cases were identified in two large hospitals in Porto, Portugal, and controls were randomly sampled among city dwellers. Food intake was assessed with a previously validated semiquantitative food-frequency questionnaire. A commercially available chromatographic immunoassay was used for the detection of immunoglobulin G antibodies. Complete questionnaire information and serum samples were available for 233 cases and 311 controls. Compared with subjects in the lowest tertile of dietary intake, the odds ratios (ORs) for those in the highest were 0.85 (95% confidence interval, CI = 0.45-1.60) for vitamin C, 1.04 (95% CI = 0.60-1.80) for vitamin E, and 1.33 (95% CI = 0.77-2.30) for provitamin A carotenoids after further adjusting for fruit and vegetable consumption. Fruit and vegetables remained an independent protective factor (OR = 0.45; 95% CI = 0.23-0.89) after further adjustment for the intake of antioxidant vitamins. H. pylori status had no significant interaction with dietary items. Factors other than H. pylori infection and intake of vitamin C and provitamin A carotenoids seem to account for the inverse association between fruit and vegetable consumption and gastric cancer.

Does an apple a day keep the oncologist away?

BACKGROUND

Apples have commonly been described as a healthy food. To understand better their role on risk of cancer at several sites, we analyzed data from multicenter case-control studies conducted between 1991 and 2002 in Italy.

PATIENTS AND METHODS

The studies included 598 patients with incident cancers of the oral cavity and pharynx, 304 of the oesophagus, 460 of the larynx, 1953 of the colorectum, 2569 of the breast, 1031 of the ovary and 1294 of the prostate. The comparison group included a total of 6629 patients admitted to the same network of hospitals as cases for acute, non-neoplastic diseases. Multivariate odds ratios (OR) were obtained with allowance for age, sex, study center, education, body mass index, tobacco smoking, alcohol drinking, total energy intake, vegetable consumption and physical activity.

RESULTS

Compared with subjects reporting consumption of <1 apple/day, the ORs for > or =1 apple/day were 0.79 [95% confidence interval (CI) 0.62-1.00] for cancers of the oral cavity and pharynx, 0.75 (95% CI 0.54-1.03) for oesophagus, 0.80 (95% CI 0.71-0.90) for colorectum, 0.58 (95% CI 0.44-0.76) for larynx, 0.82 (95% CI 0.73-0.92) for breast, 0.85 (95% CI 0.72-1.00) for ovary and 0.91 (95% CI 0.77-1.07) for prostate.

CONCLUSION

This investigation found a consistent inverse association between apples and risk of various cancers.

Flavonoids and Breast Cancer Risk in Italy

Few epidemiologic studies have investigated the potential relation between flavonoids and breast cancer risk. We have applied recently published data on the composition of foods and beverages in terms of six principal classes of flavonoids (i.e., flavanones, flavan-3-ols, flavonols, flavones, anthocyanidines, and isoflavones) on dietary information collected in a large-case control study of breast cancer conducted in Italy between 1991 and 1994. The study included 2,569 women with incident, histologically confirmed breast cancer, and 2,588 hospital controls. Odds ratios (OR) and 95% confidence intervals were estimated by multiple logistic regression models. After allowance for major confounding factors and energy intake, a reduced risk of breast cancer was found for increasing intake of flavones (OR, 0.81, for the highest versus the lowest quintile; P-trend, 0.02), and flavonols (OR, 0.80; P-trend, 0.06). No significant association was found for other flavonoids, including flavanones (OR, 0.95), flavan-3-ols (OR, 0.86), anthocyanidins (OR, 1.09), as well as for isoflavones (OR, 1.05). The findings of this large study of an inverse association between flavones and breast cancer risk confirm the results of a Greek study.