Fiber intake and the risk of oral, pharyngeal and esophageal cancer

Dietary fiber in bakery products: Source, processing, and function

Bakery products are prevalently consumed foods in the world, and they have been regarded as convenient dietary vehicles for delivering nutritive ingredients into people's diet, of which, dietary fiber (DF) is one of the most popular items. The food industry attempts to produce fiber-enriched bakery products with both increasing nutritional value and appealing palatability. As many new sources of DFs become available, and consumers are moving towards healthier diets, studies of using these DFs as functional ingredients in baked goods are becoming vast. Besides, the nutrition value of DF is commonly accepted, and many investigations have also revealed the health benefits of fiber-enriched bakery products. Thus, this chapter presents an overview of (1) trends in supplementation of DF from various sources, (2) impact of DF on dough processing, quality and physiological functionality of bakery products, and (3) technologies used to improve the compatibility of DF in bakery products.

Diet Quality as Measured by the Healthy Eating Index 2015 and Oral and Pharyngeal Cancer Risk

BACKGROUND

Alcohol and tobacco are the major risk factors for oral and pharyngeal cancer, but diet is likely to have a role, too.

OBJECTIVE

The objective was to analyze the relationship between adherence to the 2015-2020 Dietary Guidelines for Americans (DGA), as measured by the Healthy Eating Index 2015 (HEI-2015), and oral and pharyngeal cancer risk. Moreover, this work aimed to quantify the number of avoidable cases under different scenarios of increased adherence to the DGA, with the use of the potential impact fraction. This estimates the proportion of cases that would occur if the distribution of the risk factor in the population followed an alternative distribution.

DESIGN

A multicenter, case-control study was conducted in Italy between 1991 and 2009. Participants' usual diet for the 2 years preceding study enrolment was assessed using a food frequency questionnaire.

PARTICIPANTS AND SETTING

Cases were 946 patients admitted to major hospitals with incident, histologically confirmed oral and pharyngeal cancer. Controls were 2,492 patients admitted to the same hospitals for acute non neoplastic conditions.

MAIN OUTCOME MEASURES

The adherence to the DGA was assessed using the HEI-2015 score (range = 0 to 100), based on 13 components. The outcome was oral and pharyngeal cancer.

STATISTICAL ANALYSES PERFORMED

Odds ratios and the corresponding 95% CIs were estimated using multiple logistic regression models adjusted for tobacco, alcohol, and other relevant covariates. The potential impact fraction was estimated under different scenarios of adherence to the DGA.

RESULTS

In this Italian population the HEI-2015 score ranged from 33.4 to 97.5. A higher HEI-2015 score was associated with a lower risk of oral and pharyngeal cancer, with an odds ratio of 0.70 (95% CI 0.62 to 0.79) for a 10-point increment of the score. The estimated potential impact fraction was 64.8% under the maximum achievable reduction scenario, and it ranged from 9% to 27% following other more feasible scenarios.

CONCLUSIONS

The HEI-2015 score was inversely related to oral and pharyngeal cancer risk in this Italian population. This analysis allowed for the estimation of the fraction of preventable cases, under different feasible scenarios. A share of 9% to 27% of avoidable cases of oral and pharyngeal cancer might be obtained across real-world scenarios of adherence to the DGA as measured by the HEI-2015 score.

Fiber intake and the risk of head and neck cancer in the prostate, lung, colorectal and ovarian (PLCO) cohort

Although the protective role of dietary fiber on cancer risk has been reported in several epidemiological studies, the association of fiber intake on head and neck cancer (HNC) risk is still unclear. We investigated the association between fiber intake and the risk of HNC using data from the Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening trial. Among 101,700 participants with complete dietary information, 186 participants developed HNC during follow-up (January 1998 to May 2011). Dietary data were collected using a self-administered food-frequency questionnaire (1998-2005). We estimated hazard ratios (HRs) and the corresponding 95% confidence intervals (CI), using the Cox proportional hazards model. Higher intake of total fiber, insoluble fiber and soluble fiber was associated with decreased HNC risks, with a significant trend. The HRs of highest vs. the lowest tertile of intake were 0.43 (95%CI: 0.25-0.76) for total fiber, 0.38 (95%CI: 0.22-0.65) for insoluble fiber, and 0.44 (95%CI: 0.25-0.79) for soluble fiber. These inverse association were consistent in oral cavity and pharyngeal cases, but the impact of fiber intake was weaker in laryngeal cases. We did not observe any significant interaction of potential confounders, including smoking and drinking, with total fiber intake on HNC risk. These findings support evidence of a protective role of dietary fiber on HNC risk.

Dietary fiber intake and head and neck cancer risk: A pooled analysis in the International Head and Neck Cancer Epidemiology consortium

The possible role of dietary fiber in the etiology of head neck cancers (HNCs) is unclear. We used individual-level pooled data from ten case-control studies (5959 cases and 12,248 controls) participating in the International Head and Neck Cancer Epidemiology (INHANCE) consortium, to examine the association between fiber intake and cancer of the oral cavity/pharynx and larynx. Odds Ratios (ORs) and their 95% Confidence Intervals (CIs) were estimated using unconditional multiple logistic regression applied to quintile categories of non-alcohol energy-adjusted fiber intake and adjusted for tobacco and alcohol use and other known or putative confounders. Fiber intake was inversely associated with oral and pharyngeal cancer combined (OR for 5th vs. 1st quintile category = 0.49, 95% CI: 0.40-0.59; p for trend <0.001) and with laryngeal cancer (OR = 0.66, 95% CI: 0.54-0.82, p for trend <0.001). There was, however, appreciable heterogeneity of the estimated effect across studies for oral and pharyngeal cancer combined. Nonetheless, inverse associations were consistently observed for the subsites of oral and pharyngeal cancers and within most strata of the considered covariates, for both cancer sites. Our findings from a multicenter large-scale pooled analysis suggest that, although in the presence of between-study heterogeneity, a greater intake of fiber may lower HNC risk.

Effect of fiber blends, total solids, heat treatment, whey protein concentrate and stage of sugar incorporation on dietary fiber-fortified Kheer

Owing to the proven beneficial role of dietary fiber (DF) on human health, feasibility of incorporating commercially available soluble and insoluble DF preparations into rice-milk-pudding (kheer, a popular Indian delicacy) was studied through process modification. The novel approach of preparing reduced fat DF-fortified-kheer (DFFK) by developing liquid/cream phase and particulate/rice phase separately, and subsequently blending the two was developed. The major processing variables studied were total solids (TS) in the liquid phase, type of fiber blend, flavor-simulation through heat treatment or added whey protein, and the presence of sugar in water for pre-cooking of rice. Reduced fat DFFK made from three different pre-standardized fiber blends was quite acceptable to the sensory panel (overall rating 7.5). With increasing TS in milk up to 16.5%, sensory acceptability of DFFK increased. There was a small but perceivable improvement in the flavour of DFFK when precooking of rice was carried out in sweetened water. Reduced fat DFFK from different fiber blends was found to be reasonably close to conventional kheer. DFFK prepared from Blend-I provided 3.31 g dietary fiber/100 kcal (suitable for the claim "High-in-Fiber") with 38.71% Reduced-Fat. With the developed process of fortification of kheer with DF, it is possible to reduce fat (and thus calories) to cater to the needs of consumers seeking good health.

Fruit and vegetables and cancer risk: a review of southern European studies

High intakes of fruit and vegetables may reduce the risk of cancer at several sites. Evidence has been derived mainly from case-control studies. We reviewed the relationship between consumption of vegetables and fruit and the risk of several common cancers in a network of Italian and Swiss case-control studies including over 10,000 cases of fourteen different cancers and about 17,000 controls. Data were suggestive of a protective role of vegetable intake on the risk of several common epithelial cancers. OR for the highest compared with the lowest levels of consumption ranged from 0.2 (larynx, oral cavity and pharynx) to 0.9 (prostate). Inverse associations were found for both raw and cooked vegetables, although for upper digestive tract cancers the former were somewhat stronger. Similar inverse associations were found for cruciferous vegetables. Frequent consumption of allium vegetables was also associated with reduced risk of several cancers. Fruit was a favourable correlate of the risk of several cancers, particularly of the upper digestive tract, with associations generally weaker than those reported for vegetables. A reduced risk of cancers of the digestive tract and larynx was found for high consumption of citrus fruit. Suggestive protections against several forms of cancer, mainly digestive tract cancers, were found for high consumption of apples and tomatoes. High intakes of fibres, flavonoids and proanthocyanidins were inversely related to various forms of cancer. In conclusion, data from our series of case-control studies suggested a favourable role of high intakes of fruit and vegetables in the risk of many common cancers, particularly of the digestive tract. This adds evidence to the indication that aspects of the Mediterranean diet may have a favourable impact not only on CVD, but also on several common (epithelial) cancers, particularly of the digestive tract.

No association between fiber intake and prostate cancer risk: a meta-analysis of epidemiological studies

Background

The findings of epidemiologic studies on the association between fiber intake and prostate cancer risk remain conflicting. We aimed to examine this association by conducting a meta-analysis of epidemiological studies.

Methods

Relevant studies were identified by PubMed (1966 to March 2015) and Embase (1974 to March 2015) database search through March 2015. We included epidemiological studies that reported relative risks (RRs) or odds ratios (ORs) with 95 % confidence intervals (CIs) for the association between dietary fiber intake and prostate cancer risk. Random effects models were used to calculate the summary risk estimates.

Results

For the highest compared with the lowest dietary fiber intake, a significantly decreased risk with prostate cancer was observed in case-control studies (OR = 0.82; 95 % CI, 0.68–0.96), but not in cohort studies (RR = 0.94; 95 % CI, 0.77–1.11). The combined risk estimate of all studies was 0.89 (95 % CI, 0.77, 1.01). A significant heterogeneity was observed across studies (p = 0.005). There was no evidence of significant publication bias based on Begg’s funnel plot (p = 0.753) or Egger’s test (p = 0.946).

Conclusions

This meta-analysis suggests the absence of evidence for association between dietary fiber intake and prostate cancer risk.

Diet and esophageal cancer risk in the Eastern Cape Province of South Africa

A multicenter hospital-based case-control study comprising 670 incident cases of esophageal cancer (EC) and 1188 controls, frequency-matched for age and sex, was conducted to evaluate the role of diet on EC development in the Eastern Cape Province, South Africa. A locally relevant lifestyle and dietary questionnaire was used. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were computed using unconditional multivariable logistic regression. Individually, maize or sorghum consumption vs. never or rare consumption were not associated with EC (P > 0.1). Males and females consuming green leafy vegetables 5-7 days/wk had 38% (P = 0.04) and 50% (P = 0.007) reduced odds of developing EC, respectively, compared with consumption ≤1 day/wk. A similar reduction in odds was observed with fruit consumption. Principal component factor analysis revealed 3 distinct dietary patterns. In females, high vs. low consumption of Pattern 1 (sorghum, green leafy vegetables, green legumes, fruits, meat) was inversely associated with EC development (OR = 0.54; 95% CI: 0.34-0.89), whereas for Pattern 2 (maize, wild greens-imifino, dry beans) the odds were elevated (OR = 1.67; 95% CI: 1.04-2.67). Compared with low adherence, high adherence to Pattern 3 (wheat-based products) reduced the odds by 35% for both sexes. This study provides further evidence on the role of diet in minimizing EC risk in this population.

Dietary acrylamide and human cancer: a systematic review of literature

Cancer remains the second leading cause of death in the United States, and the number of cases is expected to continue to rise worldwide. Cancer prevention strategies are crucial for reducing the cancer burden. The carcinogenic potential of dietary acrylamide exposure from cooked foods is unknown. Acrylamide is a by-product of the common Maillard reaction where reducing sugars (i.e., fructose and glucose) react with the amino acid, asparagine. Based on the evidence of acrylamide carcinogenicity in animals, the International Agency for Research on Cancer has classified acrylamide as a group 2A carcinogen for humans. Since the discovery of acrylamide in foods in 2002, a number of studies have explored its potential as a human carcinogen. This article outlines a systematic review of dietary acrylamide and human cancer, acrylamide exposure and internal dose, exposure assessment methods in the epidemiologic studies, existing data gaps, and future directions. A majority of the studies reported no statistically significant association between dietary acrylamide intake and various cancers, and few studies reported increased risk for renal, endometrial, and ovarian cancers; however, the exposure assessment has been inadequate leading to potential misclassification or underestimation of exposure. Future studies with improved dietary acrylamide exposure assessment are encouraged.

Mediterranean diet and cancer: epidemiological evidence and mechanism of selected aspects

Background

Populations living in the area of the Mediterranean Sea suffered by decreased incidence of cancer compared with those living in the regions of northern Europe and US countries, attributed to healthier dietary habits. Nowadays, we are assisting to a moving away from the traditional Mediterranean dietary pattern, but whether this changing is influencing risk of cancers is still unclear. The aim of the study was to review recent evidence on potential relationship between the adherence to the Mediterranean diet and cancer.

Discussion

The most recent pooled analyses of epidemiological studies supported strongly the hypothesis that the Mediterranean diet may play a role in preventing several types of cancers, especially those of digestive tract, whereas contrasting results were reported for hormone-dependent cancers. Specific aspects of the Mediterranean diet such as high fruit and vegetables and low red processed meat intake may explain such protective effects. Moreover, evidence regarding olive oil and whole grains increase the beneficial effects of such dietary pattern against cancer.

Conclusions

Literature evidence actually demonstrates that the increased adherence to the Mediterranean dietary pattern is beneficial to health across populations and may translate a protective effect with certain cancers.

Higher glycemic index and glycemic load diet is associated with increased risk of esophageal squamous cell carcinoma: a case-control study

Several studies have indicated the association between intake of foods high in dietary glycemic index (GI) and glycemic load (GL) with an increased risk of digestive tract cancers. We hypothesized that GI and GL may be associated with risk of esophageal squamous cell carcinoma (ESCC) in a high-risk population in Iran. In total, we interviewed 47 cases with incident of ESCC and 96 frequency-matched hospital controls, then calculated the average dietary GI and GL via a validated food frequency questionnaire. Dietary GL was calculated as a function of GI, carbohydrate content, and frequency of intake of certain foods. Dietary GI and GL levels were significantly higher among the ESCC cases compared with the controls (P < .05). After adjustment for potential confounders, those in the highest tertile of dietary GI had 2.95 times higher risk of ESCC compared with those in the lowest (95% confidence interval, 1.68-3.35; P for trend = .002). In addition, being in the highest tertile of dietary GL was positively associated with an ESCC risk (odds ratio, 3.49; 95% confidence interval, 2.98-4.41; P for trend = .001). Findings of the present study indicate that diets with high GI and GL might have potentially unfavorable effects on ESCC risk and suggest a possible role for excess circulating insulin and related insulin-like growth factor 1 in esophageal cancer development.

Dietary fiber and the risk of precancerous lesions and cancer of the esophagus: a systematic review and meta-analysis

Dietary fiber has several anticarcinogenic effects and is thought to be protective against esophageal cancer. The aim of this systematic review was to quantify the association between dietary fiber and the risk of esophageal cancer by investigating histological subtypes of esophageal cancer and the stage at which fiber may influence the carcinogenic pathway. Systematic search strategies were used to identify relevant studies, and adjusted odds ratios (ORs) were combined using random-effects meta-analyses to assess the risk of cancer when comparing extreme categories of fiber intake. Ten relevant case-control studies were identified within the timeframe searched. Pooled estimates from eight studies of esophageal adenocarcinoma revealed a significant inverse association with the highest fiber intakes (OR 0.66; 95% confidence interval [CI] 0.44-0.98). Two studies also identified protective effects of dietary fiber against Barrett's esophagus. Similar, though nonsignificant, associations were observed when results from five studies of fiber intake and risk of squamous cell carcinoma were combined (OR 0.61; 95%CI 0.31-1.20). Dietary fiber is associated with protective effects against esophageal carcinogenesis, most notably esophageal adenocarcinoma. Potential methods of action include modification of gastroesophageal reflux and/or weight control.

Dietary pattern and oral cancer risk--a factor analysis study

OBJECTIVES

The role of diet in cancer risk has mainly been investigated based on intake of individual food items. However, food consumption is made up of a combination of various food items. This study aims to determine the association of dietary patterns with oral cancer risk.

METHODS

A total of 306 matched cases and controls were recruited in this study. Data on dietary intake were obtained using food frequency questionnaire (FFQ). Factor analysis (FA) was performed to identify dietary patterns based on the intake of nine major food groups, resulting in four factors/components being retained. The odds ratio (OR) was computed for each component using conditional logistic regression.

RESULTS

The first pattern labelled as 'modern' was loaded with processed foods and snacks, whereas the second pattern termed as 'prudent' was characterized by intake of fruits and vegetables. The third pattern labelled as 'traditional' consisted of beverages and starches, while the fourth pattern termed as 'combination' was loaded with intakes of dairy, fermented/salted and meat/by-products. A significant reduced risk was found for 'prudent' (OR 0.53, 95% CI = 0.28-0.98), whereas an increased risk was found for both 'combination' (OR 2.43, 95% CI = 1.33-4.45) and 'traditional' (OR 2.32, 95% CI = 1.23-4.25) patterns. However, after adjusting for risk habits of tobacco smoking, alcohol consumption and betel quid chewing, only 'combination' (aOR 2.99, 95% CI = 1.55-5.75) and 'traditional' (aOR 2.08, 95% CI = 1.09-3.97) patterns remained significant.

CONCLUSION

Consumption in the highest tertile of 'traditional' and 'combination' patterns may induce twice and thrice the risk of oral cancer, respectively.

A review of the epidemiology of oral and pharyngeal carcinoma: update

Oral and pharyngeal cancers are the sixth most common cancers internationally. In the United States, there are about 30,000 new cases of oral and pharyngeal cancers diagnosed each year. Furthermore, survival rates for oral and pharyngeal cancers have not significantly improved over the last three decades. This review examines the scientific literature surrounding the epidemiology of oral and pharyngeal cancers, including but not limited to risk factors, disparities, preventative factors, and the epidemiology in countries outside the United States. The literature review revealed that much of the research in this field has been focused on alcohol, tobacco, and their combined effects on oral and pharyngeal cancers. The literature on oral and pharyngeal cancer disparities among racial groups also appears to be growing. However, less literature is available on the influence of dietary factors on these cancers. Finally, effective interventions for the reduction of oral and pharyngeal cancers are discussed.

Dietary fiber and grain consumption in relation to head and neck cancer in the NIH-AARP Diet and Health Study

BACKGROUND

Dietary fiber and grain consumption may reduce the risk of head and neck cancer; however, the epidemiological evidence is limited. We investigated this relationship in the National Institutes of Health (NIH)-AARP Diet and Health Study.

METHODS

Cox proportional hazards models were used to calculate multivariable hazard ratios (HR) and 95% confidence intervals (CI) to investigate dietary fiber and grain intake in relation to head and neck cancer.

RESULTS

During approximately 11 years of follow-up, 1,867 (401 women/1,466 men) cases of head and neck cancer were diagnosed. Our data indicated that the relationship between fiber and grain intake and head and neck cancer is modified by sex (p-interactions < 0.001 and 0.001, respectively). Women with higher intake of total fiber and total grains had a lower risk of head and neck cancer (HR (10 g/day) = 0.77, 95% CI = 0.64-0.93; HR (serving/1,000 kcal) = 0.89, 95% CI = 0.80-0.99, respectively); this inverse relation was consistent across subtypes of fiber and grains. Conversely in men, the inverse associations were weaker and nonsignificant.

CONCLUSIONS

In the largest prospective cohort study to investigate this relation to date, intake of total fiber and grain foods was inversely associated with head and neck cancer incidence among women, but not among men.

Chemoprevention in Barrett's oesophagus

Barrett's oesophagus normally affects the distal oesophagus when metaplastic columnar lined epithelium replaces stratified squamous epithelium which predisposes to cancer development. This develops as a consequence of chronic gastroesophageal reflux (GORD). Those with Barrett's have a 40 fold increased risk of oesophageal adenocarcinoma [1]. There are is still a lack of understanding of the natural history of the cell of origin. This does hamper research into this area. We accept that there is a limitation in testing of the pathogenesis of Barrett's oesophagus due to a lack of a universally accepted animal model. The major questions surrounding Barrett's oesophagus include validity of surveillance strategies, the optimal treatment and more importantly an agent that can prevent progression to cancer without unacceptable side effects. The main chemopreventative agents that show promise are aspirin and proton pump inhibitors (PPIs). There are other agents such as green tea, berries and antioxidants and diet that have been suggested; we discuss the evidence available for these strategies. We hope for continued improvement in the clinical trial infrastructure to facilitate testing of new pharmacological and endoscopic interventions for Barrett's oesophagus.

Chemoprevention of esophageal adenocarcinoma

The incidence of esophageal adenocarcinoma (EAC) is rising rapidly in Western countries, and effective chemoprevention for this malignancy is lacking. Endoscopic surveillance of patients with Barrett's esophagus is currently employed to diagnose EAC at earlier stages, but this strategy has several limitations. Non-steroidal anti-inflammatory drugs and proton pump inhibitors are the most promising agents for prevention of EAC, and a randomized controlled trial of aspirin and esomeprazole is ongoing. Other agents under investigation include green tea, berries, and antioxidants. Cost-effectiveness analyses have shown that chemopreventive agents need to be highly effective at preventing EAC in order to have benefit beyond endoscopic surveillance.

Dietary lignans: physiology and potential for cardiovascular disease risk reduction

The present review of the literature on lignan physiology and lignan intervention and epidemiological studies was conducted to determine if lignans decrease the risks of cardiovascular disease in Western populations. Five intervention studies using flaxseed lignan supplements indicated beneficial associations with C-reactive protein, and a meta-analysis that included these studies also suggested lignans have a lowering effect on plasma total and low-density lipoprotein cholesterol. Three intervention studies using sesamin supplements indicated possible lipid- and blood pressure-lowering associations. Eleven human observational epidemiological studies examined dietary intakes of lignans in relation to cardiovascular disease risk. Five showed decreased risk with either increasing dietary intakes of lignans or increased levels of serum enterolactone (an enterolignan used as a biomarker of lignan intake), five studies were of borderline significance, and one was null. The associations between lignans and decreased risk of cardiovascular disease are promising, but they are yet not well established, perhaps due to low lignan intakes in habitual Western diets. At the higher doses used in intervention studies, associations were more evident.

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.

Dietary patterns and risk of oral and pharyngeal cancer: a case-control study in Rio de Janeiro, Brazil

The study investigated the association between dietary patterns and oral cancer as part of a Latin American multicenter hospital-based case-control study, and included 210 incident cases of oral cancer and 251 controls. Dietary data were collected using a Food Frequency Questionnaire (FFQ). Factor analysis was used to define dietary patterns, which were categorized into terciles. Odds ratios (OR) with 95% confidence intervals (95%CI) were calculated using unconditional multiple logistic regression. The patterns "prudent", characterized mainly by vegetables and fruits, and "traditional", by rice, and pulses showed an inverse association with oral cancer for the higher tercile, respectively, OR = 0.44; 95%CI: 0.25-0.75, p value for trend (p tend) = 0.03; OR = 0.53; 95%CI: 0.30-0.93, p tend = 0.06. The "snacks pattern" was not associated with oral cancer. Besides the protective effect of a diet rich in vegetables and fruit, our data suggest that the traditional Brazilian diet, consisting mostly of rice and beans, may improve protection against oral cancer.

Diet and cancer in Mediterranean countries: carbohydrates and fats

Objective

Several aspects of the diet characteristic of the Mediterranean countries are considered favourable not only on cardiovascular disease, but also on cancer risk. We considered some aspects of the Mediterranean diet (including, in particular, the consumption of olive oil and carbohydrates) on cancer risk.

Design, Setting and Subjects

Data were derived from a series of case-control studies, conducted in Italy since the early 1990s, on over 10 000 cases of thirteen cancer sites and over 17 000 controls.

Results

Olive oil, and other mono- and unsaturated fats, appear to be favourable indicators of breast, ovarian, colorectal, but mostly of upper aero-digestive tract cancers. Whole grain foods are also related to reduced risk of upper aero-digestive tract and various other cancers. In contrast, refined grain intake and, consequently, glycaemic index and glycaemic load were associated to increased risk for several cancer sites. Fish, and hence a diet rich in n-3 polyunsaturated fatty acids, tended to be another favourable diet indicator, while frequent red meat intake was directly related to some common neoplasms. An a priori defined Mediterranean diet score was inversely related to upper digestive and respiratory tract cancers.

Conclusions

These data provide additional evidence that major characteristics of the Mediterranean diet favourably affect cancer risk.

Dietary acrylamide and human cancer

Low levels of acrylamide have been found in several foods cooked at high temperatures. While there is sufficient evidence for the carcinogenicity of acrylamide in experimental animals, the few epidemiologic studies conducted to date on occupational and dietary exposure to acrylamide have found no consistent evidence of association with human cancer risk. Using data from an integrated network of Italian and Swiss hospital-based case-control studies, we analyzed the relation between dietary acrylamide intake and cancers of the oral cavity and pharynx (749 cases, 1,772 controls), esophagus (395 cases, 1,066 controls), large bowel (1,394 cases of colon, 886 cases of rectal cancer, 4,765 controls), larynx (527 cases, 1,297 controls), breast (2,900 cases, 3,122 controls), ovary (1,031 cases, 2,411 controls) and prostate (1,294 cases, 1,451 controls). All the studies included incident, histologically confirmed cancer cases and controls admitted to the same network of hospitals for acute nonneoplastic conditions. We calculated odds ratios (ORs) using multivariate logistic regression models, adjusted for energy intake and other major covariates of interest. The ORs for the highest versus the lowest quintile of acrylamide intake were 1.12 (95% CI = 0.76-1.66) for cancer of the oral cavity/pharynx, 1.10 (95% CI = 0.65-1.86) for esophageal, 0.97 (95% CI = 0.80-1.18) for colorectal, 1.23 (95% CI = 0.80-1.90) for laryngeal, 1.06 (95% CI = 0.88-1.28) for breast, 0.97 (95% CI = 0.73-1.31) for ovarian and 0.92 (95% CI = 0.69-1.23) for prostate cancer. None of the trend in risk was significant. This uniquely large and comprehensive data set does not show any consistent association between intake of acrylamide and the risk of breast and several other common cancers.

Folate intake and squamous-cell carcinoma of the oesophagus in Italian and Swiss men

BACKGROUND

Dietary folate has been inversely related to the risk of several cancers. However, studies on the role of dietary folate in oesophageal cancer are scanty.

PATIENTS AND METHODS

Using data from a multicentric case-control study conducted in Italy and Switzerland between 1992 and 1999, we investigated the association between dietary folate intake and oesophageal squamous-cell carcinoma (OSCC) among 351 men with incident, histologically confirmed OSCC and 875 hospital controls admitted for acute, non-neoplastic conditions, unrelated to alcohol and smoking consumption. Intake of folate and other nutrients was computed from a validated food frequency questionnaire.

RESULTS

The multivariate odds ratios (ORs) of OSCC were 0.68 (95% confidence intervals, CI: 0.46-1.00) for the highest versus the lowest tertile of folate intake, and 0.84 (95% CI: 0.72-0.99) for an increment of folate intake equal to a standard deviation (98 microg/day). The inverse relation was somewhat stronger in strata of high methionine, vitamin B6 and alcohol intake, and did not vary substantially according to age and smoking habits.

CONCLUSION

Dietary folate was inversely related to OSCC risk in this population with high alcohol consumption and infrequent use of supplements and multivitamins.

Role of fried foods and oral/pharyngeal and oesophageal cancers

We investigated the role of fried foods on oral-pharyngeal and oesophageal cancers, using data from two case–control studies conducted in Italy and Switzerland between 1992 and 1999, one with a total of 749 (634 men) cases of oral/pharyngeal cancer and 1772 (1252 men) controls, the other with 395 (351 men) cases of oesophageal cancer and 1066 (875 men) controls. Controls were admitted for acute, non-neoplastic conditions, unrelated to alcohol and smoking consumption. After allowance for sex, age, centre, education, body mass index, tobacco smoking, alcohol drinking and nonalcohol energy intake, the multivariate odds ratios (ORs) for an increment of one portion per week of total fried foods were 1.11 (95% confidence interval (CI): 1.05–1.17) for oral-pharyngeal and 1.16 (95% CI: 1.08–1.26) for oesophageal cancer. The ORs were consistent across strata of gender (OR in men only were 1.10 and 1.16, respectively), age, alcohol, tobacco consumption and body mass index.

Mediterranean diet and cancer risk

Various aspects of the Mediterranean diet are considered favourable with regard to cancer risk. These aspects were analysed using data from a series of case-control studies conducted in northern Italy between 1983 and 2001 on over 12,000 cases of 20 cancer sites and 10,000 controls. For most epithelial cancers, the risk decreased with increasing vegetable and fruit consumption, with odds ratios (OR) between 0.3 and 0.7 for the highest versus the lowest tertile. Subjects reporting frequent red meat intake showed ORs above unity for several common neoplasms. Conversely, fish (and consequently, n-3 fatty acids) tended to be another favourable dietary indicator. Wholegrain food intake was related to reduced risk of several types of cancer, particularly of the upper digestive tract, probably on account of its high fibre content. Fibres were in fact found to be protective with regard to colorectal and other selected cancers. In contrast to wholegrain, refined grain intake, and consequently glycaemic load, was associated with an increased risk of different types of cancer, including those of the upper digestive tract, colorectum, breast and endometrium. These results thus suggest that a low-risk diet for cancer entails increasing vegetables and fruit, reducing meat, but also refined carbohydrate consumption. Furthermore, olive oil and other unsaturated fats, which may be a unique common characteristic of the Mediterranean diet, should be preferred to animal and saturated fats. A score summarizing the major characteristics of the Mediterranean diet was inversely and consistently related to the risk of selected cancer sites. Regular consumption of pizza, one of the most typical Italian foods, showed a reduced risk of digestive tract cancers. Pizza could however simply be an indicator of a typical Italian diet.

Fibre intake and prostate cancer risk

Dietary fibre has been reported to protect from several neoplasms, but the issue remains controversial. No previous study considered in depth the topic of fibres and prostate cancer. A multicentre case-control study was conducted in Italy from 1991 to 2002, including 1,294 men with incident, histologically confirmed prostate cancer and 1,451 controls admitted to the same network of hospitals as cases with acute nonmalignant conditions. Multivariate odds ratios (OR) and 95% confidence intervals (CI) were obtained after allowance for major identified confounding factors, including total energy intake. Compared to the lowest quintile, the OR of prostate cancer for the highest quintile of total fibre intake was 0.93 (95% CI 0.71-1.22). The risk was inversely related with soluble fibre (OR = 0.89, 95% CI 0.78-1.02, for a difference between 80th and 20th percentile), cellulose (OR = 0.88, 95% CI 0.78-1.01) and vegetable fibre (OR = 0.82, 95% CI 0.73-0.93). These relationships were consistent across strata of age, family history of prostate cancer, body mass index and education. Vegetable fibres appear, therefore, to have a favourable association with prostate cancer risk.

Diet and risk of seromucinous benign ovarian cysts

OBJECTIVE

To analyze the relation between selected dietary indicators and the risk of seromucinous benign ovarian cysts.

STUDY DESIGN

We used data from a case-control study on risk factors for benign ovarian cysts conducted in Italy between 1984 and 1994. Cases included 225 women with a histologically confirmed diagnosis of benign seromucinous ovarian neoplasm dating back no more than 2 years. Controls were 450 women below the age of 65 years admitted for acute non-gynecological, non-hormonal, non-neoplastic conditions.

RESULTS

Women with seromucinous cysts reported more frequent consumption of beef and other red meat and cheese and less frequent consumption of green vegetables. The multivariate odds ratios (ORs) in highest versus less frequent consumption levels were 2.7 (95% confidence interval (CI) 1.8-4.3) for beef and other red meat, 0.6 (95% CI 0.3-0.9) for green vegetables and 1.4 (95% CI 1.0-2.2) for cheese.

CONCLUSION

Seromucinous benign ovarian cysts are associated with beef and cheese consumption, whereas high intake of green vegetables seems to have a protective effect.

Fried potatoes and human cancer

A considerable public concern about cancer risk from acrylamide-rich foods followed the announcement that high concentrations of acrylamide are found in fried potatoes and potato chips and, more generally, in starch-containing foods cooked at high temperatures. From a series of hospital-based case-control studies conducted in Italy and Switzerland between 1991 and 2000, we have analyzed the relation between intake of fried/baked potatoes and cancer risk. The cancer sites considered were oral cavity and pharynx (749 cases, 1772 controls), esophagus (395 cases, 1066 controls), larynx (527 cases, 1297 controls), large bowel (1225 colon and 728 rectum cases, 4154 controls), breast (2569 cases, 2588 controls) and ovary (1031 cases, 2411 controls). All cancer cases were incident and histologically confirmed. Controls were subjects admitted to the same network of hospitals of cases for acute, non-neoplastic conditions. All the odds ratios (OR) for the highest vs. the lowest tertile of intake ranged between 0.8-1.1. We found no evidence of interaction with age, gender, alcohol and tobacco use. Our data provide reassuring evidence for the lack of an important association between consumption of fried/baked potatoes and cancer risk.

Fibre intake and laryngeal cancer risk

BACKGROUND

Consumption of vegetables, fruit and whole grain cereals has been inversely related to laryngeal cancer risk. Among the potential protective agents found in these foods, information on dietary fibres and laryngeal cancer risk are scanty.

PATIENTS AND METHODS

A multi-centric, hospital-based case-control study was conducted on 527 patients with squamous-cell carcinoma of the larynx and 1,297 non-neoplastic controls. Cases and controls, frequency matched by age, sex and study centre, were interviewed using a validated food frequency questionnaire.

RESULTS

Compared with the lowest quintile of fibre intake, the odds ratios (ORs) for the highest quintile were 0.3 [95% confidence interval (CI) 0.2-0.4] for total fibre, 0.3 (95% CI 0.2-0.5) for soluble non-cellulose polysaccharides (NCP) and for total insoluble fibre, including cellulose (OR = 0.3, 95% CI 0.2-0.4) and insoluble NCP (OR = 0.4, 95% CI 0.3-0.7). The ORs were 0.2 (95% CI 0.1-0.4) for fibre from vegetables, 0.5 (95% CI 0.3-0.7) from fruit and 1.1 (95% CI 0.6-1.9) from grains. The inverse association observed was similar among different subsites of laryngeal cancer, and consistent across strata of various covariates.

CONCLUSIONS

This study found a strong inverse association between fibre intake and laryngeal cancer risk, which points to fibre as one of the beneficial components of vegetables and fruit.

Antioxidant activity of grains

Epidemiological studies have shown that consumption of whole grains and grain-based products is associated with reduced risk of chronic diseases. The health benefits of whole grains are attributed in part to their unique phytochemical composition. However, the phytochemical contents in grains have been commonly underestimated in the literature, because bound phytochemicals were not included. This study was designed to investigate the complete phytochemical profiles in free, soluble conjugated, and insoluble bound forms, as well as their antioxidant activities in uncooked whole grains. Corn had the highest total phenolic content (15.55 +/- 0.60 micromol of gallic acid equiv/g of grain) of the grains tested, followed by wheat (7.99 +/- 0.39 micromol of gallic acid equiv/g of grain), oats (6.53 +/- 0.19 micromol of gallic acid equiv/g of grain), and rice (5.56 +/- 0.17 micromol of gallic acid equiv/g of grain). The major portion of phenolics in grains existed in the bound form (85% in corn, 75% in oats and wheat, and 62% in rice), although free phenolics were frequently reported in the literature. Ferulic acid was the major phenolic compound in grains tested, with free, soluble-conjugated, and bound ferulic acids present in the ratio 0.1:1:100. Corn had the highest total antioxidant activity (181.42 +/- 0.86 micromol of vitamin C equiv/g of grain), followed by wheat (76.70 +/- 1.38 micromol of vitamin C equiv/g of grain), oats (74.67 +/- 1.49 micromol of vitamin C equiv/g of grain), and rice (55.77 +/- 1.62 micromol of vitamin C equiv/g of grain). Bound phytochemicals were the major contributors to the total antioxidant activity: 90% in wheat, 87% in corn, 71% in rice, and 58% in oats. Bound phytochemicals could survive stomach and intestinal digestion to reach the colon. This may partly explain the mechanism of grain consumption in the prevention of colon cancer, other digestive cancers, breast cancer, and prostate cancer, which is supported by epidemiological studies.

The role of diet and specific micronutrients in the etiology of oral carcinoma

BACKGROUND

Carcinoma of the oral cavity is one of the most common cancers worldwide. Tobacco smoking and the consumption of alcoholic beverages are significant risk factors but to the authors' knowledge the role of nutrition is not adequately understood. The authors undertook an epidemiologic study of oral carcinoma occurring in Greece, where tobacco smoking and alcohol consumption are common but the incidence of the disease is among the lowest reported in Europe.

METHODS

One hundred six patients with histologically confirmed incident oral carcinoma and an equal number of control subjects matched for age and gender were studied. Dietary information was assessed through a validated extensive food frequency questionnaire and the data were analyzed using conditional logistic regression.

RESULTS

After adjustment for energy intake, tobacco smoking, and alcohol consumption, there was evidence that the consumption of cereals, fruits, dairy products, and added lipids (which in Greece are represented mostly by olive oil) was found to be associated inversely with the risk of oral carcinoma. Only with respect to meat and meat products was there adequate evidence of a positive association with the risk of oral carcinoma. Among the micronutrients studied, riboflavin, magnesium, and iron appeared to be correlated inversely with the disease.

CONCLUSIONS

Fruits, cereals, dairy products, and olive oil appear to convey protection against oral carcinoma and their effects may be mediated through higher intakes of riboflavin, iron, and magnesium. The low incidence of oral carcinoma reported in Greece may be explained in part by the higher consumption of the food groups and micronutrients that appear to protect against the disease.

Dietary risk factors for upper aerodigestive tract cancers

We examined the association between whole-grain intake and incident upper aerodigestive tract cancer in a cohort of 34,651 postmenopausal, initially cancer-free women. We also studied established risk factors for upper aerodigestive cancers, including fruit and vegetable intake, smoking and alcohol intake. A mailed questionnaire at baseline in 1986 included a food-frequency questionnaire and assessment of other cancer risk factors. During the 14-year follow-up period, 169 women developed cancer of the upper aerodigestive tract. For all upper aerodigestive cancers together, significant inverse associations were observed for the highest compared to the lowest tertile of whole grains [relative risk (RR) = 0.53, 95% confidence interval (CI) 0.34-0.81] and yellow/orange vegetables (RR = 0.58, 95% CI 0.39-0.87). In addition, those in the highest compared to lowest tertile of fiber intake from whole grain were less likely to develop upper aerodigestive tract cancer (RR = 0.56, 95% CI 0.37-0.84); fiber intake from refined grain was not significantly associated with upper aerodigestive tract cancer. Findings were generally similar for oropharyngeal (n = 53), laryngeal (n = 21), nasopharyngeal/salivary (n = 18), esophageal (n = 21) and gastric (n = 56) cancers, though numbers of cases were too small for statistical testing within individual cancers. These findings confirm previous observations that high intake of fruits and vegetables and that intake of whole grains and the fiber derived from them may reduce risk of upper aerodigestive tract cancers.

Dietary fibres and ovarian cancer risk

Data from an Italian multicentre case-control study on ovarian cancer were used to analyse the relationship between various types of fibres and ovarian cancer risk. The study, conducted between 1992 and 1999, included 1031 cases of incident, histologically-confirmed epithelial ovarian cancer. Controls were 2411 women admitted to the same network of hospitals for acute, non-malignant, non-hormonal-related diseases. Cases and controls were interviewed using a validated food frequency questionnaire (FFQ). Odds ratios (ORs), and the corresponding 95% confidence intervals (CI), were estimated using unconditional multiple logistic regression models. For total (Englyst) fibre, the OR for the highest versus the lowest quintile of intake was 0.68, and the continuous OR for the difference between the 80th and the 20th percentile of intake was 0.87. For most types of fibre, the continuous OR was significantly below 1. The OR was 0.83 for cellulose, 0.89 for soluble non-cellulose polysaccharides (NCPs), 0.86 for total insoluble fibre, 0.92 for insoluble NCP, and 0.95 (non-significant) for lignin. The inverse association was consistent across strata of age, family history and menopausal status, even if the association was apparently stronger in postmenopausal women. When fibre was classified according to the source, vegetable (but not grain) fibres, showed a significant protective effect, with an OR of 0.78.

Dietary fibre and the risk of colorectal cancer

The relationship between various types of fibre and colorectal cancer risk was investigated using data from a case-control study conducted in the Swiss Canton of Vaud between January 1992 and December 2000. The study included 286 cases of incident, histologically-confirmed colorectal cancers (149 colon and 137 rectal cancers) admitted to the University Hospital of Lausanne, and 550 controls whose admission diagnosis was of acute, non-neoplastic diseases. Dietary habits were investigated using a validated food frequency questionnaire (FFQ). Odds ratios (ORs) were computed after allowance for age, sex, education, physical activity and energy intake. Fibre was analysed both as a continuous variable and in tertiles. There was a significant inverse relationship of total fibre intake (determined by the Englyst method as non-starch polysaccharides) and of its components with the risk of colorectal cancer. ORs for a difference in intake of one standard deviation from the mean fibre intake of the control distribution was 0.57 for total fibres, 0.55 for soluble non-cellulose polysaccharides (NCPs), 0.58 for total insoluble fibres, 0.57 for cellulose, 0.62 for insoluble NCP and 0.62 for lignin. When fibre was classified according to its source, the OR was 0.60 for vegetables, 0.78 for fruit and 0.74 for grain fibre. The ORs were similar for colon and rectal cancer and consistent across the strata of the major covariates and of several types of fibres.