Dietary fibre and colon cancer: where do we go from here?

Behavior matters

Behavior has a broad and central role in health. Behavioral interventions can be effectively used to prevent disease, improve management of existing disease, increase quality of life, and reduce healthcare costs. A summary is presented of evidence for these conclusions in cardiovascular disease/diabetes, cancer, and HIV/AIDS as well as with key risk factors: tobacco use, poor diet, physical inactivity, and excessive alcohol consumption. For each, documentation is made of (1) moderation of genetic and other fundamental biological influences by behaviors and social-environmental factors; (2) impacts of behaviors on health; (3) success of behavioral interventions in prevention; (4) disease management; (5) quality of life, and (6) improvements in the health of populations through behavioral health promotion programs. Evidence indicates the cost effectiveness and value of behavioral interventions, especially relative to other common health services as well as the value they add in terms of quality of life. Pertinent to clinicians and their patients as well as to health policy and population health, the benefits of behavioral interventions extend beyond impacts on a particular disease or risk factor. Rather, they include broad effects and benefits on prevention, disease management, and well-being across the life span. Among priorities for dissemination research, the application of behavioral approaches is challenged by diverse barriers, including socioeconomic barriers linked to health disparities. However, behavioral approaches including those emphasizing community and social influences appear to be useful in addressing such challenges. In sum, behavioral approaches should have a central place in prevention and health care of the 21st century.

Science at the Crossroads: Fact or Fiction?

Modern Academic Science is largely based on the formulation of hypotheses that are then confirmed through observations and experiments. There is little scope forcuriositythat played an important role in early Science. Results carrying negative implications are not easy to publish, and hypotheses have a tendency to take on the mantra of religious beliefs. Academic Science is facing on many fronts pressures that hardly existed in the past. Financial rewards apart from salary can be very high, in the form of fees for consultants, expert legal witnesses, patent development, and even the establishment of private companies. Commercial funding forms a significant percentage of the Total Research Budgets in Science and Medicine, but this often leads to loss of control over research protocols and freedom to communicate the results. Media attention confers fame and prestige that is assiduously sought out by some individual scientists, often supported by University resources, and Press Conferences prior to or synchronous with actual publication. Scientists have long been employed full-time by Government Departments, but research contracts are being increasingly offered by the latter to academic staff on a part-time basis. These pressures and opportunities, together with the priority given to research by most University Tenure and Promotion Committees, are tending to diminish the appetite of scientists for other important responsibilities such as teaching and administration. In a few decades, University scientists have moved from the »Ivory Tower« to the High Street, and many are serving more than one master. The above scenario may bring increased remuneration and the pursuit of research that would be too expensive without these external sources, but adverse consequences have also occurred. They may lead to the complicity of scientists, through no fault of their own, in the introduction of drugs and supplements that: a) fail to deliver the benefits claimed; b) increase the risk of some unrelated illness; c) possess dangerous side effects not known or reported at the time of introduction. Examples include hormone replacement therapy and antioxidant vitamins (A and E) to protect against Coronary Heart Disease; dietary fibre to prevent colon cancer; and arguably calcium supplements to treat osteoporosis. On occasions, academic scientists have served as fronts for the publication by the manufacturers of falsified reports minimizing the risk of serious drug side-effects to ensure Regulatory Approval, as occurred with Vioxx in the treatment of arthritis, and Seroquel for schizophrenia and bipolar depression. Individual fraud or misconduct is more frequent than suspected, because most incidents are without major impact and are suppressed by Universities and Funding Agencies. Major scandals are rare, but may have serious repercussions for the general public and bring science into disrepute. Recent examples include: the Cold Fusion controversy (Low Energy Nuclear Reaction); the link age by Andrew Wakefield of autism with Rubella vaccination; the infamous creation of stem cells by somatic cell nuclear transfer falsely reported by Hwang Woo-Suk. Fraud by commercial companies is subject to the full force of the law, but Science is treated as a self-regulating profession, and as such the punishments handed out are relatively trivial. In essence, Science prior to 1950, except in North America, proceeded along a highway that segregated the traffic into Commercial, Government and Academic streams, and passed through inspiring landscapes and green pastures. It later came to a crossroads from which the alternative road led to the Marketplace, and on which segregation into the above three streams was not enforced. It has now become the main thoroughfare for Science world-wide, but there are reasons to believe that this has increased the incidence of dangerous driving and traffic accidents in the form of conflicts of interest, unethical behaviour, misconduct and even fraud. It may be too late to return to the crossroads and continue along the original highway, but there could be considerable merit in restoring the original segregation between the three streams of Science and in developing, as well as enforcing, a stricter code of behaviour, for which some elements are proposed.

Prospective study of dietary fiber and risk of chronic obstructive pulmonary disease among US women and men

Little is known about the relation between dietary fiber intake and the incidence of respiratory diseases, especially chronic obstructive pulmonary disease (COPD). The authors investigated this issue among 111,580 US women and men (Nurses' Health Study and Health Professionals Follow-up Study), with 832 cases of newly diagnosed COPD being reported between 1984 and 2000. The cumulative average intake of total fiber and of fiber from specific sources (cereal, fruit, and vegetables) was calculated from food frequency questionnaires and a food composition database and divided into quintiles. After adjustment for 11 factors (age, sex, smoking, energy intake, body mass index, US region, physician visits, physical activity, diabetes, and intakes of omega-3 and cured meat), total dietary fiber intake was negatively associated with risk of newly diagnosed COPD (for highest vs. lowest intake, relative risk = 0.67, 95% confidence interval: 0.50, 0.90; P(trend) = 0.03). For specific fiber sources (cereal, fruit, and vegetables), only cereal fiber was significantly associated with newly diagnosed COPD independently of other fiber sources (for highest vs. lowest intake, relative risk = 0.77, 95% confidence interval: 0.59, 0.99; P(trend) = 0.04). These data suggest that a diet high in fiber, and possibly specifically cereal fiber, may reduce risk of developing COPD.

Dietary fiber decreases colonic epithelial cell proliferation and protein synthetic rates in human subjects

Although it has been proposed that high fiber consumption can prevent proliferative diseases of the colon, the clinical data to support this hypothesis have been inconsistent. To provide a more robust measure of the effects of fiber on colonic mucosal growth than previous studies, we evaluated both cell proliferation and colonic mucosal protein synthesis in nine healthy volunteers after they consumed a typical Western diet (<20 g fiber/day) or a Western diet supplemented with wheat bran (24 g/day) in a randomized crossover design. Biopsies taken from the sigmoid colon were used to assess mucosal proliferation by determining proliferating cell nuclear antigen (PCNA) in crypt cells and to assess mucosal protein synthetic rate using stable isotopically labeled leucine infusion. Fiber supplementation produced a 12% decrease in labeling index (%crypt cells stained with PCNA) (P < 0.001) and an 11% decrease in mucosal protein fractional synthetic rate (FSR; P < 0.05). Moreover, mucosal protein FSR correlated directly with labeling index (r2= 0.22, P < 0.05). These data demonstrate that increased wheat bran consumption decreases colonic mucosal proliferation and support the potential importance of dietary fiber in preventing proliferative diseases of the colon.

Chemical components with health implications in wild and cultivated Mexican common bean seeds (Phaseolus vulgaris L.)

Common bean effects on health have been related to its dietary fiber content and other active compounds. This study assessed the content of flavonoids, coumestrol, phenolic acids, galactooligosaccharides, and phytic acid in wild and cultivated Mexican common bean seeds (raw and cooked) and that of flavonoids, coumestrol, and phenolic acids in germinated bean seeds. The presence of isoflavones in raw bean seeds was not confirmed by the UV spectra. Quercetin, kaempferol, p-coumaric acid, ferulic acid, p-hydroxybenzoic acid, and vanillic acid mean contents were 10.9, 52.3, 10.1, 9.6, 5.4, and 18.2 microg/g, respectively; raffinose, stachyose, verbascose, and phytic acid mean contents were 8.5, 56.3, 5.5, and 11.5 mg/g, respectively, in raw seeds. All compounds were affected by autoclaving, and germination resulted in a de novo synthesis of flavonols, phytoestrogens, and phenolic acids. The impact on health of common bean seed is affected by dietary burden, specific compounds content, and processing. On the other hand, germinated bean seed or beans sprouts may be sources of antioxidants and phytoestrogens.

Dietary fibre and colorectal cancer: A model for environment - gene interactions

As environmental factors are clearly associated with risk for colorectal cancer, we set out to model how dietary fibre, or the effects of its ingestion, might impact upon the complex events that characterise colorectal oncogenesis. The diverse nature of dietary fibre and its resultant fate in the gut is outlined. The evidence indicates that different types of fibre create different conditions in different regions of the gut. This is reflected in different effects on oncogenesis especially in animal models. Data from animal models show that insoluble fibre is protective. Evidence from human studies are not consistent, especially considering the interventional studies. However, all such studies have been dependent on biomarkers short of cancer formation, for measurement of an effect. The biological and molecular events characteristic of colorectal oncogenesis are reviewed in an effort to identify how fibre ingestion might regulate oncogenesis. While several mechanisms might account for protection, the results of fermentation and especially butyrate production provide examples of how genomic instability might be controlled. Activation of apoptosis and cell cycle arrest seem likely to be mechanisms that would enable correction of genomic events that drive oncogenesis. Butyrate itself can regulate gene expression by both epigenetic and direct effects.

Effects of exercise and diet on chronic disease

Currently, modern chronic diseases, including cardiovascular diseases, Type 2 diabetes, metabolic syndrome, and cancer, are the leading killers in Westernized society and are increasing rampantly in developing nations. In fact, obesity, diabetes, and hypertension are now even commonplace in children. Clearly, however, there is a solution to this epidemic of metabolic disease that is inundating today's societies worldwide: exercise and diet. Overwhelming evidence from a variety of sources, including epidemiological, prospective cohort, and intervention studies, links most chronic diseases seen in the world today to physical inactivity and inappropriate diet consumption. The purpose of this review is to 1) discuss the effects of exercise and diet in the prevention of chronic disease, 2) highlight the effects of lifestyle modification for both mitigating disease progression and reversing existing disease, and 3) suggest potential mechanisms for beneficial effects.

Prevention of Cancer Through Lifestyle Changes

Cancer is the second leading cause of death in the USA and an abundance of evidence suggests that lifestyle factors including smoking, the typical high-fat, refined-sugar diet and physical inactivity account for the majority of cancer. This review focuses on diet and inactivity as major factors for cancer promotion by inducing insulin resistance and hyperinsulinemia. Elevated levels of serum insulin impact on the liver primarily, increasing the production of insulin-like growth factor I (IGF-I) while reducing the production of insulin-like growth factor binding protein 1 (IGFBP-1) resulting in stimulation of tumor cell growth and inhibition of apoptosis (programmed cell death). Adopting a diet low in fat and high in fiber-rich starch foods, which would also include an abundance of antioxidants, combined with regular aerobic exercise might control insulin resistance, reduce the resulting serum factors and thus reduce the risk for many different cancers commonly seen in the USA.

Vitamin K status in patients with Crohn's disease and relationship to bone turnover

BACKGROUND

There is a high prevalence of osteopenia among patients with Crohn's disease (CD). There is some evidence that a deficiency of certain bone-active nutrients (including vitamins K and D) may have a partial role in this bone loss.

AIMS

To compare the intake and the status of vitamin K in CD patients, currently in remission, with age- and sex-matched controls, and furthermore to investigate the relationship between vitamin K status and bone turnover in these patients.

SUBJECTS

CD patients (n = 44; mean age: 36.9 yr) and matched controls (n = 44) were recruited from the Cork University Hospital and Cork City area, respectively.

METHODS

Bloods were analyzed for the total and undercarboxylated (Glu)-osteocalcin and urine analyzed for cross-linked N-telopeptides of type I collagen (NTx). Vitamin K(1) intake was estimated by food frequency questionnaire.

RESULTS

Vitamin K(1) intake in CD patients tended to be lower than that of controls (mean (SD), 117 (82) vs 148 (80) mug/d, respectively; p= 0.059). Glu and NTx concentrations in CD patients were higher than controls (mean (SD), 5.1 (3.1) vs 3.9 (2.1) ng/ml, respectively; p= 0.03 for Glu; and 49 (41) vs 25.8 (19.5) nM BCE/mM creatinine, respectively; p= 0.001 for NTx). In CD patients, Glu was significantly correlated with NTx (r= 0.488; p < 0.001), even after controlling for age, gender, vitamin D status, calcium intake, and corticosteroid use.

CONCLUSION

Vitamin K status of CD patients was lower than that of the healthy controls. Furthermore, the rate of bone resorption in the CD was inversely correlated with vitamin K status, suggesting that it might be another etiological factor for CD-related osteopenia.

Vitamin D intakes in 18–64-y-old Irish adults

OBJECTIVE

To estimate vitamin D intakes in a representative sample of Irish adults and to assess the contribution of foods to these intake estimates.

DESIGN

Vitamin D intakes in 1379, 18-64-y-old adults from the North/South Ireland Food Consumption Survey were estimated using a combination of new analytical data for vitamin D in foods, determined by HPLC, and used to revise recipe calculations, together with existing data from McCance and Widdowson's The Composition of Foods, 5th Edition plus supplements.

RESULTS

The total mean daily intake (MDI) of vitamin D (1 microg=40 IU) from all sources was 4.2 microg. The MDI was significantly higher (P<0.001) when the contribution from nutritional supplements was included (4.2 microg) compared with food sources only (3.2 microg). Men had significantly higher intakes (4.4 microg) than women (4.0 microg; P<0.001), which increased significantly (P<0.001) with age in both sexes. Meat/meat products (30.1%), fish/fish products (14.3%) and eggs/egg dishes (9.1%) were the main contributors to vitamin D intake. Supplements contributed 6.8 and 12% to MDI in men and women, respectively. In all, 74% of adults had an MDI of vitamin D that was less than the median (5 microg) of the recommended daily range of 0-10 microg.

CONCLUSION

The findings of this study suggest that a large number of Irish adults have low vitamin D intakes. This, along with emerging evidence of low vitamin D status in at least some population subgroups, suggests that strategies to increase vitamin D intakes, including fortification of food, should be investigated.