Dietary fiber intake, dietary glycemic load, and the risk for gestational diabetes mellitus.

• Zhang C,
• Liu S,
• Solomon CG,
• Hu FB.

Department of Nutrition, Harvard School of Public Health, 665 Huntington Ave., Boston, MA 02115, USA. cuilin.zhang@channing.harvard.edu

OBJECTIVE: We aimed to examine whether pregravid dietary fiber consumptions from cereal, fruit, and vegetable sources and dietary glycemic load were related to gestational diabetes mellitus (GDM) risk. RESEARCH DESIGN AND METHODS: This study was a prospective cohort study among 13,110 eligible women in the Nurses' Health Study II. GDM was self-reported and validated by medical record review in a subsample.

RESULTS: We documented 758 incident GDM cases during 8 years of follow-up. After adjustment for age, parity, prepregnancy BMI, and other covariates, dietary total fiber and cereal and fruit fiber were strongly associated with GDM risk. Each 10-g/day increment in total fiber intake was associated with 26% (95% CI 9-49) reduction in risk; each 5-g/day increment in cereal or fruit fiber was associated with a 23% (9-36) or 26% (5-42) reduction, respectively. Dietary glycemic load was positively related to GDM risk. Multivariate relative risk for highest versus lowest quintiles was 1.61 (1.02-2.53) (P for trend 0.03). The combination of high-glycemic load and low-cereal fiber diet was associated with 2.15-fold (1.04-4.29) increased risk compared with the reciprocal diet.

CONCLUSIONS: These findings suggested that prepregnancy diet might be associated with women's GDM risk. In particular, diet with low fiber and high glycemic load was associated with an increased risk. Future clinical and metabolic studies are warranted to confirm these findings.
PMID: 17003297 [PubMed - in process

Dietary fiber and body-weight regulation. Observations and mechanisms.

• Pereira MA,
• Ludwig DS.

Division of Endocrinology, Departments of Pediatrics and Medicine, Harvard Medical School and Children's Hospital, Boston, Massachusetts, USA. mark.pereira@tch.harvard.edu

Dietary fiber may be related to body-weight regulation through plausible physiologic mechanisms that have considerable support in the scientific literature. Many short-term studies suggest that high-fiber foods induce greater satiation and satiety. Epidemiologic studies generally [figure: see text] support a role for fiber in body-weight regulation among free-living individuals consuming self-selected diets, although conclusive intervention studies addressing this point are lacking.

Thus, there is considerable reason to conclude that fiber-rich diets, containing non-starchy vegetables, fruits, whole grains, legumes, and nuts, may be effective in the prevention and treatment of obesity in children. Such diets may have additional benefits, independent of changes in adiposity, in the prevention of cardiovascular disease and type 2 diabetes.

PMID: 11494646 [PubMed - indexed for MEDLINE]

Sustained reduction in the incidence of type 2 diabetes by lifestyle intervention: follow-up of the Finnish Diabetes Prevention Study.

• Lindstrom J,
• Ilanne-Parikka P,
• Peltonen M,
• Aunola S,
• Eriksson JG,
• Hemio K,
• Hamalainen H,
• Harkonen P,
• Keinanen-Kiukaanniemi S,
• Laakso M,
• Louheranta A,
• Mannelin M,
• Paturi M,
• Sundvall J,
• Valle TT,
• Uusitupa M,
• Tuomilehto J;
• Finnish Diabetes Prevention Study Group.

Diabetes Unit, Department of Health Promotion and Chronic Disease Prevention, National Public Health Institute, Mannerheimintie 166, 00300 Helsinki, Finland. jaana.lindstrom@ktl.fi

BACKGROUND: Lifestyle interventions can prevent the deterioration of impaired glucose tolerance to manifest type 2 diabetes, at least as long as the intervention continues. In the extended follow-up of the Finnish Diabetes Prevention Study, we assessed the extent to which the originally-achieved lifestyle changes and risk reduction remain after discontinuation of active counselling. METHODS: Overweight, middle-aged men (n=172) and women (n=350) with impaired glucose tolerance were randomly assigned to intensive lifestyle intervention or control group. After a median of 4 years of active intervention period, participants who were still free of diabetes were further followed up for a median of 3 years, with median total follow-up of 7 years. Diabetes incidence, bodyweight, physical activity, and dietary intakes of fat, saturated fat, and fibre were measured.

FINDINGS: During the total follow-up, the incidence of type 2 diabetes was 4.3 and 7.4 per 100 person-years in the intervention and control group, respectively (log-rank test p=0.0001), indicating 43% reduction in relative risk. The risk reduction was related to the success in achieving the intervention goals of weight loss, reduced intake of total and saturated fat and increased intake of dietary fibre, and increased physical activity. Beneficial lifestyle changes achieved by participants in the intervention group were maintained after the discontinuation of the intervention, and the corresponding incidence rates during the post-intervention follow-up were 4.6 and 7.2 (p=0.0401), indicating 36% reduction in relative risk.

INTERPRETATION: Lifestyle intervention in people at high risk for type 2 diabetes resulted in sustained lifestyle changes and a reduction in diabetes incidence, which remained after the individual lifestyle counselling was stopped.
PMID: 17098085 [PubMed - in process]

The glycemic index: methodology and use.

• Kendall CW,
• Augustin LS,
• Emam A,
• Josse AR,
• Saxena N,
• Jenkins DJ.

Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ont., Canada.

The glycemic index concept owes much to the dietary fiber hypothesis that fiber would reduce the rate of nutrient absorption and increase the value of carbohydrate foods in the maintenance of health and treatment of disease. However, properties and components of food other than its fiber content contribute to the glycemic and endocrine responses postprandially.

The aim of the glycemic index classification of foods was therefore to assist in the physiological classification of carbohydrate foods which, it was hoped, would be of relevance in the prevention and treatment of chronic diseases such as diabetes.

Over the past two decades low glycemic index diets have been reported to improve glycemic control in diabetic subjects, to reduce serum lipids in hyperlipidemic subjects and possibly to aid in weight control. In large cohort studies, low glycemic index or glycemic load diets (glycemic index multiplied by total carbohydrate) have also been associated with higher levels of high-density lipoprotein cholesterol, reduced C-reactive protein concentrations and with a decreased risk of developing diabetes and cardiovascular disease.

More recently, some case-control and cohort studies have also found positive associations between the dietary glycemic index and the risk of colon, breast and other cancers. While the glycemic index concept continues to be debated and there remain inconsistencies in the data, sufficient positive findings have emerged to suggest that the glycemic index is an aspect of diet of potential importance in the treatment and prevention of chronic diseases.

Vegetables, fruit and phytoestrogens as preventive agents.

• Potter JD,
• Steinmetz K.

Cancer Prevention Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.

The practice of medicine-both past and present-often involves the prescription of specific foods (almost always plants) or their potent derivatives, to treat a wide spectrum of illnesses. Foods that have been ascribed healing properties include the Cruciferae, the allium family, celery, cucumber, endive, parsley, radish and legumes.

Review of the epidemiological data, including both cohort and case-control studies, of all cancer sites strongly suggests that plant foods also have preventive potential and that consumption of the following groups and types of vegetables and fruits is lower in those who subsequently develop cancer: raw and fresh vegetables, leafy green vegetables, Cruciferae, carrots, broccoli, cabbage, lettuce, and raw and fresh fruit (including tomatoes and citrus fruit).

Other data suggest that foods high in phytoestrogens, particularly soy (which contains isoflavones), or high in precursor compounds that can be metabolized by gut bacteria into active agents, particularly some grains and vegetables with woody stems (which contain precursors to lignans), are plausibly associated with a lower risk of sex-hormone-related cancers.

The human evidence for these latter associations is not strong. There are many biologically plausible reasons why consumption of plant foods might slow or prevent the appearance of cancer. These include the presence in plant foods of such potentially anticarcinogenic substances as carotenoids, vitamin C, vitamin E, selenium, dietary fibre (and its components), dithiolthiones, isothiocyanates, indoles, phenols, protease inhibitors, allium compounds, plant sterols, and limonene.

Phytoestrogens are also derived from some vegetables and berries as well as grains and seeds. Most of the data for the observations on the anticarcinogenic potential of all of these compounds have come from animal and in vitro studies.

At almost every one of the stages of the cancer process, identified phytochemicals are known to be able to alter the likelihood of carcinogenesis-occasionally in a way that enhances risk but usually in a favourable direction.

For example, glucosinolates and indoles, thiocyanates and isothiocyanates, phenols, and coumarins can induce a multiplicity of phase II (solubilizing and usually inactivating) enzymes; ascorbate and phenols block the formation of carcinogens such as nitrosamines; flavonoids and carotenoids act as antioxidants, essentially disabling the carcinogenic potential of specific compounds; lipid-soluble compounds such as carotenoids and sterols may alter membrane structure or integrity; some sulphur-containing compounds suppress DNA and protein synthesis; carotenoids can suppress DNA synthesis and enhance differentiation; and phytoestrogens compete with estradiol for estrogen receptors in a way that is generally antiproliferative.

Consumption of diets low in plant foods results in a reduced intake of a wide variety of those substances that can plausibly lower cancer risk. In the presence of a diet and lifestyle high in potential carcinogens (whether derived from fungal contamination, cooking or tobacco) or high in promoters (such as salt and alcohol), overall risk of cancer at many epithelial sites is elevated.

Plant foods appear to exert a general risk-lowering effect; the patterns of exposure to cancer initiators and promoters and of genetic susceptibility may determine the variations in the site-specific risks of cancer seen across populations.

A prospective study of dietary fiber intake and risk of cardiovascular disease among women.

• Liu S,
• Buring JE,
• Sesso HD,
• Rimm EB,
• Willett WC,
• Manson JE.

Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA. simin.liu@channing.harvard.edu

OBJECTIVES: This study was designed to examine the hypothesis that higher intake of dietary fiber is inversely related to the risk of cardiovascular disease (CVD) and myocardial infarction (MI) in a large prospective cohort of women. BACKGROUND: Although dietary fiber has been suggested to reduce the risk of coronary disease, few prospective studies have examined the association between the types and amounts of dietary fiber and CVD risk, particularly among women.

METHODS: In 1993, we used a semi-quantitative food frequency questionnaire to assess dietary fiber intake among 39,876 female health professionals with no previous history of CVD or cancer. Women were subsequently followed for an average of six years for incidence of nonfatal MI, stroke, percutaneous transluminal coronary angioplasty, coronary artery bypass graft or death due to CVD confirmed by medical records or death certificates. RESULTS: During 230,006 person-years of follow-up, 570 incident cases of CVD were documented, including 177 MIs.

After adjustment for age and randomized treatment status, a significant inverse association was observed between dietary fiber intake and CVD risk. Comparing the highest quintile of fiber intake (median: 26.3 g/day) with the lowest quintile (median: 12.5 g/day), the relative risks (RR) were 0.65 (95% confidence interval [CI]: 0.51, 0.84) for total CVD and 0.46 (95% CI: 0.30, 0.72) for MI. Additional adjustment for CVD risk factors reduced the RRs to 0.79 (95% CI: 0.58, 1.09) for total CVD and 0.68 (95% CI: 0.36, 1.22) for MI.

The inverse trends across categories generally remained, although they were no longer statistically significant. Inverse relations were observed between both soluble and insoluble fiber and risk of CVD and MI, and among those who had never smoked and those with body mass index <25.

CONCLUSIONS: A higher intake of dietary fiber was associated with a lower risk of CVD and MI, although the association was not statistically significant after further adjusting for multiple confounding factors. Nevertheless, these prospective data generally support current dietary recommendations to increase the consumption of fiber-rich whole grains and fruits and vegetables as a primary preventive measure against CVD.

PMID: 11755286 [PubMed - indexed for MEDLINE]

Fiber and colon cancer.

• Jacobs LR.

University of California, Los Angeles.
The human evidence that dietary fiber prevents the development of colon cancer has been reviewed. The correlational studies are consistent with a protective effect in 61.9 per cent of reports. However, these studies are all retrospective and largely uncontrolled. The case-control studies provide evidence of a protective effect in only 48 per cent of reports.

It is of additional concern that some human studies have found an association between tumor enhancement and some fiber-containing foods. Whereas this is not sufficient evidence to implicate dietary fiber as a promoter of human colon cancer, it does perhaps argue for a more conservative approach to recommending high-fiber diets as a means of cancer prevention. The animal data show that different sources of dietary fiber produce markedly different effects on colon carcinogenesis.

Although some fibers exhibit protective properties, others clearly promote tumor development. The mechanisms behind these opposing actions require further investigation. However, one thing is clear and that is that dietary fibers do modulate the carcinogenic process and as such provide a valuable tool for probing the mechanisms and stages of colon tumor development.

Dietary fiber appears to play a major role in the regulation of normal intestinal function and in the maintenance of a healthy intestinal mucosa. Although there is some evidence that a fiber-deficient diet predisposes to colon carcinogenesis, it is still not known whether an increase in fiber consumption will prevent the development of colon cancer.

This is further complicated by not knowing what constitutes a normal level of fiber intake. In the interim, physicians should perhaps advise their patients to consume a moderate diet that contains vegetables, fruits, and whole grains. This will provide a varied source of fiber-containing foods and if consumed in sufficient quantity will optimize intestinal transit and bulk according to individual needs. Isolated fiber supplements have not been shown to be effective in colon cancer prevention.

Further attempts to be more specific about what type of fiber to recommend seem premature at this time. However, an intake in the range of 20 to 35 gm per day of dietary fiber from foods has recently been recommended by an Expert Panel.

PMID: 2852641 [PubMed - indexed for MEDLINE

Dietary fiber and the chemopreventive modelation of colon carcinogenesis.

• Alabaster O,
• Tang Z,
• Shivapurkar N.

Institute for Disease Prevention, George Washington University Medical Center, Washington DC, USA.

Comparative international epidemiological data indicate that the difference between the highest and lowest colon cancer incidence is approximately 10-fold. This suggests that the dominant causes of colon cancer are environmental rather than genetic in origin, with the dominant environmental cause being the typical diet of Western industrialized countries.

Many epidemiological and experimental studies have suggested an important role for dietary fiber in the prevention of colon cancer. Using the Fischer-344 rat as the experimental model, data clearly demonstrate a strong protective effect of a diet that is low in fat, high in fiber and high in calcium (low-risk diet). Such a diet prevents the development of both preneoplastic aberrant crypt foci (ACF) and colon tumors.

Recent experiments have also demonstrated a direct relationship between a ras point mutation in ACF at different stages of rat colon carcinogenesis, and a ras point mutation that is subsequently present in colon tumors. Using wheat bran as the model dietary fiber source, its effects were compared to the effects of psyllium, phytic acid, vitamin E, beta-carotene, folic acid, alone or in combination, for their ability to prevent colon cancer in rats on high-risk Western-style diets.

Our studies clearly demonstrated the ability of wheat bran to reduce ACF and colon tumors in rats that consumed high-fat, Western-style diets. Although phytic acid, which is a constituent of wheat bran, alone demonstrated strong cancer-preventive potential, our experiments provided evidence for the cancer-preventive effect of the crude fiber fraction that is independent of the effect of phytic acid.

The synergistic combination of wheat bran with the soluble fiber psyllium led to enhanced protection; while the combination of wheat bran with beta-carotene showed only an additive effect. Beta-carotene appeared to show higher protection than wheat bran at an intake level that is nutritionally relevant to humans, suggesting the possibility of using beta-carotene to enhance the effects of dietary fiber in high-risk Western populations.

Using ACF as an intermediate endpoint, it was also shown that vitamin E and beta-carotene appear to inhibit progression of ACF to colon cancer, while wheat bran and folic acid appeared to have weak cancer-preventive potential at this late stage of carcinogenesis. In conclusion, wheat bran alone, or in combination with psyllium, appears to have greater potential to inhibit earlier phases of carcinogenesis, while beta-carotene and vitamin E may also inhibit later stages of carcinogenesis.

Despite considerable epidemiological and experimental evidence that increasing the fiber and lowering the fat content of the Western diet could substantially reduce the risk of cancer and heart disease, the real challenge is to find effective ways to educate and motivate people to overcome their intrinsic cultural resistance to such changes in their eating habits.

Dietary fiber, potassium, magnesium and calcium in relation to the risk of preeclampsia.

• Frederick IO,
• Williams MA,
• Dashow E,
• Kestin M,
• Zhang C,
• Leisenring WM.

Center for Perinatal Studies, Swedish Medical Center, Seattle, WA 98122, USA. ihunnaya.frederick@swedish.org

OBJECTIVE: To explore the relation between preeclampsia risk and maternal intake of dietary fiber, potassium, magnesium and calcium. STUDY DESIGN: We conducted a case-control study of 172 preeclamptics and 339 normotensive controls. Maternal dietary intake was assessed using a food frequency questionnaire. Logistic regression procedures were used to estimate the association between each dietary factor and preeclampsia risk.

RESULTS: Fiber intake was inversely associated with the risk of preeclampsia. When extreme quartiles of total fiber intake were compared, the odds ratio (OR) for preeclampsia was 0.46 (95% confidence interval [CI] 0.23-0.92). The multivariate OR for preeclampsia for women in the top quartile of potassium intake (> 4.1 g/d) versus the lowest quartile (< 2.4 g/d) was 0.49 (95% CI 0.24-0.99).

There was some evidence ofa reduced risk of preeclampsia with a high intake of magnesium and calcium, though these results were not statistically significant. Intake offruits and vegetables, low-fat dairy products, total cereal and dark bread were each associated with a reduced risk of preeclampsia.

CONCLUSION: Our results support previous reports that suggest that diets high in fiber and potassium are associated with a reduced risk of hypertension. Maternal intake of recommended amounts of foods rich in fiber, potassium and other nutrients may reduce the risk of preeclampsia.

Treatment of constipation in older adults.

• Hsieh C.

Thomas Jefferson University, Department of Family Medicine, Philadelphia, Pennsylvania 19107, USA.

Constipation is a common complaint in older adults. Although constipation is not a physiologic consequence of normal aging, decreased mobility and other comorbid medical conditions may contribute to its increased prevalence in older adults.

Functional constipation is diagnosed when no secondary causes can be identified, such as a medical condition or a medicine with a side effect profile that includes constipation. Empiric treatment may be tried initially for patients with functional constipation.

Management of chronic constipation includes keeping a stool diary to record the nature of the bowel movements, counseling on bowel training, increasing fluid and dietary fiber intake, and increasing physical activity. There are a variety of over-the-counter and prescription laxatives available for the treatment of constipation.

Fiber and laxatives increase stool frequency and improve symptoms of constipation. If constipation is refractory to medical treatment, further diagnostic evaluation may be warranted to assess for colonic transit time and anorectal dysfunction. Alternative treatment methods such as biofeedback and surgery may be considered for these patients.

Preventing diverticular disease. Review of recent evidence on high-fibre diets.

• Aldoori W,
• Ryan-Harshman M.

Nutritionals at Whitehall-Robins Inc, Mississauga, Ont. harsh@durham.net

OBJECTIVE: To review recent evidence on dietary factors associated with diverticular disease (DD) with special emphasis on dietary fibre.

QUALITY OF EVIDENCE: MEDLINE was searched from January 1966 to December 2001 for articles on the relationship between dietary and other lifestyle factors and DD. Most articles either focused on dietary intervention in treating symptomatic DD or were case-control studies with inherent limitations for studying diet-disease associations. Only one large prospective study of male health professionals in the United States assessed diet at baseline and before initial diagnosis of DD.

MAIN MESSAGE: A diet high in fibre mainly from fruits and vegetables and low in total fat and red meat decreases risk of DD. Evidence indicates that the insoluble component of fibre is strongly associated with lower risk of DD; this association was particularly strong for cellulose. Caffeine and alcohol do not substantially increase risk of DD, nor does obesity, but higher levels of physical activity seem to reduce risk of DD.

CONCLUSION: A diet high in fibre and low in total fat and red meat and a lifestyle with more physical activity might help prevent DD.

PMID: 12449547 [PubMed - indexed for MEDLINE]

Trends and dietary determinants of overweight and obesity in a multiethnic population.

• Maskarinec G,
• Takata Y,
• Pagano I,
• Carlin L,
• Goodman MT,
• Le Marchand L,
• Nomura AM,
• Wilkens LR,
• Kolonel LN.

Cancer Research Center of Hawaii, Honolulu, 96813, USA. gertraud@crch.hawaii.edu

OBJECTIVES: To describe trends in BMI among different ethnic groups in Hawaii and to explore the relation of nutrient and food intake with excess weight.

RESEARCH METHODS AND PROCEDURES: We pooled demographic, anthropometric, and nutritional data derived from a detailed diet history for 159,683 participants of 18 population-based epidemiological studies conducted in Hawaii over a 25-year period. The age-adjusted prevalence of excess weight (BMI > or = 25 kg/m(2)) was estimated for 5-year intervals. To explore dietary determinants of excess weight, we computed odds ratios using logistic regression.

RESULTS: During the study period, the prevalence of excess weight increased considerably among all ethnic groups. Native Hawaiians had the highest and Asian Americans had the lowest prevalence of excess weight at all times. Although the percentage of calories consumed from carbohydrates increased, the percentage of calories from fat decreased over time. On an individual level, fat and protein consumption predicted a higher BMI, and dietary fiber intake predicted a lower BMI.

Similarly, a higher consumption of meat, poultry, and fish was related to excess weight, whereas fruit and vegetable intake were inversely associated with excess weight. After stratification by ethnicity, the associations were not materially altered among women, but carbohydrates seemed to have a stronger association with excess weight among Native Hawaiian and Japanese men than among white men

DISCUSSION: In this large ethnically diverse population, plant-based foods and dietary fiber emerged as a potential protective factor against excess weight regardless of ethnicity.

Fibre intake and prostate cancer risk.

• Pelucchi C,
• Talamini R,
• Galeone C,
• Negri E,
• Franceschi S,
• Dal Maso L,
• Montella M,
• Conti E,
• La Vecchia C.

Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy. pelucchi@marionegri.it

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. Copyright 2003 Wiley-Liss, Inc.

Nutrition and health: epidemiology of diet, cancer and cardiovascular disease in Italy.

• La Vecchia C,
• Chatenoud L,
• Altieri A,
• Tavani A.

Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, 20157 Milano, Italy. garimoldi@marionegri.it

Most epidemiological data suggest a protective role for fruits and vegetables in the prevention of several common epithelial cancers, including digestive and major non-digestive neoplasms.

The relation between frequency of consumption of vegetables and fruit and cancer and myocardial infarction risk was analysed using data from a series of case-control studies conducted in Italy.

For digestive tract cancer, population attributable risks for low intake of vegetables and fruit ranged between 15 and 40%. A selected number of antioxidants showed a significant inverse relation with breast and colorectal cancer risk, although the main components responsible for the favourable effect of a diet rich in vegetables and fruit remain undefined.

Fish tends to be another favourable indicator of reduced cancer risk. In contrast, subjects reporting frequent red meat intake showed a relative risk consistently above unity for several common neoplasms. Whole grain food intake was consistently related to reduced risk of several types of cancer, particularly of the upper digestive tract neoplasms.

Epidemiological evidence of the relation between fiber and colorectal cancer indicated a possible protections. In contrast, refined grain intake was associated to increased risk of different types of cancer, pointing to a potential role of insulin-like growth factor 1 (IGF-1).

A low risk diet for cardiovascular disease includes high consumption of fish, vegetables and fruit, and hence rich in ascorbic acid and other antioxidants, thus sharing several aspects with a favourable diet for cancer.

Role of fibre and fruit in the Mediterranean diet to protect against myocardial infarction: a case-control study in Spain.

• Martinez-Gonzalez MA,
• Fernandez-Jarne E,
• Martinez-Losa E,
• Prado-Santamaria M,
• Brugarolas-Brufau C,
• Serrano-Martinez M.

Department of Epidemiology and Public Health, University of Navarre, Pamplona, Spain. mamartinez@unav.es

OBJECTIVE: To assess the association between a first acute myocardial infarction and the consumption of fibre and fruit.

DESIGN: Hospital-based case-control study with incident cases. A validated semi-quantitative food frequency questionnaire (136 items) was used to assess food intake.

SETTING: Three third-level university hospitals in Pamplona (Spain).

SUBJECTS: Cases were subjects aged under 80, newly diagnosed with acute myocardial infarction. Each case patient (n=171) was matched to a control subject of the same gender and age (5 y bands) admitted to the same hospital.

RESULTS: An inverse association was apparent for the three upper quintiles of fibre intake. After adjustment for non-dietary and dietary confounders, an inverse linear trend was clearly significant, showing the highest relative reduction of risk (86%) for the fifth quintile (OR=0.14, 95% confidence interval: 0.03-0.67). An inverse association was also apparent for fruit intake, but not for vegetables or legumes.

CONCLUSIONS: Our data suggest that a substantial part of the postulated benefits of the Mediterranean diet on coronary risk might be attributed to a high intake of fibre and fruit.

Dietary intake and the risk of gastro-oesophageal reflux disease (GORD or GERD in the U. S.): a cross sectional study in volunteers.

• El-Serag HB,
• Satia JA,
• Rabeneck L.

Section of Gastroenterology and Health Services Research, The Houston Veterans Affairs Medical Center (152), 2002 Holcombe Blvd, Houston, TX 77030, USA. hasheme@bcm.tmc.edu

BACKGROUND: Although diet has been associated with gastro-oesophageal reflux disease (GORD or GERD), the role of dietary components (total energy, macro and micronutrients) is unknown. We examined associations of GORD(GERD) symptoms with intakes of specific dietary components.

METHODS: We conducted a cross sectional study in a sample of employees (non-patients) at the Houston VAMC. The Gastro Esophageal Reflux Questionnaire was used to identify the onset, frequency, and severity of GORD(GERD) symptoms. Dietary intake (usual frequency of consumption of various foods and portion sizes) over the preceding year was assessed using the Block 98 food frequency questionnaire. Upper endoscopy was offered to all participants and oesophageal erosions recorded according to the LA classification.

We compared the dietary intake (macronutrients, micronutrients, food groups) of participants with or without GORD(GERD) symptoms, or erosive oesophagitis. Stepwise multiple logistic regression analyses were used to examine associations between nutrients and GORD (GERD) symptoms or oesophageal erosions, adjusting for demographic characteristics, body mass index (BMI), and total energy intake.

RESULTS: A total of 371 of 915 respondents (41%) had complete and interpretable answers to both heartburn and regurgitation questions and met validity criteria for the Block 98 FFQ. Mean age was 43 years, 260 (70%) were women, and 103 (28%) reported at least weekly occurrences of heartburn or regurgitation.

Of the 164 respondents on whom endoscopies were performed, erosive oesophagitis was detected in 40 (24%). Compared to participants without GORD(GERD) symptoms, daily intakes of total fat, saturated fat, cholesterol, percentage of energy from dietary fat, and average fat servings were significantly higher in participants with GORD(GERD) symptoms. In addition, there was a dose-response relationship between GORD(GERD) and saturated fat and cholesterol.

The effect of dietary fat became non-significant when adjusted for BMI. However, high saturated fat, cholesterol, or fat servings were associated with GORD(GERD) symptoms only in participants with a BMI >25 kg/m2 (effect modification).

Fibre intake remained inversely associated with the risk of GORD symptoms in adjusted full models. Participants with erosive oesophagitis had significantly higher daily intakes of total fat and protein than those without it (p<0.05).

CONCLUSIONS: In this cross sectional study, high dietary fat intake was associated with an increased risk of GORD(GERD) symptoms and erosive oesophagitis while high fibre intake correlated with a reduced risk of GORD(GERD) symptoms. It is unclear if the effects of dietary fat are independent of obesity.

Normal-weight adults consume more fiber and fruit than their age- and height-matched overweight/obese counterparts.

• Davis JN,
• Hodges VA,
• Gillham MB.

Department of Human Ecology, The University of Texas at Austin, 1 University Station A2700, Austin, TX 78712, USA.

OBJECTIVES: To assess differences in dietary intake of overweight/obese subjects and sex-, age-, and height-matched controls and to identify dietary components associated with increased deposition of body fat. DESIGN/SUBJECTS: A convenience sample of 52 overweight/obese and 52 normal-weight adults matched for sex, age (+/-1 year), and height (+/-1 inch) were recruited from the local area. Dietary intake was assessed with the Block 60-item food frequency questionnaire, physical activity was measured by the Yale Physical Activity Survey, and percent body fat was measured via dual-energy x-ray absorptiometry.

STATISTICAL ANALYSES PERFORMED: Independent t tests compared between-group consumption of dietary components. The ability of dietary components to predict percent body fat before and after controlling for age-, sex-, and physical activity-related energy expenditure and other macronutrients was assessed with multiple regression analyses. Spearman correlation coefficients examined relationships among nutrients, Food Guide Pyramid servings, and percent body fat.

RESULTS: Overweight/obese subjects consumed more total fat, saturated fat, and cholesterol and less carbohydrate, complex carbohydrate, and dietary fiber than control subjects. Reported intake of dietary fiber was inversely related to percent body fat without (R(2)=0.052, P=0.02) and with (R(2)=0.045, P=0.013) control for potential confounding factors. Servings of fruit per day were negatively related to percent body fat (r=-0.40, P<0.01).

CONCLUSIONS: These findings suggest that the composition of a diet, especially low dietary fiber and fruit intake, plays a role in the etiology of obesity.

Associations of vegetable and fruit consumption with age-related cognitive change.

• Morris MC,
• Evans DA,
• Tangney CC,
• Bienias JL,
• Wilson RS.

Rush Institute for Healthy Aging, 1645 W. Jackson, Ste. 675, Chicago, IL 60612, USA. Martha_C_Morris@rush.edu

OBJECTIVE: To examine the association between rates of cognitive change and dietary consumption of fruits and vegetables among older persons.

METHODS: The authors conducted a prospective cohort study of 3,718 participants, aged 65 years and older of the Chicago Health and Aging Project. Participants completed a food frequency questionnaire and were administered at least two of three cognitive assessments at baseline, 3-year, and 6-year follow-ups. Cognitive function was measured using the average z-score of four tests: the East Boston Tests of immediate memory and delayed recall, the Mini-Mental State Examination, and the Symbol Digit Modalities Test.

RESULTS: The mean cognitive score at baseline for the analyzed cohort was 0.18 (range: -3.5 to 1.6), and the overall mean change in score per year was a decline of 0.04 standardized units. In mixed effects models adjusted for age, sex, race, and education, compared with the rate of cognitive decline among persons in the lowest quintile of vegetable intake (median of 0.9 servings/day), the rate for persons in the fourth quintile (median, 2.8 servings/day) was slower by 0.019 standardized units per year (p = 0.01), a 40% decrease, and by 0.018 standardized units per year (p = 0.02) for the fifth quintile (median, 4.1 servings/day), or a 38% decrease in rates.

The association remained significant (p for linear trend = 0.02) with further control of cardiovascular-related conditions and risk factors. Fruit consumption was not associated with cognitive change.

CONCLUSION: High vegetable but not fruit consumption may be associated with slower rate of cognitive decline with older age.

Dietary fiber and body weight.

• Slavin JL.

Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota, USA. jslavin@umn.edu

OBJECTIVE: This review provides an update of recent studies of dietary fiber and weight and includes a discussion of potential mechanisms of how dietary fiber can aid weight loss and weight maintenance.

METHODS: Human studies published on dietary fiber and body weight were reviewed and summarized. Dietary fiber content of popular low-carbohydrate diets were calculated and are presented.

RESULTS: Epidemiologic support that dietary fiber intake prevents obesity is strong. Fiber intake is inversely associated with body weight and body fat. In addition, fiber intake is inversely associated with body mass index at all levels of fat intake after adjusting for confounding factors.

Results from intervention studies are more mixed, although the addition of dietary fiber generally decreases food intake and, hence, body weight. Many mechanisms have been suggested for how dietary fiber aids in weight management, including promoting satiation, decreasing absorption of macronutrients, and altering secretion of gut hormones.

CONCLUSION: The average fiber intake of adults in the United States is less than half recommended levels and is lower still among those who follow currently popular low-carbohydrate diets, such as Atkins and South Beach. Increasing consumption of dietary fiber with fruits, vegetables, whole grains, and legumes across the life cycle is a critical step in stemming the epidemic of obesity found in developed countries. The addition of functional fiber to weight-loss diets should also be considered as a tool to improve success.

Vegetarian diets and weight status.

• Berkow SE,
• Barnard N.

Physician's Committee for Responsible Medicine, 5100 Wisconsin Ave., Suite 400, Washington, DC 20016, USA.

The increasing global health problems of overweight and obesity are associated with coronary heart disease, hypertension, diabetes, osteoarthritis, and certain cancers, among other health concerns. Vegetarian diets are associated with reduced body weight, lower incidence of certain chronic disease, and lower medical costs compared with non-vegetarian diets.

We reviewed the literature to ascertain the extent to which and by what mechanism(s) a plant-based diet may mediate body weight.

Nutrition and aging--practical advice for healthy eating.

• Johnson MA.

Department of Foods and Nutrition, Faculty of Gerontology, University of Georgia, Athens, USA.

This article provides practical advice about foods and dietary supplements that are beneficial for the health of older people. Overweight and obesity are among the most common nutrition-related disorders in older people.

A plant-based diet is associated with reduced risk of chronic diseases such as obesity, cardiovascular disease, cancer, and diabetes.

Vitamin B12 deficiency is prevalent in older adults, but there are misconceptions about the causes, consequences, and treatments. Diminished synthesis of vitamin D in the skin that occurs with aging and poor dietary intake contribute to the high prevalence of poor vitamin D status in older adults.

Vitamin D deficiency is associated with chronic disorders beyond poor bone health. Supplements containing vitamin B12 and vitamin D will help older adults meet their needs for these key nutrients.

Plant foods and brain aging: a critical appraisal.

• Schaffer S,
• Eckert GP,
• Schmitt-Schillig S,
• Muller WE.

Institute of Pharmacology, ZAFES, Biocenter Niederursel, University of Frankfurt, Frankfurt, Germany.

In the 21st century, human aging will be one of the biggest challenges for most societies throughout the world. The decline in human fitness is a typical hallmark of the aging process. Aside from the cardiovascular system, the brain most often suffers significantly from the life-long impact of stressors, such as reactive oxygen and nitrogen species. Oxytosis, i.e. oxidative stress-induced cell death, has been identified to play a major role in the development and onset of chronic diseases.

Foods, especially of plant origin, are rich in antioxidants and numerous in vivo data suggest that a diet rich in fruits and vegetables supports the maintenance of animal and human health. These beneficial effects also extend to the central nervous system, which, due to the presence of the blood-brain barrier, tightly controls the influx of metabolites and nutrients.

In earlier studies the impact of antioxidant vitamins, such as alpha-tocopherol and ascorbic acid, on brain health has been of interest. Recently, the focus moved to assessing the potential of unsaturated fatty acids and secondary plant metabolites, particularly of polyphenols, to act as neuroprotectants.

Considerable experimental evidence suggests that polyphenols and other plant-derived bioactivities affect animal and human brain function not only by directly lowering oxidative stress load but also by modulating various signal transduction pathways.

Mediterranean Diet, Alzheimer Disease, and Vascular Mediation.

• Scarmeas N,
• Stern Y,
• Mayeux R,
• Luchsinger JA.

Author Affiliations: Taub Institute for Research on Alzheimer's Disease and the Aging Brain.

OBJECTIVES: To examine the association between the Mediterranean diet (MeDi) and Alzheimer disease (AD) in a different AD population and to investigate possible mediation by vascular pathways.

Design, Setting, Patients, and MAIN OUTCOME MEASURES: A case-control study nested within a community-based cohort in New York, NY. Adherence to the MeDi (0- to 9-point scale with higher scores indicating higher adherence) was the main predictor of AD status (194 patients with AD vs 1790 nondemented subjects) in logistic regression models that were adjusted for cohort, age, sex, ethnicity, education, apolipoprotein E genotype, caloric intake, smoking, medical comorbidity index, and body mass index (calculated as weight in kilograms divided by height in meters squared).

We investigated whether there was attenuation of the association between MeDi and AD when vascular variables (stroke, diabetes mellitus, hypertension, heart disease, lipid levels) were simultaneously introduced in the models (which would constitute evidence of mediation).

RESULTS: Higher adherence to the MeDi was associated with lower risk for AD (odds ratio, 0.76; 95% confidence interval, 0.67-0.87; P<.001). Compared with subjects in the lowest MeDi tertile, subjects in the middle MeDi tertile had an odds ratio of 0.47 (95% confidence interval, 0.29-0.76) and those at the highest tertile an odds ratio of 0.32 (95% confidence interval, 0.17-0.59) for AD (P for trend <.001). Introduction of the vascular variables in the model did not change the magnitude of the association.

CONCLUSIONS: We note once more that higher adherence to the Mediterranean Diet is associated with a reduced risk for AD. The association does not seem to be mediated by vascular comorbidity. This could be the result of either other biological mechanisms