Glycemic index in chronic disease: a review

Food groups and risk of non-Hodgkin lymphoma: a multicenter, case-control study in Italy

Incidence of non-Hodgkin lymphoma (NHL) has been rising worldwide, but the reasons are undefined. Dietary habits may play a role in the etiology of NHL by influencing the metabolic pathways of several cells of the immune system. This case-control study investigated the relation between food consumption and NHL risk. Between 1999 and 2002, we conducted a hospital-based case-control study on NHL in 2 areas of Italy. Cases were 190 patients (median age 58 years) with incident NHL admitted to specialized and general hospitals. Controls were 484 patients (median age 63 years) with acute non-neoplastic conditions admitted to the same hospitals network of cases. A validated food-frequency questionnaire was used to assess habitual diet 2 years before interview. Unconditional multiple logistic regression was used to estimate the odds ratios (OR) and the corresponding 95% confidence intervals (CI), with allowance for energy intake, according to the residual model. Consumption of highest versus lowest quartile of pasta/rice (OR = 1.87, 95% CI: 1.04-3.36) and cheese (OR = 1.66, 95% CI: 0.98-2.83) were associated with a significantly increased NHL risk. Inverse association was found for vegetables (OR = 0.49, 95% CI: 0.28-0.87), fruits (OR = 0.51, 95% CI: 0.30-0.85), and egg consumption (OR = 0.59, 95% CI: 0.36-0.97). The association of pasta/rice was also supported by an increased risk of high glycemic load levels (OR = 1.86, 95% CI: 1.04-3.32). In conclusion, our results suggested that diet could affect NHL risk.

Dietary glycemic index and load in relation to metabolic risk factors in Japanese female farmers with traditional dietary habits

BACKGROUND

Little is known about the relation of dietary glycemic index (GI) and glycemic load (GL) to metabolic risk factors, particularly in non-Western populations.

OBJECTIVE

We examined the cross-sectional associations between dietary GI and GL and several metabolic risk factors in healthy Japanese women with traditional dietary habits.

DESIGN

The subjects were 1354 Japanese female farmers aged 20-78 y from 5 regions of Japan. Dietary GI and GL were assessed with a self-administered diet-history questionnaire. Body mass index (BMI) was calculated as weight (kg) divided by the square of height (m). Fasting blood samples were collected for biochemical measurements.

RESULTS

The mean dietary GI was 67, and the mean dietary GL (/1000 kcal) was 88 (GI for glucose = 100). White rice (GI = 77) was the major contributor to dietary GI and GL (58.5%). After adjustment for potential dietary and nondietary confounding factors, dietary GI was positively correlated with BMI (n = 1354; P for trend = 0.017), fasting triacylglycerol (n = 1349; P for trend = 0.001), fasting glucose (n = 764; P for trend = 0.022), and glycated hemoglobin (n = 845; P for trend = 0.038). Dietary GL was independently negatively correlated with HDL cholesterol (n = 1354; P for trend = 0.004) and positively correlated with fasting triacylglycerol (P for trend = 0.047) and fasting glucose (P for trend = 0.012).

CONCLUSIONS

Both dietary GI and GL are independently correlated with several metabolic risk factors in subjects whose dietary GI and GL were primarily determined on the basis of the GI of white rice.

Dietary carbohydrate intake and glycemic index in relation to cortical and nuclear lens opacities in the Age-Related Eye Disease Study

BACKGROUND

Little is known about the association between dietary carbohydrates and cataract in nondiabetic persons.

OBJECTIVE

The aim was to test whether recent dietary carbohydrate intakes or glycemic index (GI; a measure of carbohydrate intake quality) was associated with the presence of cortical or nuclear opacities.

DESIGN

A modified Block food-frequency questionnaire was used to obtain dietary information from 3377 participants (aged 60-80 y; 56% were women) in the Age-Related Eye Disease Study (AREDS). Lens status was evaluated by using the AREDS System for Classifying Cataracts. Associations were examined for eyes with only a single, or pure, type of lens opacity by using the generalized estimating approach to logistic regression to account for the lack of independence between the eyes of a person.

RESULTS

For participants in the highest quartile, dietary GI was associated with a higher prevalence of all pure nuclear opacities [grade >2; odds ratio (OR): 1.29; 95% CI: 1.04, 1.59; P for trend = 0.02] and moderate nuclear opacities (grade > or =4; OR: 1.43; 95% CI: 0.96, 2.14; P for trend = 0.052). The OR in a comparison of the highest with the lowest quartile of intake was 1.27 (95% CI: 0.99, 1.63; P for trend = 0.09) for cortical opacities of any severity (>0% of area opaque), and the OR increased somewhat for moderate cortical opacities (>5% of area opaque; OR: 1.71; 95% CI: 1.00, 2.95; P for trend = 0.056).

CONCLUSIONS

Results from the cross-sectional analysis of AREDS baseline data suggest that dietary glycemic quality and dietary carbohydrate quantity may be associated with prevalent nuclear and cortical opacities, respectively.

Linoleic acid, vitamin D and other nutrient intakes in the risk of non-Hodgkin lymphoma: an Italian case-control study

BACKGROUND

Dietary habits have been suggested as a factor related to the increase of non-Hodgkin lymphoma (NHL) incidence in western populations, but the role of individual nutrients is still unclear.

PATIENTS AND METHODS

A hospital-based case-control study was conducted in Italy, 1999-2002.

CASES

190 incident, histologically-confirmed NHL cases aged 18-84 years.

CONTROLS

484 subjects admitted to hospital for acute, non-neoplastic diseases unrelated to diet. Dietary habits were assessed by a validated food-frequency questionnaire; nutrient intakes were computed using the Italian food composition database. Odds ratios (ORs) and corresponding 95% confidence intervals (CI) for tertiles of intake of nutrient were computed using the energy-adjusted residual models.

RESULTS

Inverse association emerged for polyunsaturated fatty acids (OR=0.6; 95% CI: 0.4-0.9), linoleic acid (OR=0.6; 95% CI: 0.4-0.9), and vitamin D (OR=0.6; 95% CI: 0.4-0.9). The protective effect for linoleic acid (OR=0.3; 95% CI: 0.2-0.7) and vitamin D (OR=0.4; 95% CI: 0.2-0.9) was stronger in women; no differences emerged according to age. Linoleic acid was inversely related to follicular and diffuse large B-cell lymphoma; the protective effect of vitamin D emerged most clearly for follicular subtypes.

CONCLUSIONS

Our study suggests that a diet rich in polyunsaturated fatty acids and vitamin D is associated with a reduced risk of NHL.

Food groups and risk of benign prostatic hyperplasia

OBJECTIVES

To evaluate the role of a wide range of foods on the risk of benign prostatic hyperplasia (BPH), we conducted a case-control study in Italy between 1991 and 2002. Although BPH is an extremely common condition, particularly among older men, its risk factors, including dietary ones, remain largely undefined.

METHODS

Included in the study were 1369 patients younger than 75 years old surgically treated for BPH and 1451 controls younger than 75 years of age who had been admitted to the same hospitals as cases for a wide spectrum of acute, non-neoplastic conditions. A validated and reproducible food frequency questionnaire, including 78 foods and beverages, plus a separate section on alcoholic beverages, was used to assess patients' dietary habits 2 years before diagnosis or hospital admission. Multivariate odds ratios (OR) were obtained after allowance for energy intake and other major potential confounding factors.

RESULTS

A significant trend of increasing risk with more frequent consumption was found for cereals (OR 1.55 for the greatest versus lowest quintile), bread (OR 1.69), eggs (OR 1.43), and poultry (OR 1.39). Inverse associations were observed for soups (OR 0.74), pulses (OR 0.74), cooked vegetables (OR 0.66), and citrus fruit (OR 0.82). No association was observed for milk and yogurt products, coffee and tea, pasta and rice, fish, cheese, row vegetables, potatoes, fruit, or desserts.

CONCLUSIONS

The results of this study suggest a role for dietary habits on the risk of BPH. In particular, a diet rich in cereals and some types of meat and poor in vegetables and pulses may have an unfavorable effect in this Italian population.

Canadian Dietitians’ Use and Perceptions Of Glycemic Index in Diabetes Management

Purpose: Several health organizations, including the Canadian Diabetes Association, advocate use of the glycemic index (GI) in the nutritional management of diabetes. However, the clinical utility and applications of the GI remain controversial. Our goal was to determine, via a postal survey, whether dietitians were using the GI and barriers to its use if they were not.

Methods: This cross-sectional study was conducted in 2003. Members of Dietitians of Canada and the Ordre professionnel des diététistes du Québec (n=6,060) were first contacted by mail to identify those working with individuals with diabetes. Among respondents (n=2,857), 1,805 worked with individuals with diabetes and were sent a questionnaire. Using Chi-square analyses, users and nonusers were compared for their professional characteristics, perceived benefits, barriers, general knowledge about the concept, and confidence in teaching the GI.

Results: Among questionnaire respondents (n=1,057), 39% (n=415) used the GI and 61% (n=642) did not. Overall, users were more likely to have a greater diabetes patient caseload, perceived greater benefits and had greater confidence in teaching the concept. Nonusers cited lack of teaching tools and lack of knowledge on how to teach the concept as major barriers.

Conclusions: Further research is required to identify the clinical reasoning that triggers dietitians to apply the concept in their practice.

Consumption of sweet foods and breast cancer risk in Italy

BACKGROUND

The relation between the intake of sugar and sweets and the risk of breast cancer has been considered in ecological, prospective and case-control studies, but the results are unclear. We analyzed such a relation in a case-control study conducted between 1991 and 1994 in Italy.

PATIENTS AND METHODS

Cases were 2569 women with histologically confirmed incident breast cancer and controls were 2588 women admitted to hospital for acute, non-neoplastic, non-hormone-related conditions. Information on diet was based on an interviewer-administered questionnaire tested for reproducibility and validity. The odds ratios (OR) and 95% confidence intervals (CI) were computed by multiple logistic regression equations.

RESULTS

Compared with women with the lowest tertile of intake, women in the highest tertile of intake of desserts (including biscuits, brioches, cakes, puffs and ice-cream) and sugars (including sugar, honey, jam, marmalade and chocolate) had multivariate ORs of 1.19 (95% CI 1.02-1.39) and 1.19 (95% CI 1.02-1.38), respectively. The results were similar in strata of age, body mass index, total energy intake and other covariates.

CONCLUSIONS

We found a direct association between breast cancer risk and consumption of sweet foods with high glycemic index and load, which increase insulin and insulin growth factors.

Potato and french fry consumption and risk of type 2 diabetes in women

BACKGROUND

Potatoes, a high glycemic form of carbohydrate, are hypothesized to increase insulin resistance and risk of type 2 diabetes.

OBJECTIVE

The objective was to examine prospectively the relation between potato consumption and the risk of type 2 diabetes.

DESIGN

We conducted a prospective study of 84,555 women in the Nurses' Health Study. At baseline, the women were aged 34-59 y, had no history of chronic disease, and completed a validated food-frequency questionnaire. The participants were followed for 20 y with repeated assessment of diet.

RESULTS

We documented 4496 new cases of type 2 diabetes. Potato and french fry consumption were both positively associated with risk of type 2 diabetes after adjustment for age and dietary and nondietary factors. The multivariate relative risk (RR) in a comparison between the highest and the lowest quintile of potato intake was 1.14 (95% CI: 1.02, 1.26; P for trend = 0.009). The multivariate RR in a comparison between the highest and the lowest quintile of french fry intake was 1.21 (95% CI: 1.09, 1.33; P for trend < 0.0001). The RR of type 2 diabetes was 1.18 (95% CI: 1.03, 1.35) for 1 daily serving of potatoes and 1.16 (95% CI: 1.05, 1.29) for 2 weekly servings of french fries. The RR of type 2 diabetes for substituting 1 serving potatoes/d for 1 serving whole grains/d was 1.30 (95% CI: 1.08, 1.57). The association between potato consumption and risk of type 2 diabetes was more pronounced in obese women.

CONCLUSIONS

Our findings suggest a modest positive association between the consumption of potatoes and the risk of type 2 diabetes in women. This association was more pronounced when potatoes were substituted for whole grains.

The impact of the addition of toppings/fillings on the glycaemic response to commonly consumed carbohydrate foods

OBJECTIVE

To investigate the influence of the addition of various toppings/fillings on the glycaemic response to baked potato, pasta and toast.

DESIGN

Randomised, repeated measures design.

SETTING

Oxford, UK.

SUBJECTS

Forty normal, healthy subjects (11 males and 29 females) were recruited to the study. Subjects were staff and students from Oxford Brookes University.

INTERVENTION

Cheddar cheese, chilli con carne, baked beans and tuna were added to baked potatoes, cooked pasta and toast to determine the effect on glycaemic response.

RESULTS

No significant difference was found among the various toppings and baked potato (P=0.06), pasta (P=0.06) and toast (P=0.39). However, the addition of toppings to a carbohydrate-rich food had a consistent lowering effect on glycaemic index (GI). In particular, the addition of cheddar cheese to potato, pasta and toast reduced the GI of the test meal to a value that is considered to be low-GI (39, 27 and 35, respectively). This is particularly notable for potatoes, which, when eaten alone, had the highest GI value of all the staples.

CONCLUSIONS

This study has shown that the addition of foodstuffs to the staples baked potato, pasta and toast had a consistent lowering effect on the GI value of that meal. These findings emphasise the importance of investigating the GI of composite meals.

Dietary glycaemic index and glycaemic load in Danish children in relation to body fatness

The aim of this study was to describe dietary glycaemic index (GI) and glycaemic load (GL) values in the diets of Danish children, and to examine the associations between dietary GI, GL and body fatness. Data were collected during 1997-8 as part of the European Youth Heart Study. The study population comprised 485 children aged 10 years and 364 children aged 16 years from Odense County, Denmark. Dietary GI and GL were estimated using international food tables, and the associations between energy-adjusted dietary GI, GL and body fatness were analysed by multiple linear regression. The mean daily dietary GI value was 85 (SD 6.9) with a range of 62-111. No significant differences were found between age groups and gender. The daily dietary GL was higher among boys aged 16, with a GL of 330 (sd 95) (P<0.05), compared with girls or younger boys. Dietary GL was higher among 10-year-old boys than girls (250 (sd 81) v. 230 (sd 66) P<0.05), whereas dietary GL among 16-year-old girls was 230 (sd 56). Neither dietary GI nor GL was associated with the sum of four skinfolds (SigmaSF) among girls or among 10-year-old boys. Among 16-year-old boys, significant associations were observed between dietary GI and SigmaSF (beta=0.60, SE=0.21, P=0.006), and between dietary GL and SigmaSF (beta=0.15, SE=0.06, P=0.009). In conclusion, dietary GI and GL were positively associated with body fatness among Danish boys aged 16 years, whereas no associations were found among girls or younger boys.

Food groups and renal cell carcinoma: A case–control study from Italy

Although nutrition and diet have been related to renal cell carcinoma (RCC), the role of specific foods or nutrients on this cancer is still controversial. We evaluated the relation between a wide range of foods and the risk of RCC in an Italian case-control study including 767 patients (494 men and 273 women) younger than 79 years with incident, histologically confirmed RCC, and 1,534 controls (988 men and 546 women) admitted to the same hospitals as cases for a wide spectrum of acute, non-neoplastic conditions, not related to long term diet modifications. A validated and reproducible food frequency questionnaire, including 78 foods and beverages, plus a separate section on alcohol drinking, was used to assess patients' dietary habits 2 years before diagnosis or hospital admission. Multivariate odds ratios (OR) were obtained after allowance for energy intake and other major confounding factors. A significant direct trend in risk was found for bread (OR = 1.94 for the highest versus the lowest intake quintile), and a modest excess of risk was observed for pasta and rice (OR = 1.29), and milk and yoghurt (OR = 1.27). Poultry (OR = 0.74), processed meat (OR = 0.64) and vegetables (OR = 0.65) were inversely associated with RCC risk. No relation was found for coffee and tea, soups, eggs, red meat, fish, cheese, pulses, potatoes, fruits, desserts and sugars. The results of this study provide further indications on dietary correlates of RCC, and in particular indicate that a diet rich in refined cereals and poor in vegetables may have an unfavorable role on RCC.

Expressing the glycaemic potency of foods

The glycaemic index (GI) was introduced to guide food exchanges within equicarbohydrate food categories, and it expresses the glycaemic potency of the available carbohydrate component in a food relative to that of glucose. As GI is a relative value based on 'available carbohydrate' it cannot guide food choice for glycaemic control unless the foods are equal in available carbohydrate. Furthermore, GI cannot respond to food intake or to effects on food glycaemic potency of replacing glycaemic ingredients with non-glycaemic ingredients. The glycaemic glucose equivalent (GGE) overcomes these limitations of GI. The GGE content of an amount of food is the weight of glucose (g) that would induce a glycaemic response equal to that induced by the food. Few studies have compared GI and GGE as guides to food choice for glycaemic control, but in a direct test of the predictive validity of GGE in a group of foods of differing carbohydrate and GI, GGE predicted glycaemic potency well, whereas GI was unrelated to glycaemic effect. Furthermore, an information-processing model of the use of food information in food choice shows that GI has fundamental flaws when used outside the restriction of equicarbohydrate food exchange categories. As a general guide to food choices for the control of glycaemia GI does not satisfy the criteria predictive validity, accuracy, safety, ease of use, flexibility, sufficiency and compatability, whereas GGE does. GGE is also a scientifically precise and meaningful term with which to express glycaemic potency than is 'glycaemic load'.

The glycemic index of foods influences postprandial insulin-like growth factor-binding protein responses in lean young subjects

BACKGROUND

Growth in normal and malignant tissues has been linked to hyperinsulinemia and insulin-like growth factors (IGFs). We hypothesized that IGF and IGF-binding protein (IGFBP) responses may be acutely affected by differences in the glycemic index (GI) of foods.

OBJECTIVE

We compared the postprandial responses of IGFs and IGFBP to 2 foods of similar macronutrient composition but with greatly different GIs-pearled barley (GI: 25) and instant mashed potato (GI: 85).

DESIGN

Ten young lean subjects consumed 50-g carbohydrate portions of the 2 foods or water (extended fast) in random order after an overnight fast. Capillary blood was collected at regular intervals over 4 h for measurement of blood glucose, insulin, and components of the IGF system.

RESULTS

Serum IGFBP-1 declined markedly after both meals, but the mean (+/-SEM) change at 4 h was significantly (P < 0.01) more prolonged after the low-GI meal (-55 +/- 20 ng/mL) than after the high-GI meal (-13 +/- 15 ng/mL). Conversely, the change in serum IGFBP-3 concentration at 4 h was significantly (P < 0.05) higher after the low-GI meal (251 +/- 102 ng/mL) than after the high-GI meal (-110 +/- 96 ng/mL); the same pattern was observed at 2 h. Changes in IGFBP-2, free IGF-1, and total IGF-1 responses were minimal and did not differ significantly from those during the 4-h fast.

CONCLUSION

Acute changes in IGFBP-3 after low-GI and high-GI foods may provide a biologic mechanism linking cell multiplication with greater consumption of high-GI carbohydrates.

Glycemic load, glycemic index, and carbohydrate intake in relation to risk of cholecystectomy in women

BACKGROUND & AIMS

High-carbohydrate diets with a high glycemic response may exacerbate the metabolic consequences of the insulin-resistance syndrome. The effect on the incidence of gallstone disease is not clear.

METHODS

We examined the associations between high-carbohydrate diets with a high glycemic response and the risk of cholecystectomy in a cohort of women who were aged from 35 to 61 years in 1984 and had no history of gallstone disease. As part of the Nurses' Health Study, the women reported on questionnaires mailed to them every 2 years both their carbohydrate intake and whether they had undergone cholecystectomy.

RESULTS

During 16 years of follow-up, we ascertained 5771 new cases of cholecystectomy. After adjusting for age and other known or suspected risk factors in a multivariate model, the relative risk for the highest compared with the lowest quintile of dietary carbohydrate was 1.35 (95% CI: 1.17-1.55, P for trend < .0001). The relative risks for the highest compared with the lowest quintile were 1.50 for glycemic load (95% CI: 1.32-1.71, P for trend < .0001) and 1.32 for glycemic index (95% CI: 1.20-1.45, P for trend < .0001). Independent positive associations were also seen for intakes of starch and sucrose.

CONCLUSIONS

Our findings suggest that a higher intake of carbohydrate, dietary glycemic load, and glycemic index may enhance risk of cholecystectomy in women.

Glycemic index and load-dynamic dietary guidelines in the context of diseases

The concepts of glycemic index (GI) and glycemic load (GL) are among a new generation of so-called dynamic dietary guidelines. In contrast to classical static guidelines, these new guidelines do not primarily consider the absolute amount of energy or nutrient to be ingested within 24 h, but rather are focused on the postprandial response. It is claimed that low-GI and -GL diets favorably affect many noncommunicable diseases that are prevalent in developed countries, including type II diabetes, insulin resistance, obesity, cardiovascular disease (CVD), and cancer. During the past 20 years, considerable evidence has accumulated suggesting that low-GI or -GL diets indeed positively influence some but not all diseases. Because virtually no deleterious effects of low-GI and -GL diets have been documented thus far or are to be expected, the promotion of these diets should be considered in the management of noncommunicable diseases.

Understanding and managing disturbances in insulin metabolism and body weight in women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common clinical and metabolic condition in women of reproductive age. It is associated with short-term reproductive and long-term metabolic dysfunction. Treatment has traditionally focused on fertility and hormonal therapy. However, general obesity, central obesity and insulin resistance are strongly implicated in its aetiology and improving these factors has proved highly successful in some clinical situations, reducing the need for costly assisted reproduction. A low-fat, high-carbohydrate diet is thought to improve insulin sensitivity, aid in weight loss and reduction of metabolic and reproductive symptoms and improve the long-term maintenance of a reduced weight. However, there has been recent community interest in adopting a protocol advocating a moderate increase in dietary protein for improving weight loss and PCOS symptoms. Altering the glycaemic index of the diet has also received considerable attention as a regime for promoting satiety and reducing metabolic risk factors for type 2 diabetes mellitus and cardiovascular disease. Exercise and other lifestyle changes are essential for altering the short- and long-term effects of PCOS. It is vital that the efficacy of these strategies is assessed so that accurate medical and dietetic advice can be given both to patients and to the health-care community.

Glycaemic and insulin responses of six traditional Sudanese carbohydrate-rich meals in subjects with Type 2 diabetes mellitus

AIMS

The objective of this study was to investigate the influence of six Sudanese traditional carbohydrate-rich meals on glucose and insulin responses and to formulate appropriate dietary guidelines based on glycaemic excursions of traditional foods.

METHODS

On six occasions with 1-week intervals, 10 Type 2 diabetic subjects consumed six Sudanese traditional carbohydrate-rich meals. The following meals were tested and also analysed for their composition: wheat gorasa (pancakes), sorghum kisra (flat bread) and sorghum acida (porridge), millet kisra and millet acida and maize acida. Blood samples were collected before and after meal ingestion at 0, 30, 60, 120 and 240 min and analysed for plasma glucose and plasma insulin and incremental areas under the curves (AUC) were calculated.

RESULTS

A significant variation in AUC for glucose and insulin responses were found between meals, the over all differences in incremental AUCs between the six meals were significant for both plasma glucose (P = 0.0092) and insulin (P = 0.0001). The 2-h glucose values were 10.5 +/- 2.7 for sorghum flatbread, 9.5 +/- 3.1 for sorghum porridge, 10.3 +/- 3.4 for millet flatbread, 10.6 +/- 3.6 for millet porridge, 11.4 +/- 2.7 for maize porridge and 8.7 +/- 2.4 for the wheat pancakes. The comparison between the AUCs of the meals showed that millet acida (porridge) followed by wheat gorasa (pancakes) displayed significantly lower post-prandial glucose and insulin responses, whereas maize acida induced a higher post-prandial glucose and insulin response.

CONCLUSIONS

The comparison of glycaemic and insulin responses to six traditional Sudanese meals show differences of clinical importance, and could form a basis for dietary advice to diabetic subjects in Sudan and countries sharing similar food traditions.

Glycemic index, postprandial glycemia and cardiovascular disease

PURPOSE OF REVIEW

Several lines of evidence indicate that exaggerated postprandial glycemia puts individuals without diabetes at greater risk of developing cardiovascular disease. In large, prospective observational studies, including meta-analyses, higher 120 min post-load blood glucose and glycated hemoglobin (a measure of average blood glucose level over time) independently predict cardiovascular mortality and morbidity in individuals without diabetes. These findings imply that the glycemic nature of dietary carbohydrates may also be relevant. We aim to provide a clearer perspective on how the glycemic impact of carbohydrates may modulate development of cardiovascular disease.

RECENT FINDINGS

In ecological studies, average dietary glycemic index (a measure of the postprandial glycemic potential of carbohydrates) and glycemic load (average glycemic index x amount of carbohydrate) predicts coronary infarct and cardiovascular disease risk factors, including HDL cholesterol, triglycerides and C-reactive protein. In short-term intervention studies of overweight and hyperlipidemic patients, low glycemic index diets lead to improvements in cardiovascular disease risk factors, including reduced LDL cholesterol and improved insulin sensitivity, as well as greater body fat loss on energy-restricted diets. Molecular studies indicate that physiological hyperglycemia induces overproduction of superoxide by the mitochondrial electron-transport chain, resulting in inflammatory responses and endothelial dysfunction.

SUMMARY

Taken together, the findings suggest that conventional high-carbohydrate diets with their high glycemic index may be suboptimal, particularly in insulin-resistant individuals. Because around one in four adults has impairments in postprandial glucose regulation, the glycemic potential of carbohydrates warrants further investigation in cardiovascular disease prevention.

Carbohydrates and dietary fiber

The most widely spread eating habit is characterized by a reduced intake of dietary fiber, an increased intake of simple sugars, a high intake of refined grain products, an altered fat composition of the diet, and a dietary pattern characterized by a high glycemic load, an increased body weight and reduced physical activity. In this chapter the effects of this eating pattern on disease risk will be outlined. There are no epidemiological studies showing that the increase of glucose, fructose or sucrose intake is directly and independently associated with an increased risk of atherosclerosis or coronary heart disease (CHD). On the other hand a large number of studies has reported a reduction of fatal and non-fatal CHD events as a function of the intake of complex carbohydrates--respectively 'dietary fiber' or selected fiber-rich food (e.g., whole grain cereals). It seems that eating too much 'fast' carbohydrate [i.e., carbohydrates with a high glycemic index (GI)] may have deleterious long-term consequences. Indeed the last decades have shown that a low fat (and consecutively high carbohydrate) diet alone is not the best strategy to combat modern diseases including atherosclerosis. Quantity and quality issues in carbohydrate nutrient content are as important as they are for fat. Multiple lines of evidence suggest that for cardiovascular disease prevention a high sugar intake should be avoided. There is growing evidence of the high impact of dietary fiber and foods with a low GI on single risk factors (e.g., lipid pattern, diabetes, inflammation, endothelial function etc.) as well as also the development of the endpoints of atherosclerosis especially CHD.

Glycemic index, glycemic load and risk of prostate cancer

Dietary carbohydrates have different glycemic and insulinemic potentials depending on type (glycemic index, GI) and amount (glycemic load, GL) of carbohydrate consumed or both. Insulin in turn has been implicated as a risk factor for several cancers, including that of the prostate. We assessed the relationship of GI and GL with prostate cancer risk in a multicenter case-control study. Cases and controls were recruited between 1991 and 2002 in the network of major teaching and general hospitals in 4 Italian areas. Cases were 1,204 men (age range 46-74 years) admitted for incident, histologically confirmed prostate cancer. Controls were 1,352 men (age range 46-74 years) admitted for acute, nonmalignant conditions unrelated to long-term modifications of diet. ORs of prostate cancer and the corresponding 95% CIs were derived using unconditional multiple logistic regression, including terms for age, study center, education, family history of prostate cancer, smoking, body mass index, physical activity, alcohol consumption, intake of energy, fiber and lycopenes. Compared to the lowest quintile of GI, the ORs were 1.23, 1.24, 1.47 and 1.57 for subsequent levels of GI. The corresponding values for GL were 0.91, 1.00, 1.20 and 1.41. No heterogeneity was found among strata of selected covariates. We found direct relations between dietary GI and GL and prostate cancer risk. Correcting for potential confounding factors did not substantially modify these associations.

Association between Components of the Insulin-Like Growth Factor System and Epithelial Ovarian Cancer Risk

BACKGROUND

Components of the insulin-like growth factor (IGF) system have been associated with several cancers, but very few studies are available for ovarian cancer.

METHODS

A case-control study conducted between 1999 and 2003 in Italy, including a total of 59 women with incident, histologically confirmed ovarian cancer and 108 controls admitted to the same hospital network as cases, for acute non-neoplastic diseases. All subjects were interviewed using a validated questionnaire.

RESULTS

After adjustment for potential confounders, the multivariate odds ratios for the highest versus the lowest tertile of various IGF components were 0.6 (95% confidence interval, CI: 0.2-1.4) for free IGF-I, 0.4 (CI: 0.1-1.5) for total IGF-I, 2.6 (CI: 0.9-6.9) for IGF-binding protein (IGFBP)-1, and 0.2 (CI: 0.0-0.6) for IGFBP-3.

CONCLUSIONS

This study suggests a protective role of IGFBP-3 and a positive association of IGFBP-1 with ovarian cancer. The complex role of the IGF system in ovarian carcinogenesis deserves further clarification.

Glycemia and insulinemia in healthy subjects after lactose-equivalent meals of milk and other food proteins: the role of plasma amino acids and incretins

BACKGROUND

Milk products deviate from other carbohydrate-containing foods in that they produce high insulin responses, despite their low GI. The insulinotropic mechanism of milk has not been elucidated.

OBJECTIVE

The objective was to evaluate the effect of common dietary sources of animal or vegetable proteins on concentrations of postprandial blood glucose, insulin, amino acids, and incretin hormones [glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1] in healthy subjects.

DESIGN

Twelve healthy volunteers were served test meals consisting of reconstituted milk, cheese, whey, cod, and wheat gluten with equivalent amounts of lactose. An equicarbohydrate load of white-wheat bread was used as a reference meal.

RESULTS

A correlation was found between postprandial insulin responses and early increments in plasma amino acids; the strongest correlations were seen for leucine, valine, lysine, and isoleucine. A correlation was also obtained between responses of insulin and GIP concentrations. Reconstituted milk powder and whey had substantially lower postprandial glucose areas under the curve (AUCs) than did the bread reference (-62% and -57%, respectively). Whey meal was accompanied by higher AUCs for insulin (90%) and GIP (54%).

CONCLUSIONS

It can be concluded that food proteins differ in their capacity to stimulate insulin release, possibly by differently affecting the early release of incretin hormones and insulinotropic amino acids. Milk proteins have insulinotropic properties; the whey fraction contains the predominating insulin secretagogue.

Glycemic index, glycemic load and risk of gastric cancer

BACKGROUND

Dietary carbohydrates have been directly associated with gastric cancer risk and have been considered general indicators of a poor diet. However, elevated levels of glucose and insulin elicited by consumption of high amounts of refined carbohydrates may stimulate mitogenic and cancer-promoting insulin-like growth factors (IGF). Glycemic index (GI) and glycemic load (GL), which represent indirect measures of dietary insulin demand, were analysed to understand further the association between carbohydrates and gastric cancer.

PATIENTS AND METHODS

Data were derived from a hospital-based case-control study on gastric cancer, conducted in Italy between 1985 and 1997, including 769 cases with incident, histologically confirmed gastric cancer and 2081 controls admitted to the same hospital network as cases for acute, non-neoplastic diseases. All subjects were interviewed using a reproducible food frequency questionnaire.

RESULTS

The multivariate odds ratios (OR) for subsequent quartiles of dietary GL were 1.44 [95% confidence interval (CI) 1.11-1.87], 1.62 (95% CI 1.24-2.12) and 1.94 (95% CI 1.47-2.55). No consistent pattern of risk was seen with GI. The associations were consistent in different strata of age, education and body mass index, and were stronger in women.

CONCLUSIONS

This study supports the hypothesis of a direct association between GL and gastric cancer risk, thus providing an innovative interpretation, linked to excess circulating insulin and related IGFs, for the association between carbohydrates and risk of gastric cancer.

Mediterranean diet, antioxidants and cancer: the need for randomized trials

In nutritional epidemiology the traditional approach has been to assess single nutrients or food items. Now, a growing interest exists in dietary patterns. The study of dietary patterns with a whole-diet approach represents a needed and complementary methodology. Among a priori defined patterns, the highly palatable traditional Mediterranean diet has many options to be the first choice in the dietary prevention of cancer. However, sound epidemiologic evidence about its ability to prevent the most frequent cancers is scarce. In conjunction with large and well-designed cohort studies, randomized trials using a whole-diet approach and not a simple antioxidant supplement are needed in Mediterranean countries.

No difference in body weight decrease between a low-glycemic-index and a high-glycemic-index diet but reduced LDL cholesterol after 10-wk ad libitum intake of the low-glycemic-index diet

BACKGROUND

The role of glycemic index (GI) in appetite and body-weight regulation is still not clear.

OBJECTIVE

The objective of the study was to investigate the long-term effects of a low-fat, high-carbohydrate diet with either low glycemic index (LGI) or high glycemic index (HGI) on ad libitum energy intake, body weight, and composition, as well as on risk factors for type 2 diabetes and ischemic heart disease in overweight healthy subjects.

DESIGN

The study was a 10-wk parallel, randomized, intervention trial with 2 matched groups. The LGI or HGI test foods, given as replacements for the subjects' usual carbohydrate-rich foods, were equal in total energy, energy density, dietary fiber, and macronutrient composition. Subjects were 45 (LGI diet: n = 23; HGI diet: n = 22) healthy overweight [body mass index (in kg/m(2)): 27.6 +/- 0.2] women aged 20-40 y.

RESULTS

Energy intake, mean (+/- SEM) body weight (LGI diet: -1.9 +/- 0.5 kg; HGI diet: -1.3 +/- 0.3 kg), and fat mass (LGI diet: -1.0 +/- 0.4 kg; HGI diet: -0.4 +/- 0.3 kg) decreased over time, but the differences between groups were not significant. No significant differences were observed between groups in fasting serum insulin, homeostasis model assessment for relative insulin resistance, homeostasis model assessment for beta cell function, triacylglycerol, nonesterified fatty acids, or HDL cholesterol. However, a 10% decrease in LDL cholesterol (P < 0.05) and a tendency to a larger decrease in total cholesterol (P = 0.06) were observed with consumption of the LGI diet as compared with the HGI diet.

CONCLUSIONS

This study does not support the contention that low-fat LGI diets are more beneficial than HGI diets with regard to appetite or body-weight regulation as evaluated over 10 wk. However, it confirms previous findings of a beneficial effect of LGI diets on risk factors for ischemic heart disease.

The use of glycaemic index tables to predict glycaemic index of composite breakfast meals

The applicability of the glycaemic index (GI) in the context of mixed meals and diets is still debatable. The objective of the present study was to investigate the predictability of measured GI in composite breakfast meals when calculated from table values, and to develop prediction equations using meal components. Furthermore, we aimed to study the relationship between GI and insulinaemic index (II). The study was a randomised cross-over meal test including twenty-eight healthy young men. Thirteen breakfast meals and a reference meal were tested. All meals contained 50 g available carbohydrate, but differed considerably in energy and macronutrient composition. Venous blood was sampled for 2 h and analysed for glucose and insulin. Prediction equations were made by regression analysis. No association was found between predicted and measured GI. The meal content of energy and fat was inversely associated with GI (R(2) 0.93 and 0.88, respectively; P<0.001). Carbohydrate content (expressed as percentage of energy) was positively related to GI (R(2) 0.80; P<0.001). Using multivariate analysis the GI of meals was best predicted by fat and protein contents (R(2) 0.93; P<0.001). There was no association between GI and II. In conclusion, the present results show that the GI of mixed meals calculated by table values does not predict the measured GI and furthermore that carbohydrates do not play the most important role for GI in mixed breakfast meals. Our prediction models show that the GI of mixed meals is more strongly correlated either with fat and protein content, or with energy content, than with carbohydrate content alone. Furthermore, GI was not correlated with II.

Glycemic Index, Glycemic Load, and Carbohydrate Intake in Relation to Risk of Distal Colorectal Adenoma in Women

Case-control studies and a cohort study have shown inconsistent associations between a high glycemic index or a high glycemic load and risk of colorectal cancer. These dietary variables have not been examined in relation to risk of colorectal adenoma. We thus examined the associations between dietary glycemic index, glycemic load, and carbohydrate intake with risk of adenoma of the distal colon or rectum among 34,428 US women who were initially free of cancer or polyps, who completed a semi-quantitative food-frequency questionnaire in 1980, and who underwent endoscopy from 1980 through 1998. 1,715 adenoma cases (704 large adenomas, 894 small adenomas, 1,277 distal colon adenomas, and 504 rectal adenomas) were documented during 18 years of follow-up. Dietary glycemic index, glycemic load, and carbohydrate intake were not related to risk of total colorectal adenoma after adjustment for age and established risk factors [relative risk (RR) for extreme quintiles of glycemic index = 1.11, 95% confidence interval (CI) 0.94-1.32, P for trend = 0.66; RR for glycemic load = 0.92, 95% CI 0.76-1.11, P for trend = 0.63; RR for carbohydrate intake = 0.90, 95% CI 0.73-1.11, P for trend = 0.64]. In addition, no significant associations were found for large or small adenoma, distal colon or rectal adenoma, or across strata of body mass index. Our findings do not support the hypothesis that a high glycemic index diet, a high glycemic load diet, or high carbohydrate intake overall are associated with risk of colorectal adenoma.

Glycemic index, glycemic load, and incidence of endometrial cancer: the Iowa women's health study

Although specific foods or nutrients have not been linked consistently with risk of endometrial cancer, obesity and diabetes are associated with increased risk. These conditions may be influenced by the glycemic index or load of the usual diet. We therefore examined the association of glycemic index and load measured at baseline using a food frequency questionnaire in a cohort of 23335 postmenopausal women. Over 15 yr of follow-up, we identified 415 incident endometrial cancers. The average glycemic index was not associated with endometrial cancer occurrence. After adjustment for other risk factors, the average glycemic load was positively but weakly associated, with a relative risk of 1.24 (95% CI = 0.90-1.72) for the highest versus lowest quintile of glycemic load (P for trend = 0.08). This relative risk was 1.46 (95% CI = 1.02-2.08; P for trend = 0.02) among nondiabetic women, but the trend was in the opposite direction among diabetic women. Our study indicates that a higher dietary glycemic load may be a risk factor for endometrial cancer incidence in nondiabetic women.

Lifestyle recommendations to prevent prostate cancer, part I: time to redirect our attention?

This article provides a foundation for clinicians willing to provide lifestyle change recommendations for the prevention of prostate cancer. In part II, more general and specific lifestyle recommendations will be provided. It is imperative to provide patients with realistic and practical recommendations that are not only consistent in the medical literature, but will improve overall compliance.

Rapid carbohydrate digestion rate produced lesser short-term satiety in obese preschool children

OBJECTIVE

To examine whether high carbohydrate meals with different carbohydrate digestion rates have an effect on the short-term satiety in normal and obese preschool children.

SUBJECTS AND SETTING

In total, 48 children of both gender, 24 normal and 24 obese, according to body mass index, aged between 3 and 6 y, were selected from children who were attending to a day-care center where they consumed three meals in the day.

INTERVENTIONS

Rapid (potato-based meal) and lente (spaghetti-based meal) carbohydrate digestion rate meal were given at lunch, matching energy intake, carbohydrate, protein and fat levels, and then the preschool children's energy intake at the subsequent mealtime was observed. In this last mealtime, the children received varied types of high-acceptability foods in higher quantities than the normal serving.

RESULTS

At lunch, a significant higher energy intake, lesser satiation, was observed in both groups, normal-weight and obese children, when they consumed the potato-based meal. In the subsequent mealtime, a significant effect of carbohydrate digestion rate was demonstrated, but only in obese preschool children, being higher in the meal with rapid digestion rate carbohydrates.

CONCLUSIONS

Rapid carbohydrate digestion rate meal produced a significative lesser satiation in normal-weight and obese children. However, only in obese children a significant lesser satiety was observed after consumption of the rapid carbohydrate digestion rate meal, indicating a decreased capacity of energy regulation in obese children. The finding of the present work could provide dietary strategies required for decreasing prevalence in overweight and obesity in preschool children.

Influence of diet and genetics on hypertension and renal disease in Dahl salt-sensitive rats

Experiments examined the influence of diet and genetics on hypertension and renal disease in inbred Dahl salt-sensitive (SS/Mcw) rats and consomic rats in which chromosomes 16 (SS.BN16) or 18 (SS.BN18) of the normotensive Brown Norway rat were inserted into the genetic background of the SS/Mcw. Dahl SS/Mcw breeders and offspring were randomly placed on a purified AIN-76A diet or a grain-based diet, and male offspring were screened for cardiovascular and renal phenotypes following 3 wk on a 4.0% NaCl diet. High-salt arterial blood pressure (162 +/- 5 mmHg, n = 10), urinary protein excretion (147 +/- 16 mg/day, n = 14), and albumin excretion (72 +/- 9 mg/day, n = 14) were significantly elevated in the Dahl SS/Mcw maintained on the purified diet compared with rats fed the grain-based diet. Rats fed the purified diet also exhibited significantly more renal glomerular and tubular damage than rats fed the grain diet. Moreover, feeding the purified diet to the parents led to a significant increase in blood pressure in the offspring, regardless of offspring diet. Similar dietary effects were observed in SS.BN16 and SS.BN18 rats. In rats fed the purified diet, substitution of chromosomes 16 or 18 led to a significant decrease in arterial blood pressure, albumin excretion, and protein excretion compared with the SS/Mcw. Chromosomal substitution did not, however, affect albumin or protein excretion in the consomic rats compared with the SS/Mcw when the rats were maintained on the grain diet. These data demonstrate a significant influence of diet composition on salt-induced hypertension and renal disease in the Dahl SS/Mcw rat.

Nutritional genomics: the next frontier in the postgenomic era

The interface between the nutritional environment and cellular/genetic processes is being referred to as “nutrigenomics.” Nutrigenomics seeks to provide a molecular genetic understanding for how common dietary chemicals (i.e., nutrition) affect health by altering the expression and/or structure of an individual’s genetic makeup. The fundamental concepts of the field are that the progression from a healthy phenotype to a chronic disease phenotype must occur by changes in gene expression or by differences in activities of proteins and enzymes and that dietary chemicals directly or indirectly regulate the expression of genomic information. We present a conceptual basis and specific examples for this new branch of genomic research that focuses on the tenets of nutritional genomics: 1) common dietary chemicals act on the human genome, either directly or indirectly, to alter gene expression or structure; 2) under certain circumstances and in some individuals, diet can be a serious risk factor for a number of diseases; 3) some diet-regulated genes (and their normal, common variants) are likely to play a role in the onset, incidence, progression, and/or severity of chronic diseases; 4) the degree to which diet influences the balance between healthy and disease states may depend on an individual’s genetic makeup; and 5) dietary intervention based on knowledge of nutritional requirement, nutritional status, and genotype (i.e., “individualized nutrition”) can be used to prevent, mitigate, or cure chronic disease.

Food groups and risk of prostate cancer in Italy

Although several studies have been conducted, the relation between diet and prostate cancer remains unclear. The role of a wide range of foods on the risk of prostate cancer has thus been analyzed in a case-control study conducted in Italy between 1991 and 2002. Cases were 1,294 patients below age 75 years with incident, histologically confirmed carcinoma of the prostate; controls were 1,451 subjects below age 75 years admitted to the same hospitals as cases for a wide spectrum of acute, non-neoplastic conditions. Multivariate odds ratios (ORs) were obtained after allowance for major potential confounding factors, including calorie intake. Among the 19 food groups considered, 4 showed some significant association with prostate cancer risk. A significant trend of increasing risk with more frequent consumption was found for milk and dairy products (OR = 1.2 for highest vs. lowest quintile, p = 0.03) as well as bread (OR = 1.4, p = 0.01), whereas inverse associations were observed for soups (OR = 0.8, p = 0.02) and cooked vegetables (OR = 0.7, p = 0.01). This uniquely large study on prostate cancer and diet in a southern European population confirms that no strong association exists between any specific foods and prostate cancer, apart from an increased risk for milk and dairy products and a possible protective effect of vegetables.

Bladder cancer prevention. Part I: what do I tell my patients about lifestyle changes and dietary supplements?

PURPOSE OF REVIEW

Comprehensive reviews of lifestyle changes and dietary supplements that may prevent bladder cancer are needed in order to facilitate discussions between clinicians and patients.

RECENT FINDINGS

Novel data exist that numerous lifestyle/diet and dietary supplements may lower the risk of this disease. For example, reducing arsenic exposure, incorporating dietary changes, and vitamin E supplements continue to accumulate research that supports their use with some patients at a higher risk for this disease. Regardless, smoking cessation seems to have the largest impact on reducing risk and incorporating these other changes after smoking cessation may reduce an individual's risk to an even greater extent.

SUMMARY

However, a large percentage of cases of individuals diagnosed with this cancer apparently have no known etiology. Diets lower in calories or possibly specific sub-types of fat, and higher in fruits and especially vegetables, seem to provide some protection. Other dietary/supplement options may affect risk, but these benefits could be seriously attenuated by smoking. Dietary selenium, but currently not selenium supplements, may also affect risk, especially in non-smokers. Dietary vitamin E, and vitamin E supplements, may provide some protection. Non-selective (e.g. non-steroidal anti-inflammatory drugs) and selective cyclooxygenase-2 inhibitors are generating interest because bladder tumors seem to contain higher concentrations of this enzyme. Drinking-water quality, especially arsenic concentrations, may seriously affect risk. Providing recommendations for patients with regard to some of these lifestyle modifications is currently recommended because the majority of these alterations are also recommended currently for cardiovascular or general oncology disease reduction.