Dietary carbohydrate intake is not associated with the breast cancer incidence rate ratio in postmenopausal Danish women

Dietary Approach of Patients with Hormone-Related Cancer Based on the Glycemic Index and Glycemic Load Estimates

Hormone-related cancers, namely breast, endometrial, cervical, prostate, testicular, and thyroid, constitute a specific group of cancers dependent on hormone levels that play an essential role in cancer growth. In addition to the traditional risk factors, diet seems to be an important environmental factor that partially explains the steadily increased prevalence of this group of cancer. The composition of food, the dietary patterns, the endocrine-disrupting chemicals, and the way of food processing and preparation related to dietary advanced glycation end-product formation are all related to cancer. However, it remains unclear which specific dietary components mediate this relationship. Carbohydrates seem to be a risk factor for cancer in general and hormone-related cancers, in particular, with a difference between simple and complex carbohydrates. Glycemic index and glycemic load estimates reflect the effect of dietary carbohydrates on postprandial glucose concentrations. Several studies have investigated the relationship between the dietary glycemic index and glycemic load estimates with the natural course of cancer and, more specifically, hormone-related cancers. High glycemic index and glycemic load diets are associated with cancer development and worse prognosis, partially explained by the adverse effects on insulin metabolism, causing hyperinsulinemia and insulin resistance, and also by inflammation and oxidative stress induction. Herein, we review the existing data on the effect of diets focusing on the glycemic index and glycemic load estimates on hormone-related cancers.

Dietary glycemic index, glycemic load and cancer risk: a meta-analysis of prospective cohort studies

PURPOSE

There is considerable inconsistency in results regarding the association of dietary glycemic index (GI) and glycemic load (GL) with cancer risk. We therefore conducted this systematic review and dose-response meta-analysis of prospective cohort studies to evaluate the relationship between dietary GI/GL and cancer risk.

METHODS

We searched PubMed and Web of Science for prospective cohort studies of dietary GI/GL in relation to risks of all types of cancer up to 31 March 2021. We used a random-effect model to calculate summary relative risks (RR) and 95% confidence intervals (CI). The certainty of evidence was assessed by the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. This study was registered at PROSPERO (CRD42020215338).

RESULTS

Overall, 55 cohorts were included in the meta-analysis. We assessed the relationship between dietary GI or GL and risks of 23 cancer types, including hormone-related cancers, cancers from digestive system, respiratory system, urinary system and other cancer sites. High GI diet increased overall risk of cancer with low certainty of evidence (highest vs lowest categories, n = 3, RR 1.04, 95% CI 1.01-1.07). For site-specific cancers, high GI diet increased risks of lung cancer (highest vs lowest categories, n = 5, RR 1.08, 95% CI 1.01-1.18) and breast cancer (highest vs lowest categories, n = 14, RR 1.05, 95% CI 1.01-1.09), especially for postmenopausal breast cancer (highest vs lowest categories, n = 10, RR 1.06, 95% CI 1.00-1.13), all with low certainty of evidence. Additionally, dietary GI was positively related to risk of bladder cancer with low certainty of evidence (highest vs lowest categories, n = 3, RR 1.23, 95% CI 1.09-1.40), as well as negatively related to ovarian cancer risk with very low certainty of evidence (highest vs lowest categories, n = 4, RR 0.83, 95% CI 0.69-1.00) and lymphoma risk with low certainty of evidence (highest vs lowest categories, n = 2, RR 0.84, 95% CI 0.72-0.98). Besides, we found an inverse association of dietary GL with lung cancer risk with low certainty of evidence (highest vs lowest categories, n = 5, RR 0.87, 95% CI 0.80-0.94).

CONCLUSION

High dietary GI increased overall cancer risk with low certainty of evidence. For site-specific cancers, high GI diet increased the risks of breast cancer with low certainty of evidence and lung cancer with low certainty of evidence. Dietary GL was inversely associated with lung cancer risk with low certainty of evidence.

Total and added sugar intakes, sugar types, and cancer risk: results from the prospective NutriNet-Santé cohort

BACKGROUND

Excessive sugar intake is now recognized as a key risk factor for obesity, type 2 diabetes, and cardiovascular diseases. In contrast, evidence on the sugar-cancer link is less consistent. Experimental data suggest that sugars could play a role in cancer etiology through obesity but also through inflammatory and oxidative mechanisms and insulin resistance, even in the absence of weight gain.

OBJECTIVE

The objective was to study the associations between total and added sugar intake and cancer risk (overall, breast, and prostate), taking into account sugar types and sources.

METHODS

In total, 101,279 participants aged >18 y (median age, 40.8 y) from the French NutriNet-Santé prospective cohort study (2009-2019) were included (median follow-up time, 5.9 y). Sugar intake was assessed using repeated and validated 24-h dietary records, designed to register participants' usual consumption for >3500 food and beverage items. Associations between sugar intake and cancer risk were assessed by Cox proportional hazard models adjusted for known risk factors (sociodemographic, anthropometric, lifestyle, medical history, and nutritional factors).

RESULTS

Total sugar intake was associated with higher overall cancer risk (n = 2503 cases; HR for quartile 4 compared with quartile 1: 1.17; 95% CI: 1.00, 1.37; Ptrend = 0.02). Breast cancer risks were increased (n = 783 cases; HRQ4vs.Q1 = 1.51; 95% CI: 1.14, 2.00; Ptrend = 0.0007). Results remained significant when weight gain during follow-up was adjusted for. In addition, significant associations with cancer risk were also observed for added sugars, free sugars, sucrose, sugars from milk-based desserts, dairy products, and sugary drinks (Ptrend ≤ 0.01).

CONCLUSIONS

These results suggest that sugars may represent a modifiable risk factor for cancer prevention (breast in particular), contributing to the current debate on the implementation of sugar taxation, marketing regulation, and other sugar-related policies. This trial was registered at clinicaltrials.gov as NCT03335644.

Effect of High Fructose Corn Sirup on Pancreatic Ductal Adenocarcinoma Induced by Dimethyl Benzantracene (DMBA) in Rats

Increased risk of pancreatic cancer may be associated with consumption of sugar containing foods. The aim of this study was to evaluate the effect of peach nectar containing high fructose corn sirup (HFCS) consumption in a pancreatic carcinogenesis rat model induced by 7,12-Dimethyl benzanthracene (DMBA). Fifty-day-old male Sprague Dawley rats were fed with peach nectar containing HFCS + chow, peach nectar containing sucrose + chow and only chow. After 8 mo, feeding period, each group was divided into two subgroups, in which the rats were implanted with DMBA and no DMBA (sham). Histologic specimens were evaluated according to the routine tissue processing protocol. The animals with ad libitum access to pn-HFCS, pn-sucrose and chow (only) showed significant differences in chow consumption and glucose level. Necropsy and histopathologic findings showed tumor formation in the entire group treated with DMBA. Excluding one rat in chow group, which was classified as poorly differentiated type, the others were classified as moderately differentiated pancreatic ductal adenocarcinoma (PDAC). This study demonstrated that daily intake of HFCS did not increase body weight and there was no effect of peach nectar consumption on the development of PDAC induced by DMBA in rats.

Dairy Consumption in Adolescence and Early Adulthood and Risk of Breast Cancer

Background: Carcinogenic exposure in early life may be critical for subsequent breast cancer risk. Dairy consumption was examined during adolescence and early adulthood in relation to incident breast cancer in the Nurses' Health Study II cohort.Methods: For the analyses of early adulthood dairy consumption, we included 90,503 premenopausal women ages 27 to 44 years in 1991 who reported dairy consumption using a validated food-frequency questionnaire. From 1991 to 2013, 3,191 invasive breast cancer cases were identified. In 1998, 44,264 women recalled adolescent dairy consumption. This subgroup of women was followed up from 1998 to 2013; 1,318 invasive breast cancer cases were identified. Multivariate hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using the Cox proportional hazard regression.Results: Adolescent and early adulthood total dairy consumption was not associated with overall breast cancer risk (each serving/day during adolescence, total dairy HR = 1.02, 95% CI, 0.97-1.07; for early adulthood total dairy HR = 1.01, 95% CI, 0.97-1.04), as were intakes of calcium, vitamin D, and lactose. Adolescent consumption of total and high-fat dairy was associated with higher risk of estrogen and progesterone receptor negative (each serving/day: total dairy HR = 1.11, 95% CI, 1.00-1.24; high-fat dairy HR = 1.17, 95% CI, 1.04-1.31). However, higher adolescent high-fat dairy consumption was associated with lower risk of estrogen and progesterone receptor positive tumors (each serving/day HR = 0.91, 95% CI, 0.86-0.97).Conclusions: Our results suggest no overall association between dairy consumption during adolescence or early adulthood and breast cancer risk, but the findings may differ by hormone receptor status of tumors.Impact: Dairy consumption in adolescence or early adulthood may not be a significant predictor of breast cancer incidence. Cancer Epidemiol Biomarkers Prev; 27(5); 575-84. ©2018 AACR.

Dietary Glycemic Index and Glycemic Load and Risk of Breast Cancer by Molecular Subtype in Mexican Women

The objective was to estimate the risk of breast cancer (BC) molecular subtypes in relation to the average glycemic index (GI) and the dietary glycemic load (GL) in Mexican women. From 2007 to 2011, a study of incident cases and population controls was conducted in five states of northern Mexico. A subsample of 509 cases matched 1:1 by age with 509 controls was selected. With a food frequency questionnaire, information about diet was obtained, and GI and GL were calculated. The expression of human epidermal growth factor receptor 2 (HER2), and estrogen (ER) and progesterone (PR) receptors in tumors was obtained from medical records. Patients were classified as luminal A (RE+ and/or PR+/HER2-), HER2+ (RE+ and/or PR+/HER2+ and RE-/PR-/HER2+), or triple negative (TN) (RE-/PR-/HER2-). GI and GL associations with BC molecular subtypes were evaluated using conditional logistic regression models. GI was positively associated with luminal A (OR= 1.12; 95% CI: 1.03, 1.22), HER2+ (OR= 1.15; 95% CI: 1.02, 1.30), and TN (OR= 1.20; 95% CI: 1.03, 1.39) BC. GL was not associated with BC molecular subtypes. These results suggest that the type of carbohydrate consumed is associated with increased BC regardless of the luminal A, HER2+, and TN subtypes.

Dietary Fat and Sugar in Promoting Cancer Development and Progression

The uncontrolled cellular growth that characterizes tumor formation requires a constant delivery of nutrients. Since the 1970s, researchers have wondered if the supply of nutrients from the diet could impact tumor development. Numerous studies have assessed the impact of dietary components, specifically sugar and fat, to increased cancer risk. For the most part, data from these trials have been inconclusive; however, this does not indicate that dietary factors do not contribute to cancer progression. Rather, the dietary contribution may be dependent on tumor, patient, and context, making it difficult to detect in the setting of large trials. In this review, we combine data from prospective cohort trials with mechanistic studies in mice to argue that fat and sugar can play a role in tumorigenesis and disease progression. We find that certain tumors may respond directly to dietary sugar (colorectal and endometrial cancers) and fat (prostate cancer) or indirectly to the obese state (breast cancer).

Consumption of Sugars, Sugary Foods, and Sugary Beverages in Relation to Cancer Risk: A Systematic Review of Longitudinal Studies

High sugar intake may increase cancer risk by promoting insulin–glucose dysregulation, oxidative stress, inflammation, and body adiposity, but epidemiologic evidence is unclear. Associations between dietary sugars and lifestyle-related cancer risk from longitudinal studies were evaluated. We systematically searched PubMed, Embase, and CINAHL and identified 37 prospective cohort studies (1990–2017) reporting multivariable adjusted risk estimates for dietary sugars in relation to cancer. Of 15 and 14 studies on total sugar and sucrose respectively, 11 reported a null association in relation to cancer. Of 14 studies on fructose, 8 reported null associations, and 2 reported protective and 4 reported detrimental associations. In two of five studies on added sugars, a 60–95% increased cancer risk was observed with higher intakes. In 8 of 15 studies on sugary foods and beverages, a 23–200% higher cancer risk was observed with higher sugary beverage consumption. In conclusion, most studies were indicative of a null association, but suggestive detrimental associations were reported for added sugars and sugary beverages.

Consumption of Sugars, Sugary Foods, and Sugary Beverages in Relation to Adiposity-Related Cancer Risk in the Framingham Offspring Cohort (1991-2013)

Background: Higher sugar consumption may increase cancer risk by promoting insulin-glucose dysregulation, oxidative stress, hormonal imbalances, and excess adiposity. This prospective study investigates the association between dietary sugars (fructose and sucrose) and sugary foods and beverages in relation to combined and site-specific (breast, prostate, colorectal) adiposity-associated cancers.Methods: The analytic sample consisted of 3,184 adults, aged 26-84 years, from the Framingham Offspring cohort. Diet data were first collected between 1991 and 1995 using a food frequency questionnaire. Intakes of fructose, sucrose, sugary foods, and sugary beverages (fruit juice and sugar-sweetened beverages) were derived. Participants were followed up until 2013 to ascertain cancer incidence; 565 doctor-diagnosed adiposity-related cancers, including 124 breast, 157 prostate, and 68 colorectal cancers occurred. Multivariable-adjusted Cox proportional hazards models were used to evaluate associations. Tests for interaction with BMI and waist circumference were conducted.Results: No associations were observed between fructose, sucrose, sugary food consumption, and combined incidence of adiposity-related cancers or the examined site-specific cancers. While total consumption of sugary beverages was not associated with site-specific cancer risk, higher intakes of fruit juice were associated with 58% increased prostate cancer risk (HR: 1.58; 95% CI, 1.04-2.41) in multivariable-adjusted models. In exploratory stratified analyses, higher sugary beverage intakes increased overall adiposity-related cancer risk by 59% in participants with excessive central adiposity (HR: 1.59; 95% CI, 1.01-2.50; Ptrend = 0.057).Conclusions: In this cohort of American adults, higher sugary beverage consumption was associated with increased cancer risk among participants with central adiposity.Impact: These analyses suggest that avoiding sugary beverages represents a simple dietary modification that may be used as an effective cancer control strategy. Cancer Prev Res; 11(6); 347-58. ©2018 AACR.

Carbohydrates, glycemic index, glycemic load, and breast cancer risk: a systematic review and dose-response meta-analysis of prospective studies

Context

The investigation of dose-response associations between carbohydrate intake, glycemic index, glycemic load, and risk of breast cancer stratified by menopausal status, hormone receptor status, and body mass index (BMI) remains inconclusive.

Objective

A systematic review and dose-response meta-analyses was conducted to investigate these associations.

Data Sources

As part of the World Cancer Research Fund/American Institute for Cancer Research Continuous Update Project, PubMed was searched up to May 2015 for relevant studies on these associations.

Study Selection

Prospective studies reporting associations between carbohydrate intake, glycemic index, or glycemic load and breast cancer risk were included.

Data Extraction

Two investigators independently extracted data from included studies.

Results

Random-effects models were used to summarize relative risks (RRs) and 95%CIs. Heterogeneity between subgroups, including menopausal status, hormone receptor status, and BMI was explored using meta-regression. Nineteen publications were included. The summary RRs (95%CIs) for breast cancer were 1.04 (1.00-1.07) per 10 units/d for glycemic index, 1.01 (0.98-1.04) per 50 units/d for glycemic load, and 1.00 (0.96-1.05) per 50 g/d for carbohydrate intake. For glycemic index, the association appeared slightly stronger among postmenopausal women (summary RR per 10 units/d, 1.06; 95%CI, 1.02-1.10) than among premenopausal women, though the difference was not statistically significant (Pheterogeneity = 0.15). Glycemic load and carbohydrate intake were positively associated with breast cancer among postmenopausal women with estrogen-negative tumors (summary RR for glycemic load, 1.28; 95%CI, 1.08-1.52; and summary RR for carbohydrates, 1.13; 95%CI, 1.02-1.25). No differences in BMI were detected.

Conclusions

Menopausal and hormone receptor status, but not BMI, might be potential influencing factors for the associations between carbohydrate intake, glycemic index, glycemic load, and breast cancer.

Dietary carbohydrate, fiber and sugar and risk of breast cancer according to menopausal status in Malaysia

BACKGROUND

Dietary carbohydrate, fiber and sugar intake has been shown to play a role in the etiology of breast cancer, but the findings have been inconsistent and limited to developed countries with higher cancer incidence.

OBJECTIVE

To examine the association of premenopausal and postmenopausal breast cancer risk with dietary carbohydrate, fiber and sugar intake.

MATERIALS AND METHODS

This population based case-control study was conducted in Malaysia with 382 breast cancer patients and 382 controls. Food intake pattern was assessed via an interviewer-administered food frequency questionnaire. Logistic regression was used to compute odds ratios (OR) with 95% confidence intervals (CI) and a broad range of potential confounders were included in analysis.

RESULTS

A significant two fold increased risk of breast cancer among premenopausal (OR Q4 to Q1=1.93, 95%CI: 1.53-2.61, p-trend=0.001) and postmenopausal (OR Q4 to Q1=1.87, 95%CI: 1.03-2.61, p-trend=0.045) women was observed in the highest quartile of sugar. A higher intake of dietary fiber was associated with a significantly lower breast cancer risk among both premenopausal (OR Q4 to Q1=0.31, 95%CI: 0.12-0.79, p-trend=0.009) and postmenopausal (OR Q4 to Q1=0.23, 95%CI: 0.07-0.76, p-trend=0.031) women.

CONCLUSIONS

Sugar and dietary fiber intake were independently related to pre- and postmenopausal breast cancer risk. However, no association was observed for dietary carbohydrate intake.

Association between vegetable, fruit and carbohydrate intake and breast cancer risk in relation to physical activity

BACKGROUND

Although the nutritional may exert effect on the breast cancer risk, it is not clear whether the role diet is the same in sedentary and physically active women. The aim of this study was to evaluate the association between fruit, vegetable and carbohydrate intake and the risk of breast cancer among Polish women considering their physical activity level.

MATERIALS AND METHODS

A case-control study was conducted that included 858 women with histological confirmed breast cancer and 1,085 controls, free of any cancer diagnosis, aged 28-78 years. The study was based on a self-administered questionnaire to ascertain physical activity, dietary intake, sociodemographic characteristics, reproductive factors, family history of breast cancer, current weight and high, and other lifestyle factors. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated in unconditional logistic regression analyses including a broad range of potential confounders.

RESULTS

With comparison of the highest vs lowest quartile of intake, strong significant associations were observed for total vegetables (OR=0.37, 95%CI=0.20-0.69 P for trend <0.01 and OR=0.53, 95%CI=0.29-0.96, P for trend <0.02), and total fruits (OR=0.47, 95%CI=0.25-0.87, P for trend <0.05 and OR=0.47, 95%CI=0.24-0.90, P for trend <0.02) among women characterized by the lowest and the highest quartile of physical activity. No associations were observed for total carbohydrate intake. Additional analysis showed a positive association for sweets and desert intake among women in the lowest quartile of physical activity (OR=3.49, 95%CI=1.67-7.30, P for trend <0.009) for extreme quartiles of intake comparing to the referent group.

CONCLUSIONS

The results suggest that a higher consumption of vegetable and fruit may be associated with a decreased risk of breast cancer, especially among women who were low or most physically active throughout their lifetimes. These findings do not support an association between diet high in carbohydrate and breast cancer. However, a higher intake of sweets and deserts may by associated with an increased risk of breast cancer among women who were less physically active.

Adolescent and Early Adulthood Dietary Carbohydrate Quantity and Quality in Relation to Breast Cancer Risk

BACKGROUND

We investigated quantity and quality of dietary carbohydrate as well as insulin load and insulin index during adolescence and also early adulthood in relation to risk of breast cancer in the Nurses' Health Study II.

METHODS

During 20 years of follow-up of 90,534 premenopausal women who completed a diet questionnaire in 1991, 2,833 invasive breast cancer cases were documented. In 1998, 44,263 of these women also completed a questionnaire about their diet during high school; among these women, we documented 1,118 cases of breast cancer. Multivariable-adjusted Cox proportional hazards regression was used to model relative risks (RR) and 95% confidence intervals (95% CI) for breast cancer across categories of dietary carbohydrate, glycemic index (GI), glycemic load (GL), as well as insulin load and insulin index scores.

RESULTS

Adolescent or early adult intakes of GI or GL were not associated with risk of breast cancer. Comparing women in the highest versus lowest quintile, the multivariable-adjusted RRs were 1.14 (0.95-1.38) for adolescent GI scores and 1.03 (0.91-1.16) for early adulthood GI scores. We also did not observe associations with insulin index and insulin load scores in adolescence or early adulthood and breast cancer risk.

CONCLUSIONS

We found that diets high in GI, GL, insulin index, and insulin load during adolescence or early adulthood were not associated with an increased risk of breast cancer in this cohort study.

IMPACT

Diets with a high glucose or insulin response in adolescence or early adulthood were not significant predictors of breast cancer incidence.

Nutritional and unhealthy behaviors in women with and without breast cancer

Background:

Breast cancer is the most common malignancy in women. Global statistics indicate increasing rates of this cancer. Nutrition, diet, and healthy behaviors are among influential factors in prevalence of breast cancer, and possibly affect its incidence through inflammatory and immune system responses.

Objectives:

This study was designed to compare nutritional and unhealthy behaviors in women with and without breast cancer referred to Mahdieh Imaging Center in Hamadan in 2013.

Patients and Methods:

This cross-sectional study is conducted on 232 women with r and without breast cancer referred to Mahdieh Imaging Center of Hamadan, Iran) in 2013 using random sampling method. Data were collected using nutritional and unhealthy behaviors questionnaires, and analyzed with SPSS-17 software using descriptive statistics and Mann-Whitney, independent t, and chi-square tests.

Results:

The mean scores of feeding type in the patients with and without breast cancer was 56.14 and 66.25, respectively. Results obtained from data analysis showed that there was statistically significant difference between the two groups in terms of nutrition (P < 0.001), but no relationship was observed between breast cancer and unhealthy behaviors.

Conclusions:

Given the results, improving skills, training and awareness is necessary for women and emphasis on modified diet is recommended as a non-medical option for prevention of breast cancer.

High glycemic diet and breast cancer occurrence in the Italian EPIC cohort

BACKGROUND AND AIMS

There are theoretical reasons for suspecting that a high glycemic index (GI) or glycemic load (GL) diet may increase breast cancer risk, perhaps via an effect on the insulin-like growth factor (IGF) axis. However observational studies have produced inconsistent findings and it is controversial whether breast cancer risk is influenced by the carbohydrate characteristics of the diet. We prospectively investigated the association between dietary GI and GL and breast cancer in the Italian section of the European Prospective Investigation into Cancer and Nutrition (EPIC).

METHODS AND RESULTS

Women were recruited from 1993 to 1998 at five centers: Varese and Turin (north Italy), Florence (central Italy), and Ragusa and Naples (south Italy). Participants completed validated food frequency questionnaires from which GI and GL were estimated. Multivariable Cox proportional hazard regression models quantified the association between breast cancer risk and total carbohydrate intake, GI, and GL. During 11 years of follow-up, 879 breast cancer (797 invasive and 82 in situ) cases were indentified. High dietary GL was associated with increased breast cancer risk (RR 1.45, 95% CI = 1.06-1.99; highest vs. lowest quintile; p-trend 0.029), whereas dietary GI and total carbohydrate had no influence. The association was not modified by menopausal status or body mass index.

CONCLUSION

Our data indicate that, in a Mediterranean population characterized by traditionally high and varied carbohydrate intake, a diet high in GL plays a role in the development of breast cancer.

Dietary fiber and the glycemic index: a background paper for the Nordic Nutrition Recommendations 2012

The aim of this study is to review recent data on dietary fiber (DF) and the glycemic index (GI), with special focus on studies from the Nordic countries regarding cardiometabolic risk factors, type 2 diabetes, cardiovascular disease, cancer, and total mortality. In this study, recent guidelines and scientific background papers or updates on older reports on DF and GI published between 2000 and 2011 from the US, EU, WHO, and the World Cancer Research Fund were reviewed, as well as prospective cohort and intervention studies carried out in the Nordic countries. All of the reports support the role for fiber-rich foods and DF as an important part of a healthy diet. All of the five identified Nordic papers found protective associations between high intake of DF and health outcomes; lower risk of cardiovascular disease, type 2 diabetes, colorectal and breast cancer. None of the reports and few of the Nordic papers found clear evidence for the GI in prevention of risk factors or diseases in healthy populations, although association was found in sub-groups, e.g. overweight and obese individuals and suggestive for prevention of type 2 diabetes. It was concluded that DF is associated with decreased risk of different chronic diseases and metabolic conditions. There is not enough evidence that choosing foods with low GI will decrease the risk of chronic diseases in the population overall. However, there is suggestive evidence that ranking food based on their GI might be of use for overweight and obese individuals. Issues regarding methodology, validity and practicality of the GI remain to be clarified.

Redefining the impact of nutrition on breast cancer incidence: is epigenetics involved?

Breast cancer incidence is rising worldwide with an increase in aggressive neoplasias in young women. Possible factors involved include lifestyle changes, notably diet that is known to make an impact on gene transcription. However, among dietary factors, there is sufficient support for only greater body weight and alcohol consumption whereas numerous studies revealing an impact of specific diets and nutrients on breast cancer risk show conflicting results. Also, little information is available from middle- and low-income countries. The diversity of gene expression profiles found in breast cancers indicates that transcription control is critical for the outcome of the disease. This suggests the need for studies on nutrients that affect epigenetic mechanisms of transcription, such as DNA methylation and post-translational modifications of histones. In the present review, a new examination of the relationship between diet and breast cancer based on transcription control is proposed in light of epidemiological, animal and clinical studies. The mechanisms underlying the impact of diets on breast cancer development and factors that impede reaching clear conclusions are discussed. Understanding the interaction between nutrition and epigenetics (gene expression control via chromatin structure) is critical in light of the influence of diet during early stages of mammary gland development on breast cancer risk, suggesting a persistent effect on gene expression as shown by the influence of certain nutrients on DNA methylation. Successful development of breast cancer prevention strategies will require appropriate models, identification of biological markers for rapid assessment of preventive interventions, and coordinated worldwide research to discern the effects of diet.

Glycaemic index and glycaemic load in relation to risk of diabetes-related cancers: a meta-analysis

Diets high in glycaemic index (GI) or glycaemic load (GL) have been hypothesised to increase the risks of certain cancers by increasing blood glucose or insulin concentrations. We aimed to conduct a meta-analysis of prospective cohort studies to evaluate the association between GI or GL and diabetes-related cancers (DRC), including bladder, breast, colon-rectum, endometrium, liver and pancreas, which are associated with an increased risk for diabetes, and prostate cancer, which is associated with a reduced risk for diabetes. We searched Pubmed, EMBASE and MEDLINE databases up to September 2011 and reference lists of relevant articles. Relative risks (RR) and 95 % CI for the highest v. the lowest categories were extracted and pooled using a random-effects model. Thirty-six prospective cohort studies with a total of 60 811 DRC cases were included in the present meta-analysis. In a comparison of the highest and lowest categories, the pooled RR of DRC were 1·07 (95 % CI 1·04, 1·11; n 30) for GI and 1·02 (95 % CI 0·96, 1·08; n 33) for GL. In an analysis of site-specific cancer risks, we found significant associations for GI in relation to breast cancer (RR 1·06; 95 % CI 1·02, 1·11; n 11) and colorectal cancer (RR 1·08; 95 % CI 1·00, 1·17; n 9 studies). GL was significantly associated with the risk of endometrial cancer (RR 1·21; 95 % CI 1·07, 1·37; n 5). In conclusion, the findings of the present study suggest a modest-to-weak association between a diet that induces a high glucose response and DRC risks.

Fructose consumption and cancer: is there a connection?

PURPOSE OF REVIEW

Cancer cell metabolism is characterized by high rates of glucose uptake and anaerobic glycolysis. Sugar consumption has increased dramatically in the industrialized world, with refined fructose intake skyrocketing upwards in the USA over the past 30 years. Fructose provides an alternative carbon source for glycolysis, entering downstream of glucose and bypassing two key rate-limiting steps. Considering that glycolysis is the major pathway which fuels cancer growth, this review will focus on regulation and flux of glucose versus fructose through this pathway, and consider whether epidemiologic and experimental data support a mechanism whereby fructose might potentiate cancer growth in transformed cells.(Figure is included in full-text article.)

RECENT FINDINGS

Fructose intake is associated with increased risk of pancreatic and small intestinal cancers, and possibly others. Fructose promotes flux through the pentose phosphate, which enhances protein synthesis and may indirectly increase tumor growth. Fructose treatment is associated with more aggressive cancer behavior and may promote metastasis.

SUMMARY

Whereas glucose favors overall growth kinetics, fructose enhances protein synthesis and appears to promote a more aggressive cancer phenotype. Fructose has become ubiquitous in our food supply, with the highest consumers being teens and young adults. Therefore, understanding the potential health consequences of fructose and its role in chronic disease development is of critical importance.

Dietary glycemic index and glycemic load and breast cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC)

BACKGROUND

The glycemic potential of a diet is associated with chronically elevated insulin concentrations, which may augment breast cancer (BC) risk by stimulating insulin receptor or by affecting insulin-like growth factor I (IGF-I)-mediated mitogenesis. It is unclear whether this effect differs by BC phenotype.

OBJECTIVE

The objective was to investigate the relation between glycemic index (GI), glycemic load (GL), and total carbohydrate intake with BC by using data from the European Prospective Investigation into Cancer and Nutrition (EPIC).

DESIGN

We identified 11,576 women with invasive BC among 334,849 EPIC women aged 34-66 y (5th to 95th percentiles) at baseline over a median follow-up of 11.5 y. Dietary GI and GL were calculated from country-specific dietary questionnaires. We used multivariable Cox proportional hazards models to quantify the association between GI, GL, and carbohydrate intake and BC risk. BC tumors were classified by receptor status.

RESULTS

Overall GI, GL, and carbohydrates were not related to BC. Among postmenopausal women, GL and carbohydate intake were significantly associated with an increased risk of estrogen receptor-negative (ER(-)) BC when extreme quintiles (Q) were compared [multivariable HR(Q5-Q1) (95% CI) = 1.36 (1.02, 1.82; P-trend = 0.010) and HR(Q5-Q1) = 1.41 (1.05, 1.89; P-trend = 0.009), respectively]. Further stratification by progesterone receptor (PR) status showed slightly stronger associations with ER(-)/PR(-) BC [HR(Q5-Q1) (95% CI) = 1.48 (1.07, 2.05; P-trend = 0.010) for GL and HR(Q5-Q1) = 1.62 (1.15, 2.30; P-trend = 0.005) for carbohydrates]. No significant association with ER-positive BC was observed.

CONCLUSION

Our results indicate that a diet with a high GL and carbohydrate intake is positively associated with an increased risk of developing ER(-) and ER(-)/PR(-) BC among postmenopausal women.

Evidence-based guideline of the German Nutrition Society: carbohydrate intake and prevention of nutrition-related diseases

The relative contribution of nutrition-related chronic diseases to the total disease burden of the society and the health care costs has risen continuously over the last decades. Thus, there is an urgent necessity to better exploit the potential of dietary prevention of diseases. Carbohydrates play a major role in human nutrition - next to fat, carbohydrates are the second biggest group of energy-yielding nutrients. Obesity, type 2 diabetes mellitus, dyslipoproteinaemia, hypertension, metabolic syndrome, coronary heart disease and cancer are wide-spread diseases, in which carbohydrates could have a pathophysiologic relevance. Correspondingly, modification of carbohydrate intake could have a preventive potential. In the present evidence-based guideline of the German Nutrition Society, the potential role of carbohydrates in the primary prevention of the named diseases was judged systematically. The major findings were: a high carbohydrate intake at the expense of total fat and saturated fatty acids reduces the concentrations of total, LDL and HDL cholesterol. A high carbohydrate consumption at the expense of polyunsaturated fatty acids increases total and LDL cholesterol, but reduces HDL cholesterol. Regardless of the type of fat being replaced, a high carbohydrate intake promotes an increase in the triglyceride concentration. Furthermore, a high consumption of sugar-sweetened beverages increases the risk of obesity and type 2 diabetes mellitus, whereas a high dietary fibre intake, mainly from whole-grain products, reduces the risk of obesity, type 2 diabetes mellitus, dyslipoproteinaemia, cardiovascular disease and colorectal cancer at varying evidence levels. The practical consequences for current dietary recommendations are presented.

Low-carbohydrate diets, dietary approaches to stop hypertension-style diets, and the risk of postmenopausal breast cancer

The authors prospectively examined the association between the Dietary Approaches to Stop Hypertension diet score, overall, animal-based, and vegetable-based low-carbohydrate-diet scores, and major plant food groups and the risk of postmenopausal breast cancer in 86,621 women in the Nurses' Health Study. Diet scores were calculated by using data from up to 7 food frequency questionnaires, with follow-up from 1980 to 2006. The authors ascertained 5,522 incident cases of breast cancer, including 3,314 estrogen receptor-positive (ER+) cancers and 826 estrogen receptor-negative (ER-) cancers. After adjustment for potential confounders, the Dietary Approaches to Stop Hypertension diet score was associated with a lower risk of ER- cancer (relative risk comparing extreme quintiles = 0.80, 95% confidence interval: 0.64, 1.01; P trend = 0.02). However, this was largely explained by higher intakes of fruits and vegetables. The authors also observed an inverse association between risk of ER- cancer and the vegetable-based, low-carbohydrate-diet score (corresponding relative risk = 0.81, 95% confidence interval: 0.65, 1.01; P trend = 0.03). High total fruit and low-protein vegetable intakes were associated with a lower risk of ER- cancer (relative risk comparing extreme quintiles = 0.71, 95% confidence interval: 0.55, 0.90; P trend = 0.005). No association was found between ER+ tumors and fruit and vegetable intakes. A diet high in fruits and vegetables, such as one represented by the Dietary Approaches to Stop Hypertension diet score, was associated with a lower risk of ER- breast cancer. In addition, a diet high in plant protein and fat and moderate in carbohydrate content was associated with a lower risk of ER- cancer.

Effect of a low fat versus a low carbohydrate weight loss dietary intervention on biomarkers of long term survival in breast cancer patients ('CHOICE'): study protocol

Background

Weight loss in overweight or obese breast cancer patients is associated with an improved prognosis for long term survival. However, it is not clear whether the macronutrient composition of the chosen weight loss dietary plan imparts further prognostic benefit. A study protocol is presented for a dietary intervention to investigate the effects of weight loss dietary patterns that vary markedly in fat and carbohydrate contents on biomarkers of exposure to metabolic processes that may promote tumorigenesis and that are predictive of long term survival. The study will also determine how much weight must be lost for biomarkers to change in a favorable direction.

Methods/Design

Approximately 370 overweight or obese postmenopausal breast cancer survivors (body mass index: 25.0 to 34.9 kg/m²) will be accrued and assigned to one of two weight loss intervention programs or a non-intervention control group. The dietary intervention is implemented in a free living population to test the two extremes of popular weight loss dietary patterns: a high carbohydrate, low fat diet versus a low carbohydrate, high fat diet. The effects of these dietary patterns on biomarkers for glucose homeostasis, chronic inflammation, cellular oxidation, and steroid sex hormone metabolism will be measured. Participants will attend 3 screening and dietary education visits, and 7 monthly one-on-one dietary counseling and clinical data measurement visits in addition to 5 group visits in the intervention arms. Participants in the control arm will attend two clinical data measurement visits at baseline and 6 months. The primary outcome is high sensitivity C-reactive protein. Secondary outcomes include interleukin-6, tumor necrosis factor-α, insulin-like growth factor-1 (IGF), IGF binding protein-3, 8-isoprostane-F2-alpha, estrone, estradiol, progesterone, sex hormone binding globulin, adiponectin, and leptin.

Discussion

While clinical data indicate that excess weight for height is associated with poor prognosis for long term survival, little attention is paid to weight control in the clinical management of breast cancer. This study will provide information that can be used to answer important patient questions about the effects of dietary pattern and magnitude of weight loss on long term survival following breast cancer treatment.

Clinical Trial Registration

CA125243

Dietary glycemic load, glycemic index, and carbohydrate and risk of breast cancer in the Women's Health Initiative

Dietary glycemic load (GL), glycemic index (GI), and carbohydrate could be associated with breast cancer risk by influencing long-term blood glucose and insulin concentrations. We examined associations between GL, GI, and carbohydrate and incident breast cancer in 148,767 Women's Heath Initiative (WHI) participants. Dietary variables were estimated from food frequency questionnaires administered at baseline. Self-reported breast cancers during follow-up were confirmed by medical records review. Cox proportional hazards regression modeled time to breast cancer within quintiles of GL, GI, and carbohydrate. There were 6,115 total breast cancers after a median follow-up of 8.0 yr. We observed no associations between GL, GI, or carbohydrate and total incident breast cancer, with hazard ratios and 95% confidence intervals for the highest vs. lowest quintiles of 1.08, 0.92-1.29 (P for trend = 0.27); 1.01, 0.91-1.12 (P = 0.74); and 0.95, 0.80-1.14 (P = 0.98), respectively. There was a trend toward significance for the positive association between GL and in situ cancers (1.40, 0.94-2.13; P = 0.07). Although there was no evidence of associations between GL, GI, or carbohydrate and total breast cancer risk in WHI participants, the suggestion of an association between GL and risk of in situ cancers requires further investigation.

Macronutrient composition influence on breast cancer risk in Hispanic and non-Hispanic white women: the 4-Corners Breast Cancer Study

The association of dietary macronutrient composition with risk of breast cancer is not well understood. We investigated the macronutrient composition of diet in the 4-Corners Breast Cancer Study. Logistic regression models were used for case-control comparisons adjusted for age, center, education, smoking, total activity, calories, dietary fiber, dietary calcium, height, parity, recent hormone exposure, reference year body mass index (BMI), and the interaction of BMI and recent hormone exposure. Breast cancer risk declined with increasing dietary fat and increased with carbohydrates similarly across ethnicity and menopausal status. Associations of carbohydrate (direct) and fat (inverse), particularly saturated and monounsaturated fat, with breast cancer were present among normal and overweight postmenopausal women and absent among obese postmenopausal women. No substantive differences were noted in the association of macronutrients with risk of breast cancer between non-Hispanic white and Hispanic women. Associations of the macronutrients carbohydrate and fat with breast cancer risk were attenuated among postmenopausal obese women.

Is sugar consumption detrimental to health? A review of the evidence 1995-2006

Many countries set quantitative targets for added sugars, justifying this by expressing concern about the likely impact of sugar on weight control, dental health, diet quality, or metabolic syndrome. This review considers whether current intakes of sugar are harmful to health, and analyses recent literature using a systematic approach to collate, rank, and evaluate published studies from 1995-2006. Results from high quality obesity studies did not suggest a positive association between body mass index and sugar intake. Some studies, specifically on sweetened beverages, highlighted a potential concern in relation to obesity risk, although these were limited by important methodological issues. Diet adequacy appeared to be achieved across sugar intakes of 6 to 20% energy, depending on subject age. Studies on metabolic syndrome reported no adverse effects of sugar in the long-term, even at intakes of 40-50% energy. The evidence for colorectal cancer suggested an association with sugar, but this appeared to have been confounded by energy intake and glycemic load. There was no credible evidence linking sugar with attention-deficit, dementia, or depression. Regarding dental caries, combinations of sugar amount/frequency, fluoride exposure, and food adhesiveness were more reliable predictors of caries risk than the amount of sugar alone. Overall, the available evidence did not support a single quantitative sugar guideline covering all health issues.

Glycemic load, glycemic index and breast cancer risk in a prospective cohort of Swedish women

High-glycemic load diets have been hypothesized to increase the risk of breast cancer but epidemiologic studies have yielded inconsistent findings. We examined the associations of carbohydrate intake, glycemic index and glycemic load with risk of overall and hormone receptor-defined breast cancer in the Swedish Mammography Cohort, a population-based cohort of 61,433 women who completed a food frequency questionnaire at enrollment in 1987-1990. During a mean follow-up of 17.4 years, we ascertained 2,952 incident cases of invasive breast cancer. Glycemic load but not carbohydrate intake or glycemic index was weakly positively associated with overall breast cancer risk (p for trend = 0.05). In analyses stratified by estrogen receptor (ER) and progesterone receptor (PR) status of the breast tumors, we observed statistically significant positive associations of carbohydrate intake, glycemic index and glycemic load with risk of ER+/PR- breast cancer; the multivariate relative risks comparing extreme quintiles were 1.34 [95% confidence interval (CI) = 0.93-1.94; p for trend = 0.04] for carbohydrate intake, 1.44 (95% CI = 1.06-1.97; p for trend = 0.01) for glycemic index and 1.81 (95% CI = 1.29-2.53; p for trend = 0.0008) for glycemic load. No associations were observed for ER+/PR+ or ER-/PR- breast tumors. These findings suggest that a high carbohydrate intake and diets with high glycemic index and glycemic load may increase the risk of developing ER+/PR- breast cancer.

Consumption of sweet foods and breast cancer risk: a case-control study of women on Long Island, New York

Several epidemiologic studies have reported a positive association between breast cancer risk and high intake of sweets, which may be due to an insulin-related mechanism. We investigated this association in a population-based case-control study of 1,434 cases and 1,440 controls from Long Island, NY. Shortly after diagnosis, subjects were interviewed in-person to assess potential breast cancer risk factors, and self-completed a modified Block food frequency questionnaire, which included 11 items pertaining to consumption of sweets (sweet beverages, added sugars, and various desserts) in the previous year. Using unconditional logistic regression models, we estimated the association between consumption of sweets and breast cancer. Consumption of a food grouping that included dessert foods, sweet beverages, and added sugars was positively associated with breast cancer risk [adjusted odds ratio (OR) comparing the highest to the lowest quartile: 1.27, 95% confidence interval (CI): 1.00-1.61]. The OR was slightly higher when only dessert foods were considered (OR: 1.55, 95% CI: 1.23-1.96). The association with desserts was stronger among pre-menopausal women (OR: 2.00, 95% CI: 1.32-3.04) than post-menopausal women (OR: 1.40, 95% CI: 1.07-1.83), although the interaction with menopause was not statistically significant. Our study indicates that frequent consumption of sweets, particularly desserts, may be associated with an increased risk of breast cancer. These results are consistent with other studies that implicate insulin-related factors in breast carcinogenesis.

Dietary glycemic index, glycemic load, and risk of cancer: a prospective cohort study

Previous studies have provided limited evidence for a harmful effect of high glycemic index and dietary glycemic load on cancer. The authors analyzed associations among glycemic index, glycemic load, and risk of cancer in women and men in the National Institutes of Health-AARP Diet and Health Study. Published glycemic index values were assigned to 225 foods/food groups. Glycemic load was calculated by multiplying the glycemic index, carbohydrate content, and intake frequency of individual foods reported on a food frequency questionnaire. From 1995 through 2003, the authors identified 15,215 and 33,203 cancer cases in women and men, respectively. Cox proportional hazards models were used to estimate multivariate relative risks and 95% confidence intervals. For women and men, respectively, the relative risks for total cancer for high versus low glycemic index were 1.03 (P(trend)=0.217) and 1.04 (P(trend)=0.012) and, for glycemic load, were 0.90 (P(trend)=0.024) and 0.93 (P(trend)=0.01). Associations with total cancer held only among the overweight for glycemic index and among those of healthy weight for glycemic load. These findings suggest that glycemic index and glycemic load are not strong predictors of cancer incidence. The direction and small magnitude of associations might be explained by the manner in which high glycemic index and glycemic load track with overall diet and lifestyle patterns.

Dietary carbohydrates, fiber, and breast cancer risk in Chinese women

BACKGROUND

Few studies have investigated the association of dietary carbohydrate and fiber intake with breast cancer risk in women in China, where carbohydrate intake is traditionally high.

OBJECTIVE

The objective was to prospectively evaluate the association of dietary carbohydrates, glycemic index, glycemic load, and dietary fiber with breast cancer risk and to determine whether the effect of these dietary intakes is modified by age and selected insulin- or estrogen-related risk factors.

DESIGN

A total of 74,942 women aged 40-70 y were recruited into the Shanghai Women's Health Study, a population-based cohort study. Dietary intake was assessed by in-person interviews. A Cox proportional hazards regression model was used to evaluate associations.

RESULTS

During an average of 7.35 y of follow-up, 616 incident breast cancer cases were documented. A higher carbohydrate intake was associated with a higher risk of premenopausal breast cancer (P for trend = 0.002). Compared with the lowest quintile, the hazard ratios (and 95% CIs) were 1.47 (1.00, 2.32) and 2.01 (1.26, 3.19) for the fourth and fifth quintiles, respectively. A similar pattern was found for glycemic load. The association between carbohydrate intake and breast cancer was significantly modified by age; the increased breast cancer risk associated with carbohydrate intake was restricted to women who were younger than 50 y. No significant association of breast cancer risk with glycemic index or dietary fiber intake was found.

CONCLUSION

Our data suggest that a high carbohydrate intake and a diet with a high glycemic load may be associated with breast cancer risk in premenopausal women or women <50 y.

Dietary glycaemic index, glycaemic load and breast cancer risk: a systematic review and meta-analysis

This systematic review aimed to examine if an association exists between dietary glycaemic index (GI) and glycaemic load (GL) intake and breast cancer risk. A systematic search was conducted in Medline and Embase and identified 14 relevant studies up to May 2008. Adjusted relative risk estimates comparing breast cancer risk for the highest versus the lowest category of GI/GL intake were extracted from relevant studies and combined in meta-analyses using a random-effects model. Combined estimates from six cohort studies show non-significant increased breast cancer risks for premenopausal women (relative risk (RR) 1.14, 95% CI 0.95–1.38) and postmenopausal women (RR 1.11, 95% CI 0.99–1.25) consuming the highest versus the lowest category of GI intake. Evidence of heterogeneity hindered analyses of GL and premenopausal risk, although most studies did not observe any significant association. Pooled cohort study results indicated no association between postmenopausal risk and GL intake (RR 1.03, 95% CI 0.94–1.12). Our findings do not provide strong support of an association between dietary GI and GL and breast cancer risk.

Glycemic index, glycemic load, and cancer risk: a meta-analysis

BACKGROUND

Factors linked to glucose metabolism play an important role in the development of cancers, and both glycemic index (GI) and glycemic load (GL) have been investigated as potential etiologic factors.

OBJECTIVE

A meta-analysis was performed to explore the association between GI and GL and cancer risk from published studies.

DESIGN

A comprehensive, systematic bibliographic search of the medical literature was conducted to identify relevant studies. Case-control and cohort studies published before October 2007 that reported cancer risk estimates for GI and GL were included. Pooled relative risks (RRs) were estimated for breast, colorectal, endometrial, and pancreatic cancer.

RESULTS

Thirty-nine studies were included in the meta-analysis. The interquantile ranges of GL were significantly wider in case-control studies, most of which were conducted in European countries, than in cohort studies. Cohort studies that presented lower ranges of GL also reported lower risk estimates. Overall, both GL and GI were significantly associated with a greater risk of colorectal (summary RR = 1.26; 95% CI: 1.11, 1.44 and RR = 1.18; 95% CI: 1.05, 1.34, respectively) and endometrial (RR = 1.36; 95% CI: 1.14, 1.62 and RR = 1.22; 95% CI: 1.01, 1.49) cancer than of breast and pancreatic cancer. There was, however, a significant between-study heterogeneity for colorectal cancer (P < 0.0001). The association between GL and breast cancer disappeared when publication bias was taken into account. No association was found for pancreatic cancer.

CONCLUSION

This comprehensive meta-analysis of GI and GL and cancer risk suggested an overall direct association with colorectal and endometrial cancer.

Validity of carbohydrate, glycaemic index and glycaemic load data obtained using a semi-quantitative food-frequency questionnaire

Objective

To assess the ability of a food-frequency questionnaire (FFQ) to rank Australians according to their intake of total carbohydrate, sugar, starch, fibre, glycaemic index (GI) and glycaemic load (GL).

Design

Cross-sectional sample from a population cohort.

Setting

Two postcode areas west of Sydney, Australia.

Subjects

From 1992 to 1994, a total of 2868 older Australians provided dietary data using a 145-item Willett-derived FFQ. A representative sub-sample of 78 subjects completed three 4-day weighed food records (WFRs). Pearson and Spearman correlations, Bland–Altman plots and weighted kappa values were calculated.

Results

Compared with the WFR, the FFQ provided higher mean estimates of all nutrients except starch and GI. All Pearson and/or Spearman correlations were greater than 0.5, except for GL. For GI, sugar, starch and fibre, the regression lines from the Bland–Altman analysis indicated a non-significant linear trend (P = 0.07, P = 0.36, P = 0.28 and P = 0.10, respectively). For GL and total carbohydrate, however, there was a significant linear trend (P = 0.006 and P < 0.0001, respectively), indicating that as the GL and carbohydrate intake of individuals increased, so did the magnitude of the error between the FFQ and WFR. Weighted kappa values all indicated moderate to good agreement, with the exception of GL which was only fair. The proportions of subjects correctly classified within one quintile for all of the nutrients were over 50% and gross misclassification was low (<10%).

Conclusion

This FFQ was able to rank individuals according to their intakes of total carbohydrate, sugar, starch, fibre and GI, but not as well for GL.

Carbohydrate intake, glycemic index, glycemic load, and risk of postmenopausal breast cancer in a prospective study of French women

BACKGROUND

Diets high in carbohydrates may result in chronically elevated insulin concentrations and may affect breast cancer risk by stimulation of insulin receptors or through insulin-like growth factor I (IGF-I)-mediated mitogenesis. Insulin response to carbohydrate intake is increased in insulin-resistant states such as obesity.

OBJECTIVE

We sought to evaluate carbohydrate intake, glycemic index (GI), and glycemic load (GL) and subsequent overall and hormone-receptor-defined breast cancer risk among postmenopausal women.

DESIGN

A prospective cohort analysis of dietary carbohydrate and fiber intakes was conducted among 62 739 postmenopausal women from the E3N French study who had completed a validated dietary history questionnaire in 1993. During a 9-y period, 1812 cases of pathology-confirmed breast cancer were documented through follow-up questionnaires. Nutrients were categorized into quartiles and energy-adjusted with the regression-residual method. Cox model-derived relative risks (RRs) were adjusted for known determinants in breast cancer.

RESULTS

Dietary carbohydrate and fiber intakes were not associated with overall breast cancer risk. Among overweight women, we observed an association between GI and breast cancer (RR(Q1-Q4): 1.35; 95% CI: 1.00, 1.82; P for trend = 0.04). For women in the highest category of waist circumference, the RR(Q1-Q4) was 1.28 (95% CI: 0.98, 1.67; P for trend = 0.10) for carbohydrates, 1.35 (95% CI: 1.04, 1.75; P for trend = 0.01) for GI, and 1.37 (95% CI: 1.05, 1.77; P for trend = 0.003) for GL. We also observed a direct association between carbohydrate intake, GL, and estrogen receptor-negative breast cancer risk.

CONCLUSIONS

Rapidly absorbed carbohydrates are associated with postmenopausal breast cancer risk among overweight women and women with large waist circumference. Carbohydrate intake may also be associated with estrogen receptor-negative breast cancer.

Glycemic load, glycemic index, and pancreatic cancer risk in the Netherlands Cohort Study

BACKGROUND

Recent studies of pancreatic cancer suggest a role for hyperinsulinemia in carcinogenesis. Because insulin is secreted in response to elevated blood glucose concentrations, dietary factors that increase these concentrations may be important in pancreatic carcinogenesis.

OBJECTIVE

The objective was to examine prospectively the relation between pancreatic cancer risk and dietary glycemic load (GL), overall glycemic index (GI), and intake of total carbohydrates and mono- and disaccharides.

DESIGN

The Netherlands Cohort Study consisted of 120,852 men and women who completed a baseline questionnaire in 1986. After 13.3 y of follow-up, 408 pancreatic cancer cases were detected, 66% of which were microscopically confirmed. A validated 150-item food-frequency questionnaire, completed at baseline, was used to calculate carbohydrate and mono- and disaccharide intakes and the GL and GI of the diet.

RESULTS

Dietary GL, GI, or intake of carbohydrates and mono- and disaccharides were not associated with pancreatic cancer risk in this cohort. Also, the associations were not modified by sex. Our results did not change after the analysis was restricted to microscopically confirmed pancreatic cancer cases or after individuals who reported a history of diabetes at baseline were excluded from the analyses.

CONCLUSIONS

Overall, our findings do not support the hypothesis that GL, GI, or intake of carbohydrates and mono- and disaccharides are positively associated with pancreatic cancer risk. This is in agreement with previous prospective studies that investigated the relation between GL and GI and pancreatic cancer risk.

Glycemic index, glycemic load, and chronic disease risk--a meta-analysis of observational studies

BACKGROUND

Inconsistent findings from observational studies have prolonged the controversy over the effects of dietary glycemic index (GI) and glycemic load (GL) on the risk of certain chronic diseases.

OBJECTIVE

The objective was to evaluate the association between GI, GL, and chronic disease risk with the use of meta-analysis techniques.

DESIGN

A systematic review of published reports identified a total of 37 prospective cohort studies of GI and GL and chronic disease risk. Studies were stratified further according to the validity of the tools used to assess dietary intake. Rate ratios (RRs) were estimated in a Cox proportional hazards model and combined by using a random-effects model.

RESULTS

From 4 to 20 y of follow-up across studies, a total of 40 129 incident cases were identified. For the comparison between the highest and lowest quantiles of GI and GL, significant positive associations were found in fully adjusted models of validated studies for type 2 diabetes (GI RR = 1.40, 95% CI: 1.23, 1.59; GL RR = 1.27, 95% CI: 1.12, 1.45), coronary heart disease (GI RR = 1.25, 95% CI: 1.00, 1.56), gallbladder disease (GI RR = 1.26, 95% CI: 1.13, 1.40; GL RR = 1.41, 95% CI: 1.25, 1.60), breast cancer (GI RR = 1.08, 95% CI: 1.02, 1.16), and all diseases combined (GI RR = 1.14, 95% CI: 1.09, 1.19; GL RR = 1.09, 95% CI: 1.04, 1.15).

CONCLUSIONS

Low-GI and/or low-GL diets are independently associated with a reduced risk of certain chronic diseases. In diabetes and heart disease, the protection is comparable with that seen for whole grain and high fiber intakes. The findings support the hypothesis that higher postprandial glycemia is a universal mechanism for disease progression.

Carbohydrates and cancer: an overview of the epidemiological evidence

OBJECTIVE

To assess the epidemiological evidence on dietary carbohydrates and the risk of developing cancer.

METHOD

Review of published studies, concentrating on recent systematic reviews, meta-analyses and large prospective studies.

CONCLUSIONS

Carbohydrates have not been intensively investigated in epidemiological studies of diet and cancer. There is a moderately large amount of data on the possible association between dietary fibre and the risk for colorectal cancer; the results of studies have varied and no firm conclusion can be drawn, but the available data suggest that high intakes of dietary fibre possibly reduce the risk for colorectal cancer. There are also limited data which suggest that high intakes of sucrose might increase the risk for colorectal cancer and that high intakes of lactose might increase the risk for ovarian cancer. For other components of carbohydrates and other types of cancer, the available data are too sparse to draw even tentative conclusions. Further research is needed on the possible associations of carbohydrates with cancer risk.

Dietary glycemic index, glycemic load, and the risk of breast cancer in an Italian prospective cohort study

BACKGROUND

Interest in the roles of glycemic index (GI) and glycemic load (GL) in breast cancer etiology has been stimulated by indications that disease risk is linked to insulinemia, sex hormone bioavailability, and insulin-like growth factor 1.

OBJECTIVE

We aimed to determine whether GI and GL were associated with the risk of breast cancer in a cohort of Italian women volunteers from Northern Italy, who enrolled between 1987-1992 in the Hormones and Diet in the Etiology of Breast Tumors Study (ORDET Study).

DESIGN

Volunteers completed a semiquantitative food-frequency questionnaire, and anthropometric and lifestyle data were collected. Dietary GI and GL in relation to breast cancer risk were examined in 8926 cohort women, including 289 with breast cancer identified after a mean follow-up of 11.5 y.

RESULTS

The relative risk (RR) of breast cancer in the highest (versus lowest) quintiles of GI and GL was 1.57 (95% CI: 1.04, 2.36; P for trend = 0.040) and 2.53 (95% CI: 1.54, 4.16; P for trend = 0.001), respectively. Total carbohydrate intake was not associated with greater breast cancer risk, but high carbohydrate from high-GI foods was. When women were categorized by baseline menopausal status and body mass index (BMI; in kg/m(2)), the increased risk of dietary GL was confined to those who were premenopausal (RR = 3.89; 95% CI: 1.81, 8.34) and who had normal BMI (ie, <25) (RR = 5.79; 95% CI: 2.60, 12.90) (P for trend = 0.001 for both).

CONCLUSIONS

A high-GL diet may increase the risk of breast cancer in Italian women. The effect is particularly evident in premenopausal women and those with BMI < 25.

Dietary patterns related to glycemic index and load and risk of premenopausal and postmenopausal breast cancer in the Western New York Exposure and Breast Cancer Study

BACKGROUND

Reduced rank regression (RRR) has been used to identify dietary patterns that predict variation in a selected risk factor and may be useful in describing dietary exposures associated with glycemic index (GI) and glycemic load (GL).

OBJECTIVE

To estimate breast cancer risk, we compared the relative utility of RRR-derived dietary patterns predictive of GI and GL with those of simple GI and GL.

DESIGN

RRR was used to identify dietary patterns predicting GI and GL from food-frequency data obtained in the Western New York Exposure and Breast Cancer Study (1166 cases, 2105 controls). Odds ratios (ORs) and 95% CIs were estimated with unconditional logistic regression, adjusted for energy and nondietary breast cancer risk factors.

RESULTS

Sweets, refined grains, and salty snacks explained 34% of the variance in GI and 68% of the variance in GL. In general, breast cancer risks were not associated with GI, GL, or dietary pattern score. However, we observed a significant reduction in postmenopausal breast cancer risk with GI and GL pattern scores combined (OR: 0.68; 95% CI: 0.50, 0.93), especially in women with a body mass index (in kg/m(2)) >or=25 (OR: 0.64; 95% CI: 0.44, 0.93). Conversely, in premenopausal women, increased risks were associated with high GL pattern scores only for women with a body mass index >or=25 (OR: 2.21; 95% CI: 1.04, 4.69).

CONCLUSIONS

Although RRR may be useful in studies of diet and disease, our results suggest that RRR dietary patterns based on GI and GL provide similar information regarding the association between breast cancer, GI, and GL.

Diet and breast cancer: a review of the prospective observational studies

The role of diet for the risk of breast cancer is of great interest as a potentially modifiable risk factor. The evidence from prospective observational studies was reviewed and summarized on selected dietary factors, gene-diet interactions, and breast cancer incidence. Dietary factors were considered that, based on their nutritional constituents, are of particular interest in the context of breast cancer: fat intake, biomarkers of fat intake, fruit and vegetable consumption, antioxidant vitamins (vitamins A, C, E, and beta-carotene), serum antioxidants, carbohydrate intake, glycemic index and glycemic load, dairy consumption (including vitamin D), consumption of soy products and isoflavones, green tea, heterocyclic amines, and adolescent diet. The PubMed database was searched for all prospective studies that relate these dietary items to the incidence of breast cancer or consider gene-diet interactions. Among the prospective epidemiologic studies conducted on diet and breast cancer incidence and gene-diet interactions and breast cancer incidence, to date there is no association that is consistent, strong, and statistically significant, with the exception of alcohol intake, overweight, and weight gain. The apparent lack of association between diet and breast cancer may reflect a true absence of association between diet and breast cancer incidence or may be due to measurement error exceeding the variation in the diet studied, lack of sufficient follow-up, and focus on an age range of low susceptibility. The risk of breast cancer can be reduced by avoidance of weight gain in adulthood and limiting the consumption of alcohol.