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

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.

State of the Art Reviews: Glycemic Index, Obesity, and Chronic Disease

There is increasing evidence that both the amount and type of carbohydrate play an important role in weight management and risk of chronic disease. Classifying carbohydrates according to their post-prandial glycemic effect (ie, the glycemic index of foods) has yielded more useful insights than the historical distinctions of simple versus complex chemical structure. Diets based on carbohydrate foods that are more slowly digested and absorbed (ie, low glycemic index diets) have been independently linked to reduced risk of type 2 diabetes, cardiovascular disease, and some types of cancer. In individuals with diabetes, intervention studies have shown improvements in insulin sensitivity and glycated hemoglobin concentration with low glycemic index diets. Research also suggests that low glycemic index diets may assist with weight management through effects on satiety and fuel partitioning. Although ongoing research is needed, the current findings, together with the fact that there are no demonstrated negative effects of a low glycemic index diet, suggest that the glycemic index should be an important consideration in the dietary management and prevention of obesity and chronic disease.

Dietary carbohydrates, glycemic index, glycemic load, and endometrial cancer risk within the European Prospective Investigation into Cancer and Nutrition cohort

The associations of dietary total carbohydrates, overall glycemic index, total dietary glycemic load, total sugars, total starch, and total fiber with endometrial cancer risk were analyzed among 288,428 women in the European Prospective Investigation into Cancer and Nutrition cohort (1992-2004), including 710 incident cases diagnosed during a mean 6.4 years of follow-up. Cox proportional hazards models were used to estimate relative risks and 95% confidence intervals. There were no statistically significant associations with endometrial cancer risk for increasing quartile intakes of any of the exposure variables. However, in continuous models calibrated by using 24-hour recall values, the multivariable relative risks were 1.61 (95% confidence interval: 1.06, 2.45) per 100 g/day of total carbohydrates, 1.40 (95% confidence interval: 0.99, 1.99) per 50 units/day of total dietary glycemic load, and 1.36 (95% confidence interval: 1.05, 1.76) per 50 g/day of total sugars. These associations were stronger among women who had never used postmenopausal hormone therapy compared with ever users (total carbohydrates p(heterogeneity) = 0.04). Data suggest no association of overall glycemic index, total starch, and total fiber with risk, and a possible modest positive association of total carbohydrates, total dietary glycemic load, and total sugars with risk, particularly among never users of hormone replacement therapy.

Glycaemic index, glycaemic load and risk of endometrial cancer: a prospective cohort study

Objective

High-glycaemic-load diets may increase endometrial cancer risk by increasing circulating insulin levels and, as a consequence, circulating oestrogen levels. Given the paucity of epidemiological data regarding the relationship between dietary glycaemic index and glycaemic load and endometrial cancer risk, we sought to examine these associations using data from a prospective cohort study.

Design, setting and subjects

We examined the association between dietary glycaemic load and endometrial cancer risk in a cohort of 49 613 Canadian women aged between 40 and 59 years at baseline who completed self-administered food-frequency questionnaires between 1982 and 1985. Linkages to national mortality and cancer databases yielded data on deaths and cancer incidence, with follow-up ending between 1998 and 2000.

Results

During a mean of 16.4 years of follow-up, we observed 426 incident cases of endometrial cancer. Hazard ratios for the highest versus the lowest quartile level of overall glycaemic index and glycaemic load were 1.47 (95% confidence interval (CI) = 0.90–2.41; P for trend = 0.14) and 1.36 (95% CI = 1.01–1.84; P for trend = 0.21), respectively. No association was observed between total carbohydrate or total sugar consumption and endometrial cancer risk. Among obese women (body mass index > 30 kg m−2) the hazard ratio for the highest versus the lowest quartile level of glycaemic load was 1.88 (95% CI = 1.08–3.29; P for trend = 0.54) and there was a 55% increased risk for the highest versus the lowest quartile level of glycaemic load among premenopausal women. There was also evidence to support a positive association between glycaemic load and endometrial cancer risk among postmenopausal women who had used hormone replacement therapy.

Conclusions

Our data suggest that diets with high glycaemic index or high glycaemic load may be associated with endometrial cancer risk overall, and particularly among obese women, premenopausal women and postmenopausal women who use hormone replacement therapy.

Carbohydrate intake, glycemic index and glycemic load in relation to risk of endometrial cancer: A prospective study of Swedish women

The associations of carbohydrate intake, glycemic index and glycemic load with endometrial cancer risk were examined among 61,226 participants of the Swedish Mammography Cohort who were cancer-free at enrollment between 1987 and 1990 and completed a food frequency questionnaire. During a mean follow-up of 15.6 years, through June 2005, 608 incident cases of endometrial adenocarcinoma were diagnosed. We observed no overall association between carbohydrate intake, glycemic index or glycemic load and incidence of endometrial cancer; the rate ratios (RRs) for the highest versus the lowest quintile were 1.12 (95% CI, 0.85-1.47) for carbohydrate intake, 1.00 (95% CI, 0.77-1.30) for glycemic index and 1.15 (95% CI, 0.88-1.51) for glycemic load. However, among obese women (body mass index, BMI > or =30 kg/m2), endometrial cancer incidence was nonsignificantly elevated in the top versus bottom quintiles of carbohydrate intake (RR, 1.68; 95% CI, 0.86-3.29) and glycemic load (RR, 1.57; 95% CI, 0.82-2.99). In a subanalysis of women who completed a follow-up questionnaire in 1997, which collected information on physical activity, carbohydrate intake and glycemic load were positively related to endometrial cancer risk among overweight women (BMI > or =25 kg/m2) with low physical activity. In this subgroup, the multivariate RRs comparing extreme quartiles were 1.90 (95% CI, 0.84-4.31) for carbohydrate intake and 2.99 (95% CI, 1.17-7.67) for glycemic load. Results from this cohort study suggest that a high carbohydrate intake and a high glycemic load may increase the risk of endometrial cancer among overweight women with low physical activity.

A chlorogenic acid-induced increase in GLP-1 production may mediate the impact of heavy coffee consumption on diabetes risk

Recent prospective epidemiology links heavy coffee consumption to a substantial reduction in risk for type 2 diabetes. Yet there is no evidence that coffee improves insulin sensitivity and, at least in acute studies, caffeine has a negative impact in this regard. Thus, it is reasonable to suspect that coffee influences the risk for beta cell "failure" that precipitates diabetes in subjects who are already insulin resistant. Indeed, there is recent evidence that coffee increases production of the incretin hormone glucagon-like peptide-1 (GLP-1), possibly owing to an inhibitory effect of chlorogenic acid (CGA -- the chief polyphenol in coffee) on glucose absorption. GLP-1 acts on beta cells, via cAMP-dependent mechanisms, to promote the synthesis and activity of the transcription factor IDX-1, crucial for maintaining the responsiveness of beta cells to an increase in plasma glucose. Conversely, the "glucolipotoxicity" thought to initiate and sustain beta cell dysfunction in diabetics can suppress expression of this transcription factor. The increased production of GLP-1 associated with frequent coffee consumption could thus be expected to counteract the adverse impact of chronic free fatty acid overexposure on beta cell function in overweight insulin resistant subjects. CGA's putative impact on glucose absorption may reflect the ability of this compound to inhibit glucose-6-phosphate translocase 1, now known to play a role in intestinal glucose transport. Delayed glucose absorption may itself protect beta cells by limiting postprandial hyperglycemia -- though, owing to countervailing effects of caffeine on plasma glucose, and a paucity of relevant research studies, it is still unclear whether coffee ingestion blunts the postprandial rise in plasma glucose. More generally, diets high in "lente carbohydrate", or administration of nutraceuticals/pharmaceuticals which slow the absorption of dietary carbohydrate, should help preserve efficient beta cell function by boosting GLP-1 production, as well as by blunting the glucotoxic impact of postprandial hyperglycemia on beta cell function.

Role of diet in blood glucose response and related health outcomes: summary of a meeting

Consumption of foods that elicit a marked glycemic response have been proposed as risk factors for obesity and insulin resistance. A group of experts from around the world participated in a discussion of scientific issues about the role of diet in blood glucose response and related health outcomes. The goal was to determine how diet can best be used to prevent rather than to treat disease. This was an informed discussion rather than a formal, evidence-based review. To resolve debate on this topic, well-controlled research with healthy individuals is needed.

Inflammation: Nutritional, Botanical, and Mind-body Influences

Chronic inflammation is becoming an important risk factor to identify in regard to inhibiting disease onset and its progression. Nutritional science attempted to improve health by manipulating fats so that we could consume "healthy" nonsaturated fats while simultaneously allowing foods to have a longer shelf-life. However, despite our good intentions, trans-fats and partially hydrogenated oils have been found to promote inflammation and adversely affect health. This article reviews how essential fatty acids, the ratio of omega-3 to omega-6 fatty acids, glycemic load, the Mediterranean diet, specific foods and botanicals, and the mind-body relation influence the inflammatory cascade.

Nutrition and cancer: a review of the evidence for an anti-cancer diet

It has been estimated that 30–40 percent of all cancers can be prevented by lifestyle and dietary measures alone. Obesity, nutrient sparse foods such as concentrated sugars and refined flour products that contribute to impaired glucose metabolism (which leads to diabetes), low fiber intake, consumption of red meat, and imbalance of omega 3 and omega 6 fats all contribute to excess cancer risk. Intake of flax seed, especially its lignan fraction, and abundant portions of fruits and vegetables will lower cancer risk. Allium and cruciferous vegetables are especially beneficial, with broccoli sprouts being the densest source of sulforophane. Protective elements in a cancer prevention diet include selenium, folic acid, vitamin B-12, vitamin D, chlorophyll, and antioxidants such as the carotenoids (α-carotene, β-carotene, lycopene, lutein, cryptoxanthin). Ascorbic acid has limited benefits orally, but could be very beneficial intravenously. Supplementary use of oral digestive enzymes and probiotics also has merit as anticancer dietary measures. When a diet is compiled according to the guidelines here it is likely that there would be at least a 60–70 percent decrease in breast, colorectal, and prostate cancers, and even a 40–50 percent decrease in lung cancer, along with similar reductions in cancers at other sites. Such a diet would be conducive to preventing cancer and would favor recovery from cancer as well.

Diabetes as a risk factor for death following endometrial cancer

OBJECTIVE

To determine whether several personal or lifestyle risk factors for the occurrence of endometrial cancer are also risk factors for death following endometrial cancer.

METHODS

In 1986, we obtained risk factor information by mail on 41,836 women aged 55-69 years and living in Iowa. We followed those initially free of cancer through 2000 and identified incident endometrial cancers via linkage to a cancer registry. Women with endometrial cancer (n = 415) then were followed to identify overall and endometrial cancer deaths.

RESULTS

Over a median of 6.4 years following endometrial cancer diagnosis, 93 women died, 39 with endometrial cancer as the underlying cause. Among the various personal and lifestyle risk factors examined, only diabetes (self-reported) was related to death following endometrial cancer. Adjusted for age and extent of endometrial cancer at diagnosis, the relative risk of overall death for diabetic versus nondiabetic women was 2.79 (95% CI 1.63-4.78). For endometrial cancer as a specific cause of death, the diabetes-related relative risk was 2.38 (95% CI 1.05-5.37). Further adjustment for tumor grade strengthened these relative risks slightly.

CONCLUSIONS

Diabetes is associated with poorer survival after incident endometrial cancer, independent of tumor stage and grade. Our findings raise the possibility of a diabetes-related condition, such as hyperglycemia or hyperinsulinemia, contributing to poorer endometrial cancer survival.