Dietary Carbohydrate Intake, Glycemic Index and Glycemic Load in Relation to Adiposity‐Related Cancer Risk: Results from The Framingham Offspring Cohort (1991–2013)
Authors: Makarem Nour , Lin Yong , Bandera Elisa V. , Jacques Paul , Parekh Niyati 
Published: November 2023

ObjectiveThe aim of this prospective cohort study is to investigate the role of dietary carbohydrates, glycemic index (GI) and glycemic load (GL) in the risk of adiposity‐related cancers combined and three of the most commonly diagnosed site‐specific cancers: breast, prostate and colorectal.MethodsThe study sample consisted of 3,184 men and women from the Framingham Offspring cohort recruited in 1971–1975. Clinical exams were conducted, on average, every 4 years to collect medical, lifestyle and anthropometric data. Data on diet, collected using a food frequency questionnaire, was first available in 1991. The main exposures were total carbohydrate intake, GI and GL. Additionally, the major carbohydrate food sources in the US diet were identified using the Continuing Survey of Food Intakes by Individuals. High, medium and low GI foods were categorized using the American Diabetes Association definition. The outcomes of interest were combined incidence of all adiposity‐related cancers and first primary incidence of breast, prostate and colorectal cancers. Cancers were considered adiposity‐related if identified by the National Cancer Institute as clearly or possibly linked to overweight and obesity. Doctor‐diagnosed cancers were documented using medical records (n=565) until 2013. The study period from 1991 to 2013 represents a follow‐up of >20 years. Cox proportional hazards models were used to compute hazard ratios (HR) and 95% confidence intervals (CI) to estimate associations between dietary carbohydrates, their major food sources, GI, GL and cancer risk.ResultsAfter adjustment for multiple confounders including age, energy, smoking, alcohol, menopausal status, hormone use in addition to antioxidant, fiber, fat and red and processed meat intake, there was no association between total carbohydrate intake, GI and GL and adiposity‐related cancers combined. In contrast, carbohydrate intake, expressed as percentage of total caloric intake, in the highest versus lowest quintile was associated with 53% lower breast cancer risk (HR:0.47;95%CI:0.26–0.88). Higher GL was associated with a 78% higher risk of prostate cancer (HR:1.78;95%CI:1.02–3.10). Among food sources, consumption of low GI foods was associated with a 69% reduction in breast cancer risk (HR:0.31;95%CI:0.16–0.60). Among individual foods, legumes were associated with 35% lower adiposity‐related cancer risk (HR:0.65;95%CI:0.47–0.89); while lunch foods (pizza, burgers, meat sandwiches and casseroles) were associated with 89% higher prostate cancer risk (HR:1.89;95%CI:1.04–3.44). Among beverages, consumption of soft drinks and fruit juice was associated >3‐fold higher risk of prostate cancer.ConclusionsIn this cohort of Caucasian American adults, associations of carbohydrate quantity and quality varied by cancer site. Adiposity‐related cancers are associated with lifestyle, and therefore may benefit from a dietary modification that emphasizes healthier carbohydrates and limits sugary beverages and energy‐dense, nutrient‐poor carbohydrate‐containing foods. These results should be replicated in a racially diverse population.Support or Funding InformationThis research was supported by the American Cancer Society Research Scholar Grant (#RSG‐12‐005‐01‐CNE)