Carbohydrate nutrition and risk of adiposity-related cancers: results from the Framingham Offspring cohort (1991-2013)

Authors: MARKAREM, NOUR - Columbia University Medical Center; BANDERA, ELISA - Rutgers University; LIN, YONG - Rutgers University; JACQUES, PAUL - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; RICHARD, HAYES - New York University; PAREKH, NIYATI - New York University

Submitted to: British Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/31/2017
Publication Date: 6/29/2017
Citation: Markarem, N., Bandera, E.V., Lin, Y., Jacques, P.F., Richard, H.B., Parekh, N. 2017. Carbohydrate nutrition and risk of adiposity-related cancers: results from the Framingham Offspring cohort (1991-2013). British Journal of Nutrition. 117:1603-1614. https://doi.org/10.1017/S0007114517001489.

Interpretive Summary: Cancer is a major cause of morbidity and mortality in the United States. A number of cancer types are now linked to overweight and obese body types and are, therefore, termed "adiposity-related." Obesity, diabetes, and metabolic syndrome, all of which are characterized by glucose and insulin dysregulation, are established risk factors for cancer. Dietary carbohydrates are the main dietary component impacting blood glucose and insulin levels and have also been linked to obesity risk and various measures of body adiposity. However, their influence on chronic disease risk, particularly cancer, may vary by both quantity and type of carbohydrates consumed. Dietary glycemic index (GI) is a method for ranking a carbohydrate-containing food's effect on a person's blood glucose (sugar) level. GI is a value assigned to foods based on how slowly or how quickly those foods cause increases in blood glucose levels. Dietary glycemic load (GL,) on the other hand, is a ranking system that accounts not only for GI but also for the amount of carbohydrate in the food. GL indicates not only how quickly a food makes glucose enter the bloodstream but also how much glucose it will deliver, which gives a better indication of how a food impacts blood sugar. Epidemiological evidence on whether total carbohydrate intake and dietary GI and GL play a role cancer risk is contradictory. To further clarify the role of carbohydrate and carbohydrate-containing foods on cancer risk, we used the Framingham Offspring Study (FOS) cohort to examine carbohydrate intake, GI, and GL for the three most common adiposity-related cancers in the United States: breast, prostate, and colorectal cancers. Our results indicated that neither the amount of carbohydrate nor GI or GL was associated with combined incidence of adiposity-related cancers, though higher carbohydrate intake was associated with reduced breast cancer risk. Also, an investigation of the role of carbohydrate food sources suggested that women, in particular, might benefit from a dietary pattern that emphasizes healthier, low-GI carbohydrate-containing foods (those with a smaller effect on glucose levels,) particularly legumes. However, additional research is needed to better understand the role of a low-GI and GL diet in the risk of various cancers, within diverse ethnic groups, as an etiologic agent and not just a marker of a healthy diet.

Technical Abstract: High carbohydrate intake, glycemic index (GI), and glycemic load (GL) are hypothesized to increase cancer risk through metabolic dysregulation of the glucose-insulin axis and adiposity-related mechanisms, but epidemiologic evidence is inconsistent. This prospective cohort study investigates the impact of carbohydrates quantity and quality on the risk of adiposity-related cancers, which represent the most commonly diagnosed preventable cancers in U.S. The study sample consisted of adults from the Framingham Offspring cohort (n=3,184). Dietary data was collected in 1991-95 using a FFQ. Lifestyle and medical information was also collected during that clinical exam. From 1991 to 2013, 565 incident doctor-diagnosed adiposity-related cancers were identified. Cox proportional hazards models were used to evaluate the impact of carbohydrate nutrition on adiposity-related cancers combined and three site-specific cancers, specifically breast, prostate and colorectal cancers. GI and GL were not associated with the risk of adiposity-related cancers or any of the site-specific cancers. Carbohydrate consumption in the highest versus lowest quintile was associated with 41% lower risk of breast cancer (HR:0.59; 95% CI:0.36-0.97). Low-GI foods were associated with 49% lower breast cancer risk (HR:0.51; 95% CI:0.32-0.83). Among low-GI foods, consumption of legumes was associated with 36% lower risk of adiposity-related cancers combined (HR:0.64; 95% CI:0.47-0.88)(p=0.009). A statistically significant multiplicative interaction was observed for legumes with sex (p=0.005). Higher intakes were associated with 43% lower risk of adiposity-related cancers among women only (HR:0.57; 95% CI:0.35-0.91)(p-trend=0.020). In this cohort of Caucasian American adults, associations between carbohydrate nutrition and cancer varied by cancer site. Prevention efforts for adiposity-related cancers may include dietary modification strategies that emphasize healthier, low-GI carbohydrate-containing foods.