Dietary Glycemic Index and Cancer Risk

The dietary glycemic index (GI) ranks carbohydrate-containing foods by their postprandial blood glucose response, while glycemic load (GL) combines GI with the carbohydrate content of a portion. Diets high in GI and GL provoke repeated insulin surges, hyperinsulinemia and elevated insulin-like growth factor signalling, which can promote cell proliferation and inhibit apoptosis. Chronic exposure to these metabolic disturbances may facilitate tumour initiation and progression in tissues sensitive to insulin and growth factors.

Population studies have linked high-GI diets to modestly increased risks of colorectal, endometrial, bladder and kidney cancers, and to poorer prognosis in hormone-related malignancies. Conversely, diets emphasizing complex carbohydrates, wholegrains and dietary fibre tend to lower GI, attenuate insulin responses and are associated with reduced cancer incidence and mortality. Variations in associations by anatomical site underscore the importance of carbohydrate quality as well as quantity.

Given the global burden of diet-related cancers, adjusting dietary patterns to favour low-GI foods offers a practical, broadly applicable strategy to modulate metabolic drivers of tumour growth. Integrating GI and GL into dietary guidelines may complement established recommendations on energy balance and nutrient density, particularly in populations at elevated risk.

Research from Nature Portfolio

A seminal prospective analysis of over 45 000 Italian adults followed for 15 years examined the associations of dietary GI and GL with incident cancers. High GI intake was linked to increased risks of colon and bladder cancer, while high GL was associated with elevated incidence of colon and diabetes-related cancers but showed an inverse relation with rectal cancer. Carbohydrates from low‐GI sources were protective against colon cancer, highlighting opposing effects of food quality and quantity on cancer risk.

Dietary Glycemic Index and Cancer Risk publication trend

The graph below shows the total number of articles in dietary glycemic index and cancer risk across all publications each year (not limited to Nature Index journals).

Technical terms

Glycemic index: A scale assigning foods a value based on their ability to raise blood glucose compared with a reference food.

Glycemic load: A metric that multiplies the glycemic index of a food by its available carbohydrate content per serving, reflecting overall glucose-raising potential.

Carbohydrate Quality Index (CQI): A composite score evaluating dietary fibre, wholegrain consumption, glycemic index and the ratio of solid to liquid carbohydrates to characterise carbohydrate quality.

Insulin-like growth factor-1 (IGF-1): A hormone that stimulates cell proliferation and inhibits apoptosis, often upregulated in response to elevated insulin levels.

References

1. Carbohydrate quality, not quantity, linked to reduced colorectal cancer incidence and mortality in US populations: evidence from a prospective study. BMC Medicine (2024).
2. Dietary glycemic index, glycemic load, and renal cancer risk: findings from prostate, lung, colorectal, and ovarian cancer trial. Frontiers in Nutrition (2023).
3. Dietary Approach of Patients with Hormone-Related Cancer Based on the Glycemic Index and Glycemic Load Estimates. Nutrients (2023).
4. Dietary glycemic index, glycemic load, and cancer risk: results from the EPIC-Italy study. Scientific Reports (2017).