Grant title: Whole grains and refined grains and cancer incidence: habitual intakes, changes in intakes, substitutions and risk of 20 cancers in 4 Scandinavian cohort studies and a large American multiethnic cohort
Institution: Cancer Registry of Norway
Grant awarded: September 2025
We are very pleased to have been awarded this grant from Wereld Kanker Onderzoek Fonds and World Cancer Research Fund International. The grant will allow us to study the associations between consumption of whole grains and refined grains, and risk of several different cancer types across 5 large cohort studies. Currently there is strong evidence that whole grains protect against colorectal cancer, but data on other cancers is lacking. The findings of this project may strengthen conclusions across cancer sites and could lead to more detailed recommendations, and better estimates of how many cancer cases may be attributable to a low whole grain intake or high refined grain intake – Dr Dagfinn Aune
Background
There is strong evidence that eating large amounts of whole grain products, such as wholemeal bread, breakfast cereals with grains intact or cooked whole grains, is likely to reduce bowel cancer risk, as this has been shown in numerous studies on diet and bowel cancer conducted over the last decades. Whether whole grains may reduce other cancer types is less clear. Some studies suggest that a high whole grain intake may be related to a lower risk of cancers of the mouth, oesophagus, stomach, small intestine, liver and pancreas, and possibly also lung, breast and kidney cancer.
Refined grain products, such as products made from white flour, corn grits or white rice, have been studied less frequently and the available data do not allow for strong conclusions on whether refined grains are likely to influence cancer risk. Some evidence suggests refined grains may increase the risk of obesity and diabetes, which are risk factors for 12 and 6 cancers, respectively. We will therefore examine the association between whole grain and refined grain consumption and cancer risk, looking at a wide range of cancer types to provide a comprehensive assessment and address the knowledge gaps.
Aims and objectives
The project will investigate the association between whole grain and refined grain consumption and the risk of 20 cancers in 5 cohort studies with over 480,000 participants followed since the 1990s. Our hypothesis is that high whole grain consumption, increased whole grain intake over time, and replacing refined grains with whole grains is associated with reduced risk of cancers of the mouth, oesophagus, stomach, bowel, liver, pancreas, lung, breast and kidney, and that high refined grain consumption and increased refined grain intake over time is associated with increased risk of stomach, kidney and bladder cancers.
How it will be done
We will use data from 4 Scandinavian cohort studies including the Norwegian Women and Cancer Study (NOWAC), the Danish Diet, Cancer and Health study (DDCH), Cohort of Swedish Men (COSM) and the Swedish Mammography Cohort (SMC), and the Multiethnic Cohort Study. The Scandinavian populations are known to have a high intake and large range of whole grain intake, which will be important for detecting associations between whole grain intake and cancer risk. Dietary intake has been estimated using dietary questionnaires. We will account for other factors that are known to or may influence the risk of cancer in our analyses, including other dietary factors, physical activity, smoking, alcohol intake, and socio-demographic characteristics. We will also investigate whether changes in whole grain and refined grain intakes are associated with cancer risk as well as substitution models with refined grains being replaced by whole grains.
Potential impact
This project will clarify the associations between whole grain and refined grain consumption and risk of 20 cancer types in 5 cohort studies. This could contribute to improved dietary recommendations for cancer prevention, improved assessment of future risk of cancer in healthy individuals, and better estimates of how many cancers can be caused by low whole grain and high refined grain intake.