Colorectal cancer is the second most common cancer type in Finland and the third most common globally, and its incidence continues to rise, especially among younger age groups. Lifestyle factors play an important role in its development and, by extension, its prevention.
A University of Helsinki doctoral study at the Finnish Institute for Health and Welfare established that partially replacing red or processed meat with plant-based foods, particularly whole grains, was associated with a reduced risk of colorectal cancer in Finnish adults.
“The findings suggest that even small weekly dietary shifts towards more plant-based diet could reduce colorectal cancer risk at the population level,” says Doctoral Researcher Rilla Tammi of the University of Helsinki’s Faculty of Medicine.
A higher intake of whole grains was also associated with lower body mass index, waist circumference and serum total cholesterol concentration in Finnish men. No similar associations were observed in women.
“The whole grain research is all the more important given that low whole grain intake has been identified as one of the key dietary factors behind years of life lost to diseases,” says Tammi.
Tammi found that colorectal cancer risk factors, such as high consumption of red and processed meat, low whole grain intake, low physical activity and obesity, were collectively associated with lower gut microbiome diversity and a higher relative abundance of several bacterial species previously linked to colorectal cancer. Tammi argues that these characteristics of the gut microbiome may contribute to colorectal cancer development.
Using a colorectal cancer lifestyle index, her study assessed lifestyle and other risk factors holistically rather than individually, more accurately reflecting the real-life risk environment.
The study was conducted at the Finnish Institute for Health and Welfare using population data gathered at the institute.
Doctoral defence
Rilla Tammi, MSc, will defend her doctoral thesis entitled ‘Whole grain intake, healthy lifestyles and the gut microbiome in colorectal cancer risk’ on 20 March 2026 at 13.00 at the Faculty of Medicine, University of Helsinki.
See further details on the public defence in the University’s
The thesis is also available in electronic form through the
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Whole grains contain all edible parts of a cereal grain, retaining nutrients such as fibre, vitamins and minerals in full. In more heavily processed refined grains, some of the nutrient-rich parts are removed, leaving mostly starch behind.
Whole grain intake can be easily increased by swapping refined grain products for whole grain alternatives. When choosing bread, it is best to opt for varieties made mostly from whole grains, and do the same for cereal-based side dishes such as rice and grain mixes. Oatmeal porridge is an excellent source of whole grains.
The recommended daily intake of whole grains is 90 grams. This is achievable by, for example, eating three slices of whole grain rye bread, a bowl of oatmeal porridge and just over 100 ml of boiled barley groats (source: National Nutrition Council and Finnish Institute for Health and Welfare. Sustainable health from food – National Nutrition Recommendations 2024).