A new study on 79,952 men in the US found those who ate largest amounts of healthy plant-based foods had a 22 percent lower risk of bowel cancer compared to those who ate the least.
However, the researchers found no such link for women, of whom 93,475 were included in the study.
The team suggested the link is clearer for men, who have an overall higher risk of bowel cancer.
For the research, published in BMC Medicine, people were asked how often they ate certain foods and drink from a list of more than 180 items. They were also asked about portion size.
People could tick that they consumed each food item “never or hardly ever” right up to “two or more times a day”.
For drinks, the responses ranged from “never or hardly ever” to “four or more times a day”.
The food groups were classed as healthy plant foods (whole grains, fruits, vegetables, vegetable oils, nuts, legumes such as lentils and chickpeas, tea and coffee), less healthy plant foods (refined grains, fruit juices, potatoes, added sugars), and animal foods (animal fat, dairy, eggs, fish or seafood, meat).
The researchers then divided the daily consumption per 1,000 kcal into quintiles, from the biggest consumption to the least.
On average, men were aged 60 at the start of the study while women were aged 59.
Researcher Jihye Kim, from Kyung Hee University in South Korea, said: “Colorectal [bowel] cancer is the third most common cancer worldwide and the risk of developing colorectal cancer over a lifetime is one in 23 for men and one in 25 for women.
“Although previous research has suggested that plant-based diets may play a role in preventing colorectal cancer, the impact of plant foods’ nutritional quality on this association has been unclear.
“Our findings suggest that eating a healthy plant-based diet is associated with a reduced risk of colorectal cancer.
“We speculate that the antioxidants found in foods such as fruits, vegetables, and whole grains could contribute to lowering colorectal cancer risk by suppressing chronic inflammation, which can lead to cancer.
“As men tend to have a higher risk of colorectal cancer than women, we propose that this could help explain why eating greater amounts of healthy plant-based foods was associated with reduced colorectal cancer risk in men but not women.”
The authors found the link among men also varied by race and ethnicity.
For example, among Japanese American men, the reduced risk of cancer was 20 per cent, but it was 24 per cent for white men.
The team said more research was needed on the differences between ethnicities.
During the study, 4,976 people (2.9 per cent) developed bowel cancer and factors likely to influence the results, such as whether people were overweight, were taken into account.
Symptoms of bowel or colon cancer include a persistent change in bowel habit, bleeding from the back passage, or blood in stools, unexplained weight loss or tiredness, and unexplained abdominal pain.