Going vegan lowers the risk of colorectal cancer in men by more than a FIFTH, study suggests

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Dining on a diet rich in vegetables, whole grains and beans can lower the risk of colorectal cancer in men by more than a fifth, a study suggests.

South Korean researchers analyzed data collected from around 80,000 American men over two decades.

Those who ate the most plants in their diet were 22 per cent less likely to develop the cancer compared to those who ate the least.

But no such link was seen in women, of whom 93,475 were included in the study. Overall, men have a higher risk of colorectal cancer. 

Colorectal cancer is the third most common type worldwide, with one in 23 men and one in 25 women affected in their lifetimes. 

About 100,000 American adults are diagnosed with the disease every year, estimates suggest.

Experts recommend Americans get checked once every 10 years from the age of 45 avoid the cancer.

Men who had the most vegetables in their diet had a 22 per cent lower risk of colorectal cancer compared to those who ate the least vegetables (stock image)

Men who had the most vegetables in their diet had a 22 per cent lower risk of colorectal cancer compared to those who ate the least vegetables (stock image)

The study — published today in BMC Medicine — recruited 79,000 men and 93,000 women from Los Angeles and Hawaii.

On average, men were about 60 years old at the start of the study while women were aged 59 years.

To assess diets, participants 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.

WHAT IS COLORECTAL CANCER? 

Bowel, or colorectal, cancer affects the large bowel, which is made up of the colon and rectum.

Such tumours usually develop from pre-cancerous growths, called polyps.

Symptoms include:

  • Bleeding from the bottom
  • Blood in stools 
  • A change in bowel habits lasting at least three weeks 
  • Unexplained weight loss 
  • Extreme, unexplained tiredness 
  • Abdominal pain 

Most cases have no clear cause, however, people are more at risk if they: 

  • over 50
  •  Have a family history of the condition
  • Have a personal history of polyps in their bowel
  • Suffer from inflammatory bowel disease, such as Crohn’s disease
  • Lead an unhealthy lifestyle 

Treatment usually involves surgery, and chemo- and radiotherapy.

More than nine out of 10 people with stage one bowel cancer survive five years or more after their diagnosis.

This drops significantly if it is diagnosed in later stages.

According to Bowel Cancer UK figures, more than 41,200 people are diagnosed with bowel cancer every year in the UK – and 17,000 die.

It affects around 40 per 100,000 adults per year in the US, according to the National Cancer Institute.

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 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, 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.

‘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% but it was 24% 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 colorectal cancer and factors likely to influence the results, such as whether people were overweight, were taken into account.

Dr Helen Croker, head of research interpretation at World Cancer Research Fund, said: ‘We welcome this research which adds to our own evidence that eating vegetables, wholegrains and beans reduces the risk of developing bowel cancer.

‘We also recommend that people limit the amount of red meat they eat and avoid processed meat altogether.

‘Interestingly in this paper, plant-based diets were only associated with a lower risk of bowel cancer in men. It’s speculated that one reason for this may be because men in general had a lower intake of plant foods and a higher intake of animal foods than women – so there was perhaps a ceiling effect to the benefits that women may experience.’

Beth Vincent, health information manager at Cancer Research UK, said: ‘This American study adds to lots of existing evidence on the benefits of eating a balanced diet high in fruit, vegetables and fibre for both men and women.

‘The research tried to compare ‘healthy plant foods’ and ‘unhealthy plant foods’ and found a link with bowel cancer in men. But because of the design of the study, the authors themselves acknowledge we can’t read too much into their results.

‘The study relied on people remembering what they had eaten up to a year ago. It also made the assumptions that participants’ diets stayed the same over many years, and that all meat and animal products were unhealthy – which isn’t the case.

‘Eating a well-balanced diet can help with maintaining a healthy weight, which reduces the risk of cancer.

‘Not smoking, cutting down on alcohol and staying safe in the sun are other important ways to reduce your cancer risk.’

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