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(Health Secrets Newsletter) Cereal fiber is one of the many foods that causes controversy among nutritionists, with many believing that it can protect us from bowel and rectal cancers, while others believe it should be avoided altogether and that it actually irritates the gut, increasing the risk of colorectal cancer.
With this in mind, a systematic review conducted by researchers in the UK and the Netherlands and published in the British Medical Journal has attempted to clarify once and for all whether dietary fiber really can protect us from colorectal cancer. Its conclusion is that fiber can indeed reduce our risk of developing these common cancers, and that we should all ensure we eat three portions of whole grains each day to improve gut health.
What Does The Study Show?
The researchers from Imperial College London, and the University of Leeds in the UK, and Wageningen University in the Netherlands, decided to review all the relevant research that has been done into the link between fiber and colorectal cancer, and to use it to compile a meaningful conclusion.
The researchers identified twenty-one appropriate studies, twelve from America, five from Europe and four from Asia. These were either prospective cohort studies where the diets of participants had been recorded and then they had been followed to see if they developed colorectal cancer, or case-control studies that had compared people with and without colorectal and then reviewed their diet before they developed cancer.
When they assessed these studies the researchers classified participants as consuming ‘high’ or ‘low’ levels of dietary fiber intake and compared the cancer risk for these groups. They also looked at the impact of specific sources of fiber, such as cereal fiber, fruit fiber, vegetable fiber, and of whole grains. Finally they looked for a ‘dose response’ meaning that the amount of fiber consumed would have an impact on the extent of its effect.
The highlights of their findings were as follows:
- People that consumed a high level of any dietary fiber were 12% less likely to develop colorectal cancer than those that consumed a low level
- People that consumed a high level of cereal fiber were 10% less likely to develop colorectal cancer than those that consumed a low level
- People that consumed a high level of whole grains were 21% less likely to develop colorectal cancer than those that consumed a low level
- To reduce the risk of colorectal cancer by 10% required the consumption of 10g of general dietary fiber, 10g of cereal fiber, or 90g of whole grains per day.
Surprisingly there appeared to be no correlation between the consumption of fruit, vegetable, or legume fiber and the risk of developing colorectal cancer. It has often been thought that fruit and vegetable fiber could have a similar protective action to cereal fiber, but this seems not to be the case.
Overall it seems that by including 90g, or three portions, of whole grain in our diets each day, we can reduce our risk of developing colorectal cancer, the third most prevalent cancer in the world, by around 20%.
How To Include Whole Grain In Your Diet
There are a number of ways of making sure you get plenty of whole grain in your diet. Here are four simple changes you can make to get your three portions a day:
- Switch to wholegrain bread, pasta, and rice, rather than using the white varieties that have had the fiber stripped out
- Use wholemeal flour in baking rather than white flour
- Look for snacks such as cereal bars or chips that contain whole grain rather than eating chocolate bars or potato chips
- Eat porridge or bran flakes for breakfast as these are both good sources of fiber and they will fill you up reducing the risk of overeating
