Whole grain diets could reduce the risk of bowel cancerby Jennifer Bowden
There’s good news and bad about New Zealand’s second-biggest cancer killer.
Bowel cancer – also known as colon, rectal or colorectal cancer – is a malignant growth that develops in the intestine. It is the second-highest cause of cancer death in New Zealand. A family history of bowel cancer is a risk factor, and as we age, the chance of getting it increases.
Bowel cancer appears to be affecting more younger adults. A recent study based on 1995-2012 New Zealand National Cancer Registry data, published in the British Journal of Surgery, found the rate is climbing in people under 50. In contrast, there was a fall in the incidence in those aged 50-79.
New Zealand began rolling out a free national bowel-screening programme in July. However, its two-yearly checks are offered only to those aged 60-74.
The causes of the disease are unknown, but dietary and lifestyle factors have been linked to it. In September, the World Cancer Research Fund (WCRF) released a report analysing global research on the relationships between diet, nutrition, physical activity, weight and colorectal-cancer risk.
It concluded there was “convincing” evidence that processed meat, alcohol, being overweight or obese – and being tall – increased bowel-cancer risk. There was also a “probable” link to red-meat consumption.
On the positive side, the report said it is “probable” that whole grains, foods containing dietary fibre, dairy products and calcium supplements reduce the risk. This might give pause to paleo-diet followers, who avoid whole grains and, in many cases, dairy products. And also on the plus side is that physical activity reduces the risk.
It is the first time the WCRF has linked whole grains to reduced bowel-cancer risk. Its analysis suggests that eating three servings (about 90g) of whole grains a day cuts the risk by about a fifth. A serving is defined as half a cup of muesli or porridge, two wheat biscuits, a slice of wholegrain bread, or a cup of cooked brown rice or wholegrain pasta. So three servings could equate to two slices of wholegrain bread and half a cup of wholegrain muesli, for example.
There are a number of ways in which whole grains could be reducing bowel-cancer risk. For a start, whole grains are a source of dietary fibre, a fuel source for gut bacteria that in turn produce short-chain fatty acids, which have anti-inflammatory and anti-carcinogenic effects. Dietary fibre also reduces food’s transit time through the bowel, and may bind to carcinogens and prevent insulin resistance.
Whole grains are also a rich source of valuable biologically active compounds such as vitamin E, selenium, copper, zinc, lignans, phytoestrogens and phenolic compounds, many of which have “plausible anti-carcinogenic properties”, says the WCRF report.
Replacing refined grains with more wholesome ones is easy:
- Eat wholegrain cereals for breakfast – try an oat-based porridge or whole-wheat cereal.
- Swap white bread for whole-wheat or rye varieties.
- Eat whole-wheat tortillas instead of white ones.
- Replace white rice with brown or wild rice or bulgar.
- Eat wholegrain pasta instead of standard pasta.
- Add wild rice or barley to soups, stews, casseroles and salads.
- In recipes, replace breadcrumbs with rolled oats or crushed whole-wheat bran.
- Eat bran muffins rather than fruit muffins or scones.
This article was first published in the October 7, 2017 issue of the New Zealand Listener.
I predicted Bill English would lose the election and the winner would be Winston Peters. But no forecaster, including the PM, predicted her pregnancy.Read more
New essays on New Zealand-born US artist Len Lye elevate him to the status of Australasia’s most notable 20th-century artist.Read more
For about a third of infertility cases in New Zealand, there is no obvious reason why seemingly fertile couples struggle to conceive.Read more
More than one million images from Rykenberg Photography, taken around Auckland, are now in the Auckland Libraries Collection. But who are the people?Read more
A Golden Bay man spending his first night in his new house says he woke to find his bed, walls and floor covered in hundreds of creepy crawlies.Read more
There's a growing movement to stop the amount of wasteful plastic that goes into our oceans, but what about the tiny bits we can hardly see?Read more
The inconvenience to chlorine refuseniks is tiny compared with the risk of more suffering and tragedy from another Havelock North-style contamination.Read more