Six foods that increase or decrease cancer risk
By The Conversation
| January 20th 2019
If you believe cancer is a disease that strikes from nowhere with little in your control to prevent it, you’d be mistaken on both counts. Most cases of cancer are considered preventable by positive nutrition and lifestyle choices.
Six new nutrition cancer prevention guidelines published today in the Journal of the American College of Nutrition reinforce some sound advice, but also include a surprise or two.
Eat plenty of fruits and vegetables
Unfortunately, there is no “cancer prevention superfood”; it is a combination of food variety that gives the greatest benefit. One group of vegetables you may care to give a closer look at during your weekly shop, are the dark leafy greens. These include broccoli, spinach, leaf lettuce and kale – foods that are true nutrient powerhouses.
Limit or avoid alcohol
Alcohol is strongly linked to cancer of the mouth, oesophagus, breast, colon and liver; the more you drink, the greater the risk.
Alcohol through conversion to acetaldehyde can directly damage cellular DNA. It can also damage the liver, increase the solubility of other cancer-causing chemicals, increase the level of estrogen, and decrease the levels of some beneficial nutrients such as folate.
Avoid red and processed meat
The advice on avoiding processed meat is well supported by evidence. This agrees with the biggest voice in the cancer prevention business, the World Cancer Research Fund (WCRF) which rates the link between red meat and colorectal cancer as “convincing” – the highest level of evidence possible.
Meat lovers can take some solace though. The WCRF recommends keeping consumption of red meat to under 500 grams of cooked meat per week. Fish and chicken are good alternatives if the thought of missing a daily steak is too much for you.
Following on from the advice on limiting red meat, is a recommendation to avoid overcooking meat; especially from grilling and frying. When meat, chicken and fish is overcooked at high temperatures for a long time, natural reactions in the food can produce heterocyclic amines (HCAs).
HCAs are considered potent causes of breast, lung, colon, stomach and prostate cancer – at least in animal models.
Women: eat soy foods to reduce your risk of breast cancer
This is a surprising recommendation, more so that when groups such as the WCRF have looked at the evidence, it barely made it to the “limited” level of evidence.
Soy contains a class of phytochemicals called isoflavones which have chemical structures similar to estrogen. These isoflavones are thought to partly inhibit a woman’s own natural estrogen in stimulating cell growth. That’s the theory at least.
Soy foods are a staple of vegetarian diets and the recommendation advises choosing natural soy foods such as edamame, tempeh or tofu and to steer clear of protein concentrates often found in supplements.
Women who are being treated for estrogen-receptor-positive breast cancer should avoid soy supplements because they contain high concentrations of isoflavones.
Men: limit or avoid dairy products to reduce your risk of prostate cancer
This recommendation is a good example of needing to balance risk when it comes to lifestyle choices in preventing cancer. While there is some limited evidence that dairy products can raise a man’s risk of prostate cancer, there is also a higher level of evidence (which the WCRF classifies as “probable”) that milk and calcium can lower the risk of colorectal cancer.
A diet high in calcium can lead to a decrease in vitamin D production. Vitamin D is an important regulator of cell growth and proliferation so less of it may lead to prostate cancer cells growing unchecked.
In the colon, though, it’s a different matter. Calcium can bind to potentially carcinogenic compounds in the intestine, making them insoluble and easily excreted. Calcium can also directly influence cell development, slowing down proliferation.
What’s a guy to do? If you enjoy dairy foods, there is no need to avoid them. If you have a family history of prostate cancer, you may want to have a bit less. If colon cancer runs in your family, a bit more could help.
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