Last month, in Part 1 of this article series, we visited the issues of:
In Part 2 of this series, we will review whether red meat and processed meats are safe, and whether eating a low-fat diet or a high-fiber diet can reduce your risk of cancer coming back.
To recap, we have based our discussion and recommendations on guidance by the American Cancer Society, the European Society of Medical Oncology, Cancer Australia and a few other large cancer societies.
Should I eat red meat? What about processed meats?
Firstly, what is red meat? Red meat includes beef, lamb, mutton, pork, veal, venison and goat. Processed meats refer to meat that has been preserved by smoking, curing, salting, or adding preservatives. These include sausages, bacon, ham, deli meats such as salami, pates, and canned meat such as SPAM and corned beef, and sliced luncheon meats.
Lean red meat is a good source of protein and iron. It can be included as part of the healthy diet. The association between red meat and cancer is unclear but some studies have linked eating large amounts of red meat and processed meats with increased risk of bowel, prostate and stomach cancers.
One of the potential ways through which red meat could increase the risk of bowel cancer is due to the heme iron found in red meat. This compound, which gives red meat its red colour, is thought to irritate the the bowel lining and may ultimately lead to carcinogenesis - which is the mutation of normal cells to cancer cells. Moreover, nitrate and nitrites, which are added as preservatives to processed meats, can form cancer-causing compounds that also increases your risk of cancer.
Some research suggests frying, broiling or grilling meat at very high temperatures creates chemicals that might increase the risk of some types of cancers.
For these reasons, the American Cancer Society and other cancer societies recommend limiting your intake of red meats to 500g a week and avoiding processed meats altogether. They also discourage cooking red meat at high temperatures.
Even though the research on safety of red meat and processed meats were not done in cancer survivors, this recommendation may also be applied to cancer survivors to encourage general good health and prevention of other cancers.
Should I eat a low-fat diet?
A low-fat diet is an eating plan that is low in total fat, unhealthy fat and cholesterol. Typically, a low-fat diet would include foods such as oats, lean meats, white fish, skimmed milk, vegetables, lentils and fruit.
A large study (The WINS study) looked at whether reducing fat intake after a diagnosis of early stage breast cancer affects the risk of cancer recurrence. On average, women who decreased their fat intake to 20% of their calorie intake had a 24% reduction in breast cancer recurrence. However, on average, these women also lost 2.7 kg over the course of the study. Therefore, it is unclear whether the reduction in breast cancer recurrence was due to eating less fat in their diet or from losing weight.
On the flip side, another large study, the Women's Healthy Eating and Living (WHELS) study did not find any survival difference between women with breast cancer who limited their fat intake and those who didn't.
Some studies suggest that omega-3 fatty acids, usually found in salmon, cod liver oil, walnuts and flaxseeds, have benefits for cancer survivors but these findings are not consistent and more research is needed. Regardless, including foods rich in omega-3 fatty acids in the diet is encouraged because it is associated with a lower risk of heart disease and longer lifespan.
Should I eat a high-fiber diet?
Fiber can be categorized into soluble and insoluble fiber. Soluble fiber is found in foods like oat bran, barley, nuts, seeds, beans, lentils, peas and some fruits and vegetables while insoluble fiber is found in foods like wheat bran, vegetables and whole grains.
Soluble fiber helps lower the risk of heart disease. Fiber is also linked to improved bowel function. Good sources of fiber are beans, vegetables, whole grains, nuts and fruits. Eating these foods is recommended because they also contain other good nutrients that may help reduce cancer risk and provide other health benefits.
Eating more vegetables and fruits has been associated with a lower risk of lung, mouth, oesophageal, stomach and colon cancers. Again, few studies exist on whether a diet high in vegetables and fruits can reduce the risk of cancer recurrence or improve survival for cancer patients although some studies suggest it may help prevent recurrence or increase survival for breast, prostate and ovarian cancer survivors.
Nonetheless, consistent with general dietary guidelines, cancer survivors are encouraged to aim for at least 5 servings of vegetables and 2 servings of fruit each day because of their health benefits. As it is not known which of the many compounds in vegetables and fruits may be most protective, the best advice is to eat plenty of a variety of colourful vegetables and fruits each day.
I hope this article has been helpful in clearing some of the confusion around food. Unfortunately, confusion exists when there is lack of solid evidence one way or the other. In this situation, I find it best to be guided by the large cancer societies.
In the next part of this article series, we will review if being vegetarian or vegan helps prevent cancer recurrence, whether we should be eating organic food, touch briefly on the alkaline diet, and discuss dietary supplements.
If you would like to be updated when the next article is published, make sure you follow us on Facebook @moretonbaycancercare
This article is part of a series of articles discussing the common questions about food that cancer survivors often have.
Being diagnosed with cancer is likely to leave you eager to do all you can to prevent the cancer from coming back. You may be frustrated that there’s only so much about cancer prevention you can control. But you do have control over one area of your life; your diet.
After a diagnosis of cancer, people tend to re-evaluate their nutrition and health practices. Many wonder what caused this cancer to occur and what lifestyle changes they should be making. Eating well can help you optimize your weight, improve your energy and may also help protect you from cancer recurrence in the future.
We know a diet that is high is vegetables, fruits, whole grains and beans, low in fat and high in fiber is cancer protective. But a lot of these factors have not been studied in detail in people who have already been diagnosed with cancer and we don’t know if having such a diet would prevent the cancer from coming back. Still, there is every reason to believe that having a healthy balanced diet that is cancer-protective to begin with would be protective as well for cancer survivors.
Many people believe they must make significant diet changes to ensure a good outcome following cancer treatment. Trying to research what to eat and what not to eat can be confusing. We have based our discussion and recommendations on guidance by the American Cancer Society, the European Society of Medical Oncology, Cancer Australia and a few other large cancer societies. Hopefully this series of articles will help clear some of the confusion you have surrounding food.
Can I drink alcohol? How much can I safely drink?
It is estimated that 5.6% of cancer cases in Australia each year can be traced back to long-term alcohol use. In fact, around 20% of Australians drink more than 2 standard drinks daily.
The link between alcohol and some cancers have been confirmed, including cancers of the mouth, throat, food tract, liver and breast. In people who have already received a diagnosis of cancer, alcohol intake could also increase their risk of a new cancer in these areas.
It is not the type of alcoholic drink that is important, but the total intake of alcohol (ethanol) that counts. Cancer Australia recommends that men drink no more than 2 standard drinks on any day of the week and women limit alcohol to one standard drink a day to reduce their cancer risk. If you do not usually drink alcohol, abstaining from alcohol is an excellent habit to continue!
Is soy good for me?
Studies so far have found no negative effects of soy food intake on cancer recurrence. However, the evidence for soy supplements is not clear. There is also lack of evidence that soy foods can lower your risk of any cancer. Therefore, Cancer Council Australia recommends that soy foods like soy milk, tofu or tempeh can be included as part of a healthy varied diet but have advised people to avoid soy supplements.
Does sugar feed cancer?
All the cells in the body use sugar for fuel, and cancer cells seem to take up blood sugar more rapidly than do healthy cells. A few small studies have shown that eating high sugar food does not directly increase the risk or progression of cancer. However, sugars and major sources of these sugars add high amounts of calories to the diet and can cause weight gain, which is linked to worse cancer outcomes. In addition, most foods that are high in added sugar do not contribute many nutrients to the diet and often replace more nutritious food. Therefore, limiting food with added sugar is recommended.
For cancer protection, research supports maintaining healthy blood sugar and insulin levels with weight control, regular exercise, a high-fiber diet and avoiding large loads of refined carbohydrates (think white bread, cake, biscuits etc).
On the flip side, not eating any sugar at all is not a good idea. It is hard to 'starve' cancer of sugar as our body has a fail-safe mechanism that never lets our blood sugar level drift below a certain number. So if we don't have any sugar, it will just make our bodies use its remaining resources to produce sugar for fuel. This will make us feel washed-out and tired. It will also take away your body's precious resources that could be better used to recover from cancer treatment instead. Plus, you need to remember that vegetables, fruits and other healthy food get converted to sugar so if you follow a strict 'no sugar' diet, you will be restricting yourself from important nutritious food.
That is it for the first part of this series. We will be talking about whether you should eat red meat, whether eating a low-fat diet and whether a high-fibre diet can reduce your risk of cancer coming back next.
Follow us on our Facebook page to be updated when the next post is published!
Medical information disclaimer
The medical information provided is correct to the best of our knowledge, but no warranty as to accuracy is given. You must not rely on the information on our website as an alternative to medical advice from your doctor.
If you have any concerns about your health, you should seek immediate medical attention.