According to the Cancer Council, at least one in three cancer cases are preventable. A healthy diet can not only help treat cancer, it could also act as a preventative.

Treatments for cancer can be immensely physically challenging, but while your immune system is being knocked around, getting the best possible nutrition can help you fight back. It's not easy to have the healthiest diet when you are nauseous or find your appetite has gone west. However, there are strategies that can help.

Why you need to eat well

When undergoing cancer treatment you have two key nutrition goals: to maintain a healthy weight and to help fight infection. And once you've got through the treatment, your next goal is to maintain your good health. For people used to eating well that might sound pretty straightforward, but there are quite a few possible side effects from cancer treatments that can make healthy eating much more difficult to achieve.

Dealing with side effects

One of the more common side effects is a loss of appetite, causing weight loss. Changes in smell and taste can make foods less appealing or even downright disgusting. A dry or sore mouth, thick saliva, or difficulties swallowing can make eating certain foods difficult. Both diarrhoea and constipation are also common. See our suggestions following for ideas on how you can overcome these problems. You should also make sure you consult your doctor as they may be able to help. For example, a loss of appetite could be related to a simple yeast infection that can be easily treated.

Improve recovery

If you are able to eat a healthy diet, you'll be in a better position to cope with the treatment and fight the cancer. Maintaining a healthy body weight during treatment can help reduce your risk of infection, enhance your speed of recovery and help maintain your strength and energy. Even losing as little as 5% of your body weight is undesirable, so if you just can't eat, try using liquid foods like Resource Plus or Ensure Plus.

Eating during cancer treatment

It can be very frustrating when the side effects of your cancer treatment interfere with your ability to eat a healthy diet, but there are still things you can do to take control and help yourself.

Low appetite or weight loss

• Eat smaller, more frequent meals.
• If you can only eat a little, choose high protein, high energy foods.
• If your appetite is better in the morning, have your biggest meal in the morning.
• Drink between meals; drinking with meals may fill you up.
• Use liquid or powdered nutritional supplements between meals to increase your energy intake, eg. Resource Plus or Ensure Plus.
• Take a walk before mealtimes to enhance your appetite.

Constipation

• Drink at least 8 glasses of fluids each day to avoid hard stools. Vary with cold or warm water, prune or other juices, black, green or herbal teas.
• Eat high fibre foods.
• Increase your physical activity.

Diarrhoea

• Get plenty of fluids to prevent dehydration; avoid caffeinated drinks.
• A high fibre diet may worsen symptoms: try white bread, white rice and noodles instead of wholegrains; limit legumes and pulses; peel fruits and vegetables to reduce the fibre.
• Avoid foods that are spicy, fatty, or very sweet.

Vomiting

• Keep your diet bland until you can tolerate more: start with clear fluids like clear juices, water, sports drinks or clear soups; progress to soft foods like yoghurt or mashed potato.
• Keep your fluid intake up to avoid dehydration.

Nausea

• Sip fluids frequently to help settle your stomach.
  Eat smaller more frequent meals: not eating at all can worsen nausea.
• Avoid fatty, spicy, or high-fibre foods as well as gas-producing foods (like beans, onions, carbonated drinks and chewing gum).
• Eat sitting up; avoid lying down after a meal, unless your head is elevated.

Taste changes

• Try new flavours; use different marinades, sauces, herbs and spices.
• Decrease the smell of food by serving cold or at room temperature.
• Add a little sugar to bitter or salty foods; add a pinch of salt to over-sweet foods.

Prevention

Almost every week there is some news story about something that causes cancer. It's hard to keep up-to-date with all the foods that are implicated in cancer. In December 2007 scientists working for the World Cancer Research Fund (WCRF) from nine universities in four countries reviewed the available research and published their findings in a report called Food, Nutrition, Physical Activity, and the Prevention of Cancer. Their key findings? That a healthy weight can protect against some cancers, exercise seems to have a preventative effect even apart from helping to lose weight, and finally that we should be careful how much alcohol we drink and eat more fruit and vegetables.

10 ways to fight cancer

1. Be as lean as possible within the normal range of body weight (BMI 18.5-25). Avoid weight gain and increases in waist circumference throughout adulthood.
2. Be physically active as part of everyday life. As fitness improves, aim for 60 minutes or more of moderate, or 30 minutes or more of vigorous, physical activity every day.
3. Limit consumption of energy-dense foods and avoid sugary drinks. Consume fast-food sparingly, if at all.
4. Eat mostly foods of plant origin.
   – Eat at least five serves of a variety of non-starchy vegetables and fruits each day.
   – Eat relatively unprocessed cereals (grains) and/or pulses with every meal.
   – Limit refined starchy foods.
5. Limit intake of red meat and avoid processed meats. Eat less than 500g cooked (700-750g uncooked) red meat each week and very little (if any) processed meat (smoked, cured, salted meats).
6. Limit alcoholic drinks. No more than two drinks a day for men and one drink a day for women.
7. Limit consumption of salt and avoid mouldy cereals or pulses.
   – Avoid salt-preserved, salted or salty foods.
   – Aim for less than 6g salt (2.4g sodium/2400mg sodium) a day.
8. Aim to meet nutritional needs through diet alone. Dietary supplements are not recommended for cancer prevention.
9. Breastfeeding. Breastfeed infants exclusively (with no other food or drink, including water) up to six months and continue with complementary feeding thereafter.
10. Cancer survivors. If able to do so, and unless otherwise advised, aim to follow the recommendations for diet, healthy weight and activity.

Soy vs cow's milk

There's a lot of scare-mongering around both soy and cows' milk. Some claim soy is bad because it contains phytoestrogens (despite its long safe history of use in Asian countries where it's been associated with reducing the risk of hormone-sensitive cancers). Others claim cow's milk is bad and that it has a high level of hormones and growth factors, like IGF-1. However, in a recent study Professor Lynn Ferguson, head of the Discipline of Nutrition at Auckland University found no evidence to support this.

Websites for more information

Cancer Council Australia
National Cancer Institute, US National Institutes of Health
American Cancer Society