Institute of Epidemiology & Health Care


Frequently Asked Questions

Many people look to news reports and studies for information and advice about diet and physical activity, which may not always be reliable or present the whole picture.

We have only included healthy habits in this programme that have good scientific evidence for people diagnosed with cancer, and for cancer prevention.

Following Treatment

Following my treatment, I am more sensitive to certain foods, especially fibre - so how do I increase my fibre intake without causing a flare up? 

If your treatment has affected your bowel, you will need to be guided by medical advice, and by your body. Experiment with varieties of bread - try a mixture of white and wholemeal bread, or plain wholemeal bread or oatmeal bread, rather than wholegrain. 

See what levels suit you and try to eat varieties with the maximum amount of fibre you can tolerate. Keep a record of any 'trigger' foods that cause flare ups for you and see if you find alternatives. 

These can vary from person to person. For example, some people find they cannot tolerate iceberg lettuce, but are OK with baby spinach or rocket. If you do have a flare up, take it easy for a few days, and try to get back to your habits when you feel better.

Special Precautions

Are there any special precautions I should take when exercising? 

Some effects of treatment may increase the risk of exercise-related problems. For instances:

  • People with severe anaemia (low red blood cell count) should delay activity until the anaemia is better
  • Those with a weak immune system should avoid public gyms and other public places until their white blood cell count returns to safe levels
  • People getting radiation should avoid swimming pools because chlorine may irritate the skin at the treatment area

If you were not active before diagnosis, you should start with low intensity activities and then slowly increase your activity level. Certain people should use extra caution to reduce their risk of falls and injuries:

  • Older people
  • Those with bone (cancer in the bones or thinning bones, such as osteoporosis) 
  • People with arthritis
  • Anyone with nerve damage (peripheral neuropathy)

Speak to your doctor before trying any vigorous exercise. If you are joining a gym or exercise class, let your instructor know about your diagnosis and treatment.


Should I take supplements? 

A healthy diet should provide you with all the essential vitamins and minerals and this is much more beneficial for your health than taking supplements.

There is no evidence that dietary supplements can reduce the risk of cancer coming back. Your doctor may advise you to take supplements, if you have deficiency of a certain nutrient.

If you take daily multivitamins and minerals, avoid mega-dose ones, because higher intakes of specific nutrients may cause more harm than good.


How much water and other fluids should I drink?

Symptoms like fatigue, light-headedness, dry mouth, a bad taste in the mouth, and nausea can be caused by dehydration (loss of fluid from the body). To help prevent this, try to take enough fluids. This is especially important if you are losing fluid through vomiting or diarrhea. 

Healthy men need about 3.7 litres of water a day, while women need about 2.7 litres. 

If water tastes unpleasant to you, take in more liquid through items such a soup, tea, milk, or milk substitutes such as almond milk, or a sports drink. Or flavour your water by adding fresh cut fruit.

If you are having trouble eating or drinking or are losing fluid (because of problems with vomiting or diarrhea for instance) you may not be able to take in enough fluid. You should talk to your health care team because you might need to be treated with intravenous fluids.

Fruit and Vegetables

Should I juice my vegetables and fruits? 

Juicing can add variety to your diet and can be a good way to get vegetables and fruits, especially if you have trouble chewing or swallowing, or are suffering from mouth sores or gum infections. Juices do contain less fibre and you should limit fruit juice to one glass a day as it is high in sugar. 

Buy juice products that are 100% vegetable or fruit juices and pasteurized to remove harmful germs. These are better for everyone, but are especially important for people who may have weak immune systems, such as those getting chemotherapy.

Fresh, frozen or canned?

Is there a difference in the nutritional value of fresh, frozen and canned vegetables and fruits?

Yes, but they can all be good choices. Fresh foods are usually thought to have the most nutritional value. But some frozen foods can have more nutrients than fresh. This is because they are often picked ripe and quickly frozen, and nutrients can be lost in the time between harvesting and eating fresh foods. 

Canning is more likely to reduce the heat-sensitive and water soluble nutrients because of the high temperatures used in the canning process.

Also, be aware that some fruits are packed with heavy syrup, and some canned vegetables are high in sodium.


Should I include soy-based foods in my diet? 

Soy foods are an excellent sources of protein and can be good options for meals without meat. Soy contains many phytochemicals, some of which have weak estrogen activity and seem to protect against hormone-dependent