Nutritional tips to reduce the risk of infections for those with an impaired immune system

The immune system protects against infections and diseases. However, it may not work as well during and after cancer treatment.

On this page:

> Who’s at increased risk?
> What you can do
> Hygienic food measures
> Foods to avoid

Treatments such as chemotherapy reduce the growth and division of cancer cells but may also affect normal cells. Some of these normal cells, such as white blood cells, are an important part of the immune system. If the immune system works less well, your defences decrease, and you become more at risk of infections.

Who is at increased risk?

Some cancers, including leukaemia and other blood cancers, are treated with intensive chemotherapy. This means that the patients receive an extra high dose and/or a longer course of chemotherapy. This reduces the number of white blood cells in the body, which leads to reduced resistance to infection. This is also referred to as ‘the dip’ after chemotherapy. During this period there is a higher risk of catching an infection, this includes infections that can be caught from food. A hygienic diet (see below) is recommended for these patients.

Following strict hygiene practices during food preparation may also be necessary if medicines that reduce resistance to infections are used after a stem cell transplant. These patients are at greater risk of an infection, including those from food (such as salmonella).

Situations when there is reduced immunity:

  • The ‘dip’ after chemotherapy. For example, when the white blood cell (leucocyte) count is lowered.
  • During and after chemotherapy and/or radiation, defences may be impaired, and the risk of infections is increased.
  • The use of medication that suppresses the immune system.

What can I do?

  • Eating well and staying active during treatment can help your immune system function properly.
  • The best way to support the immune system is to ensure that your diet provides all the necessary nutrients and contains enough energy and protein. For further guidance, it’s best to speak to your doctor or dietitian.

Hygienic food measures

How can I prepare food hygienically?

  • Wash your hands before preparing and eating a meal.
  • Change your tea, hand, and dishcloths/towel daily. Wash them at a minimum of 60 degrees.
  • Use clean kitchen utensils such as serving spoons and chopping boards.
  • Wash vegetables and fruit well under running water. Make sure that fruit and vegetables are fresh and undamaged.
  • Cook meat, fish, chicken, and eggs thoroughly.
  • Reheat any previously made dishes thoroughly. Don’t reheat dishes more than once.
  • Keep raw food away from the prepared food. Do not use chopping boards, knives, and other utensils that have come into contact with raw food or any other food.
  • Defrost frozen meat in the refrigerator or the microwave. Rinse away the moisture that forms when defrosting, and wipe away any spilt thawing liquid with paper towels.

Which foods should I avoid?

Raw products more often contain harmful bacteria. It is therefore best to avoid the following foods:

  • Raw or partly raw meat or meat products, such as steak, roast beef, carpaccio, roulade, steak tartare, raw ham, Parma ham, and chorizo. If you cook these products thoroughly you can eat them.
  • Liver sausage, liver pate and pate.
  • Raw fish, such as raw tuna, and sushi or sashimi made with raw fish. You can eat pre-packed sour herring from a jar or pot because it has been heated.
  • Pre-packaged smoked fish such as trout and mackerel. This also applies to vacuum packaging. If you cook the fish thoroughly, you can eat it. Pre-packed smoked salmon is okay to eat if eaten within 24hrs of opening.
  • Raw shellfish, such as oysters and mussels.
  • Raw milk and soft cheese made from raw milk (this will state “unpasteurised” or “raw milk” on the package). You can eat hard cheeses and blue cheese made from pasteurised milk if stored at a maximum of 4⁰C for a maximum of 4 days. You can drink pasteurised milk (most milk is pasteurised).
  • Raw/soft-boiled eggs. The yolk must be solid if you want to eat eggs.
  • Raw sprouts such as bean sprouts and garden cress.
  • Probiotics such as Yakult, Actimel, and Activia. With probiotics, the type of bacteria is clearly stated on the packaging. The lactic acid bacteria (Lactobacillus Bulgaricus and Streptococcus thermophilus) contained in yoghurt are not probiotics. That’s why you can eat yoghurt.

Where next?

> Order a free copy of our eat well during cancer guide

> Stay active during cancer

In association with

NIHR cancer and nutrition collaboration logo


British Dietetic Association logo