The Truth Behind Food and Cancer

Clodagh Scannell, co-author of ‘The Truth Behind Food and Cancer’ and Julian Harte Barry of Breakthrough Cancer Research at the launch of a new book which exposes the most common myths and misconceptions around the links between food and cancer, and offers simple explanations and advice based on medical evidence.
Press Release
March 31, 2022


New free booklet exposing myths about food and cancer was launched by Breakthrough Cancer Research and UCC at today’s Irish Association for Cancer Research annual conference

Elaine Tierney, Cancer Survivor, said “No jargon, no nonsense, straight up, accessible advice from experts without an agenda.”

  • Popular trend of intravenous vitamins can interfere with chemotherapy or radiation treatments.
  • More than half of cancer patients feel confused by nutrition information.
  • Scientific findings relating to organic diets, superfoods, dairy, soya, sugar, meat, artificial sweeteners, juicing, fasting, coffee enemas and more.

The Truth Behind Food and Cancer – Book Cover

Do you want to know if you should avoid red meat, soya, alcohol, gluten, sugar, and artificial sweeteners? Do new trends like vitamin infusions work? Are special diets and organic foods beneficial in preventing and treating cancer?

A recent survey of over 1000 Irish cancer survivors reported more than half (56%) felt confused by nutrition information available in the media and offered by people around them¹. Almost 4 in 10 (37%) were following, or had tried, alternative diets from restricting certain foods to herbal remedies, juicing or detoxes, and 3 in 10 (32%) reported avoiding specific foods like processed meat or dairy¹.

In response to the lack of scientific based information available to cancer patients and the general public interested in the link between diet and cancer, and the sometimes-dangerous alternative diets that people experiment with, Breakthrough Cancer Research and University College Cork have published a new booklet that delves into ‘The Truth Behind Food and Cancer’ which was released today at the Irish Association for Cancer Research annual conference.

Written and compiled by senior cancer/oncology dietitians Dr. Aoife Ryan, UCC, and Clodagh Scannell RD, along with consultant medical oncologist Dr Derek Power and research nutritionist Michelle Hanna BSc, UCC, it provides accurate information on fad diets that have not yet been proven to be safe or effective in the prevention or treatment of cancer. It exposes the most common myths and misconceptions around the links between food and cancer, and offers simple explanations and advice based on medical evidence.

Top line interesting conclusions from The Truth Behind Food and Cancer include:

  • SOYA: There is no link between consuming soya and cancer.
  • VITAMIN & MINERAL SUPPLEMENTS: should not be required. People should take a food first approach. A diet rich in fruit and vegetables, wholegrains, dairy products or fortified non-dairy alternatives, good quality lean meat and fish, in addition to healthy fats from oils, nuts and seeds is an important part of preventing cancer. Vitamins and minerals are best absorbed when eaten in food. An exception is Vitamin D, which is recommended for all adults in Ireland between October and March.
  • VITAMIN INFUSIONS: There is no evidence that administering vitamin C or any other vitamin by intravenous drip can cure or treat cancer. It is not currently recommended by any major international cancer organisation. It has been suggested that high doses of antioxidants like vitamin C may reduce the effectiveness of chemotherapy or radiation treatments.
  • ORGANIC: There is no strong evidence that shows that organic food reduces the risk of developing cancer.
  • SUPERFOODS: There is no single food or nutrient that can prevent or cure cancer. Claims surrounding superfoods are often very misleading. It has also been suggested that high doses of turmeric may interact with some chemotherapy drugs and make them less effective. Cancer patients taking spices, or any herbal remedies need to inform their oncology team.
  • DAIRY: There is no strong evidence that links dairy products to an increased risk of cancer³. The myth that dairy is linked to cancer often comes from concerns the public have surrounding the addition of hormones to milk and meat products. In Europe, the addition of hormones to milk or meat is strictly banned and the sale of meat from countries where the addition of hormones is allowed is also illegal. So there is no need to worry about this.
  • SUGAR: Restricting the amount of sugar you eat has not been proven to slow down or control the growth of cancer cells. Sugar does not need to be totally avoided and can be included as part of a balanced diet. However, there is an indirect link between sugar and cancer. Eating a lot of foods with added sugar such as fizzy drinks, chocolate, biscuits, and cake, can increase your risk of being overweight or obese, which increases cancer risk. There is no need to avoid any fruit because of its sugar content. Fruit is full of fibre, vitamins and minerals which are very beneficial for your health.
  • ARTIFICIAL SWEETENERS: Large studies have shown there is no link between artificial sweeteners and increased risk of cancer.
  • KETOGENIC DIET: The ketogenic diet, a high-fat, moderate to low protein and very-low carbohydrate diet, is not recommended for cancer patients or cancer prevention.

Other areas addressed include intermittent fasting, alkaline diets, juicing and detoxing, Gerson therapy, coffee enemas, apricot kernels & vitamin B17, and alternative treatment centres. The booklet also contains simple advice on eating well and top tips during chemotherapy and cancer treatment, along with recipes and nourishing meal suggestions.

‘The Truth Behind Food and Cancer’ strongly recommends that anyone who is undergoing cancer treatment should talk to their consultant and oncology team before making any changes to their diet or adding any supplements as it may interfere with their cancer treatment.

Clodagh Scannell, co-author of ‘The Truth Behind Food and Cancer’ and Julian Harte Barry of Breakthrough Cancer Research at the launch of a new book which exposes the most common myths and misconceptions around the links between food and cancer, and offers simple explanations and advice based on medical evidence.

Speaking about this new resource one of the authors Clodagh Scannell said, “Research shows that almost 60% of Irish cancer survivors feel confused about messages relating to cancer and nutrition and 37% had tried an alternative dietary strategy that may be detrimental for their overall health. Today there is a lot of misinformation in the media and the aim of this resource is to provide people who have been diagnosed with cancer accurate and reliable information that is backed up by scientific evidence. I hope this resource will bring some clarity to anyone who has been diagnosed with cancer and reassure them that nutrition does not need to be over-complicated”.

Commenting on the publication of ‘The Truth Behind Food and Cancer’, co-author Dr. Aoife Ryan, said, “People choose to follow complementary or alternative diets for a variety of reasons. They may hope to prevent cancer or improve their symptoms and reduce treatment side-effects. They may seek to boost their immune system. They may even hope to cure their disease or reduce the risk of recurrence. Some people surveyed say they follow specific diets to gain some control over their cancer journey. Thanks to generous funding from Breakthrough Cancer Research, we are now in a position to make scientific and evidence-based information about the link between cancer and food available to the public”.

Production of the booklet was supported by Breakthrough Cancer Research, a leading Irish medical research charity focused on cancer. Breakthrough CEO, Orla Dolan, said, “Breakthrough is committed to funding research to improve cancer care and outcomes. We are passionate about providing evidence-based information for people with cancer and their families. When someone is going through a cancer diagnosis they can be faced with rafts of misinformation. After a diagnosis, patients and their families have many questions about foods – what to eat and what to avoid. We are proud to support publication of this new booklet on ‘The Truth Behind Food and Cancer’, which aims to answer common questions patients have about diet cancer and tried to debunk some common myths.”

Prof Michaela Higgins, President of the Irish Society of Medical Oncology (ISMO) said, “Patients and their carers often seek advice on diet and nutrition while undergoing treatment for cancer. This new booklet provides sounds advice with support from scientific sources. It is very important to let your care team know if you are considering a change to your diet or taking supplements, as some of these may impact your treatment or cause harm. ISMO are happy to endorse this helpful, free resource.”

Louise Reynolds, Irish Nutrition and Dietetic Institute, said, “With so much information out there on the internet it can be hard for people with cancer to know where to go for trusted advice. We are thrilled to endorse this new booklet which provides simple explanations based on scientific evidence. It is written by registered dietitians specialising in oncology and a medical oncologist. It is tremendous that Breakthrough Cancer Research is making this vital resource available for free for patients, something which has not been available up to now. It provides clear evidence-based advice from those with experience with the nutrition needs of those with cancer. We have no doubt it will be extremely helpful for patients.”

Elaine Tierney, Cancer Survivor, said “No jargon, no nonsense, straight up, accessible advice from experts without an agenda… Invaluable for those of us going through & beyond active treatment. I know this booklet will also be so useful for people and carers looking for evidence-based advice to support and help loved ones diagnosed with cancer.”

The advice in this booklet comes from evidence-based sources including the World Cancer Research Fund and the American Institute for Cancer Research. Recommendations made by these organisations are endorsed by the World Health Organisation and many other international reputable organisations.

Free copies can be obtained in local hospitals and cancer support centres, or by contacting

1 Sullivan E, Rice N, Kingston E, Kelly A, Reynolds JV, Feighan J, Power DG, Ryan AM.A national survey of oncology survivors examining nutrition attitudes, problems and be haviours, and access to dietetic care throughout the cancer journey. Clinical Nutrition ESPEN 2021 Feb;41:331-339
3 Thorning, T. K., Raben, A., Tholstrup, T., Soedamah-Muthu, S. S., Givens, I., & Astrup, A. (2016). Milk and dairy products: good or bad for human health? An assessment of the totality of scientific evidence.Food & nutrition research, 60, 32527.


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