Decoding cancer diets
Victoria Holthaus reports from a talk aimed at separating fact from fiction on cancer-fighting diets

“We haven’t been prepared for the success,” says Dr Robert O’Connor, Head of Research in the Irish Cancer Society. “We haven’t prepared for moving into that next phase.” 

According to Dr O’Connor, more than half of all cancer patients being diagnosed will be cured, depending on their stage and other factors. He says there will be between 40,000-44,0000 people diagnosed with cancer this year and in Ireland today, there are only 35 specialist oncology dieticians. With half of those doctors residing in one hospital, this creates a major informational gap for patients, before, during, and after treatments regarding nutrition. 

Dr O’Connor was speaking at a public talk last week organised by the Irish Cancer Society in partnership with the Irish Nutrition and Dietetic Institute (INDI), which aimed to separate the facts around diet and cancer from the fiction.

The internet is full of theories on how what you eat can affect your chances of developing and beating a diagnosis of cancer- from superfoods to fad diets - but much of this information can be misleading and contradictory.

“When it comes to looking for information on nutrition and cancer, when you go online and put nutrition and cancer into the search engine and google everything, you get a huge amount of results. Unfortunately, a lot of these results aren’t reliable information,” says Fiona Roulston RD, Dietitian Manager at St Luke’s Radiation Oncology Network, Dublin.

The lack of resources in nutritional advisement for cancer has become a cause for concern in how it affects the chances of beating cancer and protecting patients from being exploited by the “quackery” and profiteers. 


As one attendee mentioned, “One thing that these peddlers of diets, nutrition and alternatives medicines do quite well is that they are good at marketing and they are very good at giving you that feeling of certainty. And even though it’s not true and its invalid, maybe there is no evidential base for it, it’s what cancer patients crave because everything else feels uncertain and out of their control.”

Patients like British army officer Naima Houder-Mohammaed mentioned by Prof. Mike Gibney, Professor of Food and Health at the UCD Institute of Food and Health, who set out to debunk some of the myths around nutrition and diet in his talk. Ms Houder-Mohammed was diagnosed with breast cancer in 2010 and sought treatment from Dr Robert O Young, an American alternative health writer and the father of the alkaline diet, when she discovered him on the internet. She paid tens of thousands of dollars for his alkaline treatment, which consisted mainly of intravenous infusions of baking soda.

After her condition worsened, Ms Houder-Mohammed was flown back to the UK to die surrounded by her family at the age of 27. Dr Young was convicted with two charges of practising medicine without a license and faces up to three years in prison.

Prof. Gibney also discussed the main causes of cancer, the research challenges and myths involved in cancer and diet, including the trend of superfoods. To this subject, he quotes the World Cancer Research Fund:

“However, although many of us would like to believe that eating a single type of vegetableor fruit will improve our health, the truth is that no single food is going to make up for an unhealthy diet and lifestyle.”


He also discussed the weaknesses of phytochemicals and detoxification. The bottom line on diet and cancer for Prof. Gibney is to try and have a healthy weight while being physically active and eating plenty of fruit, vegetables and whole grains whenever possible. One should limit intake of cured high salt meats, moderate alcohol intake and avoid high fat diets, especially ones in high saturate. 

For more of a guide on nutrition, Prof. Gibney recommends the American Cancer Society’s Complete Guide for Nutrition for Cancer Survivors.

“It deals with prevention, it deals with treatment, it deals with complications and it deals with surviving. It covers absolutely everything as fairly as you can,” he says.

As a CORU registered professional dietitian, Ms Roulston used her expertise in diet to talk about after diagnosis care and its importance in relation to nutrition.

“Malnutrition is a common but often under recognised problem in cancer. This can vary depending on tumour type – rates of 8-84% have been reported,” she says.

Malnutrition can be caused by many different factors including poor appetite, nausea and vomiting, fatigue, pain and dry mouth. This unintentional weight loss can lead to increased risk of infection and/or treatment toxicity, reduced tumour response to treatment and reduced quality of life or survival. It can be associated with loss of muscle mass and loss of muscle strength.

“A lot of the patients may be overweight or obese, that doesn’t mean that they’re not actually losing their muscle mass,” says Ms Roulston.


She also discussed the various areas that a dietician may look at when assessing a patient’s nutritional status. This includes anthropometry, biochemistry, clinical details and dietary information.

“It’s a really individualised assessment, there is no one size fits all. And even the advice that I’m giving this evening, it won’t be applicable to every single cancer patient.”

Ms Roulston also mentioned the World Cancer Research Fund report on Food, Nutrition, Physical Activity and the Prevention of Cancer report. 

It features eight key recommendations in relation to physical activity and diet including; be as lean as possible, be physically active, limit consumption of energy-dense foods and avoid sugary drinks, eat mostly foods of plant origin, limit intake of red meat and avoid processed meat, alcoholic drink, consumption of salt and aim to meet nutritional needs through diet alone. 

Ms Roulston recommends that patients be assisted in maintaining body mass, especially during treatment and helped to manage symptoms or side effects of treatment.

When it comes to getting the right message and resources out there, Robert O’Connor hopes that we move to a situation of continuous care.


“It behoves all of us to lobby for that, to make sure all of those resources and support are in there. It is as important as making sure the x-rays are there, the MRIs, the medicine and the qualified professionals in their areas,” Dr O’Connor says.

“So we focus initially on the diagnosis, know what we’re dealing with, make sure the right medicine, the right treatment that is there. But that this dietician and exercise advice is in there at the start as well. It’s built in. 

“And then as we transition out of that medical phase, that you’re brought almost by the hand so to speak, through all of the emotions and practical things that you need, stage by stage and that there is somebody there. Not that you’re left sitting at home with Dr Google because that’s a very vulnerable situation.

As Ms Roulston says: “I think it’s important to remember that the goal of nutrition in cancer isn’t to treat the cancer itself, but to maintain the person to withstand their cancer treatments.

“There is also a light at the end of the tunnel as more and more patients are becoming survivors of cancer,” she says.

“In Ireland today there are well over 150,000 cancer survivors. In the next couple of years, 1 in 20 people you might randomly meet on the street will be a cancer survivor,” Dr O’Connor says.


*To access dietetic services, ask your doctor or nurse specialist or visit the Irish Nutrition and Dietetic Institute or the Self Employed Dietitians of Ireland websites: www.indi.ie or www.sedi.ie