There’s no shortage of cancer miracle diets and ‘superfoods’ spruiking a cure — but how does the science stack up?
Google the word ‘cancer’ and you’ll come across millions of web pages, each offering a different diet that causes, prevents and even cures cancer. With so many myths surrounding the relationship between food and cancer, it can be hard to distinguish fact from fiction. And while many of these claims are inaccurate, some of them are downright dangerous.
All of this ‘noise’ can leave patients, friends and family confused and vulnerable to dodgy information. From sugar detoxes and juice cleanses, to vitamin C infusions, HFG sorts through some of the most persistent, controversial myths. We then look at the scientific evidence to ensure you receive the best nutrition possible throughout and beyond your treatment.
Claim: Sugar feeds cancer
There’s a widespread belief that sugar ‘feeds’ cancer cells. This myth is very often harmful as it leads people to avoid all foods containing carbohydrates, which can prove to be counterproductive for anyone who is struggling to maintain their weight during cancer treatment.
Carbohydrates, whether from cake or a carrot, are broken down into sugars, and are one of our body’s main sources of energy. The sugar theory suggests that if cancer cells need sugar to thrive, then you should cut out carbohydrates as a strategy to starve the cancer cells.
Unfortunately, it’s not that simple. All our cells need glucose (sugar) for energy, and when your body has no fuel from carbohydrates it will break down its fat and protein stores. So, cutting out sugar will not ‘starve’ the cancer cells — your body will just make sure it gets fuel from other sources.
Eliminating carbs can cause weight loss, fatigue and muscle weakness, all of which you want to minimise during treatment. It’s good for overall health to limit foods with processed or added sugar — but eliminating sugar won’t cure cancer.
Claim: Vitamin C infusions can cure cancer
Alternative medicine advocates have claimed injections of vitamin C in high doses will prevent or slow cancer growth by increasing the body’s ability to dispose of damaged cells.
In Australia, some health professionals with a focus on complementary health offer vitamin C injections alongside the conventional treatments of surgery, radiotherapy and chemotherapy.
While animal studies suggest a potential benefit, there is currently no evidence that vitamin C infusions cure cancer in humans. Some patients reported experiencing improved energy levels and pain management after they received infusions, prompting further studies.
If you are considering vitamin C infusions, discuss this with your oncology team to ensure it won’t interfere with your current treatment.
Claim: Red meat causes cancer
Eating red meat may increase your risk of some cancers; however, an increased risk is not necessarily a direct cause. But Australia is a barbecue-loving nation, so how much is too much?
Eating a lot of processed meat (bacon, ham and sausage) and red meat has been shown to be associated with an increased risk of bowel cancer, and possibly also with stomach and pancreatic cancers. The exact reasons are still being investigated by researchers.
Lean red meat is an important source of iron, protein, zinc and vitamin B12. There’s no need to cut meat completely from your diet, but in order to balance meat’s risks and benefits as outlined above, the dietary guidelines currently recommend limiting or avoiding processed meat. The guidelines also advise us to eat less than 455g cooked lean red meat per week, which is approximately 700g when raw.
Try having a couple of meat-free meals a week, and keep your portion to your palm’s size. The Cancer Council recommends you don’t blacken or overcook meat on the grill or barbecue.
Limit red meat to a palm-sized portion two to three times a week to reduce cancer risk.
Claim: Artificial sweeteners cause cancer
Artificial sweeteners, such as aspartame and saccharin, which are commonly found in diet soft drinks, were once thought to cause cancer in any amount consumed. We now know that this is not in fact the case.
This myth has been around for a while and was based on poorly designed animal studies which have been highly criticised by the scientific community. It has since been clearly shown by thorough scientific research that artificial sweeteners are safe for human consumption — and that they are not cancer-causing agents.
Claim: Juice cleanse or detox cures cancer
Holistic bloggers have claimed that extracting juice from fruit and vegetables — and drinking this instead of eating the whole fruit or vegetable — can rid your body of toxins and even prevent cancer. What does the evidence say?
This myth fails to acknowledge that your body already has an effective detox system — your liver, kidneys and lungs. Drinking only fruit and vegetable juices can contribute to headaches, low energy levels and weight loss — from a lack of balanced nutrients (protein and carbohydrates) and decreased kilojoule intake.
You may also lack fibre, which is often removed in the juicing process. Fibre is important for bowel function, and may have a protective effect for some cancers. Eating fruit and vegetables in their whole form ensures that you gain all the nutrition they have to offer — so go for ‘two and five’ a day!
Claim: ‘Superfoods’ cure cancer
In the health food aisle, the word ‘superfood’ appears on foods from chia seeds right through to dark chocolate. One of the common claims made about superfoods by advocates is that these foods alone have ‘super’ powers which allow them to fight or retard cancer.
There is no such thing as a ’superfood’. It’s a marketing label given to some foods that are higher in specific nutrients (vitamins, minerals or antioxidants) than others. Some of the most cited examples of these include blueberries, broccoli, kale, beetroot, garlic and green tea.
They can be a wonderful and nutritious addition to your diet, but there’s no hard evidence that one food alone will prevent or cure cancer.
Claim: Vegetarian diets prevent cancer
Plenty of research has shown that plant-based foods, such as vegetables, fruit, whole grains, nuts and seeds, are the basis of some of the world’s healthiest populations. We also know large intakes of processed and red meats are linked to higher cancer rates. So, should we all go vego?
Vegetarian diets provide fibre, vitamins and minerals, which benefit immune function, heart health and general well-being.
A scientific review of studies into vegetarianism and cancer risk concluded that vegetarian diets are a useful strategy for reducing cancer risk. A recent study also found that Seventh-day Adventists who ate a vegetarian diet had a 22 per cent lower risk of bowel cancer than those who weren’t vegetarian.
It is acceptable to suggest vegetarian diets may help lower your risk of some cancers. However, these benefits can be offered by non-vegetarian diets that include plenty of vegetables and fruit, and limit processed meats and saturated fats.
What’s the bottom line?
A balanced, nutritious diet will help you to keep as well as possible and cope with the side effects of treatment. An Accredited Practising Dietitian can be one of your best sources of information.
If you have cancer and want to learn more about what to eat during treatment, you can read more here.
Cut your risk
Fortunately, at least one in three cancer cases are preventable. Below are 10 simple changes you can make from today.
Watch your weight: Being overweight or obese is a risk factor for several types of cancer.
Turn to plants: Aim for at least five serves of colourful vegies every day. Eat the rainbow!
Cut processed foods: Limit fast food and highly processed snacks that are high in added salt, sugar and saturated fat.
Move more: Make exercise a daily routine. Start by going for a 30 to 60-minute power walk to the nearest park every day.
Don’t smoke: Roughly one in eight cancer cases are caused by smoking. These are some of the most preventable cancers.
Be booze wise: Limit alcohol (which increases cancer risk) to two standard daily drinks. Have two alcohol-free days each week.
Increase fibre: Bowel cancer is less common in those who eat lots of vegies, legumes, fruit, nuts, cereal fibre and whole grains.
Go slow: Use gentler cooking methods where possible. Try to casserole or braise your meat, rather than barbecuing or frying.
Sip smarter: Swap sugary soft drinks, juices and other sweetened drinks for water in order to prevent weight gain.
Be sun smart: Wear a hat and sunscreen when outside, or seek the shade.
What about miracle diets?
The internet is full of misleading websites claiming their ‘miracle diet’ will cure cancer. Examples include alkaline, raw food and ketogenic diets. What they fail to mention in their claims are the finer details, notably the lack of robust scientific evidence, and that they can be expensive, stressful and often harmful. Most of these diets are based on anecdotal stories from people claiming their diet cured their cancer. But we do not know their full medical history, or whether they’ve had other treatments. Many of these diets are restrictive, cutting out entire food groups and risking vitamin and mineral deficiencies, poor immune function and reduced quality of life.