The trouble with the NET (Part 5) – Cancer Diet Myths

Updated 29th June 2025…… Keep reading.

Certain popular ideas about how cancer starts and spreads – though scientifically wrong, can seem to make sense, especially when those ideas are rooted in old theories. To a certain extent, it can be the case with treatment too. But wrong ideas about cancer can lead to needless worry and even hinder good prevention and treatment decisions. Even food and nutritional supplements fall into this area. Be cautious about believing information about, or paying for, any alternative cancer therapy on the internet.

Common dietary myths (this is not a complete list!)

There are numerous (alleged) ‘anti-cancer’ diets and foods in the media and on the internet but some of the most common ones are highlighted in the section below.

This summary cannot cover all dietary myths that you may encounter but it could be helpful to try empowering fellow patients to question the credibility of the diet claims they are coming across. The tips below can help you guide a fellow patient to check the credibility of a diet claim:

Check the source – reputable sources can be medical journals, a reputable cancer charity, health professionals. See 5 below also.
What is the evidence for the diet based on? Large population intervention studies on people with cancer would be a good basis for a reputable diet.
Is the diet being sold? Be careful if dietary products are being sold – the profit rather than science may be driving any health claims.
Diets highlighting only eating a few foods are unlikely to be balanced or healthy and may do damage overall.
Celebrities sometimes think they are ‘influencers’ – but be careful following their lead as much of what they say will not have been subjected to rigours clinical study. The only talk about the positives but fail to mention the risks. These risks can be amplified in a person with cancer and be dangerous.

In one study, a surprising 40% of Americans believe cancer can be cured solely through alternative therapies, according to the American Society of Clinical Oncology (ASCO)’s second annual National Cancer Opinion Survey. In a similar study in UK, the NHS blamed social media for the spread of fake healthcare news.

These surveys are not surprising as social media ‘misinformation’ includes ‘alleged’ cures for various ailments including cancer extending to the use of “food” and “food supplements”. I think we’ve all been there, we check twitter, Facebook, Pinterest etc and we find the ubiquitous miracle cures and claims for every illness under the sun. Easy to find, easy to read and worryingly, easy to share. Surely these cures must be true, after all…..it’s on the ‘NET’.

Has wide access to the internet exacerbated this problem?

The rise of the (Inter)NET has allowed people to use ‘social technology’ to help shape the world’s events and culture. Additionally, the NET has increased the speed of how relationships develop, the way information is shared and (whether you like it or not) how influence can be leveraged for gain. Facebook has taught us new ways to communicate and collaborate through features like feeds, profiles and groups. At the same time, smartphones and tablets provide mobile and instantaneous access to information from any location. Whether you like it or not, we are witnessing the power of social media and its effect on society. However, the ‘NET’ can also provide ‘misinformation’ and it’s REALLY GOOD at it.

This problem also appears in cancer support communities and the list below is some of the most common (but not all) claims I witness in patient groups.

Below, I have provided links to trustworthy sources to counter what I see on some of the comments I see in patient groups and within the NET community generally. Good group moderation should prevent these claims from being widely shared to vulnerable people.

Sugar

The biggest myth you will find on the internet. Much of the confusion stems from the fact that the most common PET scan used in cancer uses ‘sugar’ based tracers to find cancer – not as simple as that! And while research has shown that cancer cells consume more sugar (glucose) than normal cells, no studies have shown that eating sugar will make your cancer worse or that, if you stop eating sugar, your cancer will shrink or disappear. It’s also worth noting that every cell in our body uses sugar to function, for example, the body uses sugars and starches from carbohydrates to supply glucose to the brain and provide energy to cells around the body.

This doesn’t mean you should eat a high-sugar diet, though. Consuming too many calories from sugary foods has been linked to weight gain, obesity, and diabetes, which increase the risk of developing cancer and other health problems. Read more on Cancer Research UK

Hear Tara Whyand (international NET Dietitian specialist) dismiss this too.
See Episode 4 – Sugar, Cancer and the Ketogenic Diet

Click here to read

Artificial sweeteners

Eating food and drink with artificial sweeteners in is unlikely to cause cancer. Sugar doesn’t directly cause cancer. But eating too much sugar can make it harder to keep a healthy weight, and being overweight or obese increases the risk of cancer. Source Cancer Research UK

Click here

Green tea and matcha (powdered green tea)

Green tea and matcha (powdered green tea) do not reduce the risk of cancer. Some people have suggested that green tea might reduce the risk of cancer. This is because it contains catechin – an antioxidant that seems to stop tumour growth in rats. But results from large studies have not shown that green tea reduces the risk of cancer in humans.

Vitamin, mineral and herb supplements (nutritional supplements)

Due to the side effects of Neuroendocrine Tumours, in particular surgery, many NET patients might be advised to take nutritional supplements.

I read a lot about high dose vitamin intake and I have also read a lot of about the dangers of doing so. You don’t need too much as there can be consequences. For example, the manufacturers sometimes go on to claim that they not only restore vitamin balance but they also have an effect on a myriad of illnesses. But they fail to provide the evidence via standard clinical research methods. Many of these things make their way to social media due to ‘influencers’ including household names. Again, these should be considered anecdotal and not on any basis of scientific evidence of their applicability to you.

There is no reliable evidence that dietary or nutritional supplements can prevent, cure or control the growth of cancer. However, you might need to have dietary supplements if you have low levels of particular nutrients. Or, your cancer might stop you from easily absorbing nutrients from your food. So your doctor might prescribe nutritional supplements. Always check with your specialist before you take any supplements to make sure they won’t interfere with any cancer treatment you are having (including surgery).

Read more on Cancer Research UK

See one example of high does vitamin intake via something called the Myers’ Cocktail, in particular the side effects and dangers rather than the hype. In fact, in 2018, the US Federal Trade Commission (FTC) charged a company marketing and selling the Myers’ cocktail and other IV vitamin and mineral infusions of making “deceptive and unsupported health claims” about the ability of these infusions to treat such diseases as cancer, multiple sclerosis, diabetes, fibromyalgia, and heart failure. The FTC argued that these health treatment and efficacy claims were false or not supported by competent and reliable scientific evidence. Read more here.

Caveat Emptor. Most NET patients will not need such high doses. Always talk to your Oncologist or NET Aware Dietitian before proceeding with anything that will potentially harm you or at least waste your money.

Essiac therapy/Essiac tea

Essiac is a herbal remedy from Canada. It has 4 ingredients: burdock root, sheep sorrel, slippery elm, Indian Rhubarb root. A modified Essiac product called Flor Essence also includes watercress, blessed thistle, red clover, kelp.

There is no scientific evidence to support its use as a treatment for cancer.

Read more on Cancer Research UK

Dandelion tea/root extract

There’s a lot online about dandelion tea but many people associate that with dandelion root extract which is alleged to have anti-cancer properties. Check full fact evidence by clicking below.

Dandelion root is not a proven cancer cure – Full Fact

Tumeric

Myth: Taking turmeric supplements prevents and treats cancer.

Facts:

Curcumin, the yellow pigment extracted from turmeric has antioxidant and anti-inflammatory properties – however studies have not been able to show how much can be absorbed by the body to have an affect on cancer cells.
There are some early human studies showing some promise but the cytochrome p450 enzyme in turmeric has been shown to interfere with some chemotherapies.
Therefore it is advised to have turmeric in food or tea but not as a high dose supplement. Cancer Diets: Myths and More – from the British Dietetic Association – this link is worth exploring, there are many more, some of which are not here in my own list.

Mushrooms

Mushrooms are often talked about as a treatment for cancer. There may be some health benefits (although always seek advice) but there is currently no evidence that any type of mushroom can prevent or cure cancer.

Read more on Cancer Research UK

On well known doctor’s site WebMD, they noted that Reishi mushrooms (much touted by those who sell it) are a bitter-tasting fungus with no proven health benefits. It is thought to have some effects on the immune system. Reishi mushroom is used for Alzheimer disease, cancer, diabetes, and many other conditions, but there is no good scientific evidence to support these uses. They also provided the following warnings:

Reishi mushroom extract is possibly safe when used for up to one year. Powdered whole reishi mushroom is possibly safe when used for up to 16 weeks.

Reishi mushroom can cause dizziness, dry mouth, itching, nausea, stomach upset, and rash. There isn’t enough reliable information to know if reishi mushroom is safe to use when pregnant or breast feeding. Stay on the safe side and avoid use. High doses of reishi mushroom might increase the risk of bleeding in some people with certain bleeding disorders, particularly if used before or during surgery. Stop using reishi mushroom at least 2 weeks before a scheduled surgery.

Milk thistle

Milk thistle is a plant that comes from the same group of flowers as the daisy. It is not a treatment for cancer.

Summary

The medicinal compound in milk thistle is silymarin, an extract of milk thistle seeds.
Milk thistle might help to treat some liver diseases such as hepatitis and cirrhosis.
More research is needed before we will know if milk thistle can help prevent or treat cancer.

Read more on Cancer Research UK

Oncolyn (Onculyn in Canada)

Onculyn is a plant-based antioxidant dietary supplement. This supplement has been around for 20 years. It is not a treatment for cancer.

Summary

Health Canada recalled this supplement in 2006 with the following reason “Health Hazard Evaluation conducted by NHPD concluded the sale of this product is a Type II health risk due to the health claims for the treatment of cancer which are associated with the product as well as the implied claim of the brand name “Oncolyn”. Furthermore, the product contains undeclared hawthorn extract with no label warnings contraindicating the product’s use by pregnant women, and by those with cardiac conditions and/or taking cardiac drugs. Branding Note: The nutritional supplement formerly called Oncolyn (with a middle ‘o’) is no longer available for sale in Canada. Onculyn is the Canadian version of this product.
Read more on Health Canada

Laetrile (amygdalin or vitamin B17)

You can find this easy on the internet (worryingly). Many websites promote laetrile as a cure for cancer. But no reputable scientific cancer organisations support any of these claims. Be cautious about believing this type of information or paying for any alternative cancer therapy over the internet. One review by the well known scientific organisation Cochrane said …. “It also found a risk of serious side effects from cyanide poisoning after laetrile or amygdalin, especially after taking it by mouth”

Some people call laetrile vitamin B17, although it isn’t a vitamin. Some sites sell it as “apricot kernels”. WebMD, well known scientific evidence based website said “The most obvious reason is that amygdalin can cause cyanide poisoning. Your blood pressure could drop very low, you may damage your liver, or you might go into a coma. In the worst-case scenario, high doses – 50-60 apricot kernels, or 50 grams of Laetrile — can kill you.”

There is no reliable evidence that it works as a cancer treatment – or as a treatment for anything else. It’s not available for sale in the UK or Europe, due to lack of evidence of its effectiveness.

Sources:

Cancer Research UK

The Institute of Cancer Research

St. John’s Wort

This popular supplement is a plant native to Europe that has yellow, star-shaped flowers. The supplement tends to be taken to help with mental health conditions like depression. However, St. John’s wort has been associated with potentially serious interactions with certain drugs

Taking St. John’s wort with certain antidepressants can lead to an increase in serotonin levels that can be life threatening (i.e. serotonin syndrome). Symptoms can appear within minutes or hours and can include diarrhea, agitation, fast heartbeat, high blood pressure, and hallucinations.

St. John’s wort can also weaken antidepressants. Other medications that St. John’s wort can weaken include:

Birth control pills
Cyclosporine (a drug used to prevent the body from rejecting organ transplants)
Digoxin (a heart failure medication)
Oxycodone (a pain medication)
Some HIV drugs, like indinavir
Some cancer medications, like irinotecan
Warfarin (a blood thinner)

Source US National Institute of Health

Mistletoe (including European Mistletoe)

According to the US National Cancer Institute, Mistletoe is a plant that grows on many types of trees, including apple, oak, maple, elm, pine, and poplar. It has been used for hundreds of years to treat medical conditions such as epilepsy, asthma, hypertension, headaches, menopausal symptoms, infertility, dermatitis, arthritis, and rheumatism.

The US National Institute for Health reported that European mistletoe berries and leaves can cause serious harmful effects when taken orally (by mouth) and that it is probably unsafe for use during pregnancy. Little is known about whether it’s safe for use while breastfeeding and that injected European mistletoe extract may cause soreness and inflammation at the injection site, headache, fever, and chills. A few severe allergic reactions have been reported. Finally they stated that European mistletoe is not a proven cancer treatment. It should not be used as a treatment for cancer outside of clinical trials.

The US FDA has not approved the use of mistletoe extract as a treatment for cancer or any other medical condition.

There is no scientific evidence this is in any way advantageous as an anti-cancer therapy for Neuroendocrine Cancer.

Source US National Institute of Health

Black Cohosh

Black cohosh (Actaea racemosa or Cimicifuga racemosa), a member of the buttercup family, is a perennial plant native to North America. Other, mostly historical, names for this herb include snakeroot, black bugbane, rattleweed, macrotys, and rheumatism weed. Black cohosh has a long history of use. Native Americans used it, for example, to treat musculoskeletal pain, fever, cough, pneumonia, sluggish labour, and menstrual irregularities. European settlers used black cohosh as a tonic to support women’s reproductive health.

Across the world, reports have described at least 83 cases of liver damage, including hepatitis, liver failure, elevated liver enzymes, and assorted other liver injuries associated with black cohosh use. However, there is no evidence of a causal relationship. It is possible that at least some reported cases of hepatotoxicity were due to impurities, adulterants, or incorrect Acteae species in the black cohosh products used. However, no one independently analysed these products to confirm the existence of these problems.

In 2007, the Australian Department of Health began requiring that products containing black cohosh carry the following label statement: “Warning: Black cohosh may harm the liver in some individuals. Use under the supervision of a healthcare professional”. In 2008, the U.S. Pharmacopeia (a non-profit standard-setting organization for foods and drugs) recommended labelling black cohosh products with the following cautionary statement: “Discontinue use and consult a healthcare practitioner if you have a liver disorder or develop symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice”. However, the U.S. Food and Drug Administration does not require such a warning on black cohosh product labels.

The American Herbal Products Association recommends that pregnant women not take black cohosh except under the supervision of their health care provider because studies have not rigorously evaluated its use during pregnancy. The U.S. Pharmacopeia advises that individuals with liver disorders should also avoid black cohosh. It adds that users who develop symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice, while taking the supplement should discontinue use and contact their doctor.

There is no scientific evidence that black cohosh can treat or prevent cancer.

Sources

1. Black Cohosh – Health Professional Fact Sheet (nih.gov)

2. Black cohosh | Complementary and alternative therapy | Cancer Research UK

Paw Paw

Pawpaws are the fruit of the Asimina triloba tree, which is native to the eastern United States and southern Canada. It can be sold as a dietary supplement called Paw Paw Cell-Reg.

Asimina triloba, commonly known as pawpaw, is native to North America and has edible bean-shaped fruits. The plant extract is used in anti-lice shampoo and in pesticides.

The major components of pawpaw are compounds known as acetogenins. They prevent the cell from making ATP, an important energy source. In lab studies, the extract killed cancer cells resistant to commonly used chemotherapy drugs such as Adriamycin. It also appeared to be more toxic to cancer cells than to normal cells. However, studies on these effects have not been conducted in humans.

Side effects are said to include allergic reactions, nerve toxicity and vomiting.

Health began requiring that products containing black cohosh carry the following label statement: “Warning: Black cohosh may harm the liver in some individuals. Use under the supervision of a healthcare professional”. In 2008, the U.S. Pharmacopeia (a non-profit standard-setting organization for foods and drugs) recommended labelling black cohosh products with the following cautionary statement: “Discontinue use and consult a healthcare practitioner if you have a liver disorder or develop symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice”. However, the U.S. Food and Drug Administration does not require such a warning on black cohosh product labels.

The long, prickly soursop fruit comes from the graviola tree, an evergreen native to Mexico, the Caribbean, and Central and South America. Practitioners of herbal medicine use soursop fruit and graviola tree leaves to treat stomach ailments, fever, parasitic infections, hypertension and rheumatism. It’s used as a sedative, as well.

Soursop may also be referred to by other terms, such as:

Guanabana
Custard apple
Brazilian paw paw
Graviola
Guyabano

Sources:

Graviola (soursop)

Graviola is promoted as an alternative cancer treatment. There is not enough reliable evidence that graviola works as a treatment for cancer.

Many websites promote graviola as a cure for cancer. But no reputable scientific cancer organisations support any of these claims.

1. Graviola (soursop) | Complementary and alternative therapy | Cancer Research UK

Ginseng

First, let’s talk about what ginseng isn’t: a miracle drug, a cure-all, or a one-size-fits-all remedy. Some claim that it can reduce stress, alleviate erectile dysfunction, ward off dementia, strengthen the immune system, prevent cold or flu, reduce infections, improve digestion, and even cure cancer. However, there isn’t much research to support any of that. The only two conditions where American ginseng has been found to be possibly effective is with regulating type 2 diabetes and upper respiratory infections. However, it shouldn’t be used to treat any kind of disease without medical supervision, and to be wary of anyone who tells you it can. While it’s often added to energy drinks and foods — to boost energy, productivity, and even memory — there’s no evidence to support those claims, either.

Read this and more on Healthline

Ashwagandha

You may have seen social media influencers touting its benefits or have a friend who swears by it — ashwagandha has surged in popularity in recent years as a way to manage stress and improve overall health. As rates of health problems like anxiety, burnout and sleep issues rise, people are turning to plant-based supplements, especially since they are more accessible over the counter. But how effective are they exactly? When I look at the contraindications at the source below, I personally wouldn’t touch this as a NET patient. There are no data that support its use to prevent or to treat cancer.

Source: Should you take an Ashwagandha supplement? Risks and Benefits of Herbal Supplements

Ketogenic diet

The ketogenic diet is a low carb, high fat diet commonly used for weight loss. Restricting carbs and increasing fat intake can lead to ketosis, a metabolic state in which your body relies primarily on fat for energy instead of carbs. Just by reading this bit, I can see some red flags for many patients with NET issues.

In one of my go to sources for general health information, healthcare professionals indicate that this diet also carries risks you should be aware of and I think this is of use to NET patients. Read more on Healthline

Hear Tara Whyand (international NET Dietitian specialist) dismiss this too.
See Episode 4 – Sugar, Cancer and the Ketogenic Diet

Click here to read

Carnivore diet

The carnivore diet at its core is extremely restrictive. And when you omit entire food groups from your diet, there’s bound to be consequences.

“The carnivore diet is super low in fiber, which will cause a lot of constipation,” says Patton. And the risks become much more serious than a failure to poop.

“If you have a pre-existing chronic condition, like high blood pressure, high cholesterol, any history of stroke or other cardiovascular diseases, you should definitely not try this diet,” Patton says pointedly. “Even if you have digestive issues, this diet can make things worse with all that protein and fat, which takes a lot longer to digest.”

The carnivore diet is high in saturated fats which can cause elevated LDL or bad cholesterol and put you at risk for heart disease. What’s more, many different kinds of processed meats like bacon and some lunch meats are loaded with sodium and have been linked to certain types of cancer. And a diet high in sodium can cause kidney problems and high blood pressure.

In one of my go to sources for general health information, healthcare professionals indicate this diet carries some big risks. Read more on Cleveland Clinic.

Intermittent Fasting (IF)

The IF dietary model is characterized by episodic periods of little to no calorie consumption with variation that can range from every-other-day complete 24h fasting to fasting on 1 or 2 non-consecutive days per week (referred as the 6:1 and 5:2, respectively). Many fasting programs recommend no or small caloric intake during the fasting period together with an unlimited number of calorie-free beverages, such as water, coffee (without sugar or milk), bone broth, and diet soft drinks. The most popular approach is the alternate-day fasting (ADF) in which meals can be either high or low fat if they are less than 500 calories; another variation of IF is named time restricted feeding (TFR) and requires a limited consumption of calories, typically between 4 and 12h daily.

This type of diet is focused on calorie reduction and is mostly used in weight loss regimes. Clearly for some people, weight loss can lead to better health outcomes. It follows that it might reduce your cancer risk.

However, this does not mean IF helps reduce cancer cells or cures cancer for those already diagnosed with cancer. And these false claims can be found on the internet. Scientific research does not support any of these claims.

Read more on Cancer Research UK

Alternative diets

I only reference two alternative diets here but there are many more that crop up. But there is no scientific evidence that alternative diets can cure cancer. You can also read about others here, including (but not limited to), alkaline diet, macrobiotic diet, fasting, organic diet, dairy. Read more on Cancer Research UK.

Cannabis, CBD oil

Many hundreds of scientific papers looking at cannabinoids and cancer have been published so far, but these studies simply haven’t found enough robust scientific evidence to prove that these can safely and effectively treat cancer. In fact some studies say that it can sometimes encourage cancer cells to grow or cause damage to blood vessels. Evidence is emerging that it can help with sickness and pain in some people.

Cannabis products can be smoked, vaporized, ingested (eating or drinking), absorbed through the skin (in a patch) or as a cream or spray. CBD oil normally comes as a liquid or in capsules, but edibles are available (e.g. gummies).

Cannabis that contains high levels of THC can cause panic attacks, hallucinations and paranoia. There are also many cannabis-based products available online without a prescription. The quality of these products can vary. It is impossible to know what substances they might contain. They could potentially be harmful to your health and may be illegal.

Other than where medical cannabis is approved by drug regulatory authorities for prescription use for specified conditions, in many countries, it can be illegal to have, sell or buy cannabis.

Word of caution

Cannabis is a class B drug and illegal in the UK and other countries. There are internet scams where people offer to sell cannabis preparations to people with cancer. There is no knowing what the ingredients are in these products, and they could harm your health. Some of these scammers trick cancer patients into buying ‘cannabis oil’ which they then never receive. It is also possible this could happen in countries where the use of cannabis is legal.

Placeholder for future additions

Other sources

I like to use Cancer Research UK as a research tool, they take an evidence based approached to stuff so it’s not just “don’t eat this”, they also explain why. You can search their site for other ‘debunking’ including the frequently shared acidic diet and baking soda myths.

Cancer Research UK is not alone in trying to help dispel some of these myths, and it’s not just food myths, you can also fact check on the big US site Cancer.Gov – see their myth-busting article here.

I also like the list from Cancer.NET – American Society of Clinical Oncology (ASCO) – read it here. (Science Fact or Science Fiction).

And if you wanted to hear from one of the world’s most experienced NET dietitians, check out Tara Whyand talking about sugar and KETO:

And the biggest myth of all

Those who push these alternative cures have an agenda. They will tell you that cancer treatments poison us and make cancer worse. Cancer is easy to kill. If you put some cancer cells in a dish and pour some bleach on them, they won’t survive for very long. Pouring bleach on some bacteria growing in a petri dish would have much the same effect, but we don’t take bleach when we have an infection, for the same reason we don’t take it when we have cancer. The reason finding cancer treatments is so hard is because cancer cells are just normal cells which have turned malignant. Anything that kills a cancer cell is therefore likely to kill your own healthy cells as well. The ideal cancer drug is selectively toxic – it will only harm the cancer cells and leave your own cells unscathed. While older chemotherapy treatments are famously difficult for patients and come with a whole host of nasty side effects, modern research is focused on developing smarter, kinder treatments. Many of these treatments focus on training your immune system to spot cancer cells and fight them, or therapies which target the genes that have caused the cancer in the first place. While some older cancer treatments may not be as kind as more modern therapies, they don’t make cancer worse.

They will also tell you that pharmaceutical companies (big pharma) do not want to find a cheap cure because it will mean losing constant streams of revenue. If this was true, it would be the worst kept secret in the history of humankind. Modern cynicism and the rise of social media continues to spread this patently false but to many vulnerable people, persuasive claim. Those who spread this myth will never provide any clear evidence of the huge conspiracy involving tens of thousands of people that would need to be involved in hiding the truth.

Hope is great, false hope is not.

Disclaimer

I am not a doctor or any form of medical professional, practitioner or counsellor. None of the information on my website, or linked to my website(s), or conveyed by me on any social media or presentation, should be interpreted as medical advice given or advised by me.

Neither should any post or comment made by a follower or member of my private group be assumed to be medical advice, even if that person is a healthcare professional.

Please also note that mention of a clinical service, trial/study or therapy does not constitute an endorsement of that service, trial/study or therapy by Ronny Allan, the information is provided for education and awareness purposes and/or related to Ronny Allan’s own patient experience. This element of the disclaimer includes any complementary medicine, non-prescription over the counter drugs and supplements such as vitamins and minerals.