Diet and Cancer - What's the Best Diet?

What are the best diets for the prevention and treatment of cancer?

Article Card image

With the number of diets floating around at the moment, it can be confusing to know what to eat, or not to eat, to prevent cancer and treat cancer. When someone recently asked me if I could help as a support for a family who have an eight-year-old with stomach cancer I thought I’d look into diet to try to understand what his recommended diet will be.

I set out to find what is recommended during chemo and realized it’s individual and varies from case to case — you always have to consult a dietician. Different foods interact with different medications and different symptoms also require different foods. While it’s easy to think chemo causes weight loss, it can also cause weight gain if the person is given steroids. And in the case of stomach cancer, surgery may affect appetite and diet as well.

This was, of course, not the straight forward answer I was looking for. However, I did learn a few things, which I will share below, but I also decided to look into diet recommendations for the prevention and treatment of cancer in general. Having written health articles for the past couple of years, I’ve found that every edible vegetable, fruit, spice and herb seem to come with a number of different health benefits.

The problem is that some herbs and spices interact with medicines and can also have adverse effects if consumed in the wrong quantities, or when suffering from a certain disease. Consulting herbologists and doctors (you need both — one understands herbs, the other the interaction with different medicines), is therefore crucial before using large amounts of herbs and spices.

Researching the best diet for the prevention and treatment of cancer I found that there are certain foods to avoid, others to include. I also found some tips for managing diet when undergoing chemo. I will share it below. Again though, you have to talk to a dietician if you are already being treated for cancer, as you may have problems digesting certain foods.

Foods to Avoid

According to the Cancer Center the foods and drinks that have been linked to cancer include processed meat, red meat, charred meat/meat cooked at high temperatures, very hot beverages (beverages that are hotter than 65 degrees Celsius/149 degrees Fahrenheit) and alcohol (one serving per day as a woman and two servings per day as a man may be safe). (1)

Dairy has been a much-debated food, not least as many adults outside of the Nordics can’t digest dairy as adults. When we are first born we need milk, thus we are able to break it down, but for most of the world’s population, that ability stops as soon as we no longer need milk. In the Nordics there was a gene mutation a long time ago, so most people can break down milk later in life. However, in Asia, almost no one can break down milk as they grow older.

Due to this debate, I had a look to see if dairy was linked to cancer in any way and found two interesting articles on Healthline that looked at different studies. Their conclusion was that drinking milk may be best avoided, but dairy, when eaten in moderation and granted it’s high-quality dairy products (i.e. grass-fed, non-hormone treated, etc.), in general, does not seem to have adverse effects. Sometimes it can even be beneficial. (2)(3)

One of the articles on Healthline also mentioned that, in addition to previously mentioned hazards, sugar and foods high in refined carbs may cause cancer in the long run. In other words, opt for wholemeal grains and stick to sweeteners that don’t give you a spike in your blood sugar, as this has been associated with a higher risk for cancer. (3)

As I was googling stomach cancer in particular at first, I also found an informative article by the Center for Research that looked at the link between stomach cancer and diet. This is what they reported:

After looking at 89 studies that examined nearly 77,000 cases of stomach cancer, the report concluded that each of the following can increase a person’s risk for developing stomach cancer. (4)

Drinking three or more alcoholic drinks per day.

Eating foods preserved by salting, such as pickled vegetables and salted or dried fish, as traditionally prepared in East Asia.

Eating processed meats that have been preserved by smoking, curing or salting, or by the addition of preservatives. Examples: ham, bacon, pastrami, salami, hot dogs, and some sausages

Being overweight or obese, as measured by body mass index (BMI).

Foods That Prevent Cancer

Thankfully, there are many more foods that may possibly prevent cancer than cause cancer. As mentioned at the beginning of this article, having written articles related to health for many years, almost every fruit, nut, seed and vegetable, as well as all edible herbs and spices, appear to come with health benefits. When it comes to preventing cancer, it is recommended by most doctors that you eat a balanced diet, including lots of fruits and vegetables (carbohydrates that contain fiber), plenty of protein and healthy fats.

Looking for foods that are specifically good, I found two articles on Healthline that looked at a number of different studies that had shown promising results for particular foods. They found that olive oil, garlic (and possibly other types of onions such as leeks and regular onions), fatty fish, nuts, berries, carrots, cruciferous vegetables, citrus fruits, tomatoes, flaxseeds, cinnamon, turmeric, beans and legumes had shown promise in various different studies. They also concluded that there is some evidence to suggest that plant-based diets and the keto diet may be beneficial in the prevention and treatment of cancer. This may be as a result of people on those diets consuming less processed foods and less refined sugar. (5)(6)

I must say that reading about the studies mentioned in the Healthline articles left me feeling optimistic as it shows what a positive effect diet can have in the prevention and treatment of cancer.


Eating Hacks When Undergoing Chemo

Malnutrition is common among cancer patient, no matter what their weight due to the treatments they are undergoing. Nutrition, therefore, becomes an important part of the treatment plan. A good diet can help the overall treatment being more effective and, also, less unpleasant. Getting sufficient amounts of protein, carbs and fats is important.

Taking all the above into account regarding diets that cause and prevent cancer, I found it shocking that several medical health institutions still recommend things like 7-up if you need fluids and energy while undergoing chemo. Freshly pressed juices (the kind depending on how well their stomach can handle different things), broths made from vegetables and bones, coconut water and herbal teas with honey seem like better options. Do note, however, that to keep someone hydrated they need electrolytes, sugar of some form and water. That’s why a combination of broths with low levels of salt in them (the salt is necessary), juices, teas with honey and coconut water need to be drunk and not just water.

That said about opting for a healthier option, also note that the person undergoing chemo is going through hell physically and, often, mentally. Letting them have the joy of indulging in a milkshake, instead of a protein smoothie from time to time, is possibly as important as keeping the rest of their diet nutritious. And you can actually find ice creams and milkshakes made with whole food ingredients these days, or you can make them yourself.

Definitively make eating as fun as possible and have treats ready to celebrate anything and everything that makes life worth living. This is important. 

The only thing I mean to point out is that sometimes there are healthier options, such as making your own ice cream, or blending a little bit of avocado with frozen mangoes, berries and possibly some cream, to create a delicious form of fruity “milkshake” or “ice cream.” Likewise coconut (either fresh young coconuts, or coconut milk/cream frozen in ice cubes), blended with honey, stevia and cacao makes for an excellent chocolate treat. You can swap the coconut for frozen bananas too. Vitamixes are great for making purees, soups and smoothies, but these days there are other good blenders as well.

By the end of the day you always need to consult a trained dietician before you make decisions regarding both fluids and foods. This is crucial, because what might sound like a good idea, could be really bad if it interacts with the medication, or lacks a crucial nutrient. And as healthy as your soup may be, if the person getting treatment isn’t eating it, but would eat a protein shake consisting of what you called dubious ingredients, then the protein shake may very well be the better option.

Your taste gets affected by chemo and it’s maybe hard for relatives and others to understand just how difficult eating can become.

A Delicious Smoothie Could Be an Ice Cream Alternative.

Liquid Nutrition

You need to bear in mind that someone on chemo may be unable to eat and therefore require liquid nutrition. In some cases that can include purees, soups and protein smoothies (for example, blending frozen bananas, pea protein, almond butter and coconut water to make a smoothie), in other instances you may have to make do with broths, juices, coconut water, regular water, herbal teas, etc.

Liquid nutrition can also be important if the patient needs extra nutrition in between meals. It’s recommended to eat three meals a day and provide three snacks in between meals. However, for those suffering nausea, the meals may need to be smaller and more frequent. Making sure to get protein and plenty of calories in the morning may also help.

If easy to eat meals can be included, try using freely pressed fruit juices to make jellies, blending them with agar agar or gelatin. A lot healthier than the store bought version! You can also make puddings with chia seeds and linseeds (remember it is on the list of foods that may help combat cancer) blended with fruit purees and coconut cream, or pureed bananas.

Mashed potatoes, porridge and rice pudding are other options when the person does not feel like chewing much.

Simply staying hydrated is also important. Drinking between meals and not during meals is often recommended. As many herbs and spices are known to help combat infection and boost the immune system, drinking herbal teas may considered, but always check with your healthcare practitioner first as some herbs and spices may interact with your medication. Turmeric and cinnamon are definitively worth considering including in your everyday diet as they’ve shown promise combating cancer in various studies. Turmeric blended with black pepper helps improve absorption.

Chia Seed Pudding. 


Nausea, Diarrhea and Vomiting

As some patients suffer diarrhea, abstinence from eating may be required. Instead, liquid nutrition will be provided until the stomach calms down.

Bananas, applesauce, toast, rice and potatoes (normal and sweet potatoes) are great foods when starting to eat again. Consuming fiber-rich foods are a way of helping to regulate bowel movements once the stomach is settled, but can cause diarrhea if over consumed. Avoid greasy and oily foods, as well as too spicy foods.

Others suffer constipation, in which case fiber-rich foods are recommended. Dairy, meat and eggs can cause constipation, so should be consumed in moderation. Rather eat vegetable forms of protein. Including some olive oil in meals may help.

Probiotics may be recommended to help improve gut bacteria and settle the stomach. From everything I’ve read about probiotics, they are great for overall health, boost the immune system and may also improve mental health. Thus, they may be a great support for the body, whether the person undergoing chemo has stomach problems, or not.

Ginger is known for fighting nausea, but if it’s helpful for chemo patients, I am not sure.

Scents, spicy foods, foods that are either very warm, or very cold, may all cause nausea. Many chemo patients find that eating cool foods, or room temperature foods, are the best option.

Some people who suffer nausea, find that eating a cracker, or piece of bread helps and therefore keep sit by the bedside, in case they get nauseous after sleeping.

Taking it easy after a meal — sitting down for an hour — can help. Definitively don’t lie down directly after a meal, on the other hand. Waiting for one to two hours is best.

Liquid Nutrition


Taste may also be affected and therefore foods that are low in salt but well seasoned with herbs and spices may taste better. Avoiding metal cutlery can also help. Red meat may also taste metallic. Tart products are sometimes easier to eat, as are things that don’t smell much, so they are better served at room temperature, than when they are hot. In general, anything too hot, or too cold, is often best avoided.

Mouth Hygiene

As mouth hygiene is often effected, drinking throughout the day (but not at mealtimes — rather in between meals) is important to avoid the mouth going dry.

Rinsing the mouth with lemon water can also help after meals (you may want to brush your teeth after that to avoid the acid doing a number on your teeth), and rinsing the mouth with salt water or water mixed with bicarbonate of soda, in between meals can be beneficial.

Swishing a tiny bit of olive oil in your mouth and then swallowing it can help lubricate your mouth and throat (if you absolutely can’t stand swallowing it, just spit it out).

Sucking on ice cubes is another great way of lubricating the mouth — unlike hard candies they don’t contain any sugar.

Lemon Water

Mouth Sores

Mouth sores are a common side effect of chemo and coming from a family that suffers from mouth sores I can tell you this: avoid anything with a lot of refined sugar (particularly in hard candy and chocolate, but just about anything with a lot of sugar), dried fruits, things with a lot of baking powder, acidic fruits (like pineapple — lemon juice when diluted in water is fine), salty foods, foods that can “cut” your mouth like crisps, crackers and hard breads. For some, hot spices, potatoes and nuts are also a problem. My best friend has often told me I’m lucky to have this problem because it means I can’t overindulge in sweets, or pig out on crisps too often, because, well, “my mouth cracks open.” Basically, these foods cause mouth sores and hurt to eat if you already have the sores. You want bland foods without too much salt, no sharp edges and no sugar, or acid.

Sodium laureth/lauryl sulphate can also cause mouth ulcers, so toothpastes without them, such as certain toothpastes by Sensodyne can be used instead.

From the personal experience — using my grandparents outdated, high-alcohol mouthwash — I can also attest to the fact that gurgling with alcohol hurts like hell, but then completely numbs you for about five minutes, in which time you can down a bit of food. I realized this when I had a cold/flu as a child and my gums were completely covered in mouth sores. In my grandparents' cupboards, I found salvation in the form of that very old mouth rinse.

Please note that these sores, when in the wrong spot, can hurt like hell. It can make meals very unpleasant, so avoiding foods that cause them, or aggravate them, can be important, depending on the person.


If you want to avoid refined sugar, then bananas, applesauce, honey and stevia are some options to consider. Some people also like maple syrup and agave syrup. Ground dates can also be used, just bear in mind they contain fiber so in case of diarrhea aren’t recommended.

The Importance of Not Giving Up — Keep Fighting

For some chemo means being tube fed if it gets too difficult to eat and then having to learn to eat again teaspoon-by-teaspoon. For others, it means eating teaspoon-by-teaspoon for a while. The important thing is to keep fighting. You need nutrients. You need to force yourself to want to eat. If drinking alone keeps the nausea away, then do a fluid fast, particularly on days when undergoing treatment, but try to include protein smoothies as soon as possible as you really need some protein. Fats are also essential and broths may be a good way of getting those, but it’s easy enough to stir some into protein shakes, or juices, too.

If eating isn’t fun, distract yourself while eating by watching a movie, or talking to a friend.

You need strength in the form of fats, carbs and protein and you need nutrients to stay as strong and as healthy as possible during treatment, so keep eating the good stuff and if you can’t, drink!

The Importance of Overall Physical Health

Exercise, spending time outdoors and going to bed at regular hours are all important for our physical wellbeing, just as diet is. So, talk to your doctor about what you can and can’t do to make sure you get as much exercise, time outdoors and sleep as you need. This will be different for different people and therefore you need to consult a doctor about it.

Spending Time in Nature Can Do a Lot for Your Physical and Mental Health

The Importance of Mental Health

Emotional wellbeing is just as important as physical wellbeing. Getting the right counseling and support in the form of love, both from yourself and others, is very, very important. Simply staying focused on the end result of getting well, no matter what pain you are going through, as opposed to getting lost in a myriad of negative thoughts, will help your healing process. If you are someone close to a cancer patient, the same applies. And remember the support — even if you are the support, you may require support.

Simply doing things you love and taking your mind off cancer is also important. Try to schedule in as much fun as possible.

There is a lot of debate about how emotions affect and sometimes even cause disease. The placebo effect alone shows us that our brain has the ability to help heal us. A few years ago, when suffering from RSI, I came across Dr. John E. Sarno’s book about how suppressed emotions can cause chronic pain disorders as the brain sends out signals to stifle oxygen supply which affects the muscles and nerves. With his guidance, I cured myself of my “incurable” disorder in about two weeks. I found online that tens of thousands of people had done the same. This made me realize that in some instances, the brain really does affect our wellbeing. I’d always thought so, but no matter how much I’d pondered it, I’d never understood it until I read that book. Possibly because Dr. Sarno wasn’t some new age hippie, but a trained M.D. working for New York University and who was skeptical about anything that wasn’t “traditional” medicine.

The Importance of Professional Advice

You may, or may not, agree with the overall practice of mainstream medicine, but Western doctors trained in nutrition will be able to help you understand what your diet must include. Taking charge of your own diet can be empowering and give you hope, but you still need to ensure you get the right nutrients. The internet is filled with pseudoscience. You do not want to accidentally harm yourself, or someone you love by trusting the internet alone. If you want to make your own foods, explain it to the doctors and make a meal plan. If you want to use large amounts of certain herbs, or spices, talk to a doctor and an herbologist. If you want to take any form of supplement, talk to a doctor.

If you want to find out more about general advice for diet during chemo treatment, this is a good page








cancer treatment
cancer prevention
diet to prevent cancer
diet to treat cancer
diet when on chemo
natural health
Lifestyle & Ent

Related Article