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Diet in Cancer Patients

Diet in Cancer Patients

Scientific investigations carried out many clinics around the world revealed out the significant relation between cancer and nutrition. Overconsumption of especially refined foods became predictive for the occurrence of negative effects on human health, particularly including obesity. You will discover how easy to manage eating with a good plan and evidence-based food consumption in this booklet that is authored by Onkoklinik. It is significantly important to act responsibly and be sensitive, when the subject is diet programs in cancer treatment.

Let’s start with a closer insight of “carbohydrate metabolism” that underlies the body energy.
Glucose is the principal fuel of our cells. Body cells uses the inhaled oxygen to burn the glucose in mitochondria, also known as energy factories. Glucose is the only source of energy especially for our brain. Glucose is derived from the foods and it is absorbed from the digestive system.

Ok, what is “glucose”?
It is the primary component of sugar. Purified glucose is the basic ingredient of candy, desserts, drinks and fruit juices. It is also the building block of complex carbohydrates, also known as starch.

Most of principal nutrients contain high amount of carbohydrate that is quickly metabolized into glucose after it is ingested. Bread, cake, pastry, rice, potato, fast foods and many fruits fall into this group.

Energy Conversion

How is glucose processed into energy?


After the foods with high carbohydrate value are ingested, they are absorbed in the digestive system and quickly transformed into glucose. Insulin secretion        increases in response to elevation of glucose concentration in the blood. Insulin decreases the blood glucose by forcing the glucose into the cell. If too much        glucose is absorbed, insulin converts the glucose into glycogene that is stored in muscles and liver, and sudden glucose need is fulfilled from these stores.


If the blood glucose is critically low, glucagon is secreted to process glycogen into glucose that is used by the body. If this cannot fulfill the need, glucose is synthesized from proteins. This mechanism is designed to prevent glucose deficiency in the body.

In case of hunger, healthy cells can use fats and proteins as the source of energy. Anyhow, glucose is still needed, albeit in low amounts. Liver can synthesize glucose from proteins in case of hunger. If there is no carbohydrate in the diet, proteins will be inevitably broken down. Blood glucose is maintained at a certain level by the body even in case of prolonged hunger. Fats can also be directly used as source of energy.

Conversion of fats into energy

How does conversion of fat into energy start and may ketones be used as energy?

When “High-carbohydrate diet”, also called Western type diet, is switched to low-carbohydrate diet, our body starts using fats for energy. 

Excluding our brain, almost all body cells meets energy need by “burning” fats. Brain continues using the glucose and therefore, liver synthesizes glucose from proteins and supplies to the brain. Production of ketones increases when body cells start using fats. Ketone is produced, when your body metabolizes the fatty acids. Almost all cells can use ketones as a source of energy. Following 2- to 5-day adaptation period, brain may also fulfill energy needs from ketones. Up to 80% percent of energy required for brain can be derived from ketones.  

Excess ketones do not accumulate in the body and they are excreted in urine.

Amount of ketone in urine can be analyzed with test strips. If ketone concentration further increases, it can be also excreted in breath that smells of acetone. “Ketogenic Diet” is named after presence of ketone in the urine. This metabolism activates use of fats and ketones in case of hunger. This is called ketosis that is a physiological or natural state.
It should not be confused with ketoacidosis that threatens life of diabetic patients.

Mild increase in ketones is completely normal that the brain uses ketones as a source of energy. This non-hazardous and normal state has been occurring for centuries in the human being, when low carbohydrate is ingested, and it is an adaptation mechanism.
 Glucose Addiction of Cancer Cells

Why are cancer cells greedy for glucose?

Cancer cells have a never ending hunger for glucose. Scientific studies also revealed out the abnormal appetite of cancer cells for glucose.

The German scientist Otto Warburg, who was awarded the Nobel Prize, observed 80 years ago that contrary to healthy cells, cancer cells do not use oxygen and burn fats to procedure energy. He determined that cancer cells only ferment glucose.

Cancer cells prefer only glucose without use of fat and oxygen even if fats, glucose and oxygen are available in the medium at experimental conditions. Fermentation of glucose does not cause cancer. However, it is believed that body cells use this method secondary to genetic changes that are observed in the development of cancer.

Cancer Cells

Let’s look at glucose hunger of cancer cells from biological and mathematical point of view. Glucose is the principal source of energy in normal circumstances and it follows a series of intracellular reactions, after it is transferred into body cells by the insulin. The first part of these reactions is called glycolysis. Glycolysis uses 2 ATPs to produce 4 ATPs. In other words, net gain is 2 ATPs. Pyruvate is synthesized in glycolysis and further 36 ATPs are gained that are produced in our energy factory, namely mitochondria, in case of aerobic respiration.
If the system will follow an oxygen-free process and the mitochondria - the energy factory of body - will not be used, pyruvate is converted to lactic acid that is removed out of the cell.
Cancer cells never want to use mitochondria. Why doing with only 2 ATPs rather than yielding 38 ATPs from one molecule of glucose.
Since cancer cells work so insufficiently, their glucose need is 20 times higher than healthy cells.  They need this energy or glucose in order to proliferate. Most importantly, cancer cells cannot use fats and ketones. They only need glucose. 



• They have more glucose binding proteins in order to hold more glucose.
• They do not use and like oxygen for energy production.

They continuously produce lactic acid that is transported out of the cell.


Although it seems like inefficient energy production, it also opens some doors for cancer cells from certain points of view. How?

• As they continuously produce and secrete out lactic acid, they create a sea of acid around them. This acidic environment facilitates spread of tumor by demolishing the healthy cells.

• Cancer cells modify their cell wall for self-protection in the acidic environment. The cell wall of cancer cell is stiff and less permeable and accordingly, cancer drugs cannot penetrate into the cell.

• Immune system cannot efficiently fight cancer cells due to the acidic environment.

• They do not need oxygen, as they produce energy in an oxygen-free process. Therefore, they can also resist radiotherapy, as efficiency of this therapy significantly decreases in hypoxic environment. They develop resistance to anti-cancer drugs that act more efficiently in the presence of oxygen.

• Since they do not need mitochondria to produce energy, they are also refractory to anti-cancer drugs that target the mitochondria.

First Step in Anti-cancer Treatment

Can overproduction of lactic acid by cancer cells be used as a diagnostic tool?

Lactic acid level in tissue can be detected with some special MRI (magnetic resonance imaging) techniques. Thus, a view is held to decide whether there is tumor in tissue or not.

The soft spot of cancer cells, in other words “Achilles’ heel”, is that they are glucose-dependent and they cannot use fat and ketone as energy source.
Optimal first step of cancer treatment is planned by focusing on this soft spot of cancer cells.
Fermentation of glucose (e.g. glycolysis) is different from healthy cells. Drugs used to inhibit fermentation of glucose –glycolysis- in the tumor kills the cancerous tissue, while healthy cells are not affected as they can modify their metabolisms. This treatment modalities are still investigational and successful outcomes are obtained in experiments.

Dietary modification is one of the most important phases of cancer treatment. The first step of cancer treatment is completed if we cease glucose supply to the tumor and healthy cells are fed enough to produce sufficient energy.

Ketogenic diet

We will give you some tips to make you understand the logic of "ketogenic diet" instead of creating complex diet lists. Constipation and nutrient deficiencies may be faced in the diet, albeit rarely.


Your physician will supervise this process with laboratory tests. The key factor is drinking at least 2-3 litres of water per day. The water should not contain carbohydrate or in other words, fruit juices must be avoided. Well-filtered water is the healthiest drink in the world.

Main features of ketogenic diet:

• We remove glucose and carbohydrates which are the main food source of cancer cells from our diet.
• They are substituted by sufficient amount of fat and protein to meet energy need of healthy cells.


However, we will add glucose at a certain amount to stabilize the blood glucose level.

• When daily consumption of carbohydrate decreases below 50 grams, healthy cells start to use fats and ketone as source of energy. Now, the energy source is fats and ketones rather than glucose. Nervous system cells, especially brain cells, can use ketones in line with their requirements. Traditional diets of Eskimos and Maasai consist of fish, meat and milk. There is no room for carbohydrate. However, they spend very healthy lives.
• Reduction of blood glucose and elevation of ketones can be seen in blood tests of patients who follow low-carbohydrate ketogenic diet. The prominent feature of ketogenic diet is the ability to hinder high blood glucose.
• Studies conducted in cancer patients demonstrate that quality of life is boosted and progression of cancer is slowed down by ketogenic diet. The body quickly adapts to the diet characterized by low carbohydrate and high fat and protein. Glucose derived from dietary fruits and other foods and glucose synthesized from fats and proteins by liver  are more than enough for the body.
• The most significant change that occurs when a person starts on ketogenic diet is the reduction in glucose supply to the cancer cells. Blood glucose decreases to a stable level and this is positive condition for health.
Ability to prevent fluctuating blood glucose is the most important advantage of low-carbohydrate and high- fat/protein diet. This prevents sudden alterations in insulin secretion. Insulin not only forces the glucose into the cell but it also causes growth of tumor. Less insulin means less growth in tumor.

Choosing the correct fat

How is correct fat selected in low-carbohydrate and high-fat/protein diet? Recent studies show that omega-3 fatty acids stop the tumor growth. These findings are a guiding light in selection of fat. Concrete results can be obtained if we prefer linseed oil, hemp seed oil and fish oil which are rich in omega 3. On the other hand, we should avoid sunflower seed oil, soy oil, safflower oil and wheat germ oil which are rich in omega 6.

Omega 6 suppresses proper function of the immune system by leading to inflammation in body. This leads to the growth of cancer tissue. Medium chain triglycerides (MCT) are absorbed in body without spending energy. Many studies have demonstrated that MCTs hinder growth of tumor and do not cause weight loss.

MCT should be the primary type of fat preferred in our diet. Medium chain triglycerides (MCT) are mostly found in palm oil and coconut oil.
Aside from giving up their favorite desserts and chocolates, it has been noted that the patients experience a remarkable increase in quality of life, weight loss is hindered and the energy gap is bridged by switching to ketogenic diet. In conclusion, a qualified renunciation and a healthy planning in eating habits also offer a reward.

Ketogenic diet therapy

How are ketogenic diet therapy and tumor-related excessive weight loss (cachexia) interrelated?
Generally, chemotherapy can cause loss of appetite, disorders in liver and digestive system and vomiting. Quick weight loss may be experienced along with the effect of tumor. This condition is called tumor cachexia.

Severe weight loss is fundamentally related to excessive consumption of glucose by tumor. If the patient does not take sufficient amount of glucose with diet, tumor ensures that muscles and fats are processed to glucose in the liver to maintain its own feeding. However, fats are first metabolized and it is followed by muscles.

Since accumulation of tumor cells increases glucose consumption, the result will be overproduction of lactic acid. High level of acidification develops in our body and it becomes a threat for our body. The liver uses its final energy to transform the lactic acid to glucose to clear the excess lactic acid. However, lactic acid level increases again since this glucose is also used by tumor.
This process continues as a vicious circle. Starving tumor cells take the control and bring the organism to the point of collapse.

Low-carbohydrate, high-fat/protein diet reverses this condition.

Normal cells use diet-derived fats and ketones as source of energy. No muscle is wasted, as sufficient amount of protein is ingested.

Body builders eat low-carbohydrate diets to augment and strengthen their muscles.
Medium chain triglycerides (MCT) can be used to meet high energy need of our body. However, our diets contain low amount of MCT. MCT is absorbed easily without spending energy and it directly goes to mitochondria, wherein it is burned to produce energy.
Studies reported that MCT diet prevents tumor cachexia.

Cancer and sport

How is cancer and sports related?

The relation between sports and development of cancer has been investigated for long years. Studies conducted 20 years ago also demonstrated that risk of cancer is lower amongst individuals who do sports and have an active life.

This fact was also verified in following studies and American Nutrition Association confirmed that individuals who do physical activities have lower risk for cancer.

Sports have positive effects on regulation of blood glucose. When you do sports, your body requires glucose and glycogen storages are emptied. Blood glucose level decreases.

Sports and ketogenic diet are two healthy life disciplines that walk arm in arm.
Cancer patients are recommended to do their favorite physical activities as long as their health conditions allow to do so. Less strenuous sport programs with stable activity are quite ideal. In this end, biking, walking, and jogging under supervision of a professional can be recommended. Rapid, explosive activities that require high energy should be avoided. The best one is long walks.

You can make it!

What can you do to change your diet and eating habits?

Orientation to ketogenic diet is much easier than estimated and the body can be adapted to the diet very fast. A little care while selecting foods is the most important phase.

You can use Internet to buy certain foods that are difficult to supply and cannot be found in points of sales such as shops. The most critical point is to prevent vitamin and mineral deficiencies in body. If you are interested in cooking and eating different foods, you should roll up your sleeves for yourself to eat healthy.

The most important aspect of ketogenic diet is to restrict consumption of glucose - in other words carbohydrate (maximum 50 grams/day) -, while eating sufficient amount of fats and proteins.

We do not need more! You can make it! We make the greatest change at the carbohydrate-side of plate. We will avoid potato, rice, pasta, honey, grape molasses, cake, pastry and every kind of bakery products. They will be replaced by low-carbohydrate alternatives.

Can we do without bread?

Why not? Meat can be consumed without bread.

A delicious vegetable meal cooked with olive oil or boiled foods can be made much more unique. The matter is to break the routine. You do not need any refined food.

In fact, when you start eating your meals without bread, you will notice that they are much more delicious and you will experience the real taste of foods. Further information about low-carbohydrate bread is available in following sections. You can find recipes of low-carbohydrate bread, cake, pastry etc. with some Internet search on web sites that advise low-carbohydrate diets. Moreover, you can supply products that are made of gluten and hazelnut meal.

Some special bakeries and patisseries offer low-carbohydrate breads prepared with almond flour.

Fat turns into a powerful weapon when it is used correctly!

High-quality, cold-pressed vegetable oils have an important part in ketogenic diet.

Those oils provide the basic triglycerides (especially omega-3) and fat-soluble vitamins (vitamin D). Hemp seed oil, linseed oil, rapeseed oil and fish oil are the most qualified ones. Those oils should not contact with air and should not be heated.
You can consume them in salads, especially with curd cheese, to flavor your meals. You should eat 4-6 grams of omega-3 per day in your diet. This means using 4 to 6 capsules that contain 1 g of omega-3.

Of course, the best and more affordable one is fresh linseed oil. 100 ml of linseed oil contains 55 grams of omega 3. In other words, one tablespoon of linseed oil per day meets the required amount of omega 3. It can be consumed in larger amounts. Remember that omega 3 runs out quickly, when the bottle is opened. Consumption of oils with protein is healthier. You do not need to worry about calorie gap. Those foods prevent weight loss. Especially medium chain triglycerides are very important. The ideal mix is vegetable oils and 114 medium chain triglycerides (MCT). MCT fat means a direct source of energy for our body.

In selection of daily foods, you need find ones with low amount of lactose.

Especially for yoghurt, curd cheese and their derivatives, low-calorie or low-fat – popularly known as “light” - products contain more lactose and sugar.
Therefore, prefer products with normal fat content rather than diet products.
Read the product labels carefully. Always prefer full-fat products; you can boost the taste by choosing spicy and vegetable-added ones according to the season.

Importance of breakfast

Breakfast is also important. Thus, question what you buy while shopping!

Prefer full-fat cheeses, aged kasar cheese and Alpine cheese. Those contain low amount of carbohydrate. Especially, the cheeses produced with milk of animals fed in forages are rich in omega 3 and vitamin D.
Goat’s milk cheese, sheep’s milk cheese and full-fat cream cheeses are pointed choices for diet. You can eat low–carbohydrate cheeses as much as you want. Soy products are also a good protein source. You should be careful about amount of carbohydrate in soy products.

Your primary choice should be meat.

Try preferring meats of animals fed freely in forages while you are shopping for meat.

Meats of those animals are very different regarding both taste and cooking time in addition to being rich in omega 3. It is beneficial to prefer organic products and butcher shops that you know for high quality meat and meat products.

Ready-to-eat charcuterie products like salami and sausage are added sugar to boost the flavor. Preservatives used to ensure long shelf life for those products are harmful for your health. Avoid those products as much as possible. Check all the products you buy for added sugar by reading the ingredients.
However, added sugar is not defined as “sugar” in labels of many products. Alternative titles are “dextrose, maltose, galactose, fructose, sucrose, saccharose”.

Health from the sea

We should make some room in our kitchen for health from the sea!
Cold-water fishes, such as herring, sardine, mackerel, salmon –especially if not supplied from fish farms- are very rich in omega 3. You can eat all kinds of meat and fish without need of bread in a ketogenic diet.

You can add linseed oil, olive oil, palm oil or coconut oil to flavor meats and increase their nutritional value.

Small Snacks

Is there no room for dried fruits and nuts? 

Small snacks do good!

You can add nuts (walnut, Brazil nut, Macadamia nut) and oil seeds (sunflower seed, flaxseed, hemp seed, and sesame) to your diet. They not only offer different tastes, but they are also beneficial, as they are rich in quality fatty acids.

However, not all dried nuts are in the same category.

Especially, cashew nut is not in this group, as its carbohydrate content is high. Flaxseed and hemp seed are especially rich in Omega-3. You can add side dishes to the curd cheese and salads to enrich the taste. Hemp seed and oil is easily available in markets that sell natural products.

You also need a good source of fibers and vitamins. Ok, let’s discover vegetables.
Green vegetables (broccoli, spinach, asparagus, zucchini, cucumber, cabbage and green bean), tomato, raw carrot, non-sweet pepper and all species of lettuce turn into delicious and extremely healthy side dishes for meats.

Your blood glucose is elevated by vegetables rich in starch, such as cooked carrot, sweet pea, white beans, lentils and corn. Therefore, you need to avoid this group of foods.


Colored and sour fruits are allowed!

Sweet ones that store sugar are excluded!

Although fruits are very delicious and almost a store of vitamins, you need to act carefully. They contain high concentrations of glucose and fructose.

However, strawberry varieties, such as strawberry and blackberry, are very important, as they have low carbohydrate and fight the cancer.

You can add small amount of garden strawberry and other strawberry varies to your daily fruit consumption.

However, a serving weighing >6 g is not allowed. Our tables will help you on this issue. It is very logical to avoid canned fruits. Their vitamin content is low and they also contain sweeteners. On the other hand, frozen fruits are a good option as no sweetening agent is used. You need to avoid dried grape and any and all dried nuts and fruit juices. They contain concentrated sugar.

OK, how about chocolate?

If you really like chocolate and believe that it makes you feel happy, you do not really stay away from chocolate. You can eat small pieces of bitter chocolate such that 3 to 4 grams are not exceeded in one day of the week. Prefer chocolates with cacao content equal to or above 80 percent.


Drinking plenty of water is a prerequisite of your diet!

Daily water ingestion is very important. You need to drink 2 to 3 liters of liquid per day to ensure your kidneys are healthy, prevent kidney stones and avoid formation of ketones. Water should be your primary preference. Herbal teas and green tea are also options. However, there is no liquid that can substitute water. No sugar should be added to herbal teas. Numerous studies showed the effect of green tea that prevents cancer. You can drink 6 glasses of green tea per day. You may drink coffee, but you should prefer cream and whitener rather than milk.

You need to be careful if you like to drink fruit soda water. They contain sugar. You can add a small amount of fruit soda water (around 1/10) into your glass and fill in the rest with ordinary soda water. Fresh squeezed fruit juices are allowed. Undoubtedly, in a reasonable manner.

For a more successful treatment

Convenience concentrated foods have hidden sugar content. They will harm you!

You should not drink convenience fruit juices. No alcoholic drinks, ice-tea or lemonade is allowed. Even if you want to consume alcohol, try to avoid whenever possible; you need to avoid especially beer due to its high carbohydrate content. You may prefer red wine. Red wine can be preferred, as it contains phytochemicals. You need to avoid milk and drinks that contain milk.
We believe that you already understood ketogenic diet?

Ketogenic diet is not based on the principle of weight loss. It aims modifying the body metabolism and tumor cachexia, also known as abnormal weight loss. As you have already recognized, we added meat, fish, fats, cheese and soy products to the allowed side of your dish and you are treated extremely generously.

If you want to gain weight, you need to increase amount of fat, especially MCT, in your diet. If you want to lose weight, you can decrease amount of fat. You can add abundant oil and balanced and healthy amount of salt, pepper, different vinegars, roasted hazelnuts, flaxseed and hemp seed or sesame in your salads.

Reminders and meanings of table colors:  You always need to remember that when you review the attached files, the green list includes optimal options or foods with no or low carbohydrate, the yellow list covers foods and carbohydrates that are significant for the diet and the orange list addresses vegetable oil.

Now, it is time to take action! You can do it! We are with you!

Green list: Eat as much as you can 

Green list: You can eat as much as you can, but you need to calculate carbohydrate values of vegetables.






Game animal


Deer etc.


Asparagus                  Avocado  Broccoli

Brussels sprout        Cabbage                    Cauliflower

Celery       Chicory     Lettuce    Cress

Cucumber                  Eggplant  Fennel

Green beans             Cabbage

Chard        Onion       Leek          Radish

Red cabbage             Pickled cabbage

 Curly Lettuce            Zucchini   Tomato



Carp          Pacific cod                  Eel                    Haddock

Oil Fish     Herring     Mackerel

Red sea bream         Black sea sprat                    Salmon     Shark

Trout         Tuna          Sea bass

Lettuce and green vegetables

Lettuce varieties


Rumex crispus

Lollo rosso

Garden rocket

Pepperweed etc.


All natural mushrooms

White mushrooms  Shiitake

Porcino    Truffle

Lettuce and green vegetables

Lettuce varieties      Chicory

Rumex crispus          Lollo rosso

Garden rocket          Pepperweed etc.

Nuts and Seeds

Brazil nut                     Hemp seed

Flaxseed Macademia nut

Fats and oils

Animal fats                 Argan oil

Butter       Hemp seed oil

Grape seed oil          Flaxseed oil

Olive oil    Pumpkin seed oil

Walnut oil etc.

Sea Mollusks

Octopus   Clam          Mussel


Chicken egg


Ham          Salami       Fried meat


Alpine cheese           Gouda

Dutch cheese            Sweden   Goat

Mozerella                   Parmesan                    Roquefort cheese

Sheep cheese           White cheese

Marine crustaceans

Shrimp     Lobster    Crab


Daily Products



Yellow list: Carbohydrate contents


Acerola (Barbados) cherry)

Sweet Melon







Damson plum




Black currant





Red currant











Passion fruit

Water melon








Carbohydrate in 100 g







Carrot, raw











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