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Specialist diets and brain tumours

There’s no evidence to show that any specialist diet can control or treat brain tumours.

Our Support team are often asked about whether specialist diets can help treat brain tumours. So, we’ve summarised some of the diets and dietary supplements our community have asked us about the most.

You should always talk to your doctor or dietitian before making any significant changes to your diet.

On this page, we’ll discuss:

Alkaline diet for cancer?

There’s no research to support the use of an alkaline or acid diet in brain tumour or cancer treatment.

Some people think that by changing your diet, you can alter the acidity around the cell, making it alkaline and killing the cell. This idea is based on tumour cells creating a slightly acidic environment around them.

But, it’s not possible to do this through diet. This is because the body’s acid/alkaline level (known as its pH balance) is very tightly regulated. It’s kept within a very narrow range by your kidneys and lungs. 

This narrow range is because even a small change above or below the safe range can make you very unwell. It can even be life-threatening. 

Your pH balance isn’t actually affected by what you eat, so there’s no benefit to trying to create an alkaline diet. Similarly, the pH level of your urine isn’t related to the levels in your blood. So, testing the pH levels of your urine won’t tell you the pH levels in your blood.

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Ketogenic diet

There is currently no scientific evidence to show that the ketogenic diet is effective in treating brain tumours.

Find out more

Mediterranean or rainbow diet

Mediterranean and rainbow diets are both based on having lots of different types of vegetables and fruit in the diet. This makes sure you’re eating a good mixture of phytochemicals.

Phytochemicals are chemical compounds that occur naturally in plants. They’re packed with substances called antioxidants, like vitamins C and E. 

There’s growing evidence that phytochemicals and antioxidants help to protect us from a variety of diseases, such as cancer and heart disease. 

The rainbow diet involves eating different coloured fruits and vegetables, which provides a variety of phytochemicals. 
The Mediterranean diet also has lots of fruit and vegetables, as well as plenty of fish, beans and pulses, small amounts of lean meat and some dairy foods. It also replaces saturated fats, like butter, with healthy fats, like olive oil.

This is the type of diet we should all be aiming to have and is recommended for everyone.

Organic diet

Some studies have shown that organic fruit and vegetables may have less contaminants and increased levels of some vitamins and minerals.

However, there’s no evidence that organic foods are better for brain tumour or cancer patients.

We should all aim to eat at least 5 portions of fruit and vegetables per day. They can be fresh, frozen, dried or tinned, but all fresh fruit and vegetables should be washed well before eating, whether they’re organic or not.

Sugar-free diet

There’s no need to cut sugar from your diet, unless you’re trying to lose weight (which isn’t recommended for anyone with an active tumour or who’s undergoing active treatment for a brain tumour).

Some people think that by reducing their sugar intake, they will prevent sugar from getting to the tumour cells and starve them of their energy, causing the cells to die. 

This is because research has shown that tumour cells use more glucose (a type of sugar) than normal cells, as they’re less efficient at turning the glucose into energy.

However, glucose is the main source of energy for all the cells in our bodies and our bodies will not usually allow these levels (known as blood sugar levels) to get low enough to starve the tumour cells. 

If your blood sugar levels get too low, you body will release glucose stored in your liver or “make” glucose from other nutrients by breaking down muscle and fat stores.

In addition, cutting out sugar from your diet, if done to the most restrictive level, involves cutting out most fruits and starchy vegetables. This type of diet can be difficult to follow and often leads to weight loss, nutrient deficits, nausea and constipation.


The government and World Cancer Research Fund (WCRF) all recommend that we reduce the amount of red meat and smoked or cured meat we eat and move towards a more plant-based diet.

This advice is based on reducing the risk of developing bowel cancer and improving heart health, by reducing the amount of saturated fat in your diet.

Vegan diets tend to be lower in saturated fats and higher in fibre, but to be well balanced they need to be carefully planned. You may need to take a vitamin and mineral supplement to help maintain a healthy diet.

To gain some of the benefits of a vegan diet and to increase your fruit, vegetable and fibre intake, try planning a few meat-free days per week.

Download our diet factsheet

Diet factsheet – PDF

Find out more about Diet and brain tumours in the full fact sheet.

If you have further questions, need to clarify any of the information on this page, or want to find out more about research and clinical trials, please contact our team:
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