# Nutrition and diets in brain tumors
In brain tumors, nutrition plays a supportive role. This tab discusses which dietary patterns have been studied and what is known about them. Nutrition can influence inflammatory processes, cellular energy metabolism and treatment side effects, but is never a replacement for medical therapy.
Ketogenic diet
ResearchediPositive results in clinical studies, not yet standard treatment
The ketogenic diet is a pattern in which the body burns mostly fats instead of carbohydrates. This leads to the formation of so-called ketones, substances that the brain can use as fuel. The diet is high in fats, moderate to low in proteins, and very low in carbohydrates.
In brain tumors, especially malignant gliomas (such as glioblastoma), laboratory evidence has been found that ketones may slow tumor growth by changing energy availability and dampening inflammatory reactions. A systematic review from 2026 on ketogenic diet and malignant gliomas collected available studies and concluded that there is potential interest, but human research is still limited. Most data come from test tube and animal studies.
The ketogenic diet requires great caution in patients undergoing chemotherapy or radiotherapy. It can intensify certain side effects, affect weight, and interact with medications. Long-term adherence to this diet requires continuous medical supervision, as vitamins and minerals may be insufficient and certain nutrients may be lacking.
Omega-3 fatty acids (plant-based and from fish)
ResearchediPositive results in clinical studies, not yet standard treatment
Omega-3 fatty acids are essential fats found mainly in fatty fish, flaxseed and certain plant-based oils. They play a role in inflammation regulation and healthy functioning of brain tissue.
Research on omega-3 fatty acids in brain tumors is still in an early phase. Laboratory studies do provide evidence that certain omega-3 components have neuroprotective properties — that is, they can help protect nerve cells from damage. A 2026 study examined omega-3 fatty acids in relation to brain development and nerve function. This data does not directly apply to brain tumors in patients, but suggests a possible supportive effect.
The use of omega-3 supplements can interact with blood thinners or certain chemotherapy agents. Consult with your healthcare provider for safe use.
Antioxidant-rich foods (vegetables, fruit, herbs)
ResearchediPositive results in clinical studies, not yet standard treatment
Antioxidants are substances found in vegetables, fruit, herbs and certain plant-based foods. They can protect cells against harmful free radicals and inflammatory processes.
Recent studies provide evidence that certain natural substances — such as phenolic metabolites from plants (2026) and lycopene from tomatoes — have potentially neuroprotective effects in cell models. These substances can reduce inflammatory reactions in the nervous system. Sarsasapogenin (a plant substance) also shows neuroprotective effects in laboratory models.
This research is still mainly in laboratory and animal phases. Whether there is direct benefit for brain tumor patients has not been demonstrated. However, a dietary pattern rich in vegetables and fruit — such as the Mediterranean diet pattern — is associated with less inflammation in the body, which can have a supportive effect. Note: certain antioxidant-rich supplements can interact with chemotherapy or radiotherapy, especially if these therapies themselves use reactive oxygen to damage tumor cells.
Periodic fasting
ResearchediPositive results in clinical studies, not yet standard treatment
Periodic fasting (intermittent fasting) means going without food or eating very little during certain periods. Common forms are intermittent fasting (for example 16 hours fasting, 8 hours eating window) or alternate-day fasting (fasting every other day).
A 2026 study shows that periodic fasting, specifically alternate-day fasting, can have sex-specific anti-inflammatory effects through certain pathways (TLR4 and leptin signaling). This data comes from animal research. Theoretically, disrupting energy metabolism through fasting could influence tumors, but direct research in brain tumors is scarce.
Fasting during chemo- or radiotherapy can be risky: it may worsen malnutrition, intensify side effects, and hinder the healing process. Many brain tumor patients already struggle with weight loss, poor appetite, or swallowing difficulties. Periodic fasting is generally not recommended under these circumstances without intensive guidance.
High-protein nutrition
ResearchediPositive results in clinical studies, not yet standard treatment
High-protein nutrition consists of adequate intake of fish meal, meat, eggs, dairy, legumes, and nuts. This supports muscle maintenance and cell repair.
In brain tumors, adequate protein intake can be important because chemotherapy and radiotherapy break down cells and the body needs recovery. Research on direct anti-tumor effects of protein specifically for brain tumors does not exist, but adequate protein intake is essential for overall health during treatment. Patients often lose weight and muscle tissue; sufficient protein helps counteract this.
High-protein nutrition is generally safe, but certain forms (much red meat) can add inflammation-related substances. With kidney dysfunction or certain medications, the amount sometimes needs adjustment.
Mediterranean dietary pattern
ResearchediPositive results in clinical studies, not yet standard treatment
The Mediterranean diet pattern is based on traditional cuisine around the Mediterranean Sea: plenty of vegetables, fruit, grains, oil (especially olive oil), fish, legumes, moderate amounts of dairy, and very little red meat.
This pattern is extensively studied and appears to lower inflammation levels in the body. Although no direct research on brain tumors exists, the pattern is generally associated with better neurological health and fewer chronic inflammations. This can work supportively alongside medical treatment.
The Mediterranean pattern is safe alongside chemo- and radiotherapy, as long as intake is well adjusted to appetite and side effects.
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**In conclusion:** nutritional choices with brain tumors are highly individual and depend on the tumor type, treatment, side effects, resilience, and medical circumstances. What is supportive for one person may be unsuitable for another. A dietitian specialized in oncology can help create a customized plan that aligns with treatment and health.
_This information never replaces the judgment of a doctor. Always discuss your dietary choices with your own healthcare provider or dietitian._