Glioblastoma multiforme (GBM) is a very aggressive and hard-to-treat brain cancer. Even with improvements in surgery, radiation, and chemotherapy, most patients don’t survive long, so researchers are looking for new ways to fight it. One idea gaining attention is the ketogenic diet, a high-fat, low-carb eating plan, and whether it could help manage GBM.
A recent study in Frontiers in Nutrition (Kiryttopoulos et al., 2025) suggests that this diet might help some GBM patients. However, it’s important to be careful and talk to your doctor or oncologist before trying any major diet changes. Cancer is complex, and what works for one person might not work for another. The ketogenic diet isn’t a guaranteed solution for everyone and one should always consult a professional in the field of cancer before taking on any diet.
What is Glioblastoma and Why is it so Difficult to Treat?
Glioblastoma is the most common and aggressive type of brain tumour in adults. It grows quickly, spreads into nearby brain tissue, and has a lot of variation in its genetic and metabolic makeup. The standard treatment involves surgery to remove as much of the tumour as possible, followed by radiation therapy and chemotherapy using a drug called temozolomide. However, treating glioblastoma is very challenging for several reasons.
First, it’s often hard to remove the entire tumour with surgery because doing so could harm important brain functions. Second, the tumour cells can spread widely throughout the brain, making it difficult to target all of them. Third, the cancer cells can become resistant to radiation and chemotherapy, reducing the effectiveness of these treatments. Finally, glioblastoma cells are highly adaptable and can switch between different energy sources to survive, which makes them even harder to treat. These factors contribute to the tumour’s tendency to come back after treatment.
The Ketogenic Diet: A Metabolic Approach to Cancer Therapy?
The ketogenic diet is a high-fat, very-low-carb eating plan that changes how the body gets its energy. Normally, the body uses glucose (sugar) as its main fuel, but the ketogenic diet forces it to switch to using ketones, which are made when the body breaks down fat. This shift has several effects: it lowers blood sugar levels by cutting back on carbs, increases ketone levels as an alternative energy source, and changes how the body’s metabolism works, affecting energy production and cell growth.
The idea behind using the ketogenic diet for cancer treatment comes from something called the Warburg effect. This is when cancer cells rely mostly on glucose for energy, even when oxygen is available, because their energy-producing systems (mitochondria) often don’t work properly. By reducing glucose and increasing ketones, the ketogenic diet tries to starve cancer cells of their main energy source, take advantage of the differences between cancer cells and healthy cells, make cancer cells more vulnerable to treatments like radiation and chemotherapy, and change the environment around the tumour to slow its growth and spread.
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Key Findings of the Glioblastoma Study
A study published in Frontiers in Nutrition looked at how a ketogenic diet affects tumour growth in 18 patients with glioblastoma (GBM) over eight years, from January 2016 to January 2024. Although the study had some limitations, it provided interesting results. Out of the 18 patients, only 6 stuck to the ketogenic diet for more than 6 months. Among those who followed the diet, 66.7% had a significantly higher survival rate compared to just 8.3% of those who didn’t stick to the diet.
This difference in survival rates was statistically noteworthy (66.7% vs 8.3%) (p < 0.05). The ketogenic diet was carefully monitored, with a focus on increasing the fat-to-protein and carb ratio to 3:1, aiming for ketone levels above 3.5 mM/L and glucose levels below 80 mg/dL. These findings suggest that a ketogenic diet might help some GBM patients live longer if they can follow the diet consistently. However, the study used a small test group, so researchers consider the results inconclusive and advise interpreting them with caution. Scientists need to conduct more research to fully understand the relationship between keto-diets and cancer treatment.
Important Considerations and Caveats
While the study’s results are promising, there are important factors to consider before trying a ketogenic diet for glioblastoma (GBM) or any other cancer. Most importantly, talk to your doctor or oncologist before taking up any diet, especially in relation to cancer treatment. A ketogenic diet is a big change and can affect your body either positively or adversely. Your doctor can help decide if it’s right for you based on your medical history, current treatments, and overall health. They can also guide you on how to follow the diet safely and effectively.
It’s also important to remember that cancer isn’t one single disease. Different cancers have different characteristics, so what works for GBM might not work for other types of cancer and could even be harmful. The ketogenic diet might help GBM because of how these tumors use energy, but it may not be safe or effective for everyone. If you try the ketogenic diet, you should do so under close medical supervision.
Your doctor can monitor your blood sugar and ketone levels, adjust your medications if needed, and help manage any side effects. Sticking to the diet is also key. The study showed benefits only for those who kept consistent with continuing on the diet. This could be challenging because the diet does require major lifestyle changes. You also need to make sure the diet provides all the nutrients your body needs. A registered dietitian can help plan meals and recommend supplements to avoid deficiencies.
Conclusion
Be aware that the ketogenic diet may cause side effects such as fatigue, headaches, nausea, constipation, or kidney stones, but you can often manage these with proper hydration, electrolytes, and diet adjustments. Finally, the ketogenic diet should not replace standard cancer treatments like surgery, radiation, or chemotherapy. Instead, it should be seen as an addition to these treatments that might help improve their effectiveness
The ketogenic diet could be a helpful addition to treatment for glioblastoma (GBM), but it’s not a cure-all, and it may not work for everyone. The Frontiers in Nutrition study adds to the evidence that the diet might help some GBM patients live longer if they can stick to it consistently. However, it’s important to be careful with this information and talk to your doctor or oncologist before making any big changes to your diet. Cancer is complicated, and the ketogenic diet should only be used as complimentary aid to your treatment plan, that’s closely monitored by your medical team.
Disclaimer: This information is not intended to be a substitute for professional medical advice, diagnosis or treatment and is for information only. Always seek the advice of your physician or another qualified health provider with any questions about your medical condition and/or current medication. Do not disregard professional medical advice or delay seeking advice or treatment because of something you have read here.
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