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Brain Cancer and The Ketogenic Diet: What You Need to Know


The ketogenic diet isn’t just for weight loss. In fact, the keto diet began as a nutritional treatment for children with epilepsy in the early 20th century. Now, doctors and researchers are looking at this super low-carb diet to help battle other diseases and conditions. 

And one of the better-studied ones is brain cancer.

Normal brain cells can survive on ketones, but most cancer cells can’t.

This insight has led to an interest in ketosis and the keto diet from neuro doctors, scientists, and brain cancer patients.

Learn what current evidence says about the effects of a ketogenic diet on brain cancer, including whether keto can help prevent or treat brain tumors.

What is Brain Cancer?

Any cancerous tumor of the brain is called brain cancer. Another name for a fast-growing brain tumor that contains cancer cells is malignant brain tumor.

However, some brain tumors are benign, meaning they are not cancerous. (Today, though, we’re only discussing brain cancer, not benign brain tumors.)

Primary brain cancer begins in the brain, while secondary brain cancer is the result of metastasis. Metasis is when cancer starts in one place, then spreads to another–in this case, the brain. 

Some of the most common brain cancer symptoms include[*]:

  • Headaches, particularly in the morning
  • Nausea and vomiting
  • Changes in speech, hearing, or vision
  • Problems with gait or balance
  • Difficulty with memory or cognition
  • Weakness
  • Sleepiness
  • Mood or behavior changes
  • Seizures in people who don’t usually have seizures

Doctors diagnose brain tumors using neurological exams followed by scans, tests, or biopsies.

If you receive a brain cancer diagnosis, standard treatment may include “watchful waiting,” radiation, surgery, chemotherapy, targeted drug therapy, or immunotherapy[*]. People commonly combine multiple treatments.

What is the Ketogenic Diet?

The ketogenic diet, or keto for short, is a specialized high-fat diet that’s extremely low in carbs. Many keto aficionados use the diet for weight loss, better brain function, and more energy. 

Compared to other diets, keto is unique because it forces your body to rely on fat for fuel. And as a result, your liver produces ketones, which are responsible for many of the health benefits of going keto.

Some medical keto diets, such as the ones doctors prescribe for children with epilepsy, are more severe. They usually include approximately 90% fat, 10% protein, and as close to zero carbs as possible[*].

Read more: How to get into ketosis painlessly

Can Keto Prevent Brain Cancer?

There is no direct evidence yet proving that the keto diet can prevent brain cancer.

However, there is evidence that the keto diet can inhibit the growth of some types of cancer cells[*]. 

Most (but not all) cancer cells use glucose (sugar) as their primary fuel source[*]. As a low-carbohydrate diet, keto may stop undetected cancer cells from growing by starving them before they progress[*].

Additionally, keto may reduce your brain cancer risk by decreasing certain risk factors. For example:

  • Elevated insulin levels are a risk factor for brain tumors in women[*]
  • High fasting blood glucose levels are a risk factor for brain tumors in women[*]
  • Obesity is a risk factor for brain tumors overall, including meningiomas and gliomas for women, and meningiomas for men[*

Keto might lower your risk because it can reverse insulin resistance and help support a healthy body weight[*].

Yet another way keto could help prevent cancer, possibly including brain cancer, is by promoting autophagy. 

Autophagy is the scavenging and recycling of old, mutated, or damaged cells in your body. Going keto appears to increase autophagy, including in the brain, which may have an anti-cancer effect[*][*].

Can Keto Help Brain Cancer Patients?

Compared to the topic of prevention, there’s more scientific data on using keto for brain cancer treatment. Here’s what the current evidence says.

According to a 2018 review from the journal Aging, the strongest evidence for keto diet suppressing growth of tumor cells occurs in cases of glioblastoma multiforme[*]. In contrast, the use of keto for astrocytoma and medulloblastoma had weak or no evidence.

Some types of cancer may be able to use ketones for fuel[*]. But current evidence suggests brain tumors rely on glutamine (an amino acid) and glucose for fuel, but cannot use ketone bodies[*].

When used as a metabolic therapy to starve glioblastoma cells and support the health of the brain and body, some researchers think the keto diet may improve patient outcomes[*].

A safety and feasibility study published in 2019 found that keto was feasible and safe as an adjuvant to chemo for patients with glioblastoma[*].

Unfortunately, there are no large, randomized controlled trials (yet) that establish survival rates for brain cancer patients who go keto.

Perhaps most importantly, some evidence suggests that keto may enhance the effects of other treatments like chemotherapy or radiation therapy[*].

Keto is safe for the vast majority of cancer patients, and it also has positive effects on body composition and quality of life[*]. 

The Takeaway

Early evidence for keto and brain cancer is promising, but not definitive. 

In the future, molecular studies and randomized clinical trials will add to our understanding of how keto works and the most effective ways to use it for brain cancer.

But for now, all we know for sure is that it’s safe and appears to increase cancer patients’ quality of life without unpleasant side effects.

Keto may prolong survival by starving cancer and making it more susceptible to other cancer therapy, but it’s never a good idea to jump to conclusions without solid evidence. Plus, every body is different.

By the same token, there’s no reason to avoid keto — whether or not you have brain cancer.

If you do have brain cancer and want to try keto, let your doctors know. Although evidence suggests the keto diet may help standard of care treatment options work better, you’ll definitely get better results if everyone in your support group is on the same page.

And if you’ve never gone keto before but plan to raise your ketone levels as part of your treatment plan, speak to a keto-knowledgeable dietitian or physician for support. 

Read next: The Ultimate Guide to Starting the Keto Diet

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