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Can The Keto Diet Help Cancer Patients?

A high-fat ketogenic diet offers hope for cancer patients.

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Imagine Patricia Daly of Dublin, Ireland—fit and pretty, a nutritionist and former triathlete. But in 2008, at age 28, she faced a terrifying diagnosis: a melanoma in her right eye.

Often diagnosed on the skin, melanoma is one of the deadliest of all cancers. Daly underwent surgery and radiation treatment, which shrunk the tumor. In the process, she lost her peripheral vision, and doctors predicted she would lose sight in that eye in 12–18 months. By 2012, she had developed cataracts and retinopathy. And the tumor was growing back.

Although her doctors discouraged her, Daly dug into the nutritional and medical literature and learned about the ketogenic diet. The diet—which is, incredibly, about 80 percent fat—might seem counterintuitive. After all, vegetables and fruits are often recommended for cancer prevention and to support recovery. But the ketogenic diet does have a scientific rationale and foundation.

A Different Approach

People have proposed any number of diets for cancer patients. Most have been extrapolated from personal experiences and with the best of intentions. These diets seem to work for some people, but few of them have undergone rigorous scientific study. That leads to the question: if you’re a cancer patient, are you willing to bet your life on a particular diet?

What makes the ketogenic diet different is a clear scientific understanding of how it works, along with an increasing number of studies and patient reports demonstrating its benefits. Doctors have known for decades that extremely high-fat diets can benefit children with epilepsy. High-fat ketogenic diets shift the metabolism of brain cells from glucose (blood sugar) to ketones, a byproduct of fats.

The jump from treating refractory epilepsy to cancer occurred in the mid-1990s, when doctors at Case Western Reserve University in Cleveland treated two children who had both epilepsy and brain cancer. When the children were placed on a ketogenic diet, their cancers shrunk.

Since then, Thomas Seyfried, PhD, a researcher at the Boston College campus in Chestnut Hill, Mass., has emerged as the leading advocate of ketogenic diets. His sincerity quickly comes across in conversation and, as a scientist, he’s methodical and confident that his research is on the right track. “The ketogenic diet is not a cure,” Seyfried emphasizes. Nor is it a fad. “This is a medical therapy.”

The Ketogenic Rationale

As you might expect with a weight-loss diet, the diet consists of unprocessed, whole foods that are dense in nutrients, rather than calories. But it also has a unique characteristic: carb timing. “You can use carbohydrates almost as a trellis or a guide to move cortisol back to its healthy rhythms,” says Seyfried.

The argument for the ketogenic diet as an adjunct cancer treatment dates back to Nobel laureate Otto Warburg, who correctly theorized in the 1920s that cancers were driven by mutations in cellular energy factories called mitochondria. Normal cells produce energy by using oxygen to burn (or oxidize) glucose for energy. Not so for cancer cells, which ferment glucose in an oxygen-free environment—a totally different process. Cancer cells live on a perpetual glucose feeding frenzy.

While the body makes glucose mostly from sugars and other carbohydrates, ketones are derived from fats. All healthy cells can use both glucose and ketones as fuel for energy production. However, cancer cells cannot use ketones as a fuel. So when a person adopts a ketogenic diet, several changes occur. Ketone levels increase, and glucose levels decrease. Cancer cells are starved, or they self-destruct. Seyfried says that ketones have still other anti-cancer properties, and they are also anti-inflammatory—important because inflammation also drives the growth of cancers. “Ketones are a natural product,” Seyfried points out. “We evolved to burn them.”

Patient Responses

In 2008, Seyfried collaborated with Italian doctors who used the ketogenic diet to treat a 65-year-old woman diagnosed with glioblastoma, a deadly and difficult-to-treat form of brain cancer. The patient first went on a several-day, water-only fast, which is the ideal prelude to the ketogenic diet. Fasting also boosts ketone levels and lowers glucose, and serves as an “induction phase” for the ketogenic diet.

The patient also underwent conventional radiation treatment and took vitamin and mineral supplements
to prevent deficiencies. Two months later, she had lost 20 percent of her body weight, and sophisticated medical scans could find no traces of the brain tumor. As expected, her ketones increased while her glucose decreased. All was fine until 10 weeks after the woman went off the ketogenic diet—and the tumor grew back.

Seyfried says that brain tumors are particularly good to study because there are no really good conventional treatments. And both animal studies and a growing number of case reports—from Seyfried’s lab, medical doctors, naturopathic physicians, and patients—show that the ketogenic diet works very well against a variety of cancers.

“The diet will work against pretty much every cancer, because it exploits a common cellular defect in all types of cancer,” Seyfried says. “Some people and cancers respond better than others, but all do respond.” Although he admits that we are still in the early stages of using the ketogenic diet as a cancer therapy, there’s already clinical evidence that it can help people with non-small cell lung, breast, colon, and pancreatic cancers.

Making time for adequate sleep and managing stress are essential to resetting healthy cortisol rhythms, but following the reset diet will improve your sleep and make your body more resilient to stress. And it can reduce the impact of hormonal changes as women approach menopause and men experience andropause.

High-fat ketogenic diets shift the metabolism of brain cells from glucose (blood sugar) to ketones, a byproduct of fats.

Practical Guidelines

Like any therapeutic diet, the ketogenic diet is best adopted under the supervision of a knowledgeable physician, and many naturopaths now understand and recommend the diet for cancer patients. The diet is very restrictive, so it requires a clear commitment—and sometimes a reminder that a restrictive diet is better than dying. And it’s not suited for everyone. Cancer patients with severe muscle wasting probably won’t do well on the diet because they have already lost a substantial amount of weight.

The diet is best preceded by a four-to-seven-day water-only fast, which will significantly boost ketone levels. The ideal dietary ratio is four parts fat to one part of combined carbohydrate and protein, although many people transition from a 2:1 to a 3:1 and then to a 4:1 ratio. In other words, fat calories should be four times the combined amount of protein and carbohydrate calories.

Those fats can include saturated fat, coconut oil, butter, and cream, along with a little fish, meat, and avocados. Supplemental medium-chain triglycerides (MCTs) are also helpful because the body converts them directly to ketones. Some people do better with some types of fats than others, consuming 2,000 calories a day, whereas other must limit intake to only 900 calories a day.

The key, says Seyfried, is not simply to boost ketone levels as high as possible. A patient must buy a combination ketone/glucose monitor to track both ketone and glucose levels. Ideally, ketones should be between 3 and 7 mmol/L, and glucose levels between 55 and 65 mg/dL at the same time. But Seyfried says that some patients have difficulty maintaining low glucose levels, possibly because of emotional stress. It’s also possible, he adds, that people who faithfully follow a ketogenic diet can reach a point that they no longer have to monitor their ketone and glucose levels every day.

“The diet will work against pretty much every cancer, because it exploits a common cellular defect in all types of cancer.”

Is the ketogenic diet forever? Not necessarily, says Seyfried, though he adds that it’s too soon to say so definitively. Some people do very well on the diet, and a very small number have gone off it or segued to an Atkins-like version without a recurrence of cancer. “It depends on how the patient is doing, and how the tumor is growing,” says Seyfried. Sometimes, people have to go off the diet for a few weeks to regain some of their lost weight.”

Finally, several alternative therapies appear to enhance the anti-cancer effect of the ketogenic diet. They include high-dose intravenous vitamin C and hyperbaric oxygen therapy. In addition, high doses of some supplements, including coenzyme Q10 and curcumin, appear to have anti-cancer properties.

Additional Resources

Several excellent ebooks are available to help people adopt the ketogenic diet. Other options include keotgenic diet recipe books for epilepsy:

  • Practical Keto Meal Plans for Cancer, by Patricia Daly;
  • Fight Cancer with a Ketogenic Diet, by Ellen Davis;
  • Get Started with the Ketogenic Diet for Cancer, by Miriam Kalamian;
  • Health-care professionals should read Cancer as a Metabolic Disease, by Thomas Seyfried.

To find a naturopathic physician experienced in oncology, visit