Naturally, patients diagnosed with cancer grasp at any diet or complementary therapy promising to promote survivorship and clinicians are used to fielding questions about different diet fads.
Currently, word of the ketogenic diet's ability to "starve" cancer cells of the glucose they need to proliferate is spreading on the Internet. Less frequently, patients are asking about fasting before chemotherapy and calorie restriction. Others inquire about adapting popular diets like the Paleo, vegan, blood type and Gerson diets to combat cancer.
"In the last six months, we've seen an increase in interest in the ketogenic diet," confirmed Kristina Stodola, RD, LDN, clinical oncology dietician at Cancer Treatment Centers of America at Midwestern Regional Medical Center.
Ketogenic Diet Concerns
The ketogenic diet replaces carbohydrates with fats and moderate amounts of protein. As normal cells use ketone bodies when deprived of glucose, cancer cells do not have the ability to create ketones. The ketogenic diet forces the body to use more fat for energy, instead of sugar, by increasing fat and reducing carbs.
People undertaking the ketogenic diet typically eat butter, cream, peanut butter and other high-fat options. Carbohydrates, including fruits and vegetables, are limited, as are fluids.
The ketogenic diet has been shown to reduce epileptic seizures in children who have not responded to antiepileptic medicine, but doctors are not sure why. It eliminates the need for many medications, thus reducing the potential for side effects as well.
Some studies claim that four out of 10 children with epilepsy have reduced their seizures by half and some have even better results. As the ketogenic diet became accepted in the academic epilepsy community, patients with brain cancer wonder if they can expect a similar outcome.
Stacy Kennedy, MPH, RD, CSO, LDN, senior clinical nutritionist at Dana Farber/Brigham & Women's Hospital Cancer Care, worked at the National Institute for Health 20 years ago when the ketogenic diet was being reviewed for seizures. Even though the diet was found by the NIH to improve outcomes, Kennedy advises her oncology patients to keep the bigger nutrition picture in mind.
"Many components of the ketogenic diet's basic principles include processed meats, and high-fat foods inconsistent with a plant-based diet," she said. "My stance is to adapt the ketogenic diet to be more practical to follow."
Patients are usually relieved to learn they don't have to take the follow the diet so strictly. She reminds them that following an extreme diet can be socially isolating as well and a strong support system should take on paramount importance during cancer treatment.
"It's not all-or-nothing," Kennedy noted. "I tell patients to limit sugar intake and processed foods. Having desserts now and then won't be detrimental on its own though."
Kennedy advocates for a plant-based diet. "Aspects of the plant-based diet, like half a plate of vegetables and inclusion of natural high fiber and small, frequent meals are all in line with the ketogenic diet," she said.
At Midwestern Regional Medical Center, Stodola and Kim Gorsuch, RN, encounter a number of patients already so malnourished by treatment that they need supplemental nutrition. Even at this stage, questions about the ketogenic diet arise and both try to discourage it.
"I tell them they need everything they can get right now," said Gorsuch. "A lot of them are so malnourished they can't even get treatment."
Stodola reviews the research with her patients as a way of empowering healthy choices.
"We look at the one or two research studies on mouse models, data in humans and brain cancers being studied," she explained. "We review the role of the ketogenic diet in children with epilepsy and risks for patients with cancer. Largely, people are unaware of the risks."
Constipation is a concern because the diet is low in fiber. The lack of carbs results in increased fatigue. Weight loss can quickly give way to malnourishment with this diet, said Stodola.
If patients have already started the diet, Stodola ensures they're meeting energy needs and not losing too much weight. Problematic weight loss indicating malnutrition is defined as 2.5% of their body weight weekly, 5% monthly and 10% over a six-month period.
Calorie Restriction & Fasting
Malnutrition becomes a major worry when patients ask about calorie restriction and fasting before chemotherapy.
So far, Kennedy said only a few of her patients have directly inquired about calorie restriction. Calorie restriction has been shown in murine models of breast cancer to repress tumor growth in an additive manner during radiation therapy.
However, several family caregivers have mentioned their relative's appetite is decreased after chemotherapy and wondered if they shouldn't push food intake so much.
The concept is intriguing enough for Cancer Treatment Centers of America at Western Regional Medical Center to design an IRB-approved pilot study on the feasibility of short-term fasting on patients with newly diagnosed breast cancer. But it's still in Phase I and there are nothing else conclusive has been published on this diet yet.
"There's just not a lot of good data for us to respond to this right now," she said. "The studies have all been with mice. I tell patients an empty stomach is a huge trigger for nausea. If they reduce their calorie intake too much, they'll feel dehydrated, fatigued, and could end up immune compromised."
It's a different story with calorie restriction, which has been gaining traction since a NIH-funded clinical trial began on the effects of reducing caloric intake by 25% for two years on diseases associated with aging.
Thus far, there's no definition on the exact level when calorie restriction is helpful so the risks are still too great to initiate this plan for any patients.
"The science is interesting and people really can't wait for more research to come out," concluded Kennedy. "What patients can do at this point is be proactive but still evidence-based."
Robin Hocevar is on staff at ADVANCE. Contact firstname.lastname@example.org