While cancer is caused by many factors, diet, in particular, has a profound effect on a person’s risk.
In a recent review published in JAMA Oncology, researchers compared the two popular diets to see which one had more evidence supporting its potential to lower cancer risk and improve the health of cancer survivors.
The winner: Plant-based.
High in fat
Moderate in protein
Low in carbohydrates
Low in fat
Moderate-to-high in carbohydrates
Study author Urvi Shah, MD, a hematologic oncologist at Memorial Sloan Kettering Cancer Center, told Verywell the review was challenging because of the volume of studies dedicated to keto diets for cancer compared to whole food plant-based diets. But using the clinical trial data they had, researchers determined a plant-based diet can better negate several risk factors for cancer, including excess fat, inflammation, insulin resistance, and elevated levels of insulin-like growth factor 1 (a protein known to promote cancer development).
Plus, because plant-based foods are also rich in phytochemicals (plant chemicals) such as flavonoids, they offer cancer-fighting antioxidant and anti-inflammatory effects, Shah said.
A whole food plant-based diet is focused on nutrient-dense plant-based foods, like nuts, fruits, vegetables, and beans. It’s low in fat with a moderate-to-high intake of carbohydrates. People who follow this diet also limit their intake of processed foods, oils, and animal products.
A keto diet, on the other hand, focuses more on the macronutrients consumed than specific food choices. Overall, a keto diet is high in fat, moderate in protein, and low in carbohydrates.
The study authors defined a ketogenic diet as one that is rich in animal proteins with some starchy vegetables.
If the evidence favors a whole plant-based diet, are there any benefits to going keto? According to Laura Dority, MS, RD, LD, a registered dietitian who specializes in the ketogenic diet, the first thing to understand is that not all keto diets are created equal. In fact, some can rely heavily on plants.
Dority said that the phrase “ketogenic diet” is more of an umbrella term for different aspects of fat intake. One person’s keto diet may be heavy in animal-based saturated fat. But another person’s keto diet may emphasize plant-based fats, such as olive oil and avocado.
Both diets can provide the correct quantities of macronutrients to achieve ketosis—the desired effect of using fat for energy.
“There is no rule that says a ketogenic diet has to include animal products,” Dority said. “The human body can achieve ketosis with plant foods only when they are well-chosen.”
If you want to follow a keto diet that offers some of the benefits of a whole food plant-based diet, focus on incorporating:
Dority added that a keto diet may offer unique physiological benefits to people with cancer—specifically, through what’s known as the Warburg effect.
“Most cancer cells need large amounts of glucose for survival,” she said. “So, the theory of reducing carbohydrates (glucose) to help combat cancer has now flowed from a treatment approach into using this diet as a prevention tool.”
At the end of the day, Shah reminds people not to overcomplicate their dietary choices.
“When in doubt, remember that if a food is derived from plants and not processed, it is most likely going to have beneficial effects on one’s overall health, risk of obesity, diabetes, and risk of cancer,” said Shah. “Therefore, it is best to prioritize these foods, which include legumes, seeds, nuts, whole grains, fruits, and vegetables, and make this the bulk of your meals.”
Both a ketogenic diet and a whole foods plant-based diet may offer health benefits in the oncology world, but marrying the two dietary patterns to create a lower-carb/higher fat plant-based whole food eating pattern could be the “sweet spot” for people trying to lower their cancer risk or support their health after having cancer.
That said, if the approach is too restrictive, emphasizing nutrient-dense foods and limiting refined sweets and carbohydrates is a healthful step.