Dr. Seyfried has spent decades studying cancer metabolism. He argues that cancer is fundamentally a metabolic disease, with impaired mitochondrial energy metabolism playing a central role in the development and growth of cancer.
His work builds on the Warburg effect—the observation that many cancer cells consume unusually large amounts of glucose and rely heavily on fermentation even when oxygen is available. Seyfried also emphasizes glutamine as an important fuel for many cancers.
Based on this theory, Seyfried proposes metabolic therapy aimed at restricting the fuels cancer cells depend upon while placing less stress on healthy cells. His research has investigated ketogenic diets, fasting, glucose reduction, glutamine-targeting drugs, and other metabolic approaches.
The metabolic theory of cancer is an important and active area of research, but Seyfried's therapeutic approach has not been established as a treatment for prostate cancer. Much of the evidence for his specific strategy comes from laboratory and animal studies, with human research still developing.
Nearly a century ago, Nobel Prize-winning scientist Otto Warburg observed that cancer cells often process energy differently from normal cells.
Most healthy cells rely heavily on their mitochondria and oxygen to produce energy. Many cancer cells, however, consume unusually large amounts of glucose and convert much of it to lactate through fermentation, even when oxygen is available. This is known as the Warburg effect.
This unusual glucose metabolism is well established and has practical importance in cancer medicine. It helps explain why FDG-PET scans can detect many tumors: the radioactive tracer resembles glucose and accumulates in tissues with high glucose uptake.
Seyfried argues that the Warburg effect is not simply a consequence of cancer. He believes it reflects underlying mitochondrial dysfunction that plays a central role in causing and sustaining the disease. That interpretation is a key part of his metabolic theory of cancer.
Seyfried emphasizes two major fuels that many cancer cells use: glucose and glutamine.
Glucose receives the most attention because many tumors consume it at unusually high rates. A ketogenic diet lowers blood glucose and insulin while raising ketones, which healthy cells can often use efficiently for energy.
But Seyfried argues that reducing glucose alone is not enough. Many cancer cells can also use glutamine, an amino acid that plays important roles throughout the body. His research therefore explores ways of restricting glucose while also targeting glutamine metabolism.
This is why Seyfried's approach is more complex than the popular phrase “sugar feeds cancer.” His strategy attempts to create metabolic stress in cancer cells by targeting more than one fuel pathway while maintaining energy for healthy cells.
Seyfried proposes a strategy he calls ketogenic metabolic therapy, designed to place metabolic stress on cancer cells while supporting healthy cells.
A central component is therapeutic ketosis, usually achieved through a very-low-carbohydrate ketogenic diet, sometimes combined with calorie restriction or fasting. This lowers glucose and insulin while increasing ketones as an alternative fuel for healthy cells.
Seyfried also studies ways to target glutamine metabolism. One experimental drug used in his research is DON (6-diazo-5-oxo-L-norleucine), a glutamine antagonist. Research involving DON remains largely preclinical.
Seyfried has also investigated combining metabolic therapy with other approaches, including hyperbaric oxygen and conventional cancer treatments.
The goal is not simply to eliminate carbohydrates. It is to alter the metabolic environment of the cancer and simultaneously target several pathways that tumor cells may depend upon.
There is strong evidence that altered metabolism is a hallmark of cancer, and the Warburg effect is well established. Researchers are also actively studying how cancer cells use glucose, glutamine, and other fuels.
Seyfried and others have reported promising results from laboratory and animal studies using ketogenic diets, calorie restriction, glutamine-targeting drugs, hyperbaric oxygen, and combinations of these approaches.
Human evidence is much more limited. Small studies and case reports suggest that ketogenic metabolic therapy may be feasible and may influence tumor metabolism in some settings, but it has not yet been shown in large clinical trials to improve survival or replace standard cancer treatment.
For prostate cancer specifically, metabolic therapies remain experimental and investigational. They may eventually prove useful as additions to established treatment, but the evidence is not strong enough to regard them as proven therapy.
Prostate cancer is especially interesting from a metabolic perspective because researchers have found connections between obesity, insulin resistance, metabolic health, and the behavior of prostate cancer.
Laboratory research also suggests that prostate cancer cells can change the fuels they use as the disease progresses. Glucose, fats, and glutamine metabolism are all being investigated as possible therapeutic targets.
Researchers are studying whether ketogenic diets or other metabolic interventions might be useful alongside conventional prostate cancer treatment. At present, however, there is not enough clinical evidence to recommend a ketogenic diet as a treatment for prostate cancer itself.
This distinction is important: maintaining good metabolic health may be beneficial for overall health during prostate cancer, while therapeutic ketosis as an anti-cancer treatment remains an area of research.
Seyfried’s major book explaining his theory of cancer metabolism.
A concise introduction to Seyfried’s central argument.
A more detailed discussion of therapeutic ketosis and cancer metabolism.
A longer discussion specifically addressing prostate cancer and metabolic therapy.
Interview with Ralph Moss, Ph.D.