Glucose and Glutamine: The Two Fuels Every Cancer Depends On
No matter how genetically different cancers are, they all depend on exactly two fuels: glucose and glutamine. The press-pulse strategy exploits this universal dependency — restrict glucose via diet, block glutamine with targeted drugs. Cancer cells cannot adapt.
"Is there any kind of cancer out there anywhere that can survive without glucose and glutamine? We haven't found one." That statement, from Dr. Thomas Seyfried of Boston College, points to something remarkable: despite the extraordinary genetic diversity of cancer — thousands of different mutations, hundreds of different tumor types — every cancer shares the same two fuel dependencies.
Why Two Fuels?
Cancer cells, as we explored in the previous article, cannot use the normal mitochondrial energy pathway efficiently. They are stuck running on fermentation — the backup pathway that uses glucose but not oxygen. This is the Warburg Effect: aerobic glycolysis.
But cancer cells are not passive. They are under severe metabolic stress, growing faster than normal cells, and they need not just energy (ATP) but also the raw material to build new cancer cells — proteins, fats, nucleic acids for DNA. Glutamine, an amino acid, provides much of this building material. It feeds into several metabolic pathways that supply the carbon and nitrogen cancer cells need to grow.
So cancer requires:
- Glucose — for energy (ATP), even via the inefficient fermentation pathway
- Glutamine — for biomass (building new cancer cell parts) and additional ATP
Critically, normal healthy cells are metabolically flexible. They can burn fat. They can use ketones — the molecules produced by the liver when glucose is scarce. They are not dependent on glucose for survival. Cancer cells, with their broken mitochondria, have lost this flexibility. They need glucose. They cannot run on ketones effectively.
The Press-Pulse Strategy
Dr. Seyfried and colleagues developed a treatment framework called Press-Pulse specifically around this fuel dependency. The idea draws from an analogy in ecology: predators use sustained pressure (press) combined with sharp targeted attacks (pulse) to take down prey. The metabolic strategy works the same way.
The Press: Restrict Glucose
The sustained pressure is dietary: a strict ketogenic diet combined with intermittent fasting. When you dramatically reduce carbohydrates and eat in a controlled window, blood glucose levels fall. The liver begins producing ketones from fat. Normal cells thrive on ketones. Cancer cells cannot.
Studies in animals and early human trials have shown that caloric restriction and ketogenic diets can slow tumor growth, improve response to chemotherapy, and in some cases dramatically extend survival. The mechanism is straightforward: you are removing the primary fuel cancer depends on while leaving normal cells well-nourished on an alternative fuel.
Travis Christofferson describes the elegance of this: "The ketogenic diet is remarkably non-toxic. You are not poisoning cells. You are simply removing the fuel that cancer cells need and cannot replace, while giving normal cells an equally good or better alternative. That asymmetry is the entire therapy."
The Pulse: Block Glutamine
The targeted attack is pharmacological. When glucose is restricted, cancer cells ramp up their use of glutamine — their backup fuel. A drug called DON (6-diazo-5-oxo-l-norleucine) inhibits glutamine metabolism. With both pathways blocked simultaneously, cancer cells have nowhere to turn.
In animal studies, the press-pulse combination — ketogenic diet/fasting plus DON — has shown striking results, achieving complete remission in some aggressive cancer models. The key to the approach is timing: the dietary press creates metabolic vulnerability in the cancer cells, and the drug pulse exploits that vulnerability at its peak.
Why Normal Cells Are Safe
The elegance of targeting cancer metabolism is the selectivity it offers. Normal cells are metabolically flexible: they can burn glucose, fat, ketones, and can meet their glutamine needs from multiple sources. Cancer cells, stuck in a rigid fermentation-dependent state, cannot adapt the same way.
This is the opposite of conventional chemotherapy, which broadly poisons any rapidly-dividing cell. The metabolic approach says: exploit the specific metabolic vulnerability that cancer cells have and normal cells do not. The therapy is not easy — ketogenic diets are demanding, and DON has side effects that researchers are working to minimize. But the underlying strategy is targeting a universal cancer weakness rather than chasing individual mutations.
Where the Research Stands
The press-pulse strategy is still in clinical development. Dr. Seyfried and colleagues at Boston College are actively researching optimized protocols. Several clinical trials are examining ketogenic diets in combination with standard-of-care treatment for glioblastoma and other cancers. The DON drug was shelved decades ago due to gastrointestinal side effects; researchers are now developing modified versions designed to deliver DON specifically to tumor tissue, reducing systemic toxicity.
The metabolic theory of cancer does not argue that surgery, radiation, and chemotherapy should be abandoned. It argues that the metabolic framework offers a more coherent understanding of what cancer is — and that targeting metabolism can complement, or in some cases replace, therapies that have been limited by the complexity of genetic targets.
What This Means for Prevention
Perhaps the most immediately actionable implication of the metabolic theory is for prevention. If cancer cells depend on glucose and cannot survive on ketones, then chronically elevated blood sugar — from diets high in refined carbohydrates and sugar — creates the metabolic environment in which cancer thrives.
This connects the metabolic theory of cancer to the broader literature on insulin resistance, metabolic syndrome, and obesity as cancer risk factors. These are not separate phenomena. They are facets of the same metabolic dysfunction: chronically elevated glucose and insulin that feed exactly the fermentation-dependent energy system that cancer exploits.
Seyfried is direct about the implication: "If you want to prevent cancer, or slow its growth if you have it, you want low blood glucose. You want elevated ketones. You want a metabolism that keeps the fuel cancer depends on as scarce as possible." Diet is not a peripheral concern in this framework. It is the first line of metabolic defense.