Healthy cells can efficiently use ketones for energy. Cancer cells, with their broken mitochondria, cannot. This creates a powerful therapeutic opportunity: a ketogenic state can nourish the body's healthy cells while simultaneously starving tumor cells of their required fuel.

Experiments show that transferring a cancer cell's dysfunctional mitochondria—but not its nucleus—into a healthy cell is what induces cancer. This disruptive finding supports the view of cancer as a metabolic disease that can be targeted by starving its mitochondria of fuels like glucose.

Every cancer specimen is genetically unique, yet all share common traits like uncontrolled division and co-opting normal cell survival mechanisms. The key to treatment is finding pathways that are different enough from normal cells to target and exploit.

Beyond producing energy, mitochondria play a crucial role in programmed cell death. A striking example is in embryonic development, where fetal hands initially look like mittens. Mitochondria then act as "assassins," eliminating the cells between the digits to form individual fingers.

Wild wolves rarely get cancer, while it's the leading killer of domestic dogs. This stark difference highlights the impact of modern lifestyles—processed foods, inactivity, and chronic stress—on mitochondrial health, making dogs a compelling parallel for the metabolic theory of cancer in humans.

The "oncogenic paradox"—how diverse agents like chemicals, radiation, and viruses all cause cancer—is solved by a common mechanism. They all inflict chronic damage on the mitochondria's ability to produce energy efficiently using oxygen.

New research shows that mitochondria can influence cells in distant organs. For example, exercise that improves mitochondria in skeletal muscles can also positively affect the brain, heart, and lungs. This suggests localized mitochondrial interventions can have widespread systemic benefits.

Mitochondria in different organs are not identical. Despite sharing the same genes, they differentiate into specialized "mitotypes" with distinct forms and functions, analogous to worker and warrior ants. This cellular division of labor is crucial for organ-specific energy needs.

The characteristic that makes stem cells invaluable—their ability to self-renew for a lifetime—is the same immortalization program that cancer cells hijack to grow without constraint. This highlights cancer's parasitic relationship with a fundamental biological process needed for survival.