Boston College biologist Thomas Seyfried has argued that the elevated cancer rates seen in affluent countries are driven more by modern living conditions than by inherited genetics.
Speaking on The Diary Of A CEO with Steven Bartlett, Seyfried said nations such as the United States, Australia and New Zealand report far more cancer cases than lower-income countries, and he believes lifestyle plays the central role in that divide.
The longtime cancer researcher, known for his work on the metabolic theory of cancer, said the everyday conditions common in richer nations place sustained strain on the body.
“We are now in a new environment where we have massive amounts of highly processed carbohydrates, inactivity, emotional stress, poor sleep habits,” he said, adding that these factors combine to chronically damage the mitochondria.
In his view, that ongoing damage affects mitochondria, the parts of cells responsible for generating energy, and may help explain why cancer is more common in wealthier parts of the world.
He pointed to countries including Niger, Gambia and Nepal as places that regularly appear among the lowest for cancer incidence, contrasting them with high-income nations that tend to rank at the top.
It is also worth noting that cancer incidence patterns are shaped by more than diet and exercise alone. Global health agencies say rates tend to rise with age, and they also vary depending on how much screening, early diagnosis and treatment a country can provide. In wealthier countries, more cancers are often detected because health systems find them earlier, while some cancers are less deadly because treatment is more accessible.
Seyfried said human beings evolved to conserve energy during periods of scarcity, but that same biological tendency can become harmful in an environment where calorie-dense food is constantly within reach.
He also referenced historical observations by physician Albert Schweitzer, saying traditional African communities living on less industrialized diets and with fewer chemical exposures appeared to have very low rates of cancer.
To reinforce his argument, Seyfried compared pet dogs with wild wolves. He noted that cancer is a major cause of death among domestic dogs but is uncommon in wolves, something he attributed to differences in diet and physical activity rather than DNA.
At the same time, mainstream cancer organizations say cancer is primarily a genetic disease driven by DNA changes that accumulate over time. The National Cancer Institute describes many cancers as arising from mutations that help cells grow, divide and spread uncontrollably.
Seyfried and his team have also created a metric called the Glucose Ketone Index, which uses measurements of blood glucose and ketones to assess metabolic status.
He explained that the figure is produced by dividing glucose levels by ketone levels, and said lower results correspond with what he called a ‘zone of prevention’.
Rather than promoting a single eating plan, Seyfried said his broader strategy focuses on cutting back on highly processed carbohydrates, staying active, managing long-term stress and getting sufficient sleep.
He emphasized that dietary choices should be made by patients in consultation with their doctors, saying, ‘no government or government official’ should tell people what to eat.
His argument, however, differs sharply from the view held by major oncology organizations such as the National Cancer Institute, which identifies cancer primarily as a genetic disease caused by mutations.
Still, public health experts note that a large share of cancers are linked to modifiable risks such as tobacco use, alcohol, excess body weight, physical inactivity, unhealthy diets, air pollution and certain infections, and that these factors help explain why cancer burdens differ so much from one country to another.
Seyfried rejects that interpretation and contends that impaired mitochondrial function, rather than genetic mutation itself, is the fundamental cause.