How Diet Affects Your Chances of Getting Cancer

When Urvi Shah was working as a research fellow in hematology and oncology, she was diagnosed with Hodgkin’s lymphoma, a cancer that attacks the lymphatic system, which is vital to a healthy immune response. Shah received four months of intensive chemotherapy, which cured the disease, but he wondered what role, if any, diet played in eradicating his cancer.

“I heard a lot of advice from friends and family about what I should and shouldn’t eat, and I realized that in medical school we didn’t learn anything about the role of nutrition in healing,” Shah says. “As a patient, I wanted to feel empowered to do something about my health.”

Intrigued by evidence that high-fiber plant foods reduce cancer incidence and recurrence, Shah refocused her research on modifiable cancer risk factors such as diet, obesity, diabetes, and the microbiome. Shah is now a myeloma specialist and associate professor at Memorial Sloan-Kettering Cancer Center in the US. He is leading four dietary intervention studies (the NUTRIVENTION trials) to provide nutritional guidance to cancer patients.

Shah’s work is part of a growing body of research suggesting that a cluster of metabolic diseases such as obesity, diabetes, hypertension, high cholesterol, and high triglycerides (which affect more than 40 percent of Americans) may be a key factor in the onset and progression of many cancers. There’s even a medical term (metabolic syndrome) for people who have three or more of these conditions. The incidence of the syndrome has been rising for decades, and the Western diet, coupled with a sedentary lifestyle, is largely to blame.

Excessive consumption of alcohol, refined carbohydrates, and high-fat foods, as well as spending most of your time on the couch or sitting at a desk, causes an inflammatory response that ultimately damages DNA. Unfortunately, the more DNA is damaged, the more likely normal cells are to become cancerous.

“Our view of cancer as a genetic disease has driven the development of treatments that target specific genetic mutations,” says Stephen Friedland, director of the Center for Comprehensive Cancer and Lifestyle Research at Cedars-Sinai in California. “But we now know that cancer is a metabolic disease with unique metabolic needs, and many of the genetic changes that occur in cancer regulate metabolism.”

The International Association of Cancer Research Centers (IARC) estimates that there will be nearly 20 million new cases of cancer and 9.7 million deaths from this cause in 2022. In many high-income countries, cancer has surpassed cardiovascular disease as the leading cause of death. And while genetic sequencing has increased our understanding of the genomic changes that occur in cancer, it has not led to many effective therapeutic targets.

Given that cancer cells have millions of genetic changes, developing specific drugs for each tumor is a challenge. What scientists do know is that faulty metabolism (the process by which cells generate and use energy) is a hallmark of cancer. This suggests that metabolic reprogramming of cancer cells may be a viable treatment strategy.

Only 5 to 10 percent of cancers are linked to a specific genetic mutation, and no single mutation is associated with all cancers. Instead, metabolic changes occur in almost all cancers. So it makes sense that cancer rates are rising along with the growing epidemic of metabolic diseases.

A 2024 study involving more than 44,000 people in China was published in the journal Cancerreported that people who had at least three of the five components of metabolic syndrome had a 30 percent higher risk of developing all types of cancer over the nine-year study period, compared with those who had fewer than three of these risk factors. The researchers found that the risk of breast, endometrial, kidney, colorectal and liver cancer among people in the group with the highest metabolic syndrome scores was two to four times higher than among those with the lowest scores.

Obesity, a component of metabolic syndrome, is associated with high levels of inflammation, which damages healthy tissue and contributes to at least 13 types of cancer. For example, studies show that obese women have a three-fold increased risk of endometrial cancer and a 2.5-fold increased risk of kidney cancer compared to their metabolically healthy, normal-weight counterparts.

“Excess fat, especially around the waist, leads to increased inflammation, blood sugar levels, and insulin-like growth factor-1 (IGF-1) production, all of which have been linked to certain types of cancer,” says Friedland. “The mechanisms may be different for different types of cancer, but metabolic dysfunction is a common denominator.”

But what we eat and how much we weigh aren’t the only factors that influence this. Research shows that even people of normal weight with metabolic syndrome have an increased risk of developing cancer. Lifestyle, for example, can change the body’s response to insulin and its ability to convert food energy into fuel.

The theory that cancer is a metabolic disease dates back to the 1920s, when German scientist Otto Warburg reported that cancer cells have a metabolic peculiarity. Unlike normal cells, cancer cells use almost exclusively glucose as an energy source, even though there is enough oxygen to break down other fuel sources such as fatty acids and proteins.

This feature enables early detection of cancer using fludeoxyglucose-18 (FDG) positron emission tomography (PET), a non-invasive imaging technique that tracks glucose uptake by cells and identifies cancer cells (those that take up more glucose).

The question is, can you starve cancer cells by suppressing sugar?

Most scientists are reluctant to take that step, but some studies have linked excess glucose intake through sugary drinks and refined carbohydrates (also known as sugar) to an increased risk of cancer. Research shows that diabetes patients who take metformin, a drug that stabilizes blood sugar levels, are less likely to develop cancer than those who don’t.

Poorly controlled blood sugar is like a cure for cancer. Unlike normal cells, which stop growing in response to hormonal signals, cancer cells’ dysfunctional metabolism interferes with these messaging systems. In fact, two key hormones produced by fat tissue (adiptin and adiponectin) can help normal cells turn cancerous when their balance is disrupted.

Low adiponectin and high leptin are associated with obesity and metabolic syndrome, Shah explains. This altered ratio “is associated with increased cancer risk due to insulin resistance and inflammation, two key drivers of cancer development.”

However, it remains unclear whether genetic changes lead to metabolic dysregulation in cancer or whether metabolic dysregulation leads to the genetic changes observed in cancer.

“Metabolic syndrome causes genetic changes that predispose to cancer,” says Suresh T. Chari, a gastroenterologist at the University of Texas MD Anderson Cancer Center who is researching whether certain metabolic biomarkers can help detect cancer early. “But the cancer itself also causes a lot of metabolic changes years before it’s diagnosed, likely for its own survival.”

That connection, Chari says, opens up new possibilities: Metabolic disorders like diabetes and factors like lipid levels and C-reactive protein (a measure of inflammation) could help detect incurable cancers earlier. And because the two processes are so intertwined, treatments for metabolic disorders could also target all types of cancer.

Scientific knowledge about the metabolic underpinnings of cancer continues to evolve. Monitoring parameters such as sugar levels, blood pressure and cholesterol levels, and taking steps to reprogram metabolic dysfunctions, may help doctors detect cancer earlier or even prevent it, Shah says.

“There is skepticism that these modifiable risk factors only create a modest risk, so we shouldn’t burden patients with this information,” Shah says. “But in my experience, patients are hungry for information about how they can prevent or reduce the disease process, and there is compelling evidence to suggest that monitoring and managing metabolic syndrome is an important prevention and treatment strategy.”

In one of Shah’s studies, sugary drinks were linked to a 40 to 60 percent increase in the risk of abnormal blood proteins associated with multiple myeloma. In contrast, eating whole grains, fruits, and vegetables was linked to a 30 to 50 percent lower risk of this precancerous condition. Research also shows that achieving a healthy metabolism through lifestyle strategies can improve your chances of survival if you already have cancer.

With so many ways to improve metabolic risk factors, patients can, at least to some extent, take control of their health. They should know that how much, when, and what they eat matters. That going to the gym instead of watching Netflix can reduce your risk of cancer and improve outcomes if you’ve already been diagnosed. And that swapping soda for water with a squeeze of lime is the best cancer prevention strategy.

“Patients have tremendous power,” says Friedland; “the decisions you make every day can significantly reduce your risk of developing cancer and other diseases.”