Kenneth Glad
Researchers are studying how diet, inflammation and environmental exposure shape long-term health. Cancer risk is influenced by a mix of genetic, lifestyle and environmental factors.
Physician, scientist and author Dr William Li has argued that cancer prevention should be viewed partly through everyday habits, including food, movement, alcohol, tobacco and environmental exposure.
Speaking on the ZOE podcast, a health and nutrition show that explores food, the gut microbiome and long-term disease risk, Li said the body regularly deals with abnormal cells and relies on immune function, blood vessel control and gut health to keep many of them in check.
Processed foods linked to inflammation
Li said genetics are not the main driver for most cancers, claiming that “90 to 95% of cancers are attributable to environment, diet, and lifestyle.”
He warned that ultra-processed foods may affect the gut microbiome and inflammation, particularly in relation to colon cancer.
He also discussed processed meats, which the World Health Organization classifies as a Group 1 carcinogen.
The podcast also covered smoking, vaping and alcohol as lifestyle risks. Li said tobacco smoke can damage DNA in lung cells and create inflammation, while vaping fluids may contain chemicals that irritate tissue and could also contribute to mutations. He warned that pipes and cigars are not risk-free, even when smoke is not deeply inhaled.
For alcohol, Li focused on heavy drinking rather than occasional use. He said repeated high intake can damage cells, strain the liver and weaken immune defences.
Plastic concerns remain unsettled
Li raised concerns about environmental exposure, including microplastics, which he said may build up through the air people breathe, the water they drink and the food they eat.
He argued that researchers should pay closer attention to whether plastics could affect inflammation, immunity or cellular damage, especially as some cancers are being diagnosed in younger adults than in previous generations.
“I would suggest trying to avoid microplastics, try to avoid food in plastic, avoid eating or drinking out of plastic,” he said.
He also advised travellers to stay hydrated without relying too heavily on disposable bottles, saying: “When you’re travelling, you should hydrate yourself but try not to drink water out of that plastic bottle.”
Cancer organisations remain more cautious. The American Cancer Society says there is not enough evidence to prove microplastics cause cancer in humans. Cancer Research UK says food and drink stored in plastic containers has not been shown to cause cancer.
Cancer Research UK also notes that small amounts of chemicals can pass from plastic packaging into food or drink, but at levels not considered harmful.
Food supports, but does not cure
Li pointed to soy, tomatoes, apples and berries as foods that may support the body’s protective systems through fibre, polyphenols and other plant compounds.
On soy, he challenged fears around plant estrogens and cited research involving women already diagnosed with breast cancer. He said higher soy intake was linked with lower mortality in that study.
“This actually lowers death,” he said.
Li also discussed cooked tomatoes, linking their lycopene content to prostate health, and said apples and berries may help through anti-inflammatory compounds and fibre that supports the gut microbiome.
His broader point was that food itself does not “fight” cancer in isolation. Instead, he argued that healthy eating patterns may help the body maintain immune, inflammatory and gut-related defences.
The takeaway is not a promise that any one habit can prevent cancer. It is a reminder that risk is shaped over years by many small exposures, choices and protections working together.
Sources: ZOE Podcast, American Cancer Society, Cancer Research UK, WHO.
