The King, 76, made the revelation in conversation with Stamford Collis at The Education and Skills Garden Party at Buckingham Palace on May 14. Collins, 22, is a student at Exeter University and is undergoing treatment for cancer.

"He was asking me about the treatment I have starting in June and spoke to me about food and diet. He also asked me if I had undergone radiation treatment, which I had earlier this year," Collis said after he met the King, The Telegraph reported.

The sovereign was heard saying, "It’s sometimes about the diet and what you eat. It can help."

King Charles has been called a "foodie" by former royal chefs, and Queen Camilla's food writer son, Tom Parker Bowles, recently revealed that the couple eats “simple, healthy and resolutely seasonal food."

In a piece for The Daily Mail ahead of the release of his book, Cooking and the Crown: Royal Recipes from Queen Victoria to King Charles III, Tom said that the royal’s pantry is filled with “seasonal bounty of the royal estates,” including “game, beef and lamb,” plus fruits and vegetables like “peas, strawberries, raspberries and chard."

"There is no waste at [King Charles’] table," Tom said.

King Charles offered his personal comment at the second royal garden party of the season, which he attended with his wife, Queen Camilla.

Buckingham Palace announced in February 2024 that King Charles was diagnosed with cancer and began treatment. Though the King had a procedure to treat a benign enlarged prostate that January, a spokesman clarified he does not have prostate cancer.

The King followed doctors' advice to postpone public-facing work for what proved to be a three-month period and resumed forward duties late that April, keeping busy ever since. Palace sources said before Christmas that the King's treatment for cancer would continue into the new year.

"His treatment has been moving in a positive direction and as a managed condition the treatment cycle will continue into next year," palace sources said.

On March 27, the palace announced that the King was briefly hospitalized following an adverse reaction to his routine cancer treatment.

The palace said that the sovereign was admitted to the London Clinic (where he had had the prostate operation) after experiencing "temporary side effects that required a short period of observation in hospital."

Sources said that such setbacks are not uncommon, with a royal source describing the scare as "the most minor bump in the road that’s very much heading in the right direction."

The King canceled his plans for that afternoon and the next day, returning to work the following week after a "restful" weekend at Highgrove House, his beloved country home.