Going vegan may halt cancer in its tracks, scientists say.

It could also make chemotherapy and radiotherapy more effective, according to their tests on mice and people. The findings were published in Nature.

The researchers focused on restricting the amino acid methionine, which affects metabolism and is found in meat, fish and dairy products.

First they cut it out of food for rodents with cancer and found that growth of tumors was “inhibited.”

When the diet was combined with the chemo drug 5-fluorouracil or radiation therapy, spread of the disease was halted.

Researchers then gave five women and a man — ages 49 to 58 — a methionine-free diet for three weeks. At the end, their levels of methionine had been cut by 83 percent and metabolism molecules in their blood were at the same level as the rodents.

Study leader Prof. Jason Locasale, a cancer biologist at Duke University in North Carolina, said: “In the people, a reduction in dietary methionine had a similar effect on metabolism to that seen in mice.

“These findings provide evidence that dietary manipulation can affect tumor-cell metabolism.”

Low-methionine foods include fruits, nuts, vegetables, grains and beans — in other words, a vegan diet favored by celebs such as Natalie Portman and Ariana Grande.

The study comes 40 years after a paper claimed cancer had “absolute methionine dependency.”