Dietary habits are closely related to the occurrence of human cancers, and their effect on cancer is actually a double-edged sword. If the diet is unreasonable, with excessive intake of red meat and insufficient intake of vegetables and fruits, or if there are bad habits such as long-term alcohol consumption, high-salt diet, preference for smoked, barbecued, fried, pickled and hot food, it will increase the risk of many kinds of cancers; if the diet is proper, paying attention to a balanced diet and regular intake of foods rich in vitamins, trace elements, plant compounds and other cancer prevention nutrients, it will help to reduce the risk of cancer in the population. Therefore, for patients who have already suffered from breast cancer, adhering to good dietary habits and reasonable intake of nutrients can prevent the recurrence of breast cancer and improve the quality of life. So, what is a good diet? In fact, it is to insist on a balanced diet. The dietary pagoda of China, the plate of Canada, the dietary pyramid of the United States, etc. all illustrate the proportion of various types of food in a balanced diet. They are simply summarized as follows: 1. diverse foods, with grains as the mainstay; 2. ensure the intake of fruits and vegetables; 3. appropriate animal foods; 4. moderate amount of dairy and soy products; 5. light and less salt. In addition, for cancer patients, they should increase the intake of fresh vegetables, fruits, whole grains, legumes and mushrooms additionally on the basis of adhering to a balanced diet, especially vegetables and fruits, and should ensure more than 1 pound of vegetables and half or eight pounds of fruits every day. The reason for this is that these foods have proven anti-cancer effects. The World Cancer Research Fund and the American Institute for Cancer Research summarize research results from countries around the world and conclude that there is stronger evidence that if fresh vegetables and fruits, legumes, and whole grains are consumed regularly, they can significantly reduce the risk of many cancers such as breast cancer. Clinical studies also found that patients who consumed >250g of vegetables per day had a higher overall quality of life than those who consumed ≤250g of vegetables per day, and those who ate fruit daily had a higher overall quality of life than those who did not eat fruit daily. The cancer-preventive effect of these foods is mainly due to the presence of various cancer-preventive nutrients, such as carotenoids, vitamin C, folic acid, selenium and lycopene, and organosulfur compounds. These substances inhibit the occurrence of cancer through various mechanisms, including blocking the production of carcinogens, helping damaged cells to repair, inhibiting the proliferation of cancer cells, and promoting apoptosis of cancer cells. The pathogenesis of breast cancer is complex and there are still many unknown factors, some of which we cannot influence, such as genetics, environmental issues, and marital history. But there is still a lot we can do, and adhering to a balanced diet is a simple and effective way. Therefore, no matter what you have experienced or what you will face in the future, we should change the diet that we can, accept the reality that we cannot, and live bravely!