What's the evidence? For starters, many studies show that women who are overweight are at greater risk for succumbing to breast cancer. Trimming away extra weight helps them survive. Plant-based diets make weight control much easier.
But the evidence goes further. The Women's Intervention Nutrition Study, which included 2,437 postmenopausal women who had previously been treated for breast cancer, tested whether a low-fat diet could reduce the risk that cancer might recur. And it did. The diet change cut recurrence risk by about 25 percent.
Adding physical exercise helps too. In the Women's Healthy Eating and Living study, which included approximately 3,000 women, all of whom had been treated for breast cancer, those who had at least five daily servings of fruits and vegetables and averaged 30 minutes of walking each day had roughly half the mortality risk, compared with women who ate fewer vegetables and fruits or who were less active.
Diet also makes a huge difference for men. Dr. Dean Ornish, who had already shown the ability of a low-fat vegetarian diet, along with other lifestyle measures, to reverse heart disease, tested a similar diet for men with prostate cancer. To track their progress, he checked a blood test called prostate-specific antigen (a rapidly rising PSA is a sign of advancing cancer). Dr. Ornish showed that, on average, men who avoided animal products actually had a drop in their PSA levels, meaning their cancer was not advancing and might actually be retreating. Meanwhile, men in a control group that made no diet changes continued to worsen.
Putting these studies together, the healthiest combination appears to be to cut out fatty foods—especially animal products—boost vegetables and fruits and lace up your sneakers.
I realize this is a lot of information, and it may be contrary to the very diet you are used to eating. But with this knowledge under your belt, it should be easier and more exciting to upgrade your diet knowing the profound effect it can have; it also gives you more control over the future of your health, knowing that what you eat really does make a difference. If you aren't sick right now, lean into the change. Give up one animal at a time and substitute veggie proteins—soy, legumes, beans, faux meats—for animal ones, until you are comfortable with your new way of eating and living. If you have been diagnosed with cancer, you might want to check in with CancerProject.org for recipes and support and leap (or lean vigorously!) into this new and joyful way of eating!