October is Breast Cancer Awareness Month, and every year those pink ribbons hit a little closer to home for me.
My maternal grandmother had breast cancer. So did my aunt. Two of my cousins. And more and more friends my own age. Women I’ve had coffee with, sat next to at school events, texted late at night after a scary appointment. I’ve watched them go through the scans, the surgeries, the chemo, and the waiting. I’ve watched their kids watch them.
So this isn’t an abstract topic for me. It’s personal. With that much breast cancer in my family, I decided a long time ago that I would do everything in my power to keep it from happening to me. Not out of fear. Out of love for my boys and the life I want to be here for.
Here’s the hopeful part. Family history matters, but it isn’t destiny. Breast surgeon Dr. Kristi Funk points out that 87% of women diagnosed with breast cancer don’t have a single first-degree relative with it. That tells us something important: what we do every day, especially what we put on our plates, plays a huge role. Genes load the gun, but diet and lifestyle pull the trigger.
So what does the research actually say? Let’s dig in. Below are the things to do and the things to avoid to help prevent breast cancer, and to support recovery and lower recurrence risk if you’ve already been diagnosed.
A quick note: I’m a certified plant-based health coach, not your doctor. If you’re in treatment or have a history of breast cancer, please talk with your oncologist before making big changes.
Foods and Habits That Help Prevent Breast Cancer
1. Eat Soy Foods: What the Research Really Says About Soy and Breast Cancer
I know. You’ve heard soy causes breast cancer. So had Dr. Kristi Funk, breast surgeon to Angelina Jolie and Sheryl Crow and author of Breasts: The Owner’s Manual. For years she told her own patients to avoid soy. Then she dug into the human research and completely changed her advice. Today she says, “I advocate for two to three servings daily in all women.”
So where did the fear come from? Soy contains isoflavones, also called phytoestrogens, because their structure looks a lot like estrogen. Scientists originally assumed that meant they’d act like estrogen in the body. But that’s not what happens.
Our bodies have two types of estrogen receptors: alpha and beta. Our own estrogen binds to the alpha receptors, which can fuel breast cell growth. Soy’s phytoestrogens prefer the beta receptors, and in doing so they help block our own estrogen from latching on. The result is an anti-estrogen effect in breast tissue. That’s actually similar to how the breast cancer drug tamoxifen works.
The human studies back this up:
- A 2006 meta-analysis of 18 studies in the Journal of the National Cancer Institute found soy had an overall protective effect against breast cancer.
- The Shanghai Breast Cancer Survival Study, published in JAMA in 2009, followed more than 5,000 breast cancer survivors. Women who ate the most soy had a 29% lower risk of death and a 32% lower risk of recurrence compared to women who ate the least. That held for both estrogen-positive and estrogen-negative breast cancers, whether or not women were taking tamoxifen.
Stick with whole, minimally processed soy foods: edamame, tofu, tempeh, unsweetened soy milk, and soy curls. Choose organic or non-GMO, and skip the soy protein isolates and soy supplement pills. The research is on soy foods.
2. Eat Berries Daily for Cancer-Fighting Antioxidants
Berries are tiny antioxidant powerhouses. They’re loaded with polyphenols like anthocyanins (the pigments that make them blue, red, and purple), which help protect your cells from oxidative damage and calm inflammation. Both of those play a role in cancer development.
In a Nurses’ Health Study analysis of nearly 9,000 women with breast cancer, every 2 servings of blueberries a week was associated with a 25% lower risk of dying from breast cancer. Two servings a week. That’s a handful in your oatmeal a couple of mornings.
Frozen berries count too. They’re flash-frozen at peak ripeness, they don’t go bad in your fridge, and they’re easy on the budget.
3. Eat Leafy Greens and Cruciferous Vegetables Like Broccoli and Kale
Harvard researchers followed more than 180,000 women in the Nurses’ Health Studies for up to 30 years. The women who ate the most fruits and vegetables had a lower risk of breast cancer, especially the more aggressive types. Cruciferous vegetables like broccoli had one of the strongest links. And among women already diagnosed, eating more green leafy and cruciferous vegetables was associated with better overall survival.
Why are cruciferous veggies so special? Broccoli, kale, cabbage, Brussels sprouts, bok choy, arugula, and cauliflower contain unique sulfur compounds that turn into isothiocyanates when you chop, chew, or blend them. These compounds have powerful anti-cancer, immune-boosting, and anti-inflammatory effects. So chop them up and chew well! Dr. Funk recommends about half a cup of broccoli a day, which is easy to toss into a stir-fry, grain bowl, or soup.
4. Eat Beans and Legumes for Fiber and Gut Health
Beans, lentils, chickpeas, and split peas are fiber champions, and fiber is one of your best friends for breast health.
Here’s how it works. When the good bacteria in your gut ferment fiber, they produce short-chain fatty acids like butyrate. These are some of the most anti-inflammatory compounds on the planet, and butyrate has been shown to inhibit cancer cell growth. Fiber also works like a vacuum cleaner in your intestines, binding to excess estrogen and escorting it out of your body instead of letting it recirculate.
A Harvard meta-analysis of 20 studies, published in the journal Cancer in 2020, found that women with the highest fiber intake had an 8% lower risk of breast cancer, and higher fiber intake was linked to lower risk in both premenopausal and postmenopausal women.
Most Americans only get about 14 grams of fiber a day. On a whole food plant-based diet, you can easily get 50 grams or more. Aim for 2 to 3 servings of legumes a day. A bowl of black bean soup, hummus with veggies, or lentil taco “meat” all count.
5. Eat Mushrooms Daily to Lower Breast Cancer Risk
Mushrooms might be the most underrated breast-protective food in your grocery store.
Here’s why. Estrogen fuels the majority of breast cancers, and after menopause, much of a woman’s estrogen is made by an enzyme called aromatase. Mushrooms contain natural compounds that act as aromatase inhibitors, helping turn down the body’s estrogen production. That’s actually the same target some breast cancer drugs go after. Mushrooms are also one of the few plant foods that contain vitamin D, and they’re packed with antioxidants and immune-supporting compounds.
The research is honestly kind of amazing. In a 2009 study published in the International Journal of Cancer, researchers compared about 1,000 Chinese women with breast cancer to 1,000 healthy women. Those who ate at least 10 grams of fresh mushrooms a day (about one small mushroom, roughly the size of your thumb) had a 64% lower risk of breast cancer. The protective link showed up in women both before and after menopause.
Then the researchers looked at green tea, and that’s where it got really exciting. Women who ate fresh mushrooms and drank green tea every day had an 89% lower risk of breast cancer than women who had neither. Even dried mushrooms paired with green tea were linked to an 82% lower risk. And it didn’t take much tea: just over 1 gram of dried green tea leaves a day, which is less than what’s in a typical tea bag.
Why might they work so well together? Green tea is rich in catechins, especially EGCG, a powerful antioxidant that has been shown in lab studies to slow the growth of breast cancer cells and help cut off the blood supply tumors need to grow. Mushrooms help lower estrogen production, while green tea works on cancer cell growth. Two different paths, one powerful team.
Then in 2021, Penn State researchers pooled 17 studies with more than 19,500 cancer patients. People who ate about 18 grams of mushrooms a day, roughly ⅛ to ¼ cup, had a 45% lower risk of cancer overall, and the strongest link of all was with breast cancer.
You don’t need anything fancy. Plain white button mushrooms count, and so do cremini, portobello, shiitake, and oyster. Slice them into stir-fries, pasta sauce, soups, and tacos, or swap them in for ground meat. Just always cook your mushrooms to be on the safe side. And pour yourself a cup of green tea while you’re at it.
6. Add Ground Flaxseed for Cancer-Protective Lignans
Flaxseeds are the richest source of lignans, a type of plant compound with anti-estrogen and anti-cancer properties. Your gut bacteria convert lignans into compounds that help balance estrogen activity in the body.
In one clinical study, postmenopausal women newly diagnosed with breast cancer ate flaxseed every day before their surgery, and their tumor growth markers dropped. And a pooled analysis of six studies found that postmenopausal women with breast cancer who had the highest lignan intake or blood levels had about a 27% lower risk of death overall and a 28% lower risk of dying from breast cancer.
Just 1 tablespoon of ground flaxseed a day gives you lignans plus your daily omega-3s, for only about 37 calories. (Make sure it’s ground. Whole flaxseeds are so tiny they pass right through you undigested.) Stir it into oatmeal, blend it into smoothies, or sprinkle it on a fruit bowl.
7. Exercise Regularly to Lower Breast Cancer Risk and Improve Survival
Exercise isn’t just about weight. It helps regulate hormones, improves insulin sensitivity, and lowers stress hormones that push your body to store fat.
For women who’ve been diagnosed, a 2023 global meta-analysis found that each 10 MET-hours per week of recreational activity after diagnosis was linked to a 14% lower risk of dying from breast cancer. Benefits kept climbing up to about 20 MET-hours a week, which was associated with a 38% lower risk of breast cancer death. In real life, that’s roughly 5 to 6 hours of brisk walking per week.
Can’t do that much yet? Start where you are. Dr. Funk notes that even 11 minutes of exercise a day has been associated with an 18% lower breast cancer risk. Walk after dinner. Dance in the kitchen. And add some resistance training 2 to 3 times a week to build muscle and protect your bones.
Foods to Avoid to Lower Breast Cancer Risk
8. Avoid Dairy: How Milk and Its Hormones Are Linked to Breast Cancer
This one surprises a lot of people, because we’ve been told our whole lives that milk does a body good.
In the Adventist Health Study-2, published in 2020, researchers followed nearly 53,000 women for about 8 years. Drinking as little as ¼ to ⅓ cup of dairy milk a day was associated with a 30% higher risk of breast cancer, and the risk climbed as high as 80% depending on how much women drank. For women already diagnosed, the Life After Cancer Epidemiology study found that eating one or more servings of high-fat dairy a day was associated with a 49% higher risk of dying from breast cancer.
Why? One big reason is hormones. Here’s something most people don’t realize: there’s no such thing as hormone-free dairy. Cows produce estrogen and progesterone naturally, just like we do, because they’re mammals. To keep the milk flowing, dairy cows are kept pregnant or nursing most of their lives, and the researchers in the Adventist study noted that about 75% of a dairy herd is often pregnant. Those hormones end up in the milk, and they get even more concentrated in cheese and butter. In fact, about 75% of the female sex hormones in our diet come from dairy.
That’s why you’ll never see a truthful “hormone-free” label on milk, cheese, or meat. The most a company can say is “no added hormones.” Organic and grass-fed included.
The good news? The same Adventist study predicted a marked drop in risk when women swapped dairy milk for soy milk. Two birds, one carton.
9. Limit Meat and Animal Protein That Raise IGF-1 Levels
Animal protein raises a hormone called IGF-1 (insulin-like growth factor 1). IGF-1 is great when you’re a kid and growing. But as an adult, it tells everything to grow, including cancer cells.
A pooled analysis of 17 studies found women with higher IGF-1 levels had about a 30% higher risk of breast cancer. And in 2020, a UK Biobank study combined with genetic analysis of roughly 430,000 women concluded that IGF-1 is a probable cause of breast cancer, not just a bystander.
Plant protein, on the other hand, is associated with lower IGF-1 levels. In one study, only the vegans, not the meat eaters or even the vegetarians, had significantly lower IGF-1. So swap the chicken for chickpeas, the ground beef for lentils, and the pork for soy curls. You’ll still get plenty of protein.
10. Avoid Processed Meats, a Group 1 Carcinogen
Bacon, hot dogs, sausage, pepperoni, ham, jerky, and yes, deli turkey. The World Health Organization classifies processed meats as a Group 1 carcinogen, the same category as cigarettes and asbestos, because the evidence linking them to cancer is so strong.
For breast cancer specifically, a UK Biobank study of more than 262,000 women found that those eating more than 9 grams of processed meat a day (about two sausages a week) had a 21% higher risk.
This one makes me a little mad, honestly. Before I went plant-based, I ate a “healthy” turkey sub on wheat almost every day for lunch. I thought I was doing everything right. Nobody told me.
How to Start Lowering Your Breast Cancer Risk Today
You don’t have to overhaul your entire life by Monday. Honestly, that approach rarely sticks anyway. Pick one thing from this list and start this week:
- Stir a tablespoon of ground flax and a handful of berries into your morning oatmeal.
- Swap your dairy milk for unsweetened soy milk.
- Trade the deli meat sandwich for a hummus and veggie wrap.
- Take a 15-minute walk after dinner.
Then add another. Small changes, repeated consistently, add up faster than you’d think.
I do this for my grandmother, my aunt, my cousins, and my friends. And I do it for my boys. Every plate is a chance to choose protection. Who are you doing it for?
Ready to start eating more of these cancer-fighting foods, but not sure where to begin? Join me for my free Plant-Based Beginner’s Bootcamp, where I’ll show you how to make whole food plant-based eating simple, easy, and delicious, with daily masterclasses, cooking demos, and a supportive community cheering you on. Save your free spot here!
Sources
- Shu XO, et al. Soy food intake and breast cancer survival. JAMA. 2009;302(22):2437–2443.
- Trock BJ, et al. Meta-analysis of soy intake and breast cancer risk. J Natl Cancer Inst. 2006;98(7):459–471.
- Forks Over Knives. Surgeon Kristi Funk on Diet and Reducing Breast Cancer Risk.
- TODAY. 6 sensible, simple ways to lower your risk of breast cancer (Dr. Kristi Funk).
- Farvid MS, et al. Postdiagnostic fruit and vegetable consumption and breast cancer survival: prospective analyses in the Nurses’ Health Studies. Cancer Res. 2020;80(22):5134–5143.
- Farvid MS, et al. Fruit and vegetable consumption and breast cancer incidence: repeated measures over 30 years of follow-up. Int J Cancer. 2018.
- Farvid MS, et al. Fiber consumption and breast cancer incidence: a systematic review and meta-analysis of prospective studies. Cancer. 2020.
- Thompson LU, et al. Dietary flaxseed alters tumor biological markers in postmenopausal breast cancer. Clin Cancer Res. 2005;11(10):3828–3835.
- Lignan intake, serum enterolactone, and breast cancer prognosis: a meta-analysis. 2021.
- Cariolou M, et al. Postdiagnosis recreational physical activity and breast cancer prognosis. Int J Cancer. 2023;152(4):600–615.
- Fraser GE, et al. Dairy, soy, and risk of breast cancer: those confounded milks. Int J Epidemiol. 2020.
- Kroenke CH, et al. High- and low-fat dairy intake, recurrence, and mortality after breast cancer diagnosis. J Natl Cancer Inst. 2013;105(9):616–623.
- Murphy N, et al. Insulin-like growth factor-1, insulin-like growth factor-binding protein-3, and breast cancer risk. Ann Oncol. 2020;31(5):641–649.
- Anderson JJ, et al. Red and processed meat consumption and breast cancer: UK Biobank cohort study and meta-analysis. Eur J Cancer. 2018;90:73–82.
- International Agency for Research on Cancer (WHO). IARC Monographs evaluate consumption of red meat and processed meat. Press release No. 240, 2015.
- Ba DM, et al. Higher mushroom consumption is associated with lower risk of cancer: a systematic review and meta-analysis. Adv Nutr. 2021.
- Zhang M, Huang J, Xie X, Holman CD. Dietary intakes of mushrooms and green tea combine to reduce the risk of breast cancer in Chinese women. Int J Cancer. 2009;124(6):1404–1408.
