Researchers looked at 9 different studies to understand how plant-based eating affects breast cancer risk. They found that eating a healthy plant-based diet—one focused on whole grains, fruits, vegetables, and legumes—was linked to a lower chance of developing breast cancer. However, eating a plant-based diet that’s heavy on processed foods didn’t provide the same protection and might even increase risk. The good news is that choosing whole plant foods over processed ones appears to matter more than simply avoiding animal products.

The Quick Take

  • What they studied: Whether eating plant-based diets helps prevent breast cancer and whether the type of plant foods matters
  • Who participated: 9 studies involving thousands of women, some who developed breast cancer and some who didn’t, tracked over several years
  • Key finding: Women who ate healthy plant-based diets had about 30-40% lower breast cancer risk in some studies, but eating processed plant foods showed no benefit or possible harm
  • What it means for you: If you’re looking to reduce breast cancer risk through diet, focus on whole plant foods like beans, vegetables, fruits, and whole grains rather than just avoiding meat. This is one piece of a larger cancer prevention puzzle—not a guarantee.

The Research Details

Scientists searched three major medical databases for studies published through August 2025 that looked at plant-based eating and breast cancer. They found 9 studies that met their strict criteria: 5 that followed healthy women over time to see who developed cancer, and 4 that compared women with breast cancer to similar women without it. Two researchers independently reviewed each study to make sure the information was accurate and consistent.

The researchers looked at three different ways to measure plant-based eating: a general plant-based diet score (which includes all plant foods), a healthy plant-based diet score (focusing on whole grains, fruits, vegetables, and legumes), and an unhealthy plant-based diet score (focusing on refined grains, sugary drinks, and processed foods). This distinction is important because not all plant-based foods are equally healthy.

They combined the results from all studies using statistical methods to see if patterns emerged. This approach is stronger than looking at single studies because it reduces the chance that one unusual study will skew the results.

This research matters because breast cancer is one of the most common cancers affecting women, and diet is one factor people can actually control. By combining multiple studies, researchers can see bigger patterns that might not show up in smaller individual studies. Understanding whether plant-based eating helps and which types of plant foods matter most can help people make informed dietary choices.

This is a systematic review and meta-analysis, which is considered high-quality evidence because it combines multiple studies rather than relying on just one. However, the studies included were different in design and size, which can affect how much we can trust the combined results. The researchers registered their plan before starting (PROSPERO registration), which is a good sign of transparency. The main limitation is that most studies were observational—they watched what people ate and what happened—rather than randomly assigning people to different diets, so we can’t be completely certain diet caused the differences in cancer risk.

What the Results Show

The research found that eating a healthy plant-based diet—one focused on whole grains, fruits, vegetables, beans, and nuts—was linked to lower breast cancer risk. In studies that compared women with and without breast cancer, those eating the most healthy plant-based foods had about 39% lower risk. In studies that followed women over time, the reduction was smaller but still meaningful at about 9%.

Interestingly, simply eating a plant-based diet without paying attention to food quality didn’t help. When researchers looked at all plant-based foods together (including processed options), there was no clear benefit for preventing breast cancer.

The most concerning finding was about unhealthy plant-based diets—those heavy in refined grains, sugary drinks, and processed plant-based foods. Women eating more of these foods had about 63% higher breast cancer risk in comparison studies, though the increase was smaller in follow-up studies.

These findings suggest that the quality of plant foods matters just as much as whether you eat them at all.

The researchers noted that most studies focused on breast cancer prevention in women who didn’t have cancer yet. Very few studies looked at whether plant-based diets help women who already have breast cancer survive longer or prevent recurrence. This is an important gap because the benefits for cancer survivors might be different than for prevention.

This research builds on earlier findings showing that plant-based diets help prevent other cancers like colorectal cancer. However, breast cancer appears to have a different relationship with plant-based eating than some other cancers. The finding that healthy plant-based diets help but unhealthy ones don’t is consistent with broader nutrition science showing that food quality matters more than food category.

The studies included were different in how they measured diet and followed participants, making it harder to combine results. Most studies were observational, meaning researchers couldn’t prove that diet caused the differences—other lifestyle factors might explain the results. The studies mostly included women from developed countries, so results might not apply to all populations. Additionally, most studies didn’t have enough information about breast cancer survivors, so we don’t know if plant-based diets help people who already have breast cancer.

The Bottom Line

If you’re interested in reducing breast cancer risk through diet, focus on eating whole plant foods: vegetables, fruits, whole grains, beans, lentils, nuts, and seeds. Limit processed plant-based foods, refined grains, and sugary drinks. This recommendation has moderate confidence based on the research. It’s important to note this is one part of cancer prevention—other factors like physical activity, maintaining a healthy weight, limiting alcohol, and avoiding smoking also matter significantly.

This research is relevant for women of all ages interested in cancer prevention, particularly those with family history of breast cancer. It’s also relevant for women who have had breast cancer and want to support their health, though more research is needed in this group. The findings apply to people eating any diet who want to make healthier plant-based choices. This is not medical advice for people currently being treated for cancer—they should follow their doctor’s recommendations.

Dietary changes typically take months to years to show health benefits. You might notice improvements in energy and digestion within weeks, but cancer prevention benefits would take much longer to measure. Think of this as a long-term investment in health rather than a quick fix.

Want to Apply This Research?

  • Track daily servings of whole plant foods (vegetables, fruits, whole grains, legumes, nuts) versus processed plant foods. Aim for 5+ servings of whole plant foods daily and note when processed plant foods are consumed.
  • Start by adding one new whole plant food to each meal rather than focusing on what to remove. For example: add beans to lunch, extra vegetables to dinner, and fruit to breakfast. This positive approach is easier to maintain than restriction.
  • Weekly check-in on plant food variety—try to eat at least 20 different plant foods per week. Use the app to photograph meals and rate them as ‘whole plant foods’ or ‘processed plant foods’ to build awareness of eating patterns over time.

This research summary is for educational purposes and should not replace professional medical advice. If you have concerns about breast cancer risk or have been diagnosed with breast cancer, please consult with your doctor or a registered dietitian. Dietary changes alone cannot prevent cancer, and this information should be considered alongside other evidence-based prevention strategies including regular screening, physical activity, and maintaining a healthy weight. If you are currently undergoing cancer treatment, discuss any dietary changes with your healthcare team first.