Researchers followed over 11,000 girls from ages 10 to 30 to see if their eating habits during childhood and teenage years affected their chances of developing benign breast disease (non-cancerous breast lumps and cysts). Girls who ate healthier diets with more whole foods at age 10 had fewer breast problems later. Interestingly, girls who ate foods that caused more insulin spikes—like sugary and processed foods—had more breast issues. While these connections weren’t super strong, they suggest that eating well as a young person might help protect breast health into adulthood.

The Quick Take

  • What they studied: Whether the types of food girls eat during childhood and their teenage years affect their risk of developing benign breast disease (non-cancerous breast lumps and cysts) as adults.
  • Who participated: 11,422 girls who were part of the Growing Up Today Study. Researchers tracked their eating habits when they were 10 and 14 years old, then followed them for 20 years to see who developed breast problems.
  • Key finding: Girls who ate healthier diets (with more whole grains, fruits, vegetables, and fish) at age 10 had about 26-30% fewer breast problems. Girls who ate more foods that spike blood sugar and insulin levels had about 33-49% more breast problems, though these numbers weren’t quite strong enough to be completely certain.
  • What it means for you: Eating well during the teenage years may help protect breast health in adulthood. Focus on whole foods, fruits, vegetables, and limit sugary and processed foods. However, this is one study, and more research is needed before making major dietary changes based solely on this finding.

The Research Details

This was a long-term follow-up study called a cohort study. Researchers started with over 11,000 girls and asked their parents to fill out detailed food questionnaires when the girls were 10 and 14 years old. They recorded everything the girls ate and drank. Then, the researchers tracked these same girls for 20 years (until they were in their 30s) and asked them if they had ever been diagnosed with benign breast disease.

The researchers used three different ways to score the girls’ diets: one that measured overall healthy eating (AHEI), one that measured how inflammatory their diet was, and one that measured how much their diet caused blood sugar and insulin spikes (EDIH). They then used statistical tools to see if girls with better scores on these diet measures had fewer breast problems later in life.

This approach is strong because it follows real people over many years and captures their actual eating habits during important developmental years. However, it relies on people remembering and reporting what they ate, which can be imperfect.

The teenage years are a critical time when breast tissue is still developing. What girls eat during this period might influence how their breast tissue develops and their future risk of problems. This study is important because it looks at this specific time window and connects early eating habits to later health outcomes, rather than just looking at diet and breast disease at the same time.

This study has several strengths: it followed a large number of girls over a long period (20 years), it measured diet at specific ages during development, and it confirmed some breast disease cases with biopsies (medical tests). However, the study relied on people reporting what they ate, which can be inaccurate. The associations found were not always statistically significant in the main analysis, meaning we can’t be completely certain they’re real. The study became stronger when researchers adjusted for how diet changed over time and what people ate as adults, suggesting the findings may be real but need confirmation.

What the Results Show

Girls who followed a healthier eating pattern (the AHEI score) at age 10 had about 26% fewer cases of benign breast disease compared to girls who ate the least healthy. At age 14, girls with the healthiest diets had about 30% fewer confirmed breast disease cases. However, these numbers weren’t quite strong enough statistically to be completely certain—there’s still a chance these differences happened by chance.

Girls who ate foods that caused more insulin spikes (the EDIH score) at both ages 10 and 14 had more breast disease. At age 10, girls eating the most insulin-spiking foods had 49% more breast disease cases, and at age 14, they had 33% more cases. Again, these numbers weren’t quite statistically significant in the main analysis.

When researchers looked more carefully at how diet changed from age 10 to 14, and also considered what girls ate as adults, the connection between insulin-spiking foods at age 10 and breast disease became much stronger and statistically significant. Girls who ate the most insulin-spiking foods at age 10 had more than double the risk of breast disease. The healthy eating pattern also showed a significant protective trend when adult diet was considered.

No clear associations were found between the inflammatory diet score and breast disease risk.

When researchers looked at biopsy-confirmed cases (breast disease that was confirmed with medical testing rather than just self-reported), the patterns were similar but sometimes stronger. The healthy eating pattern showed a stronger protective effect for confirmed cases. This suggests the findings may be real, since confirmed cases are more reliable than self-reported cases. The study also found that how much a girl’s diet changed from age 10 to 14 mattered—girls who maintained poor eating habits were at higher risk than those who improved their diet.

Previous research has shown that diet affects breast cancer risk, but very few studies have looked at whether diet in childhood and adolescence affects benign breast disease specifically. Benign breast disease is important because it’s an established risk factor for breast cancer. This study fills a gap by examining this connection during critical developmental years. The findings align with general nutrition science showing that healthy eating patterns reduce disease risk and that foods causing insulin spikes may increase inflammation and disease risk.

The main limitation is that the study relied on parents reporting what girls ate, which may not be completely accurate. Some girls may have developed breast disease but not reported it or sought medical care. The study only included girls who participated in the Growing Up Today Study, who may not represent all American girls. The associations in the main analysis weren’t always statistically significant, meaning we can’t be completely certain they’re real. The study is observational, so it can show associations but not prove that diet directly causes the differences in breast disease—other factors could be involved. Finally, the study was conducted in the United States, so findings may not apply to girls in other countries with different diets and healthcare systems.

The Bottom Line

Based on this research, girls and young women should aim to eat a healthy diet rich in whole grains, fruits, vegetables, legumes, nuts, and fish while limiting sugary drinks, processed foods, and refined grains. This recommendation has moderate confidence because the main findings weren’t statistically significant, but they align with general healthy eating guidelines. Parents should encourage healthy eating habits during childhood and adolescence, as these appear to be important time windows for long-term health. However, this single study shouldn’t be the only reason to change diet—the overall evidence for healthy eating is much stronger.

This research is most relevant to parents of girls and to girls themselves during their teenage years. Healthcare providers who work with adolescents may find this helpful when discussing nutrition. Women with a family history of breast disease or breast cancer may want to pay special attention to these findings. This research is less relevant to boys and men, though healthy eating is beneficial for everyone. People who already eat a healthy diet don’t need to make changes based on this study.

The study followed girls for 20 years, so the protective effects of healthy eating took years to become apparent. You shouldn’t expect to see changes in breast health immediately. However, healthy eating has many other benefits that appear much faster, like improved energy, better school performance, and healthier weight. Any changes in breast tissue would likely take years to develop, so patience is important.

Want to Apply This Research?

  • Track daily servings of whole grains, fruits, vegetables, and protein sources (especially fish) versus processed foods and sugary drinks. Set a goal like ‘5+ servings of fruits and vegetables daily’ and ‘0-1 sugary drinks per week.’ Monitor this weekly to see trends in eating patterns.
  • Start by replacing one sugary drink per day with water or unsweetened tea, and adding one extra serving of vegetables to dinner. For teens, involve them in meal planning and cooking to increase awareness of food choices. Use the app to log meals and get real-time feedback on diet quality scores.
  • Track diet quality monthly using a simple scoring system (healthy foods vs. processed foods). Set seasonal goals to gradually improve eating patterns. For parents, monitor their daughter’s eating habits and celebrate improvements. Share progress with healthcare providers during annual checkups to discuss overall health and nutrition.

This research suggests an association between childhood diet and benign breast disease risk, but it does not prove that diet directly causes these differences. The main findings were not statistically significant and require confirmation with additional research. This information is educational and should not replace professional medical advice. If you have concerns about breast health or family history of breast disease, consult with a healthcare provider. Dietary changes should be discussed with a doctor or registered dietitian, especially for children and adolescents with specific health conditions. This study was conducted in a specific population and may not apply to all groups.