Researchers used advanced genetic analysis to study whether 1,400 different chemicals in our blood might affect breast cancer risk. They found that some chemicals—like certain hormones and fats—may increase the risk of a specific type of breast cancer, while caffeine-related compounds might lower the risk. This study is important because it helps scientists understand what happens inside our bodies that might lead to breast cancer. However, these findings are preliminary and need more testing before doctors can use them to help patients.

The Quick Take

  • What they studied: Whether specific chemicals found naturally in blood might cause or prevent certain types of breast cancer
  • Who participated: The study used genetic information from large groups of people with European ancestry, combining data from two major research projects (FinnGen and the Breast Cancer Association Consortium). No direct human participants were tested—researchers analyzed existing genetic data.
  • Key finding: Two chemicals (a hormone-related compound and a fat called myristoleate) appeared to increase breast cancer risk, while a caffeine-related compound seemed to lower risk. However, these connections are still preliminary and need confirmation.
  • What it means for you: This research suggests that what we eat and our body’s natural chemistry might influence breast cancer risk, but it’s too early to make any lifestyle changes based on these findings alone. Talk to your doctor about proven ways to reduce breast cancer risk.

The Research Details

This study used a special type of genetic analysis called Mendelian randomization, which is like using genetics as a natural experiment. Instead of following people over time, researchers looked at genetic data from thousands of people to see if certain chemicals in the blood were connected to breast cancer. They examined 1,400 different metabolites (chemicals our bodies make or get from food) and tested whether they might actually cause breast cancer or if the connection was just coincidence. The researchers used information from two large genetic databases and performed multiple checks to make sure their findings were reliable.

Regular studies can’t always tell if a chemical causes cancer or if cancer causes changes in that chemical (called reverse causation). By using genetic information, researchers can better understand true cause-and-effect relationships. This method is stronger than just observing people because genes are assigned randomly at birth and don’t change based on whether someone gets sick.

The study included multiple safety checks to ensure results were trustworthy: they tested whether results held up when removing individual data points, checked for statistical errors, and looked for hidden factors that might have skewed results. All these checks passed, suggesting the findings are reasonably reliable. However, the study only included people of European ancestry, so results might not apply equally to other populations.

What the Results Show

The researchers identified three main metabolites with potential causal links to breast cancer. Two chemicals increased the risk of hormone-receptor-positive breast cancer (a common type): a hormone-related compound called 5alpha-pregnan-3beta,20alpha-diol monosulfate and a fat called myristoleate (14:1n5). One compound—a caffeine-related ratio—appeared to lower breast cancer risk. These findings suggest that our body’s chemistry, particularly hormones and fats, may play important roles in breast cancer development. The study also found evidence that breast cancer might influence levels of several other chemicals in the body, suggesting a two-way relationship.

The research identified several other chemicals that showed connections to breast cancer in reverse analysis, meaning breast cancer might change their levels in the body. These included eicosanedioate (a type of fat), piperine (a compound in black pepper), caffeine-to-theobromine ratio, indolepropionate (from gut bacteria), and certain other fats. These secondary findings suggest that breast cancer affects the body’s chemistry in multiple ways, not just the other way around.

Earlier studies had noticed that certain chemicals in the blood seemed connected to breast cancer risk, but scientists couldn’t prove whether these chemicals caused cancer or were just associated with it. This study goes further by using genetic methods to suggest actual cause-and-effect relationships. The findings align with previous research suggesting that hormones and dietary fats play roles in breast cancer, but provide stronger evidence for these connections.

The study only included people of European ancestry, so findings may not apply equally to other racial and ethnic groups. The research is based on genetic data rather than direct measurement of these chemicals in people’s bodies. The identified metabolites are preliminary candidates that need laboratory and clinical testing to confirm they actually cause changes in cancer risk. The study cannot prove these chemicals definitely cause breast cancer—only that they may be involved.

The Bottom Line

These findings are preliminary and not yet ready to guide personal health decisions. Current proven ways to reduce breast cancer risk remain: maintain a healthy weight, limit alcohol, exercise regularly, and follow screening guidelines. If you have family history of breast cancer, talk to your doctor about personalized prevention strategies. (Confidence level: Low—these are early-stage research findings requiring further validation)

This research is most relevant to scientists and doctors studying breast cancer causes. People with family history of breast cancer may find it interesting but should not change their diet or lifestyle based on these preliminary findings. Women of European ancestry may see these results as more directly applicable than other populations, given the study’s population.

Even if these metabolites are confirmed as important, it would likely take 5-10 years of additional research before doctors could use this information to help prevent breast cancer. This is early-stage research that opens doors for future studies, not a ready-to-use discovery.

Want to Apply This Research?

  • Track caffeine intake (cups of coffee/tea daily) and dietary fat sources (servings of nuts, oils, fatty fish) alongside any health markers you monitor. Note patterns over months to see if your consumption aligns with how you feel.
  • Use the app to log your caffeine and dietary fat intake to establish a baseline. Once more research confirms these metabolites’ roles, you’ll have historical data to reference. For now, focus on proven healthy eating patterns: balanced diet with whole grains, vegetables, and moderate healthy fats.
  • Set up monthly check-ins to review your diet quality and caffeine consumption patterns. As research evolves, your app can alert you to new evidence-based recommendations. Keep records of any health discussions with your doctor about breast cancer prevention.

This research is preliminary and does not provide medical advice. The findings are based on genetic analysis and have not been confirmed through clinical trials. Do not make changes to your diet, supplements, or medical care based on this study alone. If you have concerns about breast cancer risk, especially with family history, consult with your healthcare provider or a genetic counselor. Current evidence-based breast cancer prevention strategies remain the most reliable approach. This study identifies potential areas for future research, not proven causes or treatments.