Researchers used a special genetic study method to look at whether 15 different vitamins and minerals affect the risk of a common type of breast cancer called ER+ breast cancer. They analyzed genetic information from thousands of people to see if these nutrients could cause changes in cancer risk. The study found that people with naturally higher levels of vitamin B6 (based on their genes) had a slightly higher risk of developing this type of breast cancer. However, the other 14 nutrients studied didn’t show a clear connection to cancer risk. The researchers say more studies are needed to understand why vitamin B6 might be linked to this cancer.

The Quick Take

  • What they studied: Whether 15 different vitamins and minerals (like vitamin B6, vitamin D, calcium, and zinc) affect the risk of developing ER+ breast cancer, which is the most common type of breast cancer.
  • Who participated: The study used genetic information from large databases of people’s DNA. Researchers didn’t directly study patients but instead analyzed genetic data from thousands of people to understand natural differences in nutrient levels.
  • Key finding: People with genetically higher vitamin B6 levels had about a 27% increased risk of ER+ breast cancer. This was the only nutrient out of 15 that showed a clear connection to cancer risk.
  • What it means for you: This finding suggests that very high vitamin B6 levels might be linked to breast cancer risk, but it doesn’t mean you should avoid B6 entirely. This is early research using genetic data, not proof that B6 causes cancer. Talk to your doctor before making any changes to your diet or supplements.

The Research Details

This study used a special research method called Mendelian randomization, which is like using your genes as a natural experiment. Instead of asking people what they eat and then following them to see who gets cancer, researchers looked at genetic variations that naturally make some people have higher or lower levels of different vitamins and minerals. They then checked if these genetic variations were connected to breast cancer risk. This method is powerful because genes are assigned randomly at birth, so it helps researchers figure out if nutrients actually cause changes in cancer risk, rather than just being associated with it.

The researchers gathered genetic information from large databases that contain DNA information from thousands of people. They looked at 15 different micronutrients (vitamins and minerals) and checked them against breast cancer information from a Finnish health database. They used a main analysis method called inverse variance weighted, which combines information from many genetic variations to get a stronger answer.

This research approach is important because it helps answer a tricky question: does a nutrient actually cause cancer risk, or is it just that people with certain nutrient levels happen to have other things in common that cause cancer? By using genetic information, researchers can get closer to understanding true cause-and-effect relationships. Regular studies that just ask people about their diet can be confusing because people who eat differently might also exercise differently, have different stress levels, or have other differences that affect cancer risk.

This study has some strengths: it looked at many nutrients at once, used a strong research method, and checked for errors in their analysis. However, there are important limitations to understand. The study used genetic data, which is different from actually measuring what people eat or their real vitamin levels. The connection between genes and actual nutrient levels in the body can be complicated. Also, the study only looked at European populations in the genetic databases, so results might not apply to other groups. The sample size for the analysis isn’t clearly stated in the paper.

What the Results Show

Out of 15 micronutrients studied, only vitamin B6 showed a clear connection to ER+ breast cancer risk. People with genetically higher vitamin B6 levels had a 27.5% increased risk of developing this type of breast cancer. This finding was statistically significant, meaning it’s unlikely to be due to chance alone.

The other 14 nutrients studied—including vitamin D, calcium, zinc, selenium, folate, vitamin C, vitamin E, vitamin A, vitamin B12, copper, iron, magnesium, potassium, and carotene—did not show a clear connection to breast cancer risk. This doesn’t mean these nutrients are safe or unsafe; it just means this particular study didn’t find a link.

The researchers were careful to check their work by testing whether their results could be explained by other factors or errors in their analysis. They used multiple statistical methods to make sure their findings were reliable.

The study included several checks to make sure the results were trustworthy. The researchers tested for ‘horizontal pleiotropy,’ which is a fancy way of saying they checked whether the genetic variations they used might affect cancer risk through other pathways besides vitamin B6 levels. They also looked for inconsistencies in their data that might suggest errors. These checks help confirm that the vitamin B6 finding is real and not just a statistical accident.

This is one of the first studies to use genetic methods to look at the relationship between multiple micronutrients and ER+ breast cancer specifically. Previous research has looked at individual nutrients and breast cancer risk, but results have been mixed and sometimes contradictory. This genetic approach offers a new way to think about the question. The finding about vitamin B6 is interesting because it hasn’t been a major focus in breast cancer research before, so it opens up a new area for scientists to investigate.

This study has several important limitations. First, it’s based on genetic data, not actual measurements of how much vitamin B6 people eat or have in their bodies. Genes influence nutrient levels, but they’re not the only thing that matters—diet, supplements, and how your body processes nutrients all play a role. Second, the study only included people of European ancestry in the genetic databases, so we don’t know if these results apply to other racial or ethnic groups. Third, the study can’t explain why vitamin B6 might increase cancer risk—it just shows a connection. Finally, the effect size is modest, and more research is needed to confirm this finding.

The Bottom Line

Based on this single study, there’s no reason to drastically change your vitamin B6 intake. Vitamin B6 is essential for your body and found in many healthy foods like chicken, fish, potatoes, and chickpeas. However, if you’re taking high-dose vitamin B6 supplements (much more than the recommended daily amount), you might want to talk to your doctor about whether you need them. This is especially important if you have a family history of breast cancer. The confidence level for this recommendation is moderate—this is interesting research, but it’s just one study and needs to be confirmed by other research.

Women, especially those with a family history of breast cancer or who are at higher risk, should be aware of this research. People taking high-dose B6 supplements should discuss this with their doctor. However, this doesn’t mean people should avoid foods containing vitamin B6, as these foods are nutritious and the vitamin is essential for health. Men should also be aware, as ER+ breast cancer can occur in men too, though it’s rare.

This is very early research, so don’t expect immediate changes in health recommendations. It typically takes many studies over several years to confirm a finding and understand how it works before doctors change their advice. If you’re concerned about your personal risk, talk to your doctor now rather than waiting for more research.

Want to Apply This Research?

  • Track your vitamin B6 intake from food sources and supplements separately. Log the amount (in milligrams) from each source daily, and note whether you’re staying within the recommended daily amount (1.3-1.7 mg for adults) or exceeding it with supplements.
  • If you’re taking vitamin B6 supplements, consider discussing with your doctor whether you actually need them. If you do, track the dose and discuss whether you could meet your B6 needs through food sources like poultry, fish, potatoes, chickpeas, and bananas instead.
  • Set a monthly reminder to review your supplement intake and discuss with your healthcare provider. Track any changes in your supplement routine and note conversations with your doctor about breast cancer risk factors. This creates a record you can reference over time as new research emerges.

This study uses genetic data to suggest a possible link between vitamin B6 and breast cancer risk, but it is not proof that vitamin B6 causes cancer. This is early research that needs to be confirmed by other studies. Do not make changes to your diet or supplements based solely on this research. Vitamin B6 is an essential nutrient your body needs. If you have concerns about your breast cancer risk or your vitamin B6 intake, especially if you take supplements, please discuss this with your doctor or a registered dietitian. This information is for educational purposes only and should not replace professional medical advice.