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Study: Do Vitamin B supplements alter breast cancer risk for women with BRCA mutations?

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Contents

At a glance In-depth
Findings     limitations            
Guidelines Resources                           
Questions for your doctor  


STUDY AT A GLANCE

This study is about:

whether B vitamins lower or raise breast cancer risk in women with mutations.

Why is this study important?

Vitamin supplement use is a common. Women with a mutation can adjust use of vitamins, which may have an impact on breast cancer risk.

Study findings: 

This is a small study that looked at vitamin B supplement use among 400 women in Canada who had a mutation in or .

  • Women who took supplements that included folic acid (synthetic Vitatmin B9), Vitamin B complex, multivitamins, folic-acid specific, or prenatal vitamins - had decreased breast cancer risk compared to women who had never used these supplements if prior child birth history was considered Women who took these supplements had a 55% decrease in risk.
     
  • The decreased risk of breast cancer was observed in women who took moderate levels of folic acid (Vitamin B9) at 8-80 mcg/day or moderate levels of Vitamin B12 (.02-.34 mcg/day).
     
  • Vitamin B6 supplements did not significantly affect breast cancer risk.
     
  • Vitamin B significantly impacted women with mutations, but not women with mutations.

What does this mean for me?

If you are a woman with a mutation, use of Vitamin B9 (folic acid) and/or Vitamin B12 supplements may lower your breast cancer risk. This study suggest that folic acid taken at a level available in over-the-counter supplements may have an impact on breast risk in women with a mutation. It is important to note that current breast cancer risk-reducing guidelines for mutations carriers do not address the use of vitamin supplements. Experts do not recommend that women at high risk for breast cancer rely only on diet, exercise or nutritional supplements to lower their risk for cancer.

It is also important to know that the United States Food and Drug Administration () regulates vitamins and other supplements as foods and not as drugs. This means that companies that make and sell vitamins do not have the same strict oversight. Speak with your health care provider before beginning any supplements. If you do decide to take supplements, look for reputable companies.  

What do the guidelines say?

Experts have created national guidelines that outline the medical options for women at high risk for breast cancer. These guidelines include:

  • Increased screening for breast cancer
  • Medications to reduce breast cancer risk
  • Risk-reducing mastectomy

You can read more about the guidelines here.

Share your thoughts on this XRAYS article by taking our brief survey.

Posted 5/17/19

This article is relevant for:

High risk women with a BRCA1 or BRCA2 mutation

This article is also relevant for:

Previvors

BRCA mutation carriers

People with a genetic mutation linked to cancer risk

Women under 45

Women over 45

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IN-DEPTH REVIEW OF RESEARCH

Study background:

The B vitamins are a group of essential molecules that are commonly found in the same foods and contribute to key metabolic processes in cells. This study by Shana Kim and colleagues published in Breast Cancer Treatment and Research focuses on 3: Vitamins B6, B9 and B12. Vitamin B6 is involved in amino acid metabolism, the building blocks of proteins and in forming signaling molecules in the brain. Vitamin B9 (folate) and is involved in metabolism and repair and is essential for cell division. Folic acid, the synthetic version of folate found in supplements is slowly converted to folate in the body. Vitamin B12 is involved in metabolism of carbohydrates, lipids and proteins.

A lack of various B vitamins is associated with several diseases. Low Vitamin B6 levels are associated with skin and neurological problems. Low Vitamin B9 or folate levels can cause anemia and in pregnant women can lead to birth defects. Low Vitamin B12 levels can lead to anemia and problems.

The role of B vitamins in cancer is been controversial and complex. Some studies have observed that high folate levels and other B vitamins may be associated with cell growth in cultured cancer cells. A previous small trial by the authors of this study suggested that women with mutations who had high levels of folate also had increased breast cancer risk compared to women with lower folate levels. Meta-studies of women in the general population suggested that there may be decreased breast cancer risk with moderate levels of Vitamin B and increased breast cancer risk with high levels of Vitamin B. Other studies suggest that folate may offset the increased risk of breast cancer associated with some alcohol intake.

Researchers of this study wanted to know:

whether Vitamin B supplements alter the breast cancer risk of women with mutations.

Populations looked at in this study:

This is a follow-up study of participants who had completed a standardized questionnaire between 1994 and 2016. Breast cancer was self-reported and pathology was confirmed in 50% of cases.  A second questionnaire was sent between September 2014 and September 2016 to women in this group who had mutations (with and without breast cancer) asking about their vitamin B supplement use. Among the 910 original participants, 512 (56%)  returned the second questionnaire. Based on their responses, potential participants of this study were eliminated from eligibility if they had a cancer prior to breast cancer, had a prior mastectomy, or if they did not provide information about their mutation status or supplement use. The final group of participants for this study were 400 women age 18-70 with a mutation living in Canada; 129 had breast cancer and 271 did not.

Study design:

This is a small case-control study. Researchers asked women with mutations (with and without breast cancer)  if they had ever used Vitamin B6, Vitamin B9 (folate or folic acid) or Vitamin B12 in any supplement and to describe their daily use was (never, moderate, or high use). Vitamin B doses were self-reported or inferred by researchers from reported use. Researchers evaluated women based on multiple factors including parity (whether they had given birth), alcohol consumption, mutation status and other health factors.

Study findings:  

  • No association was made between breast cancer risk and multivitamin use or folic-acid specific supplements alone if childbirth was not considered.
  • However, when adjusted for age and status, women who took prenatal vitamins during pregnancy had a significant 43% decrease in breast cancer risk compared to women who did not take prenatal vitamins. For this reason, researchers looked more carefully at how childbirth impacted data on breast cancer risk. They evaluated the overall data on supplement use for women with different child birth histories.
  • Women who took any supplement that contained folic-acid (vitamin B complex, multivitamins, folic-acid specific, prenatal vitamins) had a significantly decreased breast cancer risk compared to women who never used these supplements if prior child birth history was considered (55% decrease, OR .4·      5, p value = .006).

Vitamin B9 (folate)

Women who took moderate levels of folic acid supplements (8-80 mcg/day) had significantly decreased risked compared to women who had never used supplements. This suggests that moderate folic acid supplements may be protective.

However, no significant difference was found between women who took high levels of folic acid supplements and those who did not take any. This suggests that too much folic acid is not protective.

Vitamin B12

Women with mutations who had taken moderate levels of Vitamin B12 supplements had a decreased risk of breast cancer (52% less) compared to women with mutations who never used Vitamin B12 supplements.

Vitamin B6

No significant differences in breast cancer risk were associated with different levels of Vitamin B6 intake.

Supplements may decrease risk for women with mutations but not those with mutations.

  • Women with mutations who took folic-acid supplements had a 70% decreased risk of breast cancer compared to women with mutations who never took folic acid-supplements.
  • Women with mutations who took folic-acid supplements had no significant difference in breast cancer risk compared to women with mutations who did not take folic-acid supplements.

Limitations:

This study is based on a small group of participants. Ideally, it should be repeated to see if these results are confirmed. Because only women with and were evaluated, tt is unclear if these results extend to women who do not have a or mutations and specifically what impact Vitamin B would have for women with mutation in other breast cancer predisposing genes.

This is a study that depends on participants' self-reporting of supplement use and any reporting inaccuracies may impact results. A trial with larger numbers of participants would help to clarify the reliability of these findings. Ideally vitamin supplement use would be tracked prospectively tracked in detail, along with dietary consumption, to best assess their impact.

Response rate to the second questionnaire on supplement use was low (56%) -  which could introduce some bias if those responding differed from the larger group of participants. A difference may also have existed among those participants who were still living at the time of questionnaire (2014-2016) and the participants who were initially enrolled (1994 to 2016).

Dietary intake of Vitamin B was not assessed. Adequate dietary intake may substitute for vitamin B supplements for some women and remains to be tested for carriers.

This study suggests that high levels of vitamin B supplements may not beneficial; no significant change in breast cancer risk was found with high levels of Vitamin B9 or 12 use. These researchers previous study showed that high circulating levels of folate (Vitamin B9) in the blood was associated with increased breast cancer risk. The data in this study suggests that while moderate levels of Vitamin B may be protective, high levels of Vitamin B may be harmful; a larger study is needed to clarify this issue. Meta-analyses of folate use in the general population suggest that very low or very high levels of folate are associated with increased breast cancer risk and moderate levels are associated with decreased breast cancer risk.

Conclusions:

Moderate levels of Vitamin B supplements may decrease risk of breast cancer for women with mutations.

It is important to note that current breast cancer risk-reducing guidelines for mutations carriers do not address the use of vitamin supplements. Experts do not recommend that women at high risk for breast cancer rely only on diet, exercise or nutritional supplements to lower their risk for cancer.

Share your thoughts on this XRAYS article by taking our brief survey.

Posted 5/17/19
 

References

Kim SJ, Zhang CXW, Demsky R, Armei S, Kim Y-I, Narod SA, Kotsopoulos J., "Folic acid supplement use and breast cancer risk in and mutation carriers: a case-control study". Breast Cancer Research and Treatment. January 2, 2019.
 

Disclosure

FORCE receives funding from industry sponsors, including companies that manufacture cancer drugs, tests and devices. All XRAYS articles are written independently of any sponsor and are reviewed by members of our Scientific Advisory Board prior to publication to assure scientific integrity.

Expert Guidelines
Expert Guidelines

The American Cancer Society (ACS) guidelines on exercise, nutrition and weight for cancer prevention recommend the following: 

Diet and nutrition

  • Follow a healthy eating pattern, including:
    • foods that are high in nutrients in amounts that help you get to and stay at a healthy body weight.
    • a variety of vegetables, fiber-rich legumes (beans and peas), and whole fruits in a variety of colors. Consume at least 2½ to 3 cups of vegetables and 1½ to 2 cups of fruit each day, depending on your calorie requirements. 
    • whole grains rather than refined grains. At least half of the grains you eat should be whole grains. 
  • A healthy eating pattern that limits or does not include:
    • red and processed meats.
    • sugar-sweetened beverages. 
    • highly processed foods and refined grain products.
  • It is best not to drink alcohol. People who choose to drink alcohol should:
    • have no more than 1 drink per day (women) or 2 drinks per day (men).

Exercise

  • Exercise regularly.
    • Adults should get at least 150 minutes of moderate-intensity activity (equal to a brisk walk) or 75 minutes of vigorous activity (heart rate is increased, breathing is faster and you are sweating) each week, preferably spread throughout the week.
    • Physical activity has been shown to lower the risk of several types of cancer, including breast, endometrial, and colon. It also reduces the risk of other serious diseases such as diabetes and heart disease.

Weight

  • Achieve and keep a healthy weight.
    • Being overweight or obese is a risk factor for many cancers, including breast, colon, endometrial and pancreatic. You can control your weight through regular exercise and healthy eating.

Other experts, including the following, also provide guidelines for exercise, nutrition and health: 

Updated: 07/19/2022

Questions To Ask Your Doctor
Questions To Ask Your Doctor

  • Is it appropriate for me to use Vitamin B supplements?
  • How much Vitamin B should I take?
  • What impact will vitamin use have on my health? on my breast cancer risk?
  • Will increasing the Vitamin B in my diet make a difference?
  • Can you refer me to a nutritionist?

Open Clinical Trials
Open Clinical Trials

The following are breast cancer screening or prevention studies enrolling people at high risk for breast cancer.   

Additional risk-management clinical trials for people at high risk for breast cancer may be found here.

Updated: 06/29/2022

Peer Support
Peer Support

FORCE offers many peer support programs for people with inherited mutations. 

Updated: 08/06/2022

Find Experts
Find Experts

You can find a registered dietician in your area using the search tool from the Academy of Nutrition and Dietetics.  

Updated: 11/13/2021

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