Melatonin is a popular supplement that’s best known for its ability to help people sleep. New evidence suggests that melatonin may also help lower your risk of breast cancer and improve treatment outcomes.

Taking melatonin is considered safe for most people with breast cancer. However, melatonin does interact with several prescription medications, so it’s best to ask a doctor if you’re considering using it.

In this article, we take a closer look at what researchers have found about the link between melatonin and breast cancer prevention and treatment.

Recent research has looked into the possibility that melatonin might help prevent breast cancer, as well as slow its growth and help treatment work more effectively. Here’s what these studies have found.

Melatonin and breast cancer prevention

A 2018 study found that the antiestrogenic (a substance that prevents cells from making and using estrogen) and antioxidant properties of melatonin might help lower the risk of breast cancer.

Researchers have also found that melatonin provided potential therapeutic use in lowering breast cancer risk.

Melatonin and breast cancer treatment

In 2021, researchers found that melatonin use might slow the growth of triple-negative breast cancer, a fast-growing and hard-to-treat type of breast cancer.

In a 2022 study, researchers found that melatonin slowed breast cancer growth and that taking melatonin during treatment helped the treatment work more effectively.

In another study from 2022, researchers concluded that melatonin was a promising anticancer agent.

More research is needed

To date, research is still ongoing. There’s not a clear answer on the effectiveness of melatonin in treating and preventing breast cancer.

Data shows that it’s likely melatonin can help prevent and slow the growth of breast cancer. But there isn’t enough information yet to show a clear link. There are no official recommendations about melatonin from any major health agencies.

Melatonin is safe for most people during breast cancer treatment. However, melatonin can interact with some medications, so it’s a good idea to talk with your doctor before you begin taking it.

There are no noted interactions with chemotherapy medications. But if you are taking medications for any additional conditions you might have while being treated for breast cancer, adding melatonin could be unsafe in some cases.

Possible interactions include certain medications for:

Additionally, the long-term use of melatonin hasn’t been fully studied. It may be possible for melatonin to alter hormonal levels if it’s taken for an extended period. This could have risks and negative side effects for some people.

Melatonin is thought to have a wide range of potential effects. It’s most known for its use as a sleep aid. Anecdotal evidence and early research suggest that melatonin might have additional effects on mental and physical health.

Known effects of melatonin for people with breast cancer include:

  • sleepiness
  • increased risk of dizziness
  • increased risk of nausea

Some people undergoing breast cancer treatments such as chemotherapy find that melatonin helps them relax and sleep. It’s been reported that melatonin can lower stress levels and help with depression, anxiety, and other mood conditions people with breast cancer can experience.

Keep in mind that these uses of melatonin aren’t backed by research and data. However, as long as you’re not taking any medications that negatively interact with melatonin, it’s safe to try taking melatonin during breast cancer treatment.

Some people find that taking supplements during breast cancer treatment helps them feel better. It can be hard to eat a standard diet during treatment, and you might not be getting the nutrients your body is used to.

Taking supplements can help your body get the right balance of support for energy and health.

Be sure to talk with your doctor before taking supplements

It’s always best to talk with a doctor before you begin any supplements. This is particularly true if you’re undergoing treatment for breast cancer.

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Supplements that are typically safe to take if you have breast cancer

The following supplements are generally considered safe and helpful to take if you have breast cancer:

  • vitamin A
  • vitamin C
  • vitamin D
  • vitamin E
  • zinc
  • calcium
  • selenium
  • folic acid
  • ginger
  • magnesium
  • fish oil
  • phenylalanine
  • valine
  • threonine
  • tryptophan
  • L-lysine
  • carotenoids

Supplements NOT to take if you have breast cancer

There are some supplements that might be dangerous during chemotherapy and other breast cancer treatments. This includes:

  • acai berry
  • B17
  • garlic
  • ginkgo
  • echinacea
  • essiac
  • ginseng
  • St. John’s wort
  • kava

Additionally, common dietary products and aids such as green tea, probiotics, and grapefruit juice have been linked to some negatives for people undergoing chemotherapy.

The above list may not be all-inclusive. Determining what supplements are safe and what aren’t safe depends on the type of treatment you’re undergoing. Be sure to talk with the doctor who’s treating your cancer about supplements they recommend or supplements you’re considering taking.

Does melatonin reduce estrogen levels?

No, melatonin hasn’t been shown to lower estrogen levels.

Does melatonin slow the growth of all breast cancer cells or just certain types of breast cancer?

Some studies have focused on the link between melatonin and specific types of breast cancer, such as triple-negative breast cancer.

However, most research so far has looked at the possibility that melatonin could lower the spread of all breast cancer cells. Although this still needs further data, evidence points to melatonin being an option for all types of breast cancer.

Can melatonin prevent breast cancer recurrence in breast cancer survivors?

There’s not enough evidence to say if melatonin can prevent breast cancer recurrence. It’s possible that melatonin could lower your overall risk of recurrence, but there isn’t enough data to prove this link.

Can melatonin prevent other types of cancers?

Melatonin’s potential link to cancer growth is being studied. There’s some evidence to suggest it could reduce tumor size, help chemotherapy treatments more effectively, and increase survival rates.

In 2021, researchers looked at the effect of melatonin on both breast and prostate cancer. The study found that melatonin might slow the growth of both cancers.

Melatonin is a common supplement that’s most known for its use as a sleep aid. New evidence and research have shown that melatonin has a range of possible additional uses. This includes lowering the risk of breast cancer, slowing the growth of breast cancer, and helping to make breast cancer treatments more effective.

These links still need further study, but current data is promising. Right now, melatonin use is considered safe for most people with breast cancer. It can interact with some medications, though, so it’s best to talk with a doctor before taking melatonin.