Melatonin effective as breast cancer preventive and treatment in animals

May 3, 2005

In this issue

Life Extension Update Exclusive:

Melatonin effective as breast cancer preventive and treatment in animals


Breast cancer

Featured Products:


Melatonin capsules

Indole-3-carbinol with Standardized Broccoli Extract

Life Extension

Save on blood tests through June 1!

Life Extension Update Exclusive

Melatonin effective as breast cancer preventive and treatment in animals
An article published in Breast Cancer Research, volume 7, issue 4, 2005 ( reported the findings of French researchers that administration of the hormone melatonin helps prevent the development of breast cancer in rats in whom the disease was induced, and also treats the disease once it has been initiated.

The researchers gave one group of female rats 10 milligrams per kilogram melatonin daily for 15 days before administering the carcinogen dimethylbenzanthracene (DMBA). A second group of rats received no melatonin prior to receiving DMBA, but were given an identical dose of melatonin each day for six months beginning one day after the cancer-inducing treatment was administered. A control group of 20 rats received DMBA alone. The rats were followed for one year after receiving DMBA.

Animals were checked for tumors every two weeks during follow up. At six months, 75 percent of the control group had mammary adenocarcinomas, compared to 43 percent of those who were given melatonin preventively, and 35 percent of those who were given melatonin as a treatment. Rats who neither received melatonin before or after treatment had an average of four tumors each at nine months, compared 1.4 in those who were treated with melatonin.

Although many explanations have been offered for melatonin’s inhibitory effect on mammary cancer, the authors write that melatonin may inhibit DNA damage because of its free radical scavenging action. They note that changes in circadian rhythms have been associated with the development of cancer, and that boosting melatonin “could restore the deficiency of the circadian clock provoked by the low secretion of melatonin induced by DMBA. Therefore, it can be envisaged that amplifying the intensity of the circadian rhythm of melatonin might help to prevent the induction of the carcinogenic process by DMBA.” Treatment with melatonin could reduce the risk of environmentally induced breast cancer in women, they conclude.

Breast cancer

One of the most important supplements for a breast cancer patient is the hormone melatonin. Melatonin inhibits human breast cancer cell growth (Cos et al. 2000) and reduces tumor spread and invasiveness in vitro (Cos et al.1998). Indeed, it has been suggested that melatonin acts as a naturally occurring anti-estrogen on tumor cells, as it down-regulates hormones responsible for the growth of hormone-dependent mammary tumors (Torres-Farfan 2003).

A high percentage of women with estrogen-receptor-positive breast cancer have low plasma melatonin levels (Brzezinski et al. 1997). There have been some studies demonstrating changes in melatonin levels in breast cancer patients; specifically, women with breast cancer were found to have lower melatonin levels than women without breast cancer (Oosthuizen et al. 1989). Normally, women undergo a seasonal variation in the production of certain hormones, such as melatonin. However, it was found that women with breast cancer did not have a seasonal variation in melatonin levels, as did the healthy women (Holdaway et al. 1997).

Low levels of melatonin have been associated with breast cancer occurrence and development. Women who work predominantly at night and are exposed to light, which inhibits melatonin production and alters the circadian rhythm, have an increased risk of breast cancer development (Schernhammer et al. 2003). In contrast, higher melatonin levels have been found in blind and visually impaired people, along with correspondingly lower incidences of cancer compared to those with normal vision, thus suggesting a role for melatonin in the reduction of cancer incidence (Feychting et al. 1998).

In tumorigenesis studies, melatonin reduced the incidence and growth rate of breast tumors and slowed breast cancer development (Subramanian et al. 1991). Furthermore, prolonged oral melatonin administration significantly reduced the development of existing mammary tumors in animals (Rao et al. 2000).

There is no proven way to prevent breast cancer, but the best and most comprehensive scientific evidence so far supports phytochemicals such as I3C (Meng et al. 2000). The results from a placebo-controlled, double-blind dose-ranging chemoprevention study on 60 women at increased risk for breast cancer demonstrated that I3C at a minimum effective dosage 300 mg per day is a promising chemopreventive agent for breast cancer prevention (Wong et al. 1997).

Featured Products

Melatonin capsules

Melatonin is released from the pineal gland, reaching its peak at night to help maintain tissues in a youthful state of health. Secretion of melatonin declines significantly with age, as the pineal gland becomes calcified.

Melatonin keeps our circadian cycle in tune as it communicates with the body’s cells. Not only does this hormone work to maintain cell health, it appears to regulate a system of self-repair and regeneration. When this hard-working hormone is diminished, our biological functions are impaired.

Indole-3-carbinol with Standardized Broccoli Extract

Indole-3-carbinol is a plant compound from cruciferous vegetables, such as broccoli and cauliflower, that has shown impressive results in maintaining healthy cell growth. Broccoli contains several compounds that help maintain healthy DNA function. The broad-spectrum benefits of cruciferous vegetables have now been combined into one capsule. The proprietary 3:1 blend of broccoli sprout concentrate provides sulforaphane for immediate absorption and glucosinolates, which must be broken down in the body to provide a broad spectrum of isothiocyanates.

Unlike other products on the market that contain only the isothiocyanate sulforaphane, I3C with Standarized Broccoli contains standardized levels of glucosinolates. Glucosinolates are precursors or the “parent” compound that include a natural spectrum of isothiocyanates.

Questions? Comments? Send them to or call 1-800-678-8989.

For longer life,

Dayna Dye
Editor, Life Extension Update
1100 West Commercial Boulevard
Fort Lauderdale FL 33309
954 766 8433 extension 7716

Sign up for Life Extension Update at

Help spread the good news about living longer and healthier. Forward this email to a friend!

View previous issues of Life Extension Update in the Newsletter Archive.