The following is a excerpt from Chapter Four of The Vitamin D Revolution: How the Power of This Amazing Vitamin Can Change Your Life written by Soram Khalsa, M.D.

…According to recent estimates by the American Cancer Society, breast cancer is the second leading cause of cancer deaths in women in the United States. Rates of breast cancer are higher in white women after the age of 40 and higher in black women before the age of 40. Black women are more likely to die from breast cancer at any age.
Despite the findings that you will read about below, the American Cancer Society published a booklet about breast cancer in 2007 that makes no mention of Vitamin D deficiency and its relationship to the disease.

Breast cancer and Vitamin D

Breast tissue has Vitamin D receptors so if there is sufficient Vitamin D available, it can be activated in the breast. This activation sets up a series of events in the breast. The presence of activated Vitamin D is believed to help protect cells from cancer, help repair cells that may be mutating with cancer, and help slow the proliferation of cancer cells that may be present. Cancer cells can be more prone to die when Vitamin D helps to maintain the cells’ function of apoptosis. Activated Vitamin D is believed also to interfere with tumors building blood vessels to feed themselves, thus starving the tumors.

Women who have a of Vitamin D blood level of less than 20 ng/ml may have a higher incidence of breast cancer by up to 50 percent. Research in human and animal studies suggests that inadequate exposure to Vitamin D during puberty could affect normal breast development. . In my opinion, optimizing Vitamin D levels is a healthy option for people who have been told that they are at risk for developing breast cancer
A 1999 study was the first to link breast cancer with sun exposure, concluding that sun and Vitamin D could potentially reduce the risk of breast cancer. By combining sun, supplements, and Vitamin D rich food, it is estimated in this study that between 70,000—150,000 new cases of breast cancer could be prevented per year, and that up to 37,500 deaths from breast cancer could be averted each year.

In another study, published in 2008, researchers measured the Vitamin D levels of 103 premenopausal women from the northeastern United States when they were newly diagnosed with breast cancer and found that 84 percent of them were deficient in Vitamin D (median levels of 15.2 ng/ml). Fewer women who were white had Vitamin D deficiency (78 percent) than women who were Black (90 percent) or Hispanic (91 percent).

For one year, the women were given the recommended daily allowance (RDA) of Vitamin D (400 IU/day). When tested again, only 10 percent of the white and Hispanic women had achieved sufficient levels of Vitamin D (above 30 ng/ml). None of the Black women had increased their levels of Vitamin D to sufficiency. The study concluded that the current RDA of Vitamin D was insufficient to raise Vitamin D levels to 30 ng/ml in women with breast cancer.

Goodwin’s Breast Cancer and Vitamin D Study

In my opinion, the most important recent study showing the association between breast cancer and Vitamin D was conducted by Dr. Pamela Goodwin and her associates and reported in the Spring of 2008 when it caused quite a stir in the media. This was a retrospective study conducted in Toronto, Canada where the researchers looked back at blood that had been taken from 512 women when they were diagnosed with breast cancer between 1989—1995.

In retrospect, the researchers saw that a startling 76 percent of the women had had insufficient or deficient levels of Vitamin D when they were initially diagnosed with breast cancer. Only 24 percent of the women had had sufficient levels of Vitamin D at the time of initial diagnosis.

The researchers made the association that the women who had had low levels of Vitamin D at the time they were diagnosed with breast cancer were 73 percent more likely to die from breast cancer within 10 years than the women with sufficient levels of Vitamin D were. Furthermore, women with insufficient or deficient Vitamin D levels at the time of diagnosis were twice as likely to have a recurrence, or spread of the cancer within 10 years of diagnosis. However, women with normal levels of Vitamin D in their blood had an 85 percent chance of surviving without further spread of cancer after 10 years. To quote the conclusion of the study: “Vitamin D deficiency is common at breast cancer diagnosis and is associated with poor prognosis.” Dr. Goodwin, lead author of the study said it appeared that having a vitamin D level of 32—48 ng/ml was ideal.

In my opinion…

My wife and I had the privilege of hearing a vitamin D expert discussing this study on the radio. In the interview, this expert advised women with the diagnosis of breast cancer against taking vitamin D until prospective randomized-controlled trials could be run.

At a staff conference, I presented this startling information about the association between vitamin D and breast-cancer prognosis to my mostly female staff.  I explained that this study was only associating higher vitamin D with a better prognosis, but that it did not actually prove that taking vitamin D would have any benefit.

My entire staff looked at me as if I were crazy. It was obvious to them that taking some vitamin D, which is inexpensive and harmless, would in no way hurt them and might significantly benefit them.

I, too, disagree with the expert who was interviewed on the radio. I realize that large, randomized-controlled trials that measure the benefit of vitamin D in the treatment and prevention of illness and disease must be run. Until then, we cannot advertise with certainty that taking vitamin D will help protect people against cancer and the other diseases that I am describing in this book.  However, it is going to take many years, even a decade, to have conclusive results.

Given all the knowledge that we have today, and the strong associations, made by experts in the field, what harm is it for a person to take 2,000 IU/day when Vitamin D is so readily available and inexpensive? Certainly it will do no harm (as we will see in the dosage chapter that up to 10,000 IU/day is safe) and in light of all the studies, it will certainly help optimize the functioning of Vitamin D in the person’s body.

The lack of randomized controlled trials (RCT) may be an argument for a “by the book” doctor to refrain from using Vitamin D for the purpose of helping a woman with her breast cancer. But as John Cannell et al., say in the January 2008 issue of Expert Opinion Pharmacother, “Is that an argument not to diagnose and treat vitamin D deficiency? If human RCTs exist showing cigarette smoking is dangerous, the authors have yet to locate them. Instead, the compelling evidence for the dangerousness of smoking exists in convincing epidemiological data and the demonstration of a mechanism of action. The same is true for vitamin D, although the diseases linked to vitamin D deficiency outnumber those linked to cigarette smoking, … and activated vitamin D, a secosteroid, has as many mechanisms of actions as genes it targets. Some would also argue that the quantity and quality of the epidemiological data for vitamin D is approaching that which existed for cigarette smoking when governments and medical bodies first acted."

Increased risk of breast cancer, and mortality with lower Vitamin D levels

According to a study presented by a large group of Vitamin D experts, insufficient Vitamin D from either sun or supplements may be associated with a high risk of developing breast cancer, as well as a high risk of death from breast cancer.

The team of researchers analyzed the pooled data collected from two studies that associated breast cancer risk with Vitamin D levels. In both studies, breast cancer risk was lower in women who had higher levels of Vitamin D. Furthermore,

It was estimated that a Vitamin D blood level of approximately 52 ng/ml would be necessary to reduce risk of breast cancer by 50 percent from the risk that is present when Vitamin D blood levels are at less than 13 ng/ml. To achieve this level of 25D, an estimated daily dose of 4,000 IU of Vitamin D would be necessary.

The researchers also estimated the number of U.S. breast cancer cases that could potentially be prevented if women maintained certain blood levels of Vitamin D. For example, at levels of 32 ng/ml 66,000 new cases of breast cancer could be prevented whereas Vitamin D levels of 52 ng/ml could potentially prevent 107,000 new cases of breast cancer.

In other words, according to Garland et al., women from these existing studies who had Vitamin D levels of about 52 ng/ml had a 50 percent less risk of breast cancer than those women with Vitamin D levels below 13 ng/ml. This is a major difference and certainly gives us a lot to think about.

Given a choice, I know that my staff, family, and friends would prefer to raise their Vitamin D levels to 52 ng/ml.