Vitamin D and Dog Cancer

Vitamin D shrinks fibroid tumors in rats


NIH-funded study suggests possible treatment for common condition


Treatment with vitamin D reduced the size of uterine fibroids in laboratory rats predisposed to developing the benign tumors, reported researchers funded by the National Institutes of Health.


Uterine fibroids are the most common noncancerous tumors in women of childbearing age. Fibroids grow within and around the wall of the uterus. Thirty percent of women 25 to 44 years of age report fibroid-related symptoms, such as lower back pain, heavy vaginal bleeding or painful menstrual periods. Uterine fibroids also are associated with infertility and such pregnancy complications as miscarriage or preterm labor. Other than surgical removal of the uterus, there are few treatment options for women experiencing severe fibroid-related symptoms and about 200,000 U.S. women undergo the procedure each year. A recent analysis by NIH scientists estimated that the economic cost of fibroids to the United States, in terms of health care expenses and lost productivity, may exceed $34 billion a year.


Fibroids are three to four times more common in African-American women than in white women. Moreover, African-American women are roughly 10 times more likely to be deficient in vitamin D than are white women. In previous research, the study authors found that vitamin D inhibited the growth of human fibroid cells in laboratory cultures.


"The study results provide a promising new lead in the search for a non-surgical treatment for fibroids that doesn't affect fertility," said Louis De Paolo, Ph.D., chief of the Reproductive Sciences Branch of the NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development, which funded the study.


First author Sunil K. Halder, Ph.D., of Meharry Medical College in Nashville conducted the research with Meharry colleagues Chakradhari Sharan, Ph.D., and Ayman Al-Hendy, M.D., Ph.D., and with Kevin G. Osteen, Ph.D., of Vanderbilt University Medical Center, also in Nashville. The findings appeared online in the journal Biology of Reproduction.


For the current study, the researchers tested the vitamin D treatment on a strain of rats genetically predisposed to developing fibroid tumors. After examining the animals and confirming the presence of fibroids in 12 of them, the researchers divided the rats into two groups of six each: those that would receive vitamin D and those that would not.


In the first group, small pumps implanted under the skin delivered a continuous dose of vitamin D for three weeks. The researchers then examined the animals in both groups. Fibroids increased in size in the untreated rats, but, in the rats receiving vitamin D, the tumors had shrunk dramatically. On average, uterine fibroids in the group receiving vitamin D were 75 percent smaller than those in the untreated group.


The amount of vitamin D the rats received each day was equivalent to a human dose of roughly 1,400 international units. The recommended amount of vitamin D for teens and adults age 70 and under is 600 units daily, although up to 4,000 units is considered safe for children over age 9, adults, and for pregnant and breastfeeding females.


"Additional research is needed to confirm vitamin D as a potential treatment for women with uterine fibroids," said Dr. Al-Hendy. "But it is also an essential nutrient for the health of muscle, bone and the immune system, and it is important for everyone to receive an adequate amount of the vitamin."


Fatty fish such as salmon, mackerel and tuna are the best natural sources of the vitamin. Very few foods naturally contain vitamin D. Fortified milk and other fortified foods provide an additional source of the vitamin. Vitamin D is also produced when ultraviolet rays from sunlight strike the skin.


Vitamin D deficiency has been associated with increased risk of colon cancer in epidemiologic and prospective clinical studies. In vitro and in vivo studies demonstrated that 1,25-dihydroxycholecalciferol [1,25(OH)2D3] and its analogs inhibit colon cancer cell proliferation. Few studies have evaluated the effect of vitamin D deficiency on the development and growth of colon cancer. To assess the antiproliferative effects of 25-hydroxyvitamin D [25(OH)D] and 1,25(OH)2D3 in vitro, we cultured MC-26 (a colon cancer cell line) in the presence of 25(OH)D3 and 1,25(OH)2D3 and performed [3H]thymidine incorporation. The proliferation of MC-26 was significantly inhibited by both 25(OH)D3 and 1,25(OH)2D3. To determine the effect of vitamin D deficiency on colon cancer proliferation, Balb/c mice were rendered vitamin D deficient by feeding them a vitamin D–deficient diet for 3 mo. A group of vitamin D–sufficient mice was given the same diet with supplemental vitamin D. The mice were injected with MC-26 colon cancer cells and the tumors were measured daily for 20 d. Vitamin D–sufficient mice had 40% smaller tumors than vitamin D–deficient mice. The tumors were evaluated for mRNA expression of the vitamin D receptor (VDR) and 25-hydroxvitamin D-1α-hydroxylase (1α-OHase) by quantitative RT-PCR. The expression of the mRNA for the VDR and the 1α-OHase was 37- and 6-fold higher, respectively, in the vitamin D–sufficient mice compared with the vitamin D–deficient mice. We conclude that vitamin D deficiency enhances the growth of colon cancer in mice. The tumor expression of VDR and 1α-OHase indicates possible autocrine/paracrine cell growth regulation by vitamin D.


As in herbivores and omnivores, the biosynthesis of vitamin D3 in the skin exposed to ultraviolet (uv) light is generally expected to also occur in the dog and the cat. The purpose of this in vitro study was to measure the concentrations of vitamin D3 and its precursor 7 dehydrocholesterol (7DHC) in dog and cat skin before and after a quantitatively and qualitatively standardized exposure to uv light. The results are compared to those obtained by the same method in the skin of the rat. The efficiency of extracting 7DHC and vitamin D3 from skin was 72 ± 8% and 67 ± 3%, respectively. In dog and cat skin the concentrations of nonesterified 7DHC were below the detection limit of the HPLC system. Therefore, skin extracts were saponified and total 7DHC and vitamin D3 concentrations were measured by normal-phase HPLC. Before irradiation with uv-B light the total concentrations of 7DHC were 1858 ± 183, 1958 ± 204, and 17,620 ± 2345 ng/cm2 skin (mean ± SEM; n = 5) for the dog, the cat, and the rat, respectively. The corresponding concentrations of vitamin D3 were 211 ± 44, 193 ± 18, and 161 ± 32 ng/cm2 skin for the dog, the cat, and the rat, respectively. Irradiation of standard solutions of 7DHC with 0.15 J uv-B light/min resulted in a time-dependent decrease in 7DHC and a concomitant increase in previtamin D3. After exposure of skin to a total of 2.25 J uv-B light no significant changes in concentrations in vitamin D3 were found in extracts of the skin of the dog and the cat, whereas a 40-fold increase in the vitamin D3 concentration occurred in the skin of the rat. It is concluded that in the skin of the dog and the cat only low concentrations of esterified 7DHC are present and that this 7DHC is also inadequately converted to vitamin D3. As shown previously there is no detectable increase in vitamin D3 in the dog exposed to uv irradiation in vivo. Therefore, these low 7DHC concentrations are not caused by high turnover of 7DHC but are due to restricted availability of this vitamin D3 precursor in the skin of the dog. Thus, the dog and the cat are, unlike herbivores and omnivores, not able to synthesize vitamin D3 adequately in the skin and are mainly dependent on its dietary intake, i.e., vitamin D3 is an essential vitamin for the dog and cat.


Vitamin D may help prevent certain cancers, and high doses may enhance chemotherapy, says Rodney Page, director of the Sprecher Institute for Comparative Cancer Research and the Program on Breast Cancer and Environmental Risk Factors, both in the College of Veterinary Medicine at Cornell.

That is why he and colleagues at the Sprecher Institute are collaborating with the Roswell Park Cancer Institute to study the role of vitamin D in cancer in several animal models.

"Vitamin D can affect regulation of many cellular processes associated with cancer development and therapy, including differentiation, proliferation and cell death," said Page.

Page and colleagues also are studying how vitamin D affects chemotherapy in dogs and cats. So far, they have determined that high doses can be safely given to dogs getting chemotherapy and that blood concentrations of vitamin D can be achieved to potentially improve cancer response. They are now planning a follow-up study to determine whether vitamin D improves the outcome in dogs with cancer.


From what I've read, here are foods containing vit D: Shitake mushrooms, herring, sardines, catfish, tuna, Sockeye salmon, eggs. Sunlight.


An acupuncture vet (a holistic one) said many holistic vets have been using Vitamin D injections for years on cancer dogs.


Vitamin D is a member of the fat-soluble class of vitamins, meaning that it is stored in the liver and fatty tissues of the body. The recommended minimum daily dose is 227 IU per pound of consumed dry dog food. This can be obtained through exposure to sunshine (converted into Vitamin D in the upper layers of the skin) and consumption of dairy products and fish liver oil and, of course, a good commercial dog food.
Vitamin D regulates the calcium:phosphorous balance in the body. It stimulates kidney retention of calcium and is vitally important to bone formation and nerve and muscle control.


"As a steroid hormone that regulates mineral homeostasis and bone metabolism, 1α, 25-dihydroxycholecalciferol also has broad spectrum anti-tumor activities as supported by numerous epidemiological and experimental studies. It potentiates the anti-tumor activities of multiple chemotherapeutics agents including DNA-damaging agents cisplatin, carboplatin and doxorubicin; antimetabolites 5-fluorouracil, cytarabine, hydroxyurea, cytarabine and gemcitabine; and microtubule-disturbing agents paclitaxel and docetaxel. Calcitriol elicits anti-tumor effects mainly through the induction of cancer cell apoptosis, cell cycle arrest, differentiation, angiogenesis and the inhibition of cell invasiveness by a number of mechanisms. It enhances the cytotoxic effects of gamma irradiation and certain antioxidants and naturally derived compounds. IT has been used in a number of clinical trials and it is important to note that sufficient dose and exposure to is critical to achieve anti-tumor effect. Several trials have demonstrated that safe and feasible to administer high doses through intermittent regimen."



"Efficacy of Vitamin D (Calcitriol) for Treatment of Canine Mast Cell Tumors." Dr. Kenneth Rassnick

Mast cell tumors are common skin tumors in dogs. There is a tremendous need to develop effective therapies for this cancer in dogs. Calcitriol is the active form of vitamin D, and the potential for calcitriol as an anti-cancer agent has been demonstrated in laboratory studies. Clinical trials of calcitriol in people with cancer are underway.

Dr. Rassnick and his colleagues have established a safe oral dosing regimen for calcitriol in dogs and have already observed regression of an advanced mast cell tumor in a dog treated with calcitriol. The objectives of this proposal are to investigate the anti-tumor activity of calcitriol against a canine mast cell tumor cell line. Additionally, they will conduct a clinical trial using oral calcitriol to treat dogs with naturally occurring mast cell tumors. They expect that the results of this research will show that calcitriol is an effective treatment for mast cell tumors in dogs. These results will significantly impact the management of dogs with mast cell tumors as they will lead to future use of calcitriol as a palliative and/or standard therapy in dogs with this disease.


VITAMIN D is also considered to be a hormone. It is not only found in food, but also sunlight. It helps with the metabolism of calcium and phosphorus in the body by increasing absorption of these in the intestines. A deficiency of this vitamin in puppies can result in rickets, stunted growth, delayed tooth development and bone deformities. The daily intake for a dog would be 100 IU or less for a small dog, 200 IU for a medium sized dog and 400 IU for a large dog. Food sources for this vitamin include fatty saltwater fish, fish liver oils and fortified dairy products. Sunlight also provides some vitamin D.




I give Lucy my 90# Lab with cancer about 2000IU in one of her meals on random days of the week.