Vitamin D is a prohormone group that consists of vitamin D, vitamin D2 (calciferol) and vitamin D3 (cholecalciferol) – and is necessary for many physiological processes in the body. Vitamin D is a vitamin, but when we think of it as a hormone we begin to see how and why it affects so many systems of the body. Vitamin D, and especially vitamin D3, impacts not only calcium absorption but also the endocrine system including thyroid function and estrogen levels.
There has been a great deal of research in recent years showing vitamin D deficiency as a contributing factor in many conditions and diseases, including cancer. In fact, studies show that women with the highest levels of vitamin D had 34% lower risk of breast cancer than those with the lowest levels of vitamin D. In animal studies, vitamin D deficiency has been shown to increase the overgrowth of breast tissue cells, increasing the instances of breast tumors and cancer.
Vitamin D Reduces the Rate of Tumor Growth
Studies have demonstrated that vitamin D inhibits tumors, especially in breast tissue. The breasts contain a high concentration of prostaglandins, a group of physiologically active lipid compounds that have diverse, hormone-like effects on the body. When these prostaglandins are released from breast cancer cells (tumors), they stimulate tumor growth by promoting cell proliferation. Vitamin D has been shown to reduce the release of these prostaglandins, significantly reducing the rate of tumor growth.
Dark Skin and Higher Rates of Vitamin D Deficiency
Vitamin D3 in particular is synthesized as a result of our exposure to sunlight. Melanin in dark skin blocks the formation of vitamin D3, so those with dark skin tend to have higher rates of vitamin D deficiency. Breast cancer mortality rates are 28% higher among black people and, while this may be in part because black people tend to be diagnosed at later stages of breast cancer than white people, it is also in part because of higher rates of vitamin D deficiency.
Vitamin D and Estrogens
Vitamin D has also been shown to inhibit both the synthesis and physiological actions of estrogens in the body. Calcitriol down-regulates the synthesis of estrogen, reducing the stimulation estrogen provides to cancer cells, encouraging them to proliferate. Inhibition of estrogen along with the anti-inflammatory actions of calcitriol plays an important role in decreasing breast cancer.
With research demonstrating how vital vitamin D is to our overall health and well-being, it is important that we ensure we are getting enough to keep our systems running smoothly. With 25% to 50% of Americans deficient in vitamin D, supplementation is an excellent way to be sure you are maintaining the levels necessary to not only ensure calcium absorption, but to also balance estrogen and progesterone levels and reduce the risk of breast cancer.
Editor’s Note: Natural Wellness’ Vitamin D3 is the most effective form of vitamin D.