In an article published early online on July 24, 2008 in the Journal of Cellular Biochemistry, researchers from the University of Medicine and Dentistry New Jersey (UMDNJ) propose a protective role for vitamin D against the development of autoimmune diseases such as multiple sclerosis (MS).
Sylvia Christakos, PhD, and colleagues at the UMDNJ School of Medicine in Newark describe several findings which point to the vitamin's protective benefit. They observe that the incidence of MS declines as vitamin D from sunlight or diet increases. The disease is mostly unknown in the world's equatorial regions, where sunlight exposure, and, consequently, vitamin D production in the body, is greatest. Areas of the world in which fish intake is high also have a low incidence of MS. Fish and fish oils are among the few food sources of the vitamin.
It has been suggested that vitamin D assists in regulating immune response. While the hormonally active form of the vitamin has been shown to promote innate immunity, it may have a limiting effect on adaptive immunity. Such autoimmune diseases as allergic encephalitis, lupus erythematosis, autoimmune thyroiditis, arthritis, and autoimmune diabetes have all been shown in laboratory models to be partially prevented by vitamin D.
"Evidence has shown that the maintenance of an adequate vitamin D level may have a protective effect in individuals predisposed to MS," Dr Christakos stated. "One device of vitamin D action may be to preserve balance in the T-cell reaction and thus avoid autoimmunity."
In view of the particularly strong reduction in the risk of multiple sclerosis that has been associated with having higher serum levels of 25-hydroxyvitamin D3 before the age of 20, the authors suggest that vitamin D supplements may provide a protective benefit if administered to adolescents and young adults, especially among those with a family history of the disease. The authors write that a large clinical trial of vitamin D or a vitamin D analog is needed to determine whether vitamin D is not only protective, but is helpful as a treatment in individuals with active MS.
Related Health Concern: Multiple sclerosis
In 2004, scientists from the Harvard School of Public Health published the results of two long-term studies on women's health and nutrition. Researchers looked at dietary and supplemental intake of vitamin D as it related to the incidence of MS. Gleaned from the Nurses' Health Study (more than 92,000 women followed from 1980 to 2000) and the Nurses' Health Study II (more than 95,000 women followed from 1991 to 2001), the data support a protective effect for vitamin D against MS, especially for women who consume more than 400 international units (IU) daily of vitamin D from supplements, but not from food sources (Munger KL et al 2004).
In addition to reducing the risk of developing MS, supplemental vitamin D may also provide relief for those actively afflicted with the disease, at least in part by inhibiting nitric oxide, according to animal studies (Garcion E et al 2003). A small clinical trial conducted at the Mayo Clinic was designed to assess the safety and tolerability of daily use for a year of calcitriol, a prescription drug form of vitamin D. Patients who enrolled in the trial were diagnosed with relapsing-remitting MS. Patients received an equivalent of 2.5 micrograms per day (mcg/day) of calcitriol (about 100 IU/day), while their dietary calcium was restricted to 800 milligrams per day (mg/day). Researchers concluded that oral calcitriol is safe and well tolerated by patients with MS who comply with dietary recommendations (Wingerchuk DM et al 2005).
Scientists have also discovered that vitamin D effectively blocks development of MS in animals. When the biologically active, hormone form of vitamin D was administered to animals in a laboratory, the disorder was prevented. Conversely, a deficiency of vitamin D tended to increase the animals' susceptibility to the induced disease. When animals were given vitamin D after developing the disease, progression of symptoms was blocked. When vitamin D supplementation was withdrawn, the disease resumed (Cantorna MT et al 1996, 2000). Numerous laboratories have replicated and expanded upon these findings, prompting one researcher to declare: "Prevention of MS by modifying an important environmental factor (sunlight exposure and vitamin D level) offers a practical and cost-effective way to reduce the burden of the disease in future generations" (Chaudhuri A 2005).
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