A diagnosis of multiple sclerosis (MS) is a hard lot. Patients typically get the diagnosis around age 30 after experiencing a series of neurological problems such as blurry vision, a wobbly gait or a numb foot.

From there, this neurodegenerative disease follows an unforgiving course. People with severe cases are typically bed-bound by age 60. Current medications don’t do much to slow the disease, which afflicts around 400,000 people nationwide, with 200 new cases diagnosed each week.

Now a team of CALS biochemists has discovered a promising vitamin D–based treatment that can halt—and even reverse—the course of the disease in a mouse model of MS. The treatment involves giving mice exhibiting MS symptoms a single dose of calcitriol, the active hormone form of vitamin D, followed by ongoing vitamin D supplements in their diet.

“All of the animals just got better and better, and the longer we watched them, the more neurological function they regained,” says CALS biochemistry professor Colleen Hayes, who led the study and published her team’s findings in the Journal of Neuroimmunology.

While scientists don’t fully understand what triggers MS, some studies have linked low levels of vitamin D with a higher risk of developing the disease. Hayes has been studying this “vitamin D hypothesis” for the past 25 years. She and her researchers have revealed some of the molecular mechanisms involved in vitamin D’s protective actions, and also explained how vitamin D interactions with estrogen may influence MS disease risk and progression in women.

In the current study, funded by the National Multiple Sclerosis Society, Hayes’ team compared various vitamin D–based treatments to standard MS drugs. In each case, vitamin D–based treatments won out. Mice that received them showed fewer physical symptoms and cellular signs of disease.

Hayes’ team compared the effectiveness of a single dose of calcitriol to that of a comparable dose of a glucocorticoid, a treatment now in use. Calcitriol came out ahead, inducing a nine-day remission in 92 percent of mice on average, versus a six-day remission in 58 percent for mice that received glucocorticoid.

“So, at least in the animal model, calcitriol is more effective than what’s being used in the clinic right now,” says Hayes.

But calcitriol can carry some strong side effects—it’s a “biological sledgehammer” that can raise blood calcium levels in people, Hayes says. After experimenting with various doses, her team arrived at a regimen of a single dose of calcitriol followed by ongoing vitamin D supplements in the diet. This one-two punch “was a runaway success,” she says. “One hundred percent of mice responded.”

While she is excited about the prospect of her research helping MS patients someday, Hayes is quick to point out that it’s based on a mouse model. The next step is human clinical trials. A multicenter clinical study is currently being designed. If trials are successful, people experiencing those first warning signs—the wobbly gait, the numb foot—could receive the new treatment and stop the disease in its tracks.

“It’s my hope that one day doctors will be able to say, ‘We’re going to give you an oral calcitriol dose and ramp up the vitamin D in your diet, and then we’re going to follow you closely over the next few months. You’re just going to have this one neurological episode and that will be the end of it,’” says Hayes. “That’s my dream.”