Appalachian State

Study Finds That Vitamin D2 Supplements Don’t Enhance Stamina

February 16, 2014

By Renee Elder

Correspondent February 16, 2014

Pit crew members for Hendrick Motorsports based in Concord served as subjects in a recent study that showed taking vitamin D2 supplements can lead to sore muscles that take longer to recover following exercise.

The study was intended to examine whether vitamin D2 supplements might boost stamina during the winter, a time when sunlight – the traditional source of vitamin D3 – is scarce, said David Nieman, director of the Appalachian State Performance Lab in Kannapolis, who oversaw the project.

The participants took D2 supplements and then underwent testing before and after exercise.

“Without much sun exposure, everybody’s vitamin D goes down in winter. We thought that if we kept their levels up, they might well have better muscle function and repair, and it would help these athletes,” Nieman said.

Instead, the study results – published in the December edition of the journal Nutrients – “send out a big red flag to the scientific community that D2 is not benign like people have thought and that athletes better stay away,” Nieman said.

The NASCAR team’s pit crews were ideal subjects for the study because of their extensive exercise regime, said Nieman, who is a professor in ASU’s Department of Health, Leisure and Exercise Science.

Need for energy

The racing season runs from February to November, but crew members continue their workouts year-round. They typically hit the gym twice daily to stay in shape for their jobs, which require strength, agility and intense bursts of movement during brief 12-second intervals, said Mark Morrison, head strengthening and conditioning coach for the Hendrick teams.

Only six people are allowed in the pit to service a car during a NASCAR race. Pit crews have two carriers to bring in the new tires; two tire changers (one for each end of the car); a jackman to raise the vehicle for servicing; and a fueler to fill the car with gasoline.

Many crew members are former college athletes whose strength and coordination are considered valuable traits, Morrison said.

Because every nanosecond counts in NASCAR, the team is always looking for ways to enhance efficiency and save time in the pit, Morrison said. This is the fourth year the pit crews have taken part in performance testing. Previous studies have examined issues related to body composition and maximum oxygen intake during exercise.

“We’re very scientific about training,” Morrison said. “The emphasis on pit crew strength and conditioning is very important. We want to do all the right things.”

The prospect of using D2 as a supplement during winter was appealing to these athletes on the pit crews at the outset of the study because of various potential benefits, the coach added.

Vitamin D acts as a catalyst for the body to absorb and metabolize calcium and phosphorus needed for healthy bones. It is also thought to be a factor in immune system development, cognitive functions and maintaining healthy body weight.

D2 versus D3

Vitamin D3 is made naturally by the body when sunlight strikes the skin. It is also available in certain types of fish and fish products, such as cod liver oil. In contrast, D2 is derived from foods such as mushrooms and other fungi that are exposed to ultraviolet light. Until recently, D2 was thought to function in the human body quite similarly to D3 and is also included in many vitamin supplements.

“Sunlight hitting the skin and producing D3 is what we are used to, and there are many healthy outcomes associated with having a good D3 intake,” Nieman said. “At the time we started the study (in early 2013), we had no idea D2 wouldn’t respond the same way as D3.”

For the study, which was funded by Dole Foods, half of the 28 athletes took capsules filled with powder from portobello mushrooms that had been enriched with vitamin D2 through exposure to ultraviolet light. The other half took a capsule containing a placebo. Neither the researchers nor the subjects knew which substance each capsule contained.

During the six-week study period, the crew members continued their regular exercise routines and had their blood drawn on several occasions.

“It’s an attractive idea – that we can use mushrooms to get vitamin D,” Nieman said. “It sounds healthy, like a great thing to do in the winter.

“But to our surprise, not only did their body’s level of D3 go down because of taking D2, the athletes had more muscle damage.”

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