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#VitaminD on Trial
http://the-Scientist.com/2012/03/01/vitamin-d-on-trial Interesting mail the med. trial where participants aren’t explicitly checked for compliance

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“Once a month for the next 5 years, 20,000 people across the United States will find a package containing 62 pills in their mailboxes. As participants in a clinical trial, the recipients agreed to swallow two of the pills daily. But inevitably as the years pass, some pill packets will become buried under a stack of letters, or forgotten in a drawer. After all, these pills contain only vitamin D, fish oil, or an inert placebo—a person doesn’t need them to make it through the day. Plus, no one monitors who takes the pills daily and who does not.”

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Scientists critical of the VITAL study question whether the daily dose of 2,000 IU is enough to distinguish the treatment group from the controls. If this were a drug trial, the placebo group would go without the drug completely. But it’s unethical to ask anyone to go without vitamin D. Doctors inform all participants that they can take up to 800 IU of vitamin D daily (the national recommendation for people over 70 years old) in addition to the pills they receive in the mail. If they do, the control group will sustain more than adequate levels. But some participants might decide to break the rules and head to the nearest corner store for high-dose supplements after being told that vitamin D may help prevent cancer and other diseases. And of course, many participants won’t follow through with taking the pills they’ve been sent in the mail. “You hope drop-ins and drop-outs will be equal on both sides, but they may not be,” warns biostatistician Gary Cutter at the University of Alabama at Birmingham.

A higher dose of vitamin D would widen the gap between the treatment and the control group, but Manson isn’t swayed. She says 2,000 IU will lift the treatment arm well above the level suggested to help protect against nonskeletal diseases, while she expects the controls to stabilize at levels sufficient for healthy bones. “Sure, we could have tested higher doses, but then right off the bat, we might have had safety issues,” Manson says.
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Nonetheless, in other disease-prevention trials, investigators are gunning for better compliance and a fighting chance of showing an effect by doling out large, periodic doses of vitamin D. In the United Kingdom, a trial looking at the effect of vitamin D on respiratory infections (including the flu) is giving participants 120,000 IU of the vitamin every 2 months. And participants in the treatment arm of a vitamin D trial for type 2 diabetes prevention take an average dose of 89,684 IU once per week.
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