by Carole Baggerly, Director at GrassrootsHealth

Today I have decided to get all the exercise I will need this month. So, I am going to get up, head to the gym and do 15 different sessions of cardio interspersed with 15 different sessions of my weight machines. Then, I will take a yoga class to round out the day. 

Ridiculous - right? 

So then why do many research studies use what is called 'bolus' dosing or dosing at higher rates, but at intervals that are far apart. For example, if they want to test what 1,000 IU of vitamin D daily would do, instead of having subjects take 1,000 IU every day (because they can't economically monitor that), they give each subject 30,000 IU once a month and have them come into a central location and watch them take the dosage (or placebo). They do this to save money - both on supplements and the cost of monitoring subjects in a trial - and to increase compliance. 

The problem is that bolus dosing does not replicate daily dosing, as described in detail below. This is why the study that is all over the news and continues to be brought up as a reason why vitamin D is ineffective, Annual High-Dose Oral Vitamin D and Falls and Fractures in Older Women, should not be considered applicable. They gave their subjects 500,000 IU vitamin D - once a year, for three to five years. You can read below why they shouldn't have improved falls and fractures and instead it would have been a better study if they had given the treatment group 2,000 IU every day.

 Learn more:

 http://www.grassrootshealth.net/blog/daily-dosing/