Back in August I started an experiment to see what Vitamin D supplements would do to my serum levels. After boosting them for 8 weeks I switched to a maintenance dose over the winter.

Process followed

Using the same tablets as before I took 2000 IU per day (two tablets) on a morning with breakfast. Compliance was good over the period I feel.

Activity has been down to 2050 steps on average due to the winter weather conditions. I’ve still managed to avoid catching respiratory illnesses, although of course the conditions this year have been very unusual due to the continuing Covid lockdowns.

The end of April/beginning of May represents the point at which the sun gets above 45 degrees at noon at my latitude, which is the point at which the sun is strong enough to trigger skin synthesis of Vitamin D. That will last until approximately the end of August.


The latest results from the lab are:

Total Vitamin D : 103.5 nmol/L

which is an increase of 15.4 nmol/L over the six months since October. That likely means that 2000 IU was a little too much and I should have stuck with single tablet 1000 IU supplementation recommended on the bottle. At this time of year you should be at the lower bound of the target useful range (allegedly around 75 nmol/L).

Follow up

I intend to drop supplementation from now on until the end of August and go back to 1000 IU per day from then. With an adequate diet and adequate sunlight over the summer that should maintain the levels.

I may test again in a year to test that theory but we’ll see. Now we have Covid vaccination we have a better way to stop the impact of the virus. I’ve had mine and it was fine. Make sure you get yours.

I hope you’ve enjoyed this short series. It’s been fun doing a little bit of actual science in the great tradition of personal experimentation. Feel free to drop onto the Discord if you have any comments or queries.