I keep seeing the bulletin boards say that vitamin D3 deteriorates fast - is it true??
Yes, vitamin D3 can deteriorate quickly. We are aware of a lot of debate on this and we have tried to clarify it.
The particular vitamin D3 we use has been tested in harsh conditions - up to 40degC and has been shown to deteriorate at a rate of less than 1% a month. We already include a small overage in the the product to compensate for this, so we are confident that meaningful levels are there well beyond the 6-9months that we recommend as the time you should change to a new pot!
Remember vitamin products are foods and should be replaced with fresh product.