Main | »

May 25, 2005


Feed You can follow this conversation by subscribing to the comment feed for this post.

Richard Trinko

This is definitely an intriguing question. I have brought this to the attention of ConsumerLab, but have not yet heard back. I did find a fairly recent journal article: Zwart, S.R. et al. 2009 - Journal of Food Science, where they evaluated many nutrients (including Vit. D by HPLC) in salmon and multivitamins consumed by astronauts. The observed loss across 880 days was variable, yet much smaller than I expected. I hope their data is accurate and helpful.

Dr. Mike

Sorry for the delay. I have little to no objective evidence to back this up. Years ago I read in a package insert that the half-life of dry vitamin D crystals in air is something like 3 weeks. I have not been able to find that insert recently. However, I also notice that when I use an old bottle of vitamin D (e.g. a month old), it does not prevent the muscle aches I get in the wintertime, but a new bottle works very well.

Bob Roberts

Have you had any further dealings with the likes of the Vitamin D Council or Professor Hollick on this?

This is the only reference I can find online to the possibility that Vitamin D may go off within a few weeks of opening a jar.

It has major consequences for those who are hoping that Vitamin D will help them with, for example, asthma as to whether we buy jars with 30, 60, 90, 120 or 360 softgels in. I have seen no one else mention this.

Look forward to hearing an update on this info.

Dr. Mike

I think if you made sure the little packets were packaged with nitrogen - and not just packaged in air like they do in some pharmacies - that this would work.


Couldn't a fair daily dosage of Vitamin D - I know it varies according to individual's weight - be wrapped in separate sealed packets?

Cathy Fletcher

Super interesting...I needed to add one line about the shelf life of Vitamin D to an ezine article we just wrote connected to our blog on Vitamin D.

Dr. Mike

This is my opinion only - but air penetrates the liquid capsules, and I believe the vitamin D in them deteriorates at the same rate.


Interesting info. But what about liquid capsules?

Dr. Mike

No I haven't. I really should. It could have a tremendous impact on the reliability of trial data. I'll get on it.


have you talked with the vitamin D council about this?

The comments to this entry are closed.