Main | »

May 25, 2005

Comments

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.

VitaminDHealth

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.

Ally

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.

wsb

have you talked with the vitamin D council about this?

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Working...
Your comment could not be posted. Error type:
Your comment has been saved. Comments are moderated and will not appear until approved by the author. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.

Working...

Post a comment

Comments are moderated, and will not appear until the author has approved them.

Your Information

(Name is required. Email address will not be displayed with the comment.)