shelf life of vitamin D

In my opinion, once you open a bottle of vitamin D, you probably only have about a week or two of useful shelf-life.

When it is synthesized in a lab, vitamin D as a powder is unstable, and oxidizes rapidly, even in cool, dry air. Manufacturers package vitamin D in an inert gas, like nitrogen, without oxygen for storage and transport. When you open the bottle, oxygen gets in and can begin the decay process of the vitamin D into inactive metabolites. This is a known phenomenon, and that's one line of evidence.

Another is multiple anecdotal stories I have heard indicating that people get a benefit after they take the first one or two doses of prescription-strength vitamin D, and then the benefit wears off. For example, if they notice a reduction in body-wide pain or muscle aches, the effect is greatest during the first few weeks. Of if they notice an increase in wintertime energy, again, the effect dissipates after a few weeks. And I have noticed this myself.

Certainly there are other explanations for these reports. There may be a brief energy surge or reduction in pain from a rapid correction of a low vitamin D level, and then after the quick change the baseline metabolic processes take over again. But this is thought provoking. And the trend is such that in my opinion, it is likely that there is some decay of the vitamin.

There are a few potential answers to this problem. One is to buy a new bottle of vitamin D every few weeks. An over the counter bottle, if you find the right store and manufacturer, can cost you about $4.00, and this is a low price every few weeks for the potential benefit that the supplement can give you. Another option might be to devise some sort of inert-gas storage system, such as used to preserve wines. I haven't tried this yet.

Comments

[wsb]

have you talked with the vitamin D council about this?

[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.

[Ally]

Interesting info. But what about liquid capsules?

[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.

[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.

[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?

[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.

[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]

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.

[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.