Q Please thank Muffin (letter, September 2006 issue) for asking a question that has long been on my mind regarding the safety of taking vitamins a year or so past their expiration date. I appreciate the difficulty in trying to answer that question, even considering that Life Enhancement Products is exceptional when it comes to quality and purity.

The only caveat I would offer to your answer is that I’ve seen many savvy people being less than savvy with their vitamins: they don’t secure the lids tightly on the bottles. Although there is no typical altitude, temperature, and humidity for all of us (as we all live in different locations and weather conditions), I would like to see Life Enhancement report on what happens to supplements when they’re exposed, short-term, to the atmosphere. You’ve probably done so in the past, but I thought this was a good opportunity to remind people about this important matter. As you said in your answer to Muffin, taking an oxidized form of a vitamin can have undesirable effects.

Also, what happens to my vitamins’ potency when they leave your facility and spend the better part of a week in the back of a delivery truck in the middle of summer? Sometimes I order $400 of product. Is there an inexpensive thermosensor that would indicate that my product had gone over 90°, 100°, even 120°? (When I worked at the airport, some jet engines had a small round sticker that changed color if the engine casing exceeded a certain temperature.) While not voiding the product, extreme temperature would likely reduce the shelf life and, therefore, the amount that I should order in advance.

MARK, Kansas City, MO

A We have received a number of reports over the years about product degradations resulting from high humidity. As you can probably guess, most such reports have come from Florida and Hawaii. Keeping the lids tight is vital, and refrigeration will always prolong shelf life (but bear in mind that when you open a cold container, condensation occurs rapidly, so the open time must be minimized).

We have also received reports, typically from the Southwest, that multinutrient formulations containing fat-soluble vitamins can blister, spot, or change color. Dietary supplements are not alike with regard to their sensitivity to temperature and light. Moreover, although most individual supplements have been stress-tested for these factors, things can change when they’re combined: a more insensitive ingredient may affect a less sensitive one. We have no precise knowledge about a correspondence between extreme temperature (and its duration) and shelf life. Thus, it’s probably best to avoid purchasing large amounts during the summer months if you live in a hot, sunny climate, unless you order air shipment. (Because of air shipment, Hawaii doesn’t seem to have much of a problem in this regard.)

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