Question Regarding the Shelf Life of Mineral Supplements

[scott123]

I'm seeing somewhat conflicting advice for storing supplements long term (longer than 5 years). First, supplements are supposed to lose their potency with age, but, minerals are supposed to be stable for a very long time- possibly even indefinitely. Looking at this list:

• magnesium glycinate
• magnesium threonate
• magnesium taurate
• magnesium malate
• copper glycinate
• selenium glycinate
• boron citrate
• boron aspartate
• boron glycinate
• chromium nicotinate glycinate
• lithium orotate
• manganese bisglycinate
• zinc gluconate
• potassium citrate

are there any entries that jump out as being inherently less stable?

I'm going to be storing these in a basement- peak temp 80F, in plastic bottles (PETE). If damp is 10 and dry is 1, I'd give it a 5. Ideally, I'd like to be able to get 10 years out of them.

 

[berkeman]

What are all of those used for?

 

[jim mcnamara]

@berkeman
They (1,2, or all) are added to filler, compressed into pills or stuffed into gelatin capsules and sold as mineral supplements.

Somewhat oversimplified answer:
One example: L-threose is a sugar. See the "L" ? That means it is a stereo isomer. R-threose is a completely different compound biochemically. "Flipping" handedness (L-threose -> R-threose) can occur in storage. Over time.

Enantiomers are non-superposable mirror images (R and L) of a single flavor of molecule. Human enzymes do not always play the same with both versions of an enantiomer. See the link below.

So the "mineral" atom is stable. Correct. The sugar molecule, amino acid or whatever may not be stable for years. Especially in home use.

Plus expiration dates may be required, and AFAIK you can put any reasonable future date on the label. Think arbitrary. Also expiration dates have a potential for increasing sales. You get to figure that one out.

Chiral chemistry has also given us non-caloric and low-calorie sweeteners (pop science):
https://www.wired.com/2003/11/newsugar/

A little more technical for chiral chemistry:
https://en.wikipedia.org/wiki/Chirality_(chemistry)

 

[Borek]

This borders self medication, which I guess was the reason @berkeman asked his question.

In general, as @jim mcnamara wrote, the organic part of all these compounds is not entirely stable, it will get slowly oxidized in time.

Part of the problem here is that the word "mineral" is used lousily. Sometimes it means mineral in geological sense, as in a "solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form", sometimes it means a mineral in a dietary or nutritional sense: "a chemical element required as an essential nutrient by organisms to perform functions necessary for life" (both definitions copied from wiki). And to make things even worse quite often the term is used as a shorthand to describe a compound used to deliver the element to organism.

So, while "minerals" in the first sense are in general stable (not all of them though, for example some require specific humidity conditions to survive), "minerals" in the last sense (as used by OP in this thread) can be quite sensitive and require short storage terms.

 

[jim mcnamara]

FWIW - some of those compounds are available in bulk packages. In that case you have to be able to measure a very tiny amount.

The US RDA for adults is 55 micrograms - The MW of Selenium Glycinate is 227.08g, so a putatively reasonable RDA dose would be less than 1mg. Good luck weighing that amount. The takeaway on this is you have to rely on pre-packaged supplements, which I think is what the OP is referring to. And yes, it is a borderline call about self-medication - which PF does not support.

 

[chemisttree]

@berkeman
They (1,2, or all) are added to filler, compressed into pills or stuffed into gelatin capsules and sold as mineral supplements.

Somewhat oversimplified answer:
One example: L-threose is a sugar. See the "L" ? That means it is a stereo isomer. R-threose is a completely different compound biochemically. "Flipping" handedness (L-threose -> R-threose) can occur in storage. Over time.

Enantiomers are non-superposable mirror images (R and L) of a single flavor of molecule. Human enzymes do not always play the same with both versions of an enantiomer. See the link below.

So the "mineral" atom is stable. Correct. The sugar molecule, amino acid or whatever may not be stable for years. Especially in home use.

Plus expiration dates may be required, and AFAIK you can put any reasonable future date on the label. Think arbitrary. Also expiration dates have a potential for increasing sales. You get to figure that one out.

Chiral chemistry has also given us non-caloric and low-calorie sweeteners (pop science):
https://www.wired.com/2003/11/newsugar/

A little more technical for chiral chemistry:
https://en.wikipedia.org/wiki/Chirality_(chemistry)

It is D and L in the case of sugars. R goes with S for stereochemistry around a single carbon atom. For molecules with multiple carbon stereocenters, the various versions or isomers that are not superimposable and not mirror images are diastereomers.

The “shrubbery” like glycinate are there to aid bioavailability or absorption in the gut. In the case of Mg L-threonate, the mineral has an active organic compound that could isomerize which probably wouldn’t affect bioavailability but the activity of the organic acid would likely be lost.

 

[jim mcnamara]

@chemisttree - thanks for the corrections. I was oversimplifying too much it seems. Also did not mention oxidation.