Understanding vitamin labelling

[Leila Choudhry]

I am confused about the labelling on vitamin supplements.

For example with Zinc, there are a number of different types and the one used is elemental where each tablet is listed as 30mg, with a Nutrient Reference Value of 300 from 100mg Zinc Citrate Dihydrate.

Asking a Pharmacist what this mean I left with the understanding that to get the 30mg elemental dose, it would take 100mg to achieve this, is that right ?

Another was Magnesium, where the tablet was 211mg from 1,456mg of Magnesium Citrate, with a "Referenced Intake" of 56.2%.

What does all this actually mean, as some companies charge more than others and I would like to know what is going on.

Also, I was told that the size of the pill isn't determined by how much of a vitamin is contained within it, as there are all manner of binders and shelf stabilisers that aren't even mentioned on the ingredients that bulk out the pill, as the vitamin amounts are so small.

[studiot]

1 hour ago, Leila Choudhry said:

I am confused about the labelling on vitamin supplements.

For example with Zinc, there are a number of different types and the one used is elemental where each tablet is listed as 30mg, with a Nutrient Reference Value of 300 from 100mg Zinc Citrate Dihydrate.

Asking a Pharmacist what this mean I left with the understanding that to get the 30mg elemental dose, it would take 100mg to achieve this, is that right ?

Another was Magnesium, where the tablet was 211mg from 1,456mg of Magnesium Citrate, with a "Referenced Intake" of 56.2%.

What does all this actually mean, as some companies charge more than others and I would like to know what is going on.

Also, I was told that the size of the pill isn't determined by how much of a vitamin is contained within it, as there are all manner of binders and shelf stabilisers that aren't even mentioned on the ingredients that bulk out the pill, as the vitamin amounts are so small.

 

Shall we start by noting that neither magnesium nor zinc are vitamins >

They are minerals.

 

Now I agree that the information is designed to impress the punters rather than inform them.

 

So look at the zinc citrate dihydrate. This is a better description because crystals of salts require what is known as 'water of crystallization' to form.
This water is made of water molecules incorporated in the crystal structure. The dihydrate tells us that there are 2 molecules of water for every molucule of zinc citrate.
So when reporting the weight of the stuff this includes this weight of this water.

 

Now looking at the Magesium citrate this presents an immediate problem as they have not told us how much water there is.

A quick google search reveals that there is a lot of it.

 

 

Note that the molecular weight declared by google as 214 g/mol is much less than the official government value of 451 g/mol

 

I'm sorry Im not familiar with US government labelling practice and terminology so someone else will need to help with refernce intake and nutrient reference values.

[exchemist]

1 hour ago, Leila Choudhry said:

I am confused about the labelling on vitamin supplements.

For example with Zinc, there are a number of different types and the one used is elemental where each tablet is listed as 30mg, with a Nutrient Reference Value of 300 from 100mg Zinc Citrate Dihydrate.

Asking a Pharmacist what this mean I left with the understanding that to get the 30mg elemental dose, it would take 100mg to achieve this, is that right ?

Another was Magnesium, where the tablet was 211mg from 1,456mg of Magnesium Citrate, with a "Referenced Intake" of 56.2%.

What does all this actually mean, as some companies charge more than others and I would like to know what is going on.

Also, I was told that the size of the pill isn't determined by how much of a vitamin is contained within it, as there are all manner of binders and shelf stabilisers that aren't even mentioned on the ingredients that bulk out the pill, as the vitamin amounts are so small.

The formula of "zinc citrate" seems to be as given here: https://pubchem.ncbi.nlm.nih.gov/compound/ZINC-citrate

According to this, it is actually trizinc dicitrate, with a molar mass of 574. This version does not appear to be hydrated. If a "dihydrate" has 2 extra molecules of water per formula unit, that would bring the molar mass to 610. So then indeed, for every 100mg of compound you would get 100 x 195/610 ~ 30 mg Zn. 

Not being a pharmacist I don't know what a "referenced intake" is, I'm afraid.

It is certainly the case that pills contain a lot of other stuff besides the active ingredient. The size of the pill won't be a good guide to how much active ingredient in present. But in all cases the amount should be written on the packaging anyway.    

 

[CharonY]

As others already commented while I was typing this up I'll just leave the stuff that has not already been explained.

There are various concepts at play here. Elemental refers to the element (not vitamin) in question (i.e. zinc). However, elements are often hard to absorb by the body, so there are often used in forms of citrates or bisglycinates etc. to make them more water soluble. 

The reference value typically refers to how much the daily recommended intake is, usually in %. So 300 would mean 3x the recommended daily intake. For adults the recommended daily amount (edit:) for magensium  for men is around 400-420 mg and for women around 310-320, for example.

I also wanted to add that supplements are a bit in the regulatory wild west almost everywhere. There are often no requirements to have the formulations checked independently and studies have found huge variations even between individual pills of a manufacturer. Also, the design of the pills is sometimes really marketing (more filler to appear more potent) but can also be simply that the the factory only produces a single size of pills and just vary concentration of the active ingredient and fill up the rest.

 

[TheVat]

This is an area where I did some research for a company I used to work for.  One thing that stood out is how many supplements offer little or nothing to a person eating a balanced diet.  Zinc is one to avoid unless there is some pathology causing deficiency.  Also, bioavailable forms of zinc, like picolinate or citrate, tend to block absorption of other minerals, especially copper.  Have some oats and nuts, maybe some pumpkin seeds, and you will be fine.

9 minutes ago, CharonY said:

For adults the recommended daily amount for men is around 400-420 mg and for women around 310-320, for example.

Where dis you get those figures?  My source (Chan School of Public Health at Harvard) has it around 8-11 mg for adults.  Anything over 40 mg is potentially toxic.

[studiot]

Something I forgot to mention before, thanks CharonY for reminding me.

 

The correct terminilogy for the inactive ingredients of the pill or preparation are called excipients.

 

Quote

https://en.wikipedia.org/wiki/Excipient

 

An excipient is a substance formulated alongside the active ingredient of a medication,^[1] included for the purpose of long-term stabilization, bulking up solid formulations that contain potent active ingredients in small amounts (thus often referred to as "bulking agents", "fillers", or "diluents"), or to confer a therapeutic enhancement on the active ingredient in the final dosage form, such as facilitating drug absorption,^[2][3] reducing viscosity,^[4] or enhancing solubility.^[5] Excipients can also be useful in the manufacturing process, to aid in the handling of the active substance concerns such as by facilitating powder flowability or non-stick properties, in addition to aiding in vitro stability such as prevention of denaturation or aggregation over the expected shelf life. The selection of appropriate excipients also depends upon the route of administration and the dosage form, as well as the active ingredient and other factors. A comprehensive classification system based on structure-property-application relationships has been proposed for excipients used in parenteral medications.^[6][7]

 

[CharonY]

1 hour ago, TheVat said:

This is an area where I did some research for a company I used to work for.  One thing that stood out is how many supplements offer little or nothing to a person eating a balanced diet.  Zinc is one to avoid unless there is some pathology causing deficiency.  Also, bioavailable forms of zinc, like picolinate or citrate, tend to block absorption of other minerals, especially copper.  Have some oats and nuts, maybe some pumpkin seeds, and you will be fine.

Where dis you get those figures?  My source (Chan School of Public Health at Harvard) has it around 8-11 mg for adults.  Anything over 40 mg is potentially toxic.

Sorry  during deleting repetitions I removed the front end of my answer. The levels refer to magnesium, the second supplement, not zinc. Your values are the correct one for zinc.

You are also correct with your assessment of supplements. Other than in situations of high deficiency, studies keep failing to show a benefit. I will state that nutritional benefits are difficult to assess in general, due to the huge range of individual differences and other factors that (again, outside of deficiency) have larger effects on overall health status. 

And heck, even defining good health measures to monitor can be rather tricky.

[Leila Choudhry]

4 hours ago, CharonY said:

There are various concepts at play here. Elemental refers to the element (not vitamin) in question (i.e. zinc). However, elements are often hard to absorb by the body, so there are often used in forms of citrates or bisglycinates etc. to make them more water soluble.

The reference value typically refers to how much the daily recommended intake is, usually in %. So 300 would mean 3x the recommended daily intake. For adults the recommended daily amount (edit:) for magensium  for men is around 400-420 mg and for women around 310-320, for example.

Yours is the only answer that I understand.

One of the Pharmacist in the shop recommended me a water soluble option for Magnesium (above is Zinc) when I mentioned the size of the tablet that I was used to. With citrates being easier to absorb I assume that the reason it is taken from Citrate Dihydrate ?

Why would they list three times the daily recommended intake and does that mean each tablet only contains 10mg ?

I am still unsure how to interpret this label.

[CharonY]

47 minutes ago, Leila Choudhry said:

Yours is the only answer that I understand.

One of the Pharmacist in the shop recommended me a water soluble option for Magnesium (above is Zinc) when I mentioned the size of the tablet that I was used to. With citrates being easier to absorb I assume that the reason it is taken from Citrate Dihydrate ?

Why would they list three times the daily recommended intake and does that mean each tablet only contains 10mg ?

I am still unsure how to interpret this label.

Ok, so it means that you got about 100 mg zinc citrate dihydrate (C12H14O16Zn3) per tablet, which corresponds to 30 mg elemental zinc (for details see exchemist's calculation). As the daily recommended dose of zinc is about 8-11 mg, this corresponds to 300% of what is recommended to consume per day.

I.e. it exceeds the recommended dosage by a fair bit and unless there is a case of serious zinc deficiency should probably not be taken regularly. The naming suggests that this is based on EU guidance levels.

[StringJunky]

Supplements in shops are for maintenance, not fixing a deficiency as the type and dosage may be wrong. Deficiencies need facetime with a doctor. Reference: My doctor.

[Leila Choudhry]

I only ever took Zinc with Magnesium because that was what the ZMA deal.

If I can get that from nuts and such then I should be fine, as you say. Anaemia I can do without.

Magnesium however I do find that I need.

[CharonY]

2 hours ago, StringJunky said:

Supplements in shops are for maintenance, not fixing a deficiency as the type and dosage may be wrong. Deficiencies need facetime with a doctor. Reference: My doctor.

That is true, but this marginalizes the roles of supplements even more. Generally, you find little or conflicting evidence of benefits. There is the theoretical consideration, which includes poor Western diets with high energy but low nutritional value but even there folks were generally not able to show benefits in any consistent way. For certain groups, e.g. aging folks or folks with restricted diets might see more benefits, but again, that still is a bit more theory than evidence-based.

Recent-ish reviews on that matter: https://doi.org/10.1136%2Fbmj.m2511 https://doi.org/10.3390/ijerph18178897

And one on vitamin D (which is often supplemented)  https://doi.org/10.1038/s41574-021-00593-z

And here is an older discussion on the subject: https://doi.org/10.7326/0003-4819-159-12-201312170-00011

Ideally one would monitor the level and trends of an individual and also check the impact on supplements if the levels appear to be at the lower end (even if it does not go into deficiency territory). But unfortunately we are not where personalized medicine is really a thing.

 

[Leila Choudhry]

ZMA definitely works.

During the pandemic my diet changed away from pastry pies and potatoes and I found my back giving way for no reason. I can't remember how I stumbled upon the information but I took some and that problem largely went away.

ZMA works for muscle related issues, fact.

[swansont]

1 hour ago, Leila Choudhry said:

ZMA definitely works.

During the pandemic my diet changed away from pastry pies and potatoes and I found my back giving way for no reason. I can't remember how I stumbled upon the information but I took some and that problem largely went away.

ZMA works for muscle related issues, fact.

Your personal experience makes it an anecdote rather than fact. One would need to point to systematic studies, as CharonY did above, to make a case for saying something works.