Fill Weights and Label Claims: Do the Numbers on Your Vitamins and Minerals Add Up?

Fill Weights and Label Claims: Do the Numbers on Your Vitamins and Minerals Add Up?

In last month’s blog post I discussed the kinds of things you need to look for when choosing a good quality multivitamin supplement.  I talked about how there should always be a table of facts on vitamin and mineral supplements and I said that sometimes brands use these tables to make false claims about their products.  In today’s post, I want to cover tables of facts and label claims in more detail.  I’ll show you what a good table of facts should look like, I’ll talk about elemental yields of minerals, and I’ll give you some tips for weeding out misleading label claims.  If you haven’t read last month’s post and you’re fairly new to the world of vitamin and mineral supplements, please go back and read that first so that you can get the most out of this month’s post. 

A good vitamin and mineral supplement always contains a table that shows you how much of which nutrients you’re getting.  It will consist of three columns:  one naming the nutrient; one specifying how much by weight of each nutrient you are getting; and one showing what percentage of the European Community Nutrient Reference Value that weight provides.  Outside of the UK and Europe, this third column might be replaced with some other Nutrient Reference Value or Daily Value, but the concept will be the same – it represents the percentage of your daily requirement provided by the product.  Official daily requirement amounts are not set for all vitamins and minerals, so sometimes this third column will be blank for some of the ingredients. 

It should be made clear whether the table of facts pertains to each capsule (or tablet or relevant individual serving) or each full daily intake.  It doesn’t matter which is chosen as long as the information is explicitly given.  For a simple, single ingredient product, it can be more convenient to give the table of facts per capsule.  For a complicated product with a daily serving of more than one capsule, it is often more sensible to have the table cover the total daily intake. 

In my opinion, the very best table of facts let consumers know what form each vitamin and mineral is presented in.  It is mandatory that this information is included somewhere on the packaging, but if it is included in the ingredients list, it can be omitted from the table of facts.  I find it easier to assess the quality and suitability of a product if the form is given in the table of facts as well as the ingredients list.  For novice shoppers, it is not always easy to tell from the ingredients list which phrase relates to which nutrient.  For example, not everyone would know that methylcobalamin is the name for a type of vitamin B12.  It is therefore preferable to have the table of facts show ‘Vitamin B12 (as methylcobalamin)’ so that inexperienced consumers can see at a glance which form of vitamin B12 is being offered. 

A very good table of facts on a British or European product would therefore look something like this:


Typically per two capsules:



Vitamin E (as D-alpha tocopheryl succinate)



Vitamin B1 (as thiamine mononitrate)



Vitamin B5 (as calcium pantothenate)



Calcium (as calcium glycerophosphate)



Folate (as methylfolate)



*European Community Nutrient Reference Value

As you can see, this table makes it very clear that the values relate to two capsules.  The form of each nutrient is given in brackets, so we can see, for example, that calcium glycerophosphate has been chosen as the calcium source instead of calcium carbonate, calcium citrate, or any other type of calcium.  The weight of each nutrient present is clearly given, along with the percentage of the European Community Nutrient Reference Value that this represents.  Weights for most nutrients are given in milligrams (mg), but you might also see micrograms (mcg or µg) and international units (iu) being used.  For liquid or powder products, you might also see millilitres (ml) or grams (g) being used, though these would normally relate to herbal products, amino acids, or other non-vitamin and mineral ingredients. 

Looking at the vitamin B1 line in the table above, it is important to note that 50mg is the amount of vitamin B1 present.  It is NOT the amount of thiamine mononitrate powder present.  The amount of thiamine mononitrate powder needed to provide 50mg of vitamin B1 is around 70mg.  This is known as the fill weight, whereas the 50mg of vitamin B1 is known as the label claim. 

Similarly, looking at the calcium line of the table, this label tells consumers that 36mg of actual elemental calcium is present in the product.  It does NOT mean that 36mg of calcium glycerophosphate has been used.  Calcium glycerophosphate yields around 18% of elemental calcium, so 200mg of calcium glycerophosphate powder will have been used in the product above to provide the 36mg of calcium claimed on the label. 

An alternative way that a brand might display its label would therefore be to write:


Typically per two capsules:                                        

Calcium glycerophosphate           200mg  

In the context of something like a multivitamin product this is far less preferable, because it requires consumers to be aware of the fact that not all of the calcium glycerophosphate is broken down into calcium.  It is therefore more difficult for people to know how much calcium the product actually provides.  For vitamins and minerals within the UK and EU, this alternative way of displaying the information is only acceptable if the weight of each actual nutrient is also provided. 

In a single ingredient product, it can sometimes be helpful to see the fill weight as well as the label claim.  On our own Simply Calci-G capsules we show the fill weight, because we realise that more people use the supplement for its acid buffering effects than as a calcium supplement to address deficiency.  However, in line with best practice, we also include a table showing the elemental yield of calcium and phosphorus that the calcium glycerophosphate provides.  For vitamin and mineral products aimed at correcting deficiencies, or for multi-ingredient products, it is far more preferable to show the amount of active nutrient than the fill weights of the powders from which the nutrients come.  After all, when you buy a vitamin D product, you want to know how much actual vitamin D you are getting, not how much the finished capsule weighs! 

When you are shopping for vitamin and mineral products, always check the label carefully to make sure you are very clear about how much of each active nutrient is in there.  If you are in doubt about whether the weights on the labels relate to fill weights or the amount of nutrient actually provided, either contact the company to ask, or do not buy the product.  Good, reputable companies set out their labels as in the first example above and they leave consumers in no doubt about the amount of active nutrient present. 

Unfortunately, companies sometimes mislead consumers by using fill weights in place of true label claims.  Sticking with the calcium glycerophosphate example above, they would use 200mg of calcium glycerophosphate powder in their product, but would write on their label:


Typically per two capsules:                                        

Calcium (as calcium glycerophosphate)                  200mg  

This would NOT be true.  By using 200mg of calcium glycerophosphate powder, they would only be providing 36mg of calcium, but it would seem to consumers as if a whole 200mg of calcium was being provided.  To provide 200mg of actual elemental calcium, 1111mg of calcium glycerophosphate would be required! 

With vitamins, it can be quite tricky to spot if you are having the wool pulled over your eyes with fill weights being used in place of label claims.  There are several types of vitamin E, for example, and three different manufacturers of raw vitamin E ingredient might each make it differently.  Someone’s end product might therefore have a vitamin E yield that is significantly higher or lower than another manufacturer.  Some vitamins have fill weights that are incredibly close to their label claim weight – for example, the 50mg of vitamin B2 in a daily serving of our No 6, Please! Capsules requires only a 56.7mg fill weight of riboflavin powder.  Others have fill weights that are wildly different from their label claims – for example, over 21mg of vitamin D ingredient might be used to provide only 50mcg of actual vitamin D. 

Minerals, however, are generally easier to figure out.  Although there might be small variations between manufacturers, the elemental yields of various types of minerals are fairly consistent.  The elemental yield is the amount of mineral provided by a particular mineral compound.  For example, if you ingest magnesium oxide powder, it is not all broken down into magnesium.  Only about 60% of it is magnesium and this is said to be the elemental yield.  This means that 100mg of magnesium oxide powder generally provides about 60mg of elemental magnesium.  If you decide you need some extra magnesium in your life and want to supplement an extra 600mg a day, you would therefore need to take 1000mg of magnesium oxide to achieve this. 

Here are the approximate elemental yields of some common types of minerals:

Magnesium oxide:  57 – 60%

Magnesium citrate:  10 – 16%

Magnesium glycinate:  10 – 18%

Magnesium lactate:  10- 12%

Magnesium ascorbate:  6%

Calcium carbonate:  40%

Calcium citrate:  21%

Calcium glycerophosphate:  18%

Calcium lactate:  13%

Calcium gluconate:  9%

Zinc oxide:  80%

Zinc citrate:  34%

Zinc bisglycinate:  20%

Zinc gluconate:  14%

Ferrous fumarate (a type of iron):  33%

Ferrous sulphate:  20 – 30%

Iron bisglycinate:  18%

It is important to note that it is not really the consumer’s job to calculate how much raw ingredient should be needed to provide a given amount of mineral.  A compliant label from a reputable company should tell you how much of the mineral you’re getting and the fill weight should be irrelevant to you.  However, if you suspect that a misleading label claim is being made about a particular mineral, you can sometimes use a bit of maths and common sense to check. 

The European Commission Nutrient Reference Value for calcium is 800mg.  This means that ideally, people should get 800mg of calcium each day to avoid deficiency conditions.  Calcium carbonate, the type of calcium with the highest elemental yield, is only 40% calcium.  This means that in order to get 800mg of actual calcium from a calcium carbonate supplement, the product must contain 2000mg (that’s two grams) of calcium carbonate.  An average size capsule shell holds around 500mg of powder.  The larger ones hold around 800mg.  The exact amount does depend on how dense the particular ingredient being used is, but for most vitamin and mineral powders, it is impossible to get 2000mg into even the largest of shells.  Therefore, if you ever see a calcium product that claims a single capsule provides a full 800mg (100% of the NRV) of calcium, it is almost certainly misleading you. 

Suppose that calcium glycerophosphate was chosen instead.  This has an elemental yield of around 18%.  To get 800mg of elemental calcium, we would therefore need to use more than 4440mg of calcium glycerophosphate powder.  That’s over four grams!  Calcium glycerophosphate is quite dense and flows easily, but even so, we’d probably need a minimum of four large capsules to hold all that powder and satisfy our daily calcium needs.  Those of you who have purchased our Simply Calci-G Capsules will be able to see what only 250mg of powder looks like and that only provides 36mg of calcium!  Imagine how large the capsule would have to be to provide your whole daily intake of calcium – or even just a half or a quarter of it! 

For some minerals (and vitamins too if you know their fill weights or percentages of active nutrient) you can therefore tell by eye if a supplement is making misleading claims.  Of course most of us take labels at face value and would never research elemental yields or fill weights unless we had some reason to be suspicious. 

Unfortunately, it is not always possible to judge by eye if the claimed mineral content of a product doesn’t match its size.  Sometimes, it would be necessary to actually weigh the product, which of course you can only do if you’ve purchased it.  Even then, if fillers or processing aids have been used, you will be none the wiser. 

As consumers, the truth is that we can never be sure that what’s in a product matches the label claim unless we purchase it and then send it away for testing.  However, by following the tips in last month’s blog post to weed out obviously poor quality products, and then using the information in this post to perform a table of facts quality check and a size of capsule common sense check, you will hopefully be better equipped to spot misleading or inferior products. 

I hope you will find this information useful and please join me next time when we will be discussing compound ingredients and ‘clean washing’! 

Wishing you the best of health for 2023 and beyond,

Tiny x

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