Vitamin C: why compound mass is not nutrient mass
Ascorbic acid against the ascorbate salts, what the panel figure really counts, tablet formats and pack comparisons.
The number on the front and the number in the panel
Vitamin C packs tend to lead with a figure on the front of the carton. The figure that is defined and regulated is the one in the nutrition panel, beside its unit and its reference percentage.
When two packs disagree, the panel is the document. Compare panels.
Ascorbic acid and the ascorbate salts
Vitamin C can be supplied as ascorbic acid or as a salt of it, such as sodium ascorbate, calcium ascorbate or magnesium ascorbate.
A salt carries a mineral as part of the molecule, so a given mass of the salt contains less vitamin C than the same mass of ascorbic acid. This is the most common misreading on a vitamin C label.
- Ingredients list: the compound actually used
- Panel: the vitamin C that compound delivers
- A mineral ascorbate may also add a row for that mineral
- Two packs quoting the same compound mass can state different nutrient amounts
Format words on a vitamin C pack
You will see tablets, coated tablets, chewables, effervescent tablets, capsules and powders. This pack is 90 tablets.
Words such as timed release or buffered describe how the tablet is made, not how much vitamin C is in it. Keep them out of your amount comparison.
The reference percentage, briefly
The percentage next to the amount expresses that amount against one fixed labelling reference figure that is the same for every brand.
Because the reference is shared, the percentage is a quick way to line up two packs without doing unit conversions in your head.
Tablets in the bottle, portions on the label
Ninety tablets is a unit count. The number of portions in the pack follows from the portion printed on the label.
Read that portion from the label rather than calculating one from the tablet count.
Pack size and price
Compare the whole pack price against the whole pack price, holding the unit count and the stated nutrient amount next to it.
A cost per portion needs the portion from the label, so work it out from the pack once it arrives.
What the label tells you
The full ingredients list, the amount per portion, allergens, dietary suitability, directions and storage are printed on the pack.
Read the label before you take any supplement, and check the product page for the format, pack size and price before you buy.
