Fictional product A
- Zinc per label serving
- 10 mg
- Units per serving
- 2
- Assumed units per day
- 1
- Daily supplemental zinc
- 5 mg
Synthetic label example · Not a customer case
How to add up duplicate ingredients across supplement labels
Convert each label’s amount per serving to the amount actually taken per day, then add the same ingredient across products. Two fictional labels below contribute 13 mg of zinc per day. A third label has an unknown amount, so the full stack total is still unknown.
Example prepared: . Products and quantities are fictional and demonstrate arithmetic only.
What does each label tell us?
Fictional product B
- Zinc per label serving
- 8 mg
- Units per serving
- 1
- Assumed units per day
- 1
- Daily supplemental zinc
- 8 mg
Fictional product C
- Zinc per label serving
- Not stated
- Units per serving
- 1
- Assumed units per day
- 1
- Daily supplemental zinc
- Unknown, not zero
Why is the known subtotal 13 mg, not 18 mg?
A: 10 mg × (1 ÷ 2) = 5 mg
B: 8 mg × (1 ÷ 1) = 8 mg
A + B = 13 mg
Product A lists 10 mg for two units, but the example assumes one unit per day, contributing 5 mg. A cross-product sum requires both serving size and actual daily use. Product C is missing an amount, so 13 mg is not the total for all three products.
What does this calculation not establish?
- An ingredient appearing twice does not by itself establish excess intake. This example gives no safety rating or recommended dose.
- The subtotal covers the stated supplement amounts, not food, fortified drinks, or unknown products.
- Different units, missing amounts, medicines, age, pregnancy, and health context need separate review with a clinician or pharmacist.
Source and method
NIH ODS explains that Supplement Facts labels state active ingredients and amounts per serving, and recommends keeping a record of products, doses, and frequency. The arithmetic here is NutriAudit’s fictional illustration, not an NIH-reviewed or endorsed result.
NIH ODS: Dietary Supplements — What You Need to KnowStart with your own supplement labels
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