Last reviewed October 27, 2026 by the Cellovi team.
The short answer
A supplement label tells you more than most people realize, once you know where to look. Check the serving size first, then the amount of each ingredient and its form, then the claims and the small print. In the US, the Food and Drug Administration (FDA) does not approve supplements before they're sold, so the label, and the brand behind it, is your best guide. Here's how to read one, using our own labels as examples.
1. Serving size comes first
Every amount on the Supplement Facts panel is per serving, and a serving can be more than one capsule (21 CFR 101.36, the federal labeling rules). Cellovi Magnesium Glycinate's serving is 3 capsules, so one capsule gives you a third of the amount listed. When you compare products, compare per day, not per capsule.
2. Amounts, forms and "elemental"
- The number is the nutrient itself. For minerals, the amount listed is the mineral, not the whole compound it's bound to. "Magnesium 275 mg (from 2,500 mg magnesium glycinate)" means you get 275 mg of magnesium (NIH Office of Dietary Supplements).
- The form is in parentheses. "Vitamin D3 (as cholecalciferol)" tells you which form you're getting, and forms can differ in how well they're absorbed.
- Units. Vitamin D is now listed in micrograms; the IU (international units) figure is optional and goes in parentheses. 1 mcg equals 40 IU, so 125 mcg is 5,000 IU (NIH ODS).
- Plants name their part. Botanicals must say which part of the plant is used, such as root or leaf (21 CFR 101.36). Our Resveratrol label says "root" for Japanese knotweed; our Ashwagandha Plus lists root for maca, ginseng and shatavari.
3. % Daily Value and the little symbol
% Daily Value shows how much of a day's reference amount one serving provides. An asterisk or dagger in that column means "Daily Value not established" (21 CFR 101.36). That's common for ingredients like CoQ10, NMN or probiotics. It says nothing about whether the ingredient works; it simply means there's no official daily target.
4. Proprietary blends
A "proprietary blend" lists the blend's total weight and its ingredients in order from most to least, but not each one's amount (21 CFR 101.36). Our Probiotic 40 Billion uses one: you see the total, the 40 billion CFU and the four strains, but not each strain's count.
For probiotics, look for CFU (colony-forming units), the count of live bacteria. The FDA allows CFU on labels alongside the weight under a 2018 draft policy (FDA). Read more in Probiotics: what strains and CFU mean.
5. Other ingredients and allergens
Below the panel, "Other ingredients" lists everything else in the product, such as the capsule shell, fillers, flavors and colors (21 CFR 101.4). It's where you'll see whether a capsule is gelatin or plant-based. Major allergens, including milk, fish and sesame, must be declared, and that applies to supplements too (FDA). Our Omega-3 says "contains fish"; our Colostrum says "contains milk."
6. Claims and the asterisk
Supplements can make three kinds of statements:
| Type | Example | Who checks it |
|---|---|---|
| Structure/function | "Supports bone health" | The brand must have evidence and notify the FDA within 30 days; the FDA doesn't pre-approve it |
| Nutrient content | "High in vitamin D" | Must meet set definitions |
| Health claim | Links a nutrient to lower risk of a disease | Only claims the FDA has authorized |
Sources: 21 CFR 101.93; 101.13; 101.14.
Every structure/function claim must carry this exact disclaimer: "These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease." It isn't a warning sign; it's required on every supplement that makes a claim. On our product pages, we also give each product's main claim an evidence grade, so you can see how much weight it holds.
7. Quality signals
- GMP. Every supplement maker in the US must follow current Good Manufacturing Practices, which require checks on identity, purity, strength and composition (21 CFR 111). "GMP-certified" means an outside auditor has also inspected the facility.
- Seals. Programs like USP Verified and NSF check that what's on the label is in the bottle and that contaminants are within limits; sport programs also screen for banned substances. Seals show quality, not that a product works (NIH ODS).
- "Third-party tested." An independent lab checks the product, for example for identity, strength or contaminants.
- "Made in USA." Without qualification, it means all or virtually all of the product is made and sourced in the US (FTC rule, 16 CFR 323). That's why we say "Made in the USA with globally sourced ingredients": our supplements are made here, and some ingredients come from abroad. Our matcha comes from Kyoto, Japan.
8. Add up what you take
Some nutrients have a Tolerable Upper Intake Level, the most that nearly all adults can take every day, long term, without risk. If you take several products, add them up (NIH ODS):
| Nutrient | Adult upper limit | Counts |
|---|---|---|
| Vitamin D | 100 mcg (4,000 IU) | All sources |
| Magnesium | 350 mg | Supplements only, not food |
| Zinc | 40 mg | All sources |
| Vitamin B6 | 100 mg | All sources |
Sources: NIH ODS fact sheets for vitamin D, magnesium, zinc and vitamin B6.
For example, Vitamin D3 + K2, Immune Support Complex and Ashwagandha Plus each contain vitamin D, so check your total with your doctor if you combine them. Read more in Vitamin D3 and K2: how much to take.
9. Red flags
The FDA and the Federal Trade Commission (FTC) list these as signs of a product to avoid (FDA; FTC):
- Promises to cure, treat or prevent a disease.
- "FDA approved." The FDA doesn't approve supplements, and its logo is for government use only.
- "Clinically proven" with no detail about what was tested, at what dose.
- Quick, dramatic results, "miracle" or "secret ingredient" language, or "one product does it all."
- "100% safe" or "no side effects." Natural doesn't always mean safe.
Your 60-second checklist
- Serving size: how many capsules or scoops?
- Amount and form of each ingredient.
- % Daily Value, and what the symbol means.
- Proprietary blend: total only, or each ingredient?
- Other ingredients and allergens.
- Claims, with the FDA disclaimer.
- Quality signals: GMP, seals, what was tested.
- Your total intake across everything you take.
And tell your doctor and pharmacist what you take, especially before surgery or if you take prescription medicines (National Center for Complementary and Integrative Health). You can see the full Supplement Facts for every Cellovi supplement on its product page.
To judge the brand behind the label, read How to tell if a supplement brand is worth your trust.
Common questions
Does the FDA approve supplements?
No. The FDA does not approve supplements before they are sold, so "FDA approved" on a supplement is a red flag. For a structure/function claim, the brand must have evidence and notify the FDA within 30 days.
What does "elemental" mean on a label?
It is the amount of the mineral itself, not the compound it is bound to. "Magnesium 275 mg (from 2,500 mg magnesium glycinate)" means you get 275 mg of magnesium.
What does "third-party tested" mean?
An independent lab checks the product, for example for identity, strength or contaminants. Cellovi supplements are made in the USA with globally sourced ingredients, in GMP-certified facilities, and third-party lab tested; our matcha comes from Kyoto, Japan, and is third-party lab tested too.
What is a proprietary blend?
A blend that lists its total weight and its ingredients from most to least, but not each one's amount. Our Probiotic 40 Billion uses one: you see the total, the 40 billion CFU and the four strains.
Sources
- Code of Federal Regulations, 21 CFR 101.4, 101.13, 101.14, 101.36, 101.93 and part 111.
- Code of Federal Regulations, 16 CFR 323: Made in USA Labeling Rule.
- NIH Office of Dietary Supplements. Dietary supplements: what you need to know; fact sheets for vitamin D, magnesium, zinc and vitamin B6.
- US Food and Drug Administration. Draft guidance on quantitative labeling of dietary supplements containing live microbials, 2018; Food allergies; 6 tip-offs to rip-offs.
- Federal Trade Commission. Common health scams.
- National Center for Complementary and Integrative Health. Using dietary supplements wisely.