Second active this price does not pay for: citrus bioflavonoids 75 mg. The price per dose counts vitamin C only.
Amount per serving
500mg vitamin C
Upper intake level
Adults, 2,000mg a day, from food, beverages and supplements together. One serving of this product holds 500mg, less than that level on its own. This level is for vitamin C only; the panel also prints citrus bioflavonoids 75 mg, which it does not cover.
An upper intake level is the largest daily intake unlikely to cause harm for most people. It is not a recommendation about what to take.
Printed on this bottle's own panel image as "Vitamin C (as Ascorbic Acid) 500 mg 556%" in a "Serving Size: One Capsule" serving, and the front prints "Vitamin C 500 mg", "with Flavonoids" and "90 CAPSULES". Milligrams of vitamin C are the comparison basis and the panel prints milligrams, so nothing is converted. The panel's second line, "Citrus Bioflavonoids 75 mg", is named on this package's row as a second active; the price per dose pays for the 500 mg of vitamin C alone, and the marking changes no ranking. The panel image carries no servings-per-container line; the page's ingredient block prints "Servings Per Container: 90" and the front prints 90 capsules, which is the figure recorded here. The side face's GLUTEN FREE mark and the page's "Gluten Free" badge are what the gluten free answer rests on; no vegan or vegetarian claim is made.
Set the quantity at the retailer; this calculator does not add items to a cart. Uses the recorded unit price with no coupon or quantity discount. Tax is extra. Delivery terms apply to the contiguous US unless the policy says otherwise.
Free Ground shipping on all retail orders within the contiguous United States, with no minimum order value, from Thorne's shipping FAQ, first read August 31, 2026 and read again on September 18, 2026 with the same terms. Alaska and Hawaii are excluded: free above $300, otherwise a variable fee with a $30 minimum. Wholesale terms differ ($200 minimum, $11.95 below it) and are not what this site prices. With no threshold to clear, delivered cost within the contiguous US equals the price at any cart size.
Ordered by price, lowest first, and labeled so you can see what each link earns us. Commission is never an input to that ordering. If the cheapest retailer pays us nothing, that is still the one we send you to. No link on this page earns us anything; every Buy button is a plain retailer link.
Price history
Latest recorded price: $23.00 at Thorne (direct), checked . Unchanged since we started checking on Oct 17 (11 checks).
We check each price about once a day, so this is the range we recorded, not necessarily every price there has been. It says what changed, not why, and nothing about where the price goes next.
Verification, Tier C: Claimed, not confirmed
Two different things reach this level, and the product page says which. Either the label or the product page names an independent third-party program, such as NSF Certified for Sport, NSF Contents Certified or Informed Sport, and we have not confirmed a listing for this package in that program’s own database; or the only test results available are ones the manufacturer or a lab it commissioned published, which may well be accurate and is simply not independent. A mark printed on a package is not the same thing as a listing anyone can open, and that gap is what this level records. It is not a finding against the product.
The testing claim we recorded for this product, with where it appeared: NSF Contents Certified mark printed on the label's side face. That is NSF's contents certification, a different program from NSF Certified for Sport, and the page makes no Certified for Sport claim for this package. NSF’s Contents Certified listings were not searched for this product, so the claim is not checked here either way.
Checked NSF Certified for Sport database on Oct 17, 2026: not listed.
Checked USP Verified database on Sep 21, 2026: not listed.
NSF Certified for Sport: checked, not listed
Checked and absent. The Certified for Sport directory as captured on Sep 23, 2026 carries 66 Thorne rows, filed under "Thorne" and "Thorne®", and none is a vitamin C product: no row under either name contains "vitamin c", "ascorb" or "flavonoid". The label on this bottle prints NSF's Contents Certified mark, which is a different NSF program and is recorded as the maker's claim on the product, not as a listing here. Absence from a database is not a failed test. NSF's whole directory was read again on Oct 17, 2026, 2,581 listings, and still holds no vitamin C listing under this brand.
Checked and absent. USP's own Verified Products directory was read page by page in a browser on Sep 21, 2026: 16 pages, 159 products, 16 brands, captured in this site's directory snapshot. This brand does not appear in the directory or in its brand facet, and no product in it names this brand. USP verifies the products a company submits to it, so this records which products were submitted and nothing else. Absence from a database is not a failed test.
Thorne does not appear as a brand in LGC's own Informed Sport product list of October 2026, 497 brands and 1,887 product lines, as read on Oct 3, 2026. Absence from a list is not a failed test: Informed Sport certifies the products a company submits, so this records only that none from this brand is in the program's published list on that date.
Thorne does not appear as a brand in LGC's own Informed Choice product list of October 2026, 201 brands and 853 product lines, as read on Oct 3, 2026. Absence from a list is not a failed test: Informed Choice certifies the products a company submits, so this records only that none from this brand is in the program's published list on that date.
No laboratory report with figures is recorded here for this product.
Not established: Heavy-metal testing, Label-accuracy testing, Vegan status.
Absence of data is not evidence that a product is clean. It means we found no published result for that testing.
Label
Form
capsule
Serving size
1 capsule
Active ingredient
Vitamin C: 500mg as labeled
Printed on this bottle's own panel image as "Vitamin C (as Ascorbic Acid) 500 mg 556%" in a "Serving Size: One Capsule" serving, and the front prints "Vitamin C 500 mg", "with Flavonoids" and "90 CAPSULES". Milligrams of vitamin C are the comparison basis and the panel prints milligrams, so nothing is converted. The panel's second line, "Citrus Bioflavonoids 75 mg", is named on this package's row as a second active; the price per dose pays for the 500 mg of vitamin C alone, and the marking changes no ranking. The panel image carries no servings-per-container line; the page's ingredient block prints "Servings Per Container: 90" and the front prints 90 capsules, which is the figure recorded here. The side face's GLUTEN FREE mark and the page's "Gluten Free" badge are what the gluten free answer rests on; no vegan or vegetarian claim is made.
Second active
citrus bioflavonoids 75 mg
Printed on the panel, and not counted in the price per dose.
Vegan
Unknown
Gluten free
Yes
Allergens
Unknown
Other ingredients
Cellulose Powder, Hypromellose (derived from cellulose) capsule, Calcium Laurate
Same category and format and, where a category is compared by strength, the same labeled strength. Different recorded ingredient-form lists are kept separate. Ordered by container price before delivery; only fresh recorded prices are shown. Formulas, flavors and allergens may differ: check each label. These are browsing options, not recommended substitutes.
What this rests on: prices we last recorded at the retailer named on each product page, which go stale, and each page says when it was checked; the products we track, not every product sold, and Amazon and Walmart are not among the stores; listings and labels read at the source, each linked from the page. Found an error? Tell us. The full method: How we compare.