The US version of The Supplement Compare is currently being prepared and will be available soon.
Stronger today. Brighter tomorrow.Evidence. Options. A healthier you.
Vitamin C Supplements
Compare US vitamin C products by actual daily vitamin C, disclosed form, serving, price and testing status. Understand 1,000 mg doses, liposomal claims and what the evidence says about colds.
We may earn a commission from qualifying purchases at no extra cost to you. Affiliate relationships never determine our scores or rankings.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Testing evidence
Evidence status
Recognised certification
Manufacturer statement
Thorne product page says: "This product has been third-party tested and certified to verify what's in the package matches what's on the label and to confirm it contains no unsafe levels of contaminants, such as heavy metals, pesticides, and microorganisms." NSF registry independently lists "Thorne® Vitamin C 1,000 mg" as a finished product under NSF/ANSI Standard 173.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Testing evidence
Evidence status
Recognised certification
Manufacturer statement
Thorne product page says: "This product has been third-party tested and certified to verify what's in the package matches what's on the label and to confirm it contains no unsafe levels of contaminants, such as heavy metals, pesticides, and microorganisms." NSF registry independently lists "Thorne® Vitamin C 1,000 mg" as a finished product under NSF/ANSI Standard 173.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Testing evidence
Evidence status
Testing claimed
Manufacturer statement
NOW Foods Canada’s Quality & Safety page states: “Our state-of-the-art, in-house laboratories test everything from raw ingredients to finished products to ensure that what’s on the label is in the bottle or package,” and its Seals & Certifications page states: “NOW® is audited and certified by Intertek as having met the Supplement Safety & Compliance Initiative (SSCI) benchmarks.”
Compare actual vitamin C per daily serving. US adult RDAs: 75 mg for women and 90 mg for men; labeling Daily Value: 90 mg. Our dose comparison band spans 75 to below 2,000 mg, the adult all-source upper limit. This is not a supplement target or proof of additional benefit. Food also counts; pregnancy, lactation and smoking change needs. Read the dose guide ↓
Thorne product page says: "This product has been third-party tested and certified to verify what's in the package matches what's on the label and to confirm it contains no unsafe levels of contaminants, such as heavy metals, pesticides, and microorganisms." NSF registry independently lists "Thorne® Vitamin C 1,000 mg" as a finished product under NSF/ANSI Standard 173.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Nature Made product page states: "USP Verified and from #1 pharmacist recommended vitamin and supplement brand.*" and "USP has tested and verified ingredients, potency and manufacturing process." USP’s own verification program page explains that USP is an independent third-party organization and that through comprehensive auditing, reviewing, and testing it verifies dietary supplements.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
NOW Foods Canada’s Quality & Safety page states: “Our state-of-the-art, in-house laboratories test everything from raw ingredients to finished products to ensure that what’s on the label is in the bottle or package,” and its Seals & Certifications page states: “NOW® is audited and certified by Intertek as having met the Supplement Safety & Compliance Initiative (SSCI) benchmarks.”
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
USP Verified Products registry lists "Nature Made Vitamin C 500 Mg Tablets" under Brand: Nature Made and Supplement Type: Vitamin, and the Nature Made quality page states the brand has "third-party verification" from USP.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Amazon listing images/text show an NSF Certified Gluten-Free badge and the text "Solgar's KOF-K certification #k-1250" on the product image, but I did not independently verify a matching certification entry on the certifier's own registry.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Manufacturer page states: “All our raw material vendors go through our strict vendor certification program…” and “Our formulas go through intensive ingredient analysis, material testing and physical trials…” plus the product page says “All of our products undergo rigorous testing…”
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
NatureWise product page says “NSF Certified Gluten Free” and “Third Party Tested.” NSF’s public listing page for NatureWise products confirms several NatureWise items are NSF-listed, but not this Vitamin C 1000 mg capsule.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
NOW Foods Certificate of Analysis page states: "A COA confirms that the product you purchased has gone through detailed testing and adheres to its product specifications and NOW standards."
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Nutricost product page states: “Third-Party Tested †” and “Nutricost products are tested by an independent, accredited lab to help verify that what’s on the label is what’s in the bottle. †”
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Amazon title says "Lab Verified" and Solaray's own Quality page says "We source our own raw materials and triple-test every lot" and "we confirm identity, potency, and purity, and screen for contaminants like heavy metals and pesticides."
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Metagenics’ Quality page says: “Our products undergo rigorous testing for heavy metals, microbial contaminants, pesticides, and more” and “every ingredient and finished product undergoes rigorous testing to ensure it meets our uncompromising standards.” The Ultra Potent-C 1000 product page also says “Ultra Potent-C® 1000 Vitamin C - 9.69% Trust Score - Metagenics,” but I did not find an independently verifiable COA, lab report, or certification registry entry for this specific product.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Manufacturer FAQ says: "All EMC products are gluten free... Our products have been tested by an independent third party laboratory that has verified our products to be under 20 parts per millions of gluten and therefore meeting the definition of gluten free."
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Pure Encapsulations’ own site says only that products are “high-quality, pure ingredients backed by verifiable science” and NSF shows a GMP facility listing for the company, but I did not find any independent product-level test/certification for this specific Ascorbic Acid product.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
British Vita product page for the same Signify Nature Vitamin C 1000mg + Zinc effervescent tablets says: "MADE IN THE USA, GPM & 3RD PARTY TESTED - PREMIUM QUALITY ASSURANCE: Trust in Signify Nature's commitment to quality. Our Vitamin C with Zinc is crafted in the USA under Good Manufacturing Practices (GMP). Rest easy knowing that our ingredients undergo rigorous Third-Party Testing to ensure the highest standards of purity, quality, and potency."
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Thorne product page says: "This product has been third-party tested and certified to verify what's in the package matches what's on the label and to confirm it contains no unsafe levels of contaminants, such as heavy metals, pesticides, and microorganisms." NSF registry independently lists "Thorne® Vitamin C 1,000 mg" as a finished product under NSF/ANSI Standard 173.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Nature Made product page states: "USP Verified and from #1 pharmacist recommended vitamin and supplement brand.*" and "USP has tested and verified ingredients, potency and manufacturing process." USP’s own verification program page explains that USP is an independent third-party organization and that through comprehensive auditing, reviewing, and testing it verifies dietary supplements.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
NOW Foods Canada’s Quality & Safety page states: “Our state-of-the-art, in-house laboratories test everything from raw ingredients to finished products to ensure that what’s on the label is in the bottle or package,” and its Seals & Certifications page states: “NOW® is audited and certified by Intertek as having met the Supplement Safety & Compliance Initiative (SSCI) benchmarks.”
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
USP Verified Products registry lists "Nature Made Vitamin C 500 Mg Tablets" under Brand: Nature Made and Supplement Type: Vitamin, and the Nature Made quality page states the brand has "third-party verification" from USP.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Amazon listing images/text show an NSF Certified Gluten-Free badge and the text "Solgar's KOF-K certification #k-1250" on the product image, but I did not independently verify a matching certification entry on the certifier's own registry.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Manufacturer page states: “All our raw material vendors go through our strict vendor certification program…” and “Our formulas go through intensive ingredient analysis, material testing and physical trials…” plus the product page says “All of our products undergo rigorous testing…”
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
NatureWise product page says “NSF Certified Gluten Free” and “Third Party Tested.” NSF’s public listing page for NatureWise products confirms several NatureWise items are NSF-listed, but not this Vitamin C 1000 mg capsule.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
NOW Foods Certificate of Analysis page states: "A COA confirms that the product you purchased has gone through detailed testing and adheres to its product specifications and NOW standards."
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Nutricost product page states: “Third-Party Tested †” and “Nutricost products are tested by an independent, accredited lab to help verify that what’s on the label is what’s in the bottle. †”
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Amazon title says "Lab Verified" and Solaray's own Quality page says "We source our own raw materials and triple-test every lot" and "we confirm identity, potency, and purity, and screen for contaminants like heavy metals and pesticides."
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Metagenics’ Quality page says: “Our products undergo rigorous testing for heavy metals, microbial contaminants, pesticides, and more” and “every ingredient and finished product undergoes rigorous testing to ensure it meets our uncompromising standards.” The Ultra Potent-C 1000 product page also says “Ultra Potent-C® 1000 Vitamin C - 9.69% Trust Score - Metagenics,” but I did not find an independently verifiable COA, lab report, or certification registry entry for this specific product.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Manufacturer FAQ says: "All EMC products are gluten free... Our products have been tested by an independent third party laboratory that has verified our products to be under 20 parts per millions of gluten and therefore meeting the definition of gluten free."
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Pure Encapsulations’ own site says only that products are “high-quality, pure ingredients backed by verifiable science” and NSF shows a GMP facility listing for the company, but I did not find any independent product-level test/certification for this specific Ascorbic Acid product.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
British Vita product page for the same Signify Nature Vitamin C 1000mg + Zinc effervescent tablets says: "MADE IN THE USA, GPM & 3RD PARTY TESTED - PREMIUM QUALITY ASSURANCE: Trust in Signify Nature's commitment to quality. Our Vitamin C with Zinc is crafted in the USA under Good Manufacturing Practices (GMP). Rest easy knowing that our ingredients undergo rigorous Third-Party Testing to ensure the highest standards of purity, quality, and potency."
Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.
One-time purchase prices; delivery and conditional discounts excluded. Daily cost uses the recorded label serving. Comparison amounts are not personal dose recommendations. Unknown Prime eligibility is not treated as confirmed.
Vitamin C forms & claims explained
Separate the ingredient from delivery and marketing claims. Unknown form remains unknown; do not fill a gap from the product title.
Ascorbic acid
Standard vitamin C
Compare
Actual vitamin C in mg
Check
Complete serving
NIH ODS describes supplemental ascorbic acid as having equivalent bioavailability to naturally occurring food vitamin C.
Buffered vitamin C
Mineral ascorbates
Examples
Calcium or sodium ascorbate
Also check
Additional mineral amounts
A buffered claim does not remove dose-related safety considerations or establish better health outcomes.
Liposomal vitamin C
Delivery claim
Compare
Vitamin C, not total blend mass
Evidence
Product and outcome specific
A study of absorption is not proof that every liposomal product prevents more illness. See the evidence section.
Time-release vitamin C
Release claim
Check
Recorded serving and instructions
Do not infer
Longer protection from illness
The term describes an intended delivery pattern. It does not establish a clinical advantage in this comparison.
Bioflavonoids, rose hips and acerola
Additional ingredients
Compare
Declared vitamin C amount
Separate
Other plant or extract weights
A 1,025 mg headline may combine 1,000 mg vitamin C with 25 mg rose hips. Read each amount separately.
Vitamin C dosage: US RDAs and 1,000 mg products
NIH ODS reference tables give adult RDAs of 90 mg for men and 75 mg for women; pregnancy uses 85 mg and lactation 120 mg. People who smoke need 35 mg more per day. The labeling Daily Value is 90 mg.
Amount
Adult comparison context
75–90 mg
RDA scale; the exact requirement depends on life stage and smoking.
1,000 mg
Above the adult RDAs, below the UL when considered alone.
2,000 mg
Adult upper limit from food and supplements combined; not a target.
The table badges compare the product’s daily serving with total-intake references. Include other supplements and food when assessing your intake. Children have different limits; this is an adult comparison.
Vitamin C benefits and liposomal claims
MedlinePlus describes vitamin C’s roles in collagen formation, wound repair and iron absorption. Those nutritional functions do not establish that a high-dose capsule improves skin appearance in someone with adequate intake. Topical serums are different products with different evidence.
Liposomal versus regular vitamin C
A US trial from Colorado State University found greater circulating vitamin C after its liposomal formulation than after unencapsulated oral vitamin C, but similar protection in an experimental ischemia–reperfusion measure. It was not a trial of fewer colds or better skin. The study disclosed industry funding and a commercial interest.
Match a claim to the actual product
The formulation, dose and outcome need to match. A delivery claim in an Amazon title does not verify the contents of the bottle or transfer a study result to every brand.
Vitamin C evidence by goal
Evidence by goal
Goal
Evidence strength
What was assessed
Typical study context
Main limitation
Adequate nutrition / deficiency
Established role
Vitamin C intake
Diet or an appropriate supplement
Not a high-dose optimization target
Preventing ordinary colds
No prevention benefit for most people
Regular supplemental vitamin C
Population and conditions matter
Immune support is not prevention proof
Shortening a cold
Small benefit with regular use
Studies differ in dose
Starting after symptoms is different
Not a cure or reason to megadose
Liposomal delivery
Some absorption evidence
Specific studied formulations
Surrogate outcomes
Better clinical outcomes not established here
Skin and collagen claims
Nutritional role is established
Oral intake differs from serum use
Baseline intake matters
Do not transfer topical claims
Read the full evidence-by-goal detail
NCCIH reports that regular vitamin C does not prevent colds in most people, though it may shorten them slightly. Starting only after symptoms appear has not shown a consistent benefit. Findings in people under extreme physical stress do not establish a general megadose recommendation.
When to take vitamin C
Use the label instructions
Choose a consistent routine that fits the product. This comparison does not establish that morning, night or fasting is best. If a product causes stomach discomfort, reassess the dose and discuss persistent symptoms.
Powders and effervescents
Use the specified measure or packet and dilution instructions. Check serving count, added sodium, sugars and sweeteners rather than assuming every dissolved product is equivalent.
Vitamin C side effects and excessive intake
Who should be cautious?If any of the following apply to you, speak to a healthcare professional before taking Vitamin C - see the full detail below for why.
Kidney disease, recurrent kidney stones or known high urinary oxalate
Hemochromatosis or another iron-overload condition
Cancer treatment, several high-dose supplements or persistent gastrointestinal symptoms
NIH ODS identifies diarrhea, nausea and stomach cramps with excessive intake. Chronic high doses can worsen iron overload in hereditary hemochromatosis. Kidney conditions warrant individualized advice.
A 1,700 mg product leaves only 300 mg before the adult UL is reached from all other sources. Being below the UL does not guarantee freedom from side effects. Check combined intake; do not double a serving just because you feel a cold starting.
Vitamin C, iron and medicines
NIH ODS advises people receiving chemotherapy or radiation to discuss antioxidant supplements with their oncology team. Interactions are treatment-specific; a supplement should not be added as a cancer treatment.
MedlinePlus explains that vitamin C helps absorb nonheme iron. That is not a reason to add iron without an indication. Read iron, zinc and other ingredients separately in “immune” blends.
Food sources and low-intake risk
MedlinePlus lists fruit and vegetables such as citrus, peppers, broccoli and berries as sources. Prolonged very low intake can cause scurvy; unusual bleeding gums, bruising or poor healing need assessment rather than an assumed supplement diagnosis.
NIH ODS identifies smoking, restricted food variety and some medical conditions as reasons intake or status may need attention. Food access and tolerability matter more than a “for men” or “for women” label.
Vitamin C labels and quality checks
Testing review pending means the detailed product evidence review is unfinished. While testing is pending, it is excluded and the score is provisional. It does not mean a product failed testing or that no evidence exists.
FDA does not approve supplements for safety and effectiveness before sale. Check the exact product and lot behind a quality claim.
A useful report identifies the product, batch, laboratory, date, methods and results. Ingredient identity, measured content and contaminant testing answer different questions. A raw-material certificate is not automatically evidence for the bottle you buy. See how we verify testing.
Look for measured vitamin C content for the finished product. A plant extract’s weight or a liposomal blend’s weight cannot substitute for the actual nutrient amount. Check allergens and added ingredients, especially in powders and effervescents.
Vitamin C blood tests: when results need context
Mayo Clinic Laboratories uses plasma ascorbic acid testing to investigate deficiency. Its current reference interval is 0.4–2.0 mg/dL; this is that laboratory’s interval, not a universal target.
Preparation affects the result
Mayo requires a fasting specimen and special sample handling. Recent vitamin intake can increase the measured concentration. Follow your own laboratory’s instructions and disclose supplements.
A test needs a clinical question
Interpret the result with symptoms, diet and the supplied range. This page does not recommend routine vitamin C screening or repeated tests to chase a higher number.
Testing evidence in this comparison
A testing claim is not the same as a verified report. No public evidence located does not mean a product has not been tested.
Testing review pending0
Recognised certification3
Verified independent evidence0
Manufacturer COA0
Testing claimed12
No public evidence located5
What does vitamin c cost?
Current US comparison set, based on the daily serving shown on each label.
$0.06Lowest daily cost
$0.13Median daily cost
$0.50Highest daily cost
Price insights
Shown only where the underlying product data is reliable.
