Nearly Half of Vitamin C Gummies in NOW's Latest Testing Round Fail Potency Claims

NOW Foods has published new results from its ongoing program of testing dietary supplements purchased on Amazon, this time turning its attention to vitamin C gummies.¹ The family- and employee-owned natural products manufacturer said the effort is part of a long-running push for greater transparency and quality standards in the supplement industry.

How Was the Testing Conducted?

For the study, NOW purchased two bottles each of 30 vitamin C gummy products on Amazon in June 2026, including its own brand, which launched in April 2026. Products were tested both in-house and by Alkemist Labs, an ISO 17025-accredited independent laboratory, using high-performance liquid chromatography (HPLC) to quantify ascorbic acid content.

What Did the Results Show?

Of the 30 products, five were established brands that NOW stated it had expected to pass, and all five met their label claims with additional overage. Only 13 of the remaining 25 brands met their stated vitamin C content. Twelve had little to no detectable vitamin C, and NOW's stability data indicate that an additional four passing products are likely to drop below label claim before their expiration dates, given that gummies can lose roughly 20% of their vitamin C content per year, according to the company.

Five brands that advertised 1,000 mg or higher of vitamin C per gummy, several citing liposomal delivery and high levels of synergistic ingredients, produced the weakest results. Each of these brands reportedly contained less than 2 mg of total vitamin C, under 1% of their labeled amounts.

“After nine years of conducting these rounds of marketplace testing, it is deeply disappointing to still see so many substandard products being sold to consumers,” stated Dan Richard, NOW’s vice president of global sales and marketing, who added that the company is sharing its findings with the FDA and Amazon.

Why Does Analytical Method Choice Matter?

As in prior rounds, NOW emphasized that analytical method selection affects reported outcomes. The company noted that non-specific methods, such as spectrophotometric assays, can be skewed by other gummy constituents like flavorings and sugars, inflating apparent potency, while HPLC's chromatographic specificity distinguishes vitamin C from related compounds.

This is a recurring theme in NOW's testing program: an April 2026 study of 35 oregano oil products found that roughly two-thirds failed to meet labeled carvacrol content, with NOW again pointing to spectrophotometric methods as a source of potential overestimation.² A May 2026 investigation into 28 lavender essential oils sold on Amazon found that only three met ISO authenticity criteria, with adulteration linked to species substitution, dilution and synthetic additives, particularly among lower-priced and foreign-sourced products.³

How Does This Fit Into NOW's Broader Quality Efforts?

The vitamin C findings also arrive amid other quality-focused initiatives at the company. In June 2026, NOW announced a collaboration with genomics company LeafWorks to build in-house DNA sequencing capability for verifying botanical identity across its ingredient portfolio, an effort aimed at improving species-level identification in processed and blended materials.⁴

"Incorporating next-generation DNA sequencing for genomic-level identification adds another valuable tool to our testing program, enhancing our ability to verify botanical identity,” Maria Mendres, microbiology manager at NOW had stated in a press release from the company. “The number of species we can test for simultaneously is unique to DNA and LeafWorks' platform, making it a good fit for NOW with over 2,000 ingredients."

NOW said it will continue purchasing and testing products from major online marketplaces and publishing results as part of its ongoing quality initiative.

References

1. NOW Foods. NOW Tests Vitamin C Gummy Supplements Sold on Amazon [press release]. Bloomingdale, IL: NOW Foods; August 20, 2026.
2. McEvoy E. NOW testing reveals potency failures in oregano oil on Amazon, raising quality concerns in supplements. Nutritional Outlook. April 2, 2026. Accessed August 20, 2026. https://www.nutritionaloutlook.com/view/now-testing-reveals-potency-failures-in-oregano-oil-on-amazon-raising-quality-concerns-in-supplements
3. McEvoy E. Widespread adulteration detected in Amazon lavender essential oil offerings. Nutritional Outlook. May 21, 2026. Accessed August 20, 2026. https://www.nutritionaloutlook.com/view/adulteration-amazon-lavender-essential-oil
4. Saraceno N. NOW Foods adopts DNA sequencing to verify botanical identity across its ingredient portfolio. Nutritional Outlook. June 23, 2026. Accessed August 20, 2026. https://www.nutritionaloutlook.com/view/now-foods-adopts-dna-sequencing-verify-botanical-identity