NOW testing shows phosphatidyl serine content in top-selling Amazon products far below labeled claims


Testing by NOW of phosphatidyl serine products purchased on Amazon showed potencies well below labeled claims.

Phosphatidyl Serine

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Testing by NOW (Bloomingdale, IL) of phosphatidyl serine (PS) products purchased on Amazon showed potencies well below labeled claims. These results are similar to those NOW found when testing CoQ10 and SAMe products for sale on Amazon.

NOW chose to test PS products because despite being a leading selling of PS in natural foods stores, NOW staff notices that sales of PS were declining on Amazon. Following an investigation, it was found that the top selling brands on Amazon were offering prices an average of 70% below NOW’s already discounted prices, which is a major red flag. For context, while most quality brands sell 100 mg PS as the standard potency, many of the brands included in NOW’s testing listed potencies as high as 500 mg.

In addition to this, their product labels often offered confusing and contradictory information. For example, front labels are listing high potencies such as 500 mg, while side panels state that amount is per two or three capsules. Other brands deceptively included terminology such as “Phosphatidyl Serine Complex” to show high potency values despite actual PS potency accounting for only 20% of that number.

NOW purchased a total of 43 samples on Amazon; an average of three bottles per brand. Three of these samples were NOW brand and were within 100-108% of the labeled PS content claims. Of the remaining brands, two samples were discarded because they contained 2.5 times the labeled potency, likely spiked wth added Serine to order to fool testing. Two samples passed their potency tests (not included in their report), while 36 samples failed. Of the failed samples, 17 contained less than 10% of labeled PS content. See results in the table below.

“That’s a shockingly poor failure rate, but not really a surprise based upon our previous experience testing supplements sold on Amazon,” said Dan Richard, vice president of global sales and marketing, in a press release. “Amazon has to find a way to raise the bar on products they sell, especially today with people buying more supplements from Amazon in order to stay healthy.”

NOW tested the samples with HPLC both in-house and independently at Eurofins Labs.

Phosphatidyl Serine

Table courtesy of NOW

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