Abstract
Millions of people consume dietary supplements either following a doctor's recommendation or at their own discretion to improve their overall health and well-being. This is a rapidly growing trend, with an associated and expanding manufacturing industry to meet the demand for new health-related products. In this study, we examined the contents and microbial viability of several popular probiotic products on the United States market. Culture-independent methods are proving ideal for fast and efficient analysis of foodborne pathogens and their associated microbial communities but may also be relevant for analyzing probiotics containing mixed microbial constituents. These products were subjected to next-generation whole-genome sequencing and analyzed by a custom in-house-developed k-mer counting method to validate manufacturer label information. In addition, the batch variability of respective products was examined to determine if any changes in their formulations and/or the manufacturing process occurred. Overall, the products we tested adhered to the ingredient claims and lot-to-lot differences were minimal. However, there were a few discrepancies in the naming of closely related Lactobacillus and Bifidobacterium species, whereas one product contained an apparent Enterococcus contaminant in two of its three lots. With the microbial contents of the products identified, we used traditional PCR and colony counting methods to comparatively assess our results and verify the viability of the microbes in these products with regard to the labeling claims. Of all the supplements examined, only one was found to be inaccurate in viability. Our use of next-generation sequencing as an analytical tool clearly demonstrated its utility for quickly analyzing commercially available products containing multiple microbes to ensure consumer safety. IMPORTANCE The rapidly growing supplement industry operates without a formal premarket approval process. Consumers rely on product labels to be accurate and true. Those products containing live microbials report both identity and viability on most product labels. This study used next-generation sequencing technology as an analytical tool in conjunction with classic culture methods to examine the validity of the labels on supplement products containing live microbials found in the United States marketplace. Our results show the importance of testing these products for identity, viability, and potential contaminants, as well as introduce a new culture-independent diagnostic approach for testing these products. Podcast: A podcast concerning this article is available.
Highlights
Millions of people consume dietary supplements either following a doctor’s recommendation or at their own discretion to improve their overall health and well-being
Probiotics are defined by the World Health Organization (WHO) as “live microorganisms which when administered in adequate amounts confer a health benefit on the host.” [1, 2] it has been recommended recently by the International Association of Probiotics and Prebiotics that the term “probiotic” be used only for products that “deliver live microorganisms with a suitable viable count of well-defined strains with a reasonable expectation of delivering benefits for the well-being of the host” [3, 4]
DNA was extracted from this mixture in the same manner as DNA was extracted from the probiotic products
Summary
Millions of people consume dietary supplements either following a doctor’s recommendation or at their own discretion to improve their overall health and well-being. The majority of probiotic products contain Lactobacillus, Bifidobacterium, Pediococcus, Streptococcus, and Lactococcus species as either a mixture or single isolates While these products report the number of CFU present per serving, as well as the type of microbes present in their product, on the label, they are not required to include this information. Genomic-scale taxonomy has become a popular identification technique, with the cost and speed of whole-genome sequencing rapidly decreasing over the past several years [18, 19] This technique can be used to identify species present in dietary supplements and determine any mislabeling of these products rapidly and accurately [20]. Whole-genome sequencing analysis of probiotics can determine the presence of any microbial contaminant that can have adverse effects on public health
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