Culture-independent assessment of probiotic supplement consistency in commercially available probiotic supplements

Abstract

The probiotic products market has experienced significant growth in recent years, driven by increasing consumer demand for health benefits. This demand is largely fueled by the widespread promotion of probiotic products, and is compounded by relatively lax regulations regarding these products compared to those for drugs. In this study, we sought to evaluate the consistency of product labels and contents for probiotic supplements in the Turkish and USA markets. A total of 44 commercially available probiotic products were included in the analysis, comprising 40 products from Turkey and 4 from the USA. Shotgun metagenome sequencing was performed to determine the microbiological content and functional characteristics of the products. Additionally, we evaluated the presence of antibiotic-resistance genes and virulence genes in each product. Our findings showed that 38.6% of the products contained microorganisms not indicated on their labels, while 15.9% of products did not contain one or more of the probiotic microorganisms specified on their labels. Moreover, over half of the probiotic products (68.2%) were found to contain at least one resistance gene, and 40.9% of the products carried multiple virulence genes. Streptococcus thermophilus being the primary contributor to the detected virulence genes. This study is the first to examine the label and content discrepancies of probiotic products in the Turkish market and one of the largest to analyze resistance gene profiles of probiotic supplements in the literature. These findings may suggest a potential public health risk and the need for whole genome sequencing analysis of probiotic supplements.