DS-01® measures viable cell count in AFU, or Active Fluorescent Units. AFU is measured with flow cytometry, a process where probiotic cells are tagged with fluorescent ‘markers’ and counted by a laser as they pass through a tube. Through AFU, we are able to calculate precise measurement of all viable cells, including ones that are efficacious, but not necessarily culturable (and therefore would not be counted in a traditional plated CFU measurement).

CFU stands for Colony Forming Units, and is reflected in plating, a classical microbiology technique that has been used since the 1800s. This technique shows the number of ‘colonies’ that are formed on a plate through a series of dilutions. CFU can vary up to 50% between batch lots, requires different plating ingredients for each species (and sometimes strain), and is best used for single strain, rather than multi-strain probiotics, or synbiotics.

Globally, there is a lot of discussion about current and future techniques for testing beyond CFU, including flow cytometry and qPCR (Quantitative Polymerase Chain Reaction), as probiotic strains can vary widely in potency based on biofermentation and production methods (from between 50 Billion AFU / gram to 800 Billion AFU / gram). As a company committed to innovation, we are always evaluating the most effective and precise technologies, including new stabilization techniques, delivery formats, and testing methods.

Today, the use of flow cytometry and its unit of measure (AFU) not only allows us to determine viable cell counts, but also allows us to precisely measure each organism in a complex community or multi-species, multi-strain formulation. Traditional plating techniques (CFU) are extremely variable when enumerating multi-species, multi-strain formulations and are further limited by parameters of time, specifically the inability to detect viable but nonculturable (VBNC) micro-organisms and nonviable cells. More specifically, AFU detection is equal to or better than CFU for the following reasons: accuracy, precision (repeatability), intermediate precision (ruggedness), specificity, limit of quantification, linearity, range, and robustness.

Most supplements, fruits, vegetables, milk-derived proteins, and natural products carry some level of heavy metals, which can be very difficult to completely eliminate from the diet due to their uptake by plants from the surrounding air, water, and soil. Food and natural products are regulated in California by CA Prop 65, or "The Safe Drinking Water and Toxic Enforcement Act of 1986", which establishes "safe harbor levels" for a list of chemicals known to the state to potentially cause cancer or reproductive toxicity. Seed abides by these stringent regulations and tests all products for the four main categories of Heavy Metals: Arsenic, Cadmium, Lead, and Mercury. As demonstrated in the table below, DS-01® falls well below the established limits.

Each batch of our final product is tested at third party accredited laboratories for over 400 pesticide residues using gas chromatography with tandem mass spectrometry. Testing certifies that each of the evaluated chemicals is absent or below the limit of quantitation of 0.010 mg/kg.

We specifically test each batch of DS-01® for the ubiquitous pesticide Glyphosate as well as its breakdown product, AminoMethylPhosphonic Acid (AMPA), using liquid chromatography with tandem mass spectrometry. Results show that glyphosate and AMPA are undetectable in the DS-01®, at a limit of quantitation of 10 parts per billion.

The full list of pesticides tested may be viewed here.

Each batch of DS-01® is tested and verified free of all 14 classes of allergens according to EFSA.