Inside the Formula | The Word "Chelated" on Your Supplement Label Probably Doesn't Mean What You Think

With Solaray & TESTED by SuppCo: Inside the Formula is a new sponsored series featuring brands in the TESTED by SuppCo certification program, where we spotlight the fascinating research behind products that have received the certification. Learn more about TESTED by SuppCo.

Here is something that should make every magnesium buyer pause: Solaray has independently tested many of the magnesium glycinates on the market… and the word "chelated" on the label does not guarantee the mineral is actually chelated.

Rachel Kilroy has been in this industry since high school. Not studying it from the outside, not writing case studies about it in grad school. She was literally working the sales floor of a health food store as a teenager, fielding questions from real customers about real products.

That formative experience, talking directly to the people who take these things every day, stayed with her through 17 years at Solaray, where she now serves as Senior Director of Global Innovation and Product Development. Her job is to be the person who decides whether an ingredient is good enough to go inside a Solaray product. 

Solaray was founded in 1973 by Jim Beck, a genuine industry pioneer who built the brand before supplement quality standards, as we understand them now, even existed. The company has grown into a catalog of more than 700 products, and here is the part that sets it apart structurally: Solaray manufactures 99% of those products in-house at its facility in Ogden, Utah. That is not a marketing claim. It is the foundational reason why nearly everything Kilroy described in our conversation is even possible.

The chelation story is where things get genuinely interesting for a scientist. Chelation is the chemical binding of a mineral to a ligand, in the case of magnesium glycinate, that ligand is the amino acid glycine. The bonding process matters because it affects how gently the mineral digests and how effectively the body absorbs it.

The problem is that "chelated" has become one of the most casually overused terms in the supplement industry. Kilroy told me plainly that many brands do not have the proper instruments to verify true chelation, let alone take any steps to do so. Solaray, on the other hand, has invested in building a chelation verification process, including a research relationship with the University of Oregon and techniques like x-ray crystallography and x-ray diffraction to confirm proper crystalline structure.

Solaray's own testing found that many magnesium glycinate products on the market, despite carrying the word "chelated" on the label, are not truly chelated. That finding may change how you shop for a mineral supplement.

As part of our TESTED by SuppCo certification process, SuppCo anonymously purchased Solaray's products the same way any consumer would, from a standard retail channel, with no advance notice. We sent it to an independent ISO 17025-accredited lab for third-party verification. The results confirmed that the products matched their active ingredient label claims.

Even after rigorous supplier vetting, Solaray rejects portions of raw material batches annually for failing to meet their internal standards. Under GMP alone, that material could have made it through.

I sat down with Rachel Kilroy, Senior Director of Global Innovation & Product Development at Better Being (Solaray), to dive deeper into the science.

JG: "Solaray manufactures 99% of its products in-house and has over 30 degree scientists on staff running ISO-accredited labs. What does that level of infrastructure actually let you do that you couldn't otherwise?"

RK: "As a vertically integrated business, we're not overly reliant on any manufacturer or supplier. Even rigorous certifications like GMP have gaps. Our integrated model allows us to go well above and beyond. GMP doesn't require lot-by-lot testing of every raw material, it allows reliance on supplier audits. We follow all of that, but we also do full panel testing on every single lot of raw material that comes in, potency, heavy metals, microbials, contaminants. And even after all of that vetting, we're still rejecting over 2% of raw material batches annually for not meeting our standards. If we were only following GMP, we could potentially miss that 2%."

JG: "Walk me through what happens from the moment a raw material arrives at your facility through quarantine to release."

RK: "Raw materials come into an entirely separate building from our main manufacturing area and stay in quarantine with our quality control team until they clear full testing. We pull a composite sample from the tops and bottoms of multiple barrels, not just one. Then we test against every relevant claim on the label. That includes:

• Identity: is this actually the ingredient we say it is, the right botanical species or correct amino acid?

• Potency: if a turmeric extract is standardized to 95% curcumin, we verify that number holds

• Microbials: E. coli, coliform, enterobacteria, staph, yeast, mold, and total plate count

• Heavy metals: arsenic, lead, cadmium, and mercury

• Forever chemicals: using an ultra-performance liquid chromatography tandem mass spectrometry instrument to screen for PFOS and related compounds

• Organoleptic testing: sensory evaluation for taste, smell, and color against our historical records for that material

A lot goes into getting a raw material cleared before it ever touches production."

JG: "Most consumers have no way of knowing whether the magnesium glycinate they're buying is actually chelated. You told me Solaray has tested every major competitor. What did you find?"

RK: "Chelation is actually a really difficult process to prove. Solaray has invested millions of dollars in perfecting this process. We work with the University of Oregon using x-ray crystallography and x-ray diffraction to ensure the proper crystalline structure of our magnesium glycinate, and then we compare every single lot to that reference sample using infrared spectroscopy. Many brands do not have the proper instruments to identify a true chelation, and they don't take any verification steps to confirm it. We know this because we've tested quite literally every magnesium glycinate on the market, and they are not always chelated, even though that word appears on the label very frequently. Solaray is one of the only consumer brands I'm aware of that has a proprietary in-house chelation testing methodology."

JG: "What ingredient do you think is genuinely underappreciated right now?"

RK: "Potassium. Everyone talks about magnesium, and that's valid, but potassium deserves to share that spotlight. The recommended daily amount is 4,700 milligrams; a banana has roughly 500 milligrams, you'd have to eat almost ten bananas a day. It may be difficult to hit your recommended daily potassium intake through food alone. Many electrolyte products won't close that gap. Most people have no idea how far below their daily target they actually are."

To hit your recommended daily potassium intake, you'd need to eat nearly ten bananas. Many electrolyte products won't close that gap.

In-House Verification Is Only Rigorous If the House Actually Has a Lab

I have seen how the supplement industry uses the language of quality as a marketing device, and I am not easily impressed by it. When a brand tells me they take quality seriously, my default assumption is that they mean they follow the minimum regulatory threshold and label it accordingly.

Solaray is different. What stood out to me most was not any single test or certification. It was the structural logic of how the whole system is built. The lab reports to the quality department, not the operations department. That means the people responsible for passing or rejecting raw materials are not incentivized to keep the production line moving, a conflict-of-interest firewall that pharmaceutical manufacturers build around but that many supplement companies never think twice about.

The chelation finding is also genuinely meaningful science, not marketing. X-ray crystallography and infrared spectroscopy are not buzzwords. They are validated analytical techniques for characterizing molecular structure. If Solaray is using those methods to confirm lot-by-lot chelation integrity and many competitors are not bothering to check at all, that is a material difference in what ends up in the capsule.

What I cannot fully evaluate from the outside is how consistently these standards are applied across all 700-plus products. That is the limitation of any conversation like this one. What I can say is that the testing framework Kilroy described, from the composite sampling protocol to the PFOS screening to the University of Oregon chelation partnership, reflects a level of scientific investment that most brands would find cost-prohibitive. The TESTED by SuppCo verification confirmed label accuracy on the specific product we purchased. The full interview is worth watching if you want to understand what the infrastructure behind that label accuracy actually looks like.

And yes, I am still thinking about the potassium point. Ten bananas a day… Not a challenge I am up for (yet).