Supplements are the new obsession, even as doctors stay wary. I went inside one of the industry's biggest factories.
· Business Insider
Henry Taylor for BI
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As soon as I stepped inside the supplement factory, the sweet smell of red berries filled the air. It reminded me of being a kid and gorging on chewable multivitamins — a not-quite-natural "mixed berry" scent that was both nostalgic and vaguely medicinal. As factory tour smells go, it could have been much worse.
Inside Thorne's headquarters, raw materials from around the world were arriving by the pallet. Under the neon lights of a giant, temperature-controlled warehouse outside Charleston, South Carolina, forklifts hummed and beeped as they stacked ingredients on towering shelves.
In here, it's always 70 degrees and dialed in to a moderate 60% humidity level. The relief stepping in from the muggy southern heat outside was immediate.
We're in factory world now.
Claire Critchell, Thorne's senior vice president of operations, shows us the encapsulation and bottling area where workers in full-body suits prepare products.Henry Taylor for BI
Studies suggest that most supplements don't contain what's advertised on the label. At Thorne, we saw some samples being tested for potency.Henry Taylor for BI
I saw pallets of creatine monohydrate, long popular with bodybuilders for improving strength, speed, and recovery. Indian barberry — the source of berberine, which influencers sometimes call "nature's Ozempic" — was also being stocked. (It's not actually comparable to GLP-1 drugs.) Flavoring agents destined to become mango limeade or blood orange electrolytes sat quarantined until they could be cleared for use. Workers in full-body suits moved between sealed mixing rooms where air pressure kept outside dust out. No perfume. No open-toed shoes. No mistakes.
Facilities like this one are increasingly common. The supplement industry has been quietly expanding its manufacturing footprint across the US, racing to meet demand that surged during the pandemic and has never slowed. Thorne's newest warehouse, which opened in 2023 and doubled its manufacturing capacity to 549,000 square feet — about six football fields — is a monument to the supplement boom. The company poured $35 million into expansion after moving from a small-town Idaho factory to this suburban South Carolina location.
Consumers are clamoring for supplements and daily powders, fueled by influencers, personalized medicine, and a fast-growing online market for both peptides and supplements that's racing ahead of regulation and bypassing doctors' recommendations. The doctors and experts I've spoken with don't dismiss supplements outright, but they warn the market is a minefield — one that patients are navigating largely on their own.
During our visit, workers encapsulated berberine and vitamin D supplements.Henry Taylor for BI
After the bottles are filled, they'll pass through a miniature metal detector to screen for contaminants.Henry Taylor for BI
Stacks have gone mainstream
The global supplement market is now estimated at $100 to $200 billion and is growing rapidly, with the US accounting for about one-fifth of worldwide demand. Once considered to exist only on the fringes of medical care, "stacks" of supplements have now become daily rituals for millions of Americans.
Before the pandemic, around 58% of US adults reported taking some kind of supplement. Today, that number is closer to 75%, according to industry estimates. Online sales are taking over. The Nutrition Business Journal's 2025 report cited annual growth of over 10% in online supplement sales, even as other pandemic-era e-commerce trends have cooled.
"It's just been an explosion of people being like, 'I should probably pay attention to my health a little bit more and think about it proactively and take it a little more into my own hands,'" Nathan Price, Thorne's chief science officer, told Business Insider from his office near Silicon Valley.
The pandemic didn't just trigger interest in immunity-boosting and hygiene; it fundamentally changed how people think about their health and what they can do to improve it. Wellness culture — especially nutrition, fitness, and longevity — moved from the margins to the mainstream.
Supplements aren't regulated the same way as drugs. They don't need to be tested for safety or efficacy before they're sold.Henry Taylor for BI
Berberine, a supplement that is very similar to the diabetes drug metformin, is a bestseller at Thorne.Henry Taylor for BI
There are many reasons for this shift. A bloated American "sick care" system that no one feels is working well. Growing distrust of one-size-fits-all medical advice. Doctors pressed for time with patients. The rise of direct-to-consumer lab tests that sample blood, spit, urine, and other substances from the body, promising to tell you exactly which pills, potions, and microbiome supplies you need to feel your best.
I'm not immune to the trend. About a year and a half ago, I did some testing at a high-end longevity clinic as part of a reporting trip and discovered I was magnesium-deficient. Now, I take a pill or two every day — not because a doctor prescribed it, but because a gargantuan 12-vial blood test led me to understand that it would be a good idea.
Other than a little increase in morning (ahem) regularity, I don't notice much difference, but my levels are back in range — which suggests it's doing something, even if I can't feel it. My doctor said she thought my dosage seemed a little high, but shrugged it off and said, "If you want to, it's fine," given my normal-looking bloodwork.
How supplements became self-directed healthcare
A decade ago, there was no way to get Thorne's supplements outside a doctor or healthcare practitioner. Today, consumers are no longer content with a one-size-fits-all multivitamin. Many track their sleep, heart rate, and workouts on smart devices, then feed that data into apps or AI tools to create personalized supplement "stacks." Podcasts and influencers amplify new studies — sometimes responsibly, sometimes not.
Now that you can get the product with just a tap of your smartphone, Thorne's marketing has followed suit. Whether it's sports, beauty, or wellness, there's a good chance someone you follow has touted a Thorne supplement. Model Karlie Kloss, tennis player Ben Shelton, Chris Hemsworth's trainer, Da Rulk, Dwayne Wade, and Ciara have all been featured in ads or promoted the brand on social media.
Thorne founder Al Czap built the brand's entire reputation around quality manufacturing.Henry Taylor for BI
Czap said many supplements aren't formulated properly, and as a result, many don't get absorbed by the body.Henry Taylor for BI
This is not the same company that founder Al Czap started in 1984. A former supplement salesman, he started the company after seeing the poor state of industry manufacturing standards. He thought there were too many additives, too many hidden ingredients, too much messy manufacturing, creating ineffective, or worse, dangerous products.
So, he started to make his own. He built a successful business selling directly to doctors, bypassing stores and advertising entirely, establishing a brand based on quality and clean manufacturing.
"I was dealing with physicians who knew nutritional medicine, and they would bring the patient in, and they would look at their blood pattern. They would look at doing urinalysis. They would get the symptoms, and they would say, 'Alright, I've had success with this product, and I would like you to take this product,'" Czap told me about the early days of Thorne.