Most supplement brands have never tested their products in a randomized controlled trial. AG1 (Athletic Greens) just did — and published the results.
That's notable. But "clinical trial" doesn't mean "definitive proof." Here's what the study actually found, and how to read it properly.
Key Takeaways
- AG1 published a randomized, double-blind, placebo-controlled trial on their flagship product — rare in the supplement industry
- Study showed statistically significant improvements in gut health markers (bifidobacterium diversity, short-chain fatty acids) after 12 weeks
- Vitamin D, B12, and magnesium levels improved in the AG1 group — expected given the formulation
- Critical caveat: participants were healthy adults without existing deficiencies — effect sizes may be smaller than in deficient populations
- Industry-funded, external CRO conducted — standard methodology, but conflict of interest to note
What an RCT Proves and What It Doesn't
A randomized controlled trial (RCT) is the gold standard method for testing whether a treatment works. Participants are randomly assigned to product or placebo, neither they nor researchers know who's taking what (double-blind), and objective biomarkers are measured.
But an RCT has inherent limitations.
First, the study population. The AG1 RCT enrolled healthy adults without pre-existing deficiencies. These are exactly the people least likely to benefit from a multivitamin supplement — they have no deficits to correct. Effects measured in this population represent minimum effects, not maximum benefits.
Second, duration. Twelve weeks measures short-term changes, not long-term health outcomes.
Third, funding. A brand-funded study can be technically rigorous — and this one appears to be — while still being subject to subtle biases in endpoint selection or result interpretation.
What the Study Found: Results in Detail
Gut health: the primary endpoint. After 12 weeks, the AG1 group showed significantly higher bifidobacteria diversity and higher short-chain fatty acid (SCFA) levels — markers associated with intestinal microbiome health. This finding is statistically significant and biologically plausible given the prebiotics and probiotics in the formulation.
Vitamin status: vitamin D, B12, and magnesium levels increased in the AG1 group. This isn't surprising — AG1 contains these vitamins at meaningful doses. The effect confirms the ingredients are absorbed. It doesn't tell you whether that's useful for someone without a deficiency. A recent University of Surrey study on vitamin D forms is a useful reminder that how a vitamin is delivered matters as much as the dose.
What didn't change: inflammatory markers (CRP), body composition, and perceived energy. These secondary endpoints showed no significant differences between AG1 and placebo.
How to Interpret These Results
The AG1 study shows the product does what its formulation suggests: it improves vitamin status and supports microbiome diversity in healthy people.
What it doesn't prove: that AG1 is necessary or superior to a balanced diet built from whole foods for someone who already eats well and has no deficiencies. For a person with a varied diet and normal vitamin levels, the incremental effect is probably small.
Who are the results most relevant for? People with restrictive diets, insufficient vegetable intake, or difficulty maintaining consistent vitamin levels. For them, a product like AG1 may fill real gaps.
What This Means for the Greens Market
AG1's decision to fund and publish an RCT shifts something in the greens powder market. Before this trial, greens brands sold on the basis of theoretically beneficial ingredients — without clinical evidence on the finished product.
If the AG1 study is replicated by independent labs, it sets an evidentiary standard that other brands will need to follow or explain why they haven't. That's ultimately good for consumers — and potentially challenging for brands whose formulations might not hold up to the same scrutiny.