The protein number on a tub isn't a measurement of protein. It's a measurement of nitrogen, converted into a protein number by arithmetic that's been standard since 1883 and gameable since about 2010.
Nitrogen spiking is what happens when a manufacturer decides to game the arithmetic.
The short version
Protein is the only macronutrient that contains nitrogen, and it contains a fairly predictable amount: roughly 16% by weight. So labs don't count protein. They burn or digest a sample, measure the nitrogen that comes off, and multiply by 6.25. Nitrogen in, protein number out.
The test has no idea where the nitrogen came from.
Add a cheap nitrogen-rich ingredient to the powder (free amino acids like glycine or taurine, sometimes creatine) and the nitrogen reading climbs. The lab reports more protein. The label prints more protein. Nothing in that chain is lying, exactly. It's just not true.
That's nitrogen spiking, also called amino spiking or protein spiking. You pay for 23 grams of protein and get something less, padded out with ingredients that cost a fraction of what real protein costs.
Illustration only. A nitrogen-based test can give the same apparent protein result for both tubs.
Why free amino acids aren't the same as protein
This is where it gets slippery, because a brand caught spiking will tell you amino acids are protein. Technically, they're the building blocks of it.
But a few grams of isolated glycine doesn't do what a few grams of complete protein does. Glycine and taurine are non-essential, meaning your body makes them on its own. They don't contribute to muscle protein synthesis the way a full amino acid profile does. Dumping them into a blend inflates the nitrogen count without improving the product.
The giveaway is usually the dose. Nobody adds 4 grams of glycine for a functional reason.
Is it legal?
Mostly, which is the frustrating part.
The FDA's standard method for determining protein on a Nutrition or Supplement Facts panel is nitrogen-based. If a manufacturer runs that method and prints the result, they've followed the rule as written. The rule just predates anyone thinking to exploit it.
Where it has been successfully challenged is in civil court. A wave of class-action suits landed in 2014 and 2015 against sports nutrition brands whose protein content, measured by amino acid profile instead of total nitrogen, came in well under label claim. Several settled. The practice got quieter afterward. It did not disappear.
How much protein is actually missing?
LGC, the lab behind Informed Sport, bought 61 protein supplements from 35 brands and tested them against their own labels in a 2025 survey.
Thirteen of them, 21%, delivered less than 98% of the protein they claimed. Five percent came in at 90% of claim or lower. The worst offender was sold as "100% Egg Protein" at 24 grams per serving and contained under 7 grams. That's 27% of what the label promised. LGC ordered a second batch to check. Same result.
Worth noting: LGC excluded from those figures any product where free amino acids or known adulterants turned up. So any spiked products aren't in the 21%. They'd be a separate problem on top of it.
How to spot it on a label
You can't always. But there are tells.
Look at the ingredient list for isolated amino acids appearing near the top: glycine, taurine, alanine, sometimes creatine or betaine. In a protein powder, a free amino acid high in the ingredient order is a question worth asking.
Look for a "protein blend" or "amino matrix" that bundles the protein sources and the free aminos into one proprietary total, so you can't see the split.
Look for an asterisk on the protein claim. Footnotes like "protein from a blend of protein and amino acids" are doing a lot of quiet work.
And look at price. Protein isolate is the most expensive thing in the tub. If a product is priced well below everything comparable and still claims the same protein, something is subsidizing it.
For the rest of what separates one protein powder from another, see our guide to choosing a clean plant-based protein powder.
Informed Protein by LGC: the certification built for this
Informed Sport has been the banned-substance standard in sports nutrition for years. In 2023, LGC launched a second program aimed squarely at the label problem: Informed Protein.
It exists because the nitrogen test alone can't be trusted on its own. So Informed Protein doesn't rely on it alone.
Certification runs in four stages. First, a review of the formulation and the manufacturing facility, covering quality systems, GMP, supplier assessment, and traceability. Then pre-certification testing: three samples from a minimum of three separate production runs, tested at LGC's protein lab for total protein via nitrogen, total carbon, free amino acids, and nitrogen-rich adulterants including melamine and its analogues. Heavy metal and pesticide results have to be submitted alongside.
The free amino acid analysis is the part that matters here. It's what separates protein-derived nitrogen from nitrogen somebody added. A spiked product can pass a nitrogen test. It cannot pass this one.
Then certification, with a public product listing consumers can check. And then the part most programs skip: ongoing monthly blind testing, where LGC buys the product off the shelf from retail, online and physical, and tests it like any other customer would receive it. Facilities get reassessed. Certification isn't a one-time event you pay for and frame.
Where we stand
So Lean & So Clean is Informed Protein certified by LGC, across every flavor. When the tub says 23 grams of protein, that number has been independently verified by a lab that also went looking for the ways it could have been faked.
It's also Informed Sport certified, screened batch by batch for over 250 banned substances, which matters if you compete and matters more broadly as a signal of how closely the product gets watched.
Both certifications sit inside our 5 Nation Standard, our testing protocol benchmarked against the strictest limits across five regulatory regions. And every lot's full results get published. You can look up your own batch number and read the Certificate of Analysis, typically eight pages or more, including the potency results.
We'd rather you check than take our word for it. That's sort of the whole point.
