Why There's No Rice in Our Pea Protein

By Dr. Eugene Capitano, DC, MSc

Dr. Eugene Capitano earned an MSc in Psychology & Neuroscience of Mental Health from King’s College London. He holds the ACSM Exercise is Medicine® (EIM) Credential and is an ACSM Certified Personal Trainer® (ACSM-CPT®). His research interests include the gut–brain axis, functional nutrition, metabolic health, and translational microbiome science.

When I first formulated this protein, it contained pea and rice.

That pairing made sense on paper. Pea protein is rich in lysine but runs low in the sulfur amino acids, methionine and cysteine. Rice is the mirror image — low in lysine, but it covers the methionine gap. Put them together and you get a complete amino acid profile from two plants. It’s a well-established principle, and it works.

Then I tested the rice.

Rice is one of the most efficient accumulators of inorganic arsenic in the plant kingdom — it draws the element up from soil and water far more readily than most crops, and concentrating rice into a protein isolate can carry that burden along with it. This isn’t fringe science; it’s why rice consistently shows the highest arsenic levels of any protein source in national food surveys.

I had our early rice-protein ingredient screened for heavy metals at the University of Guelph and measured each serving against California’s Proposition 65 limits — among the most conservative thresholds in North America. The rice came back higher than I was willing to accept.

At that point I had two choices. I could blend around it — dilute the rice with enough clean ingredients that the average per serving slipped under the line. That’s common, and technically it passes. Or I could take the rice out.

I took it out.

Removing rice meant rebuilding the amino acid profile another way. So I corrected pea’s limiting sulfur amino acids with added methionine, and added leucine — the amino acid that actually triggers muscle protein synthesis — to meet the threshold your muscle needs to respond. Same goal the rice was there to serve. No rice required, and no arsenic to blend around.

I won’t tell you our protein is “heavy-metal free” — nothing grown in soil is. What I’ll tell you is where the line is, and that we hold it even when it costs us an ingredient.

That’s the standard. It doesn’t move.

Each TLC production lot follows our Raw-to-Finished Batch Verification Process. Raw ingredients undergo documented verification and third-party testing before production. After final blending, the finished product is independently tested against the applicable heavy-metal and microbiological specifications before release. Once testing is complete, the lot-specific report is published on our Batch Quality & Reports page and connected to the lot number through the package QR code.

How does pea compare with whey?

For the muscle-building question, read Pea Protein vs Whey: What the Human Studies Show. The article separates short-term muscle-protein-synthesis studies from training trials and explains why findings from one protein formulation do not prove the performance of every finished product.