A Plant Protein Blend Matched Whey—In One Small Trial

A carefully engineered plant-protein blend matched whey for muscle protein synthesis after lifting in one small randomized trial. The result did not come from declaring all plant protein equal. It came from fixing the amino-acid gaps that make single-source plant proteins less effective.

In the study, 32 grams of a pea, brown rice, and canola blend delivered about 2.5 grams of leucine and about 10 grams of essential amino acids (EAAs). Over four hours after resistance exercise, it stimulated myofibrillar protein synthesis—the process that builds the contractile proteins in muscle—at a rate statistically equivalent to 32 grams of whey. Yet the blend produced 44% lower peak plasma EAA availability than whey.

That is an interesting acute finding, not proof that the blend builds the same amount of muscle over months. The trial included 10 people, only two of them women, and no long-term hypertrophy or strength outcomes. The formulation matters, and the evidence has not yet earned a broad claim about "plant protein."

Why single plant proteins often fall short

Whey has an amino-acid profile that happens to suit post-exercise muscle protein synthesis well: it provides abundant EAAs and leucine, an amino acid that helps trigger mTORC1 signaling. Individual plant proteins can provide plenty of total protein while still falling short on one or more amino acids.

The shortfalls differ by source. Pea, soy, and lentil proteins tend to be methionine-limited. Rice, wheat, and maize tend to be lysine-deficient. Hemp and wheat are relatively low in leucine; oat and hemp are also limited in isoleucine and valine. More scoops do not necessarily solve a limiting amino acid if the profile remains unbalanced.

The pea-rice-canola formula addressed that problem directly. Pea supplied leucine and lysine. Brown rice supplied methionine but needed lysine. Canola contributed a more balanced amino-acid profile. The goal was a complete EAA profile and a leucine dose high enough to stimulate the post-exercise response.

This logic fits earlier human work. In a randomized trial of older men, McKendry et al. (2024) found that single-source pea protein did not match whey for integrated myofibrillar protein synthesis, even when participants consumed protein beyond the recommended dietary allowance. That study involved older men, so it cannot quantify the gap in younger trained adults. It does show why pea protein alone should not be treated as interchangeable with whey.

What the blend trial actually found

Van der Heijden et al. (2024) used a double-blind, crossover design in 10 resistance-trained adults: eight men and two women. Each participant completed standardized resistance exercise and then consumed either 32 grams of whey or an isonitrogenous 32-gram blend providing 39.5% pea protein, 39.5% brown rice protein, and 21% canola protein.

The investigators measured myofibrillar protein synthesis over the next four hours with deuterium oxide tracer methods. The blend and whey produced statistically equivalent fractional synthetic rates over that window. The article does not provide a confidence interval for an equivalence estimate in the evidence summarized here, so the result should not be read as a precise estimate of how close the products were.

The lower circulating EAA response makes the finding more, not less, specific. Whey created higher peak plasma EAA availability, but the blend still reached the same measured synthesis rate. One plausible explanation is that the blend met the leucine and EAA threshold required for maximal acute stimulation; slower digestion may also have extended amino-acid delivery. The trial did not isolate those mechanisms, so neither explanation counts as proof.

The threshold model has support—but not a universal dose

Evidence in women supports the idea that amino-acid quality can matter more than the gross weight of protein in a post-workout drink. In a crossover randomized trial of 31 young resistance-trained women, Apicella et al. (2025) reported statistically equivalent post-exercise myofibrillar protein synthesis after a leucine-enriched EAA formulation described as 1.5 grams of EAA with an approximately 2-gram leucine-enriched fraction, 15 grams of whey, or 20 grams of whey.

That does not establish one magic leucine number for every person, protein source, meal, or training program. It does support a ceiling effect: once a sufficient EAA and leucine signal is reached, adding more total amino acids may not raise the acute synthesis rate further.

A separate resistance-exercise study by Aguilera et al. (2025) adds another wrinkle. Leucine-enriched EAAs supported post-exercise whole-body anabolism and mTORC1 activation, while dileucine produced greater effects than an equivalent amount of free leucine. Molecular form and delivery kinetics can therefore affect signaling and protein metabolism. This makes the blend hypothesis biologically plausible, but it does not demonstrate that the blend's lower EAA peak is an advantage.

Why the result needs a skeptical reading

The central limitation is precision. A crossover trial of 10 participants can miss modest differences that may matter after repeated training. A non-significant difference is not automatically evidence of true equivalence, especially when the study has little power to detect smaller effects. The four-hour measurement period also leaves most of the recovery window unmeasured. Lower EAA availability could matter later in the 24 to 48 hours after exercise; this study cannot answer that question.

Sex is another major gap. Only two women took part in the blend trial. In young trained women, Mallinson et al. (2023) found that post-exercise protein dose requirements and protein-synthesis responses differed by sex and varied with menstrual-cycle phase. The blend result therefore applies most directly to resistance-trained men, not to women as a group.

Other populations also produce a more nuanced picture. In a 10-day randomized trial of 27 adults aged 50 to 70, Korzepa et al. (2025) found that resistance training increased integrated myofibrillar protein synthesis regardless of whether participants ate an animal-focused, whey-supplemented diet or a plant-focused, pea-supplemented diet. That was a habitual-diet intervention in middle-to-older adults, not a direct test of this blend against whey after one workout. It suggests protein source may matter less when total dietary protein needs are met in that population.

Meanwhile, an eight-week trial in 45 elite football players found different gut-microbiota changes with animal versus plant protein supplementation, according to Kroplewski et al. (2026). It measured microbiota, not muscle growth, strength, or myofibrillar protein synthesis. The study neither confirms nor refutes hypertrophy equivalence, but it shows that chronic exposure to protein sources can have different biological effects.

What to do with this if you train

If you prefer plant protein after resistance training, look for the engineering rather than the marketing. The studied product used a specific 39.5% pea, 39.5% rice, and 21% canola blend, with about 32 grams of protein and about 2.5 grams of leucine. A label that says "pea and rice" does not establish the same amino-acid profile, leucine dose, or performance.

• Choose a complementary blend rather than single-source pea protein if your goal is to approximate whey’s acute post-exercise amino-acid profile.
• Check whether the manufacturer states leucine and total EAA content. Ingredient names alone cannot verify either.
• Treat claims of equal long-term muscle growth as unproven until larger, independently replicated trials measure lean mass, hypertrophy, and strength over at least several weeks.

The formulation deserves attention because it solved a real nutritional design problem. The result deserves restraint because one four-hour trial in 10 mostly male trainees cannot settle what happens across a training block. The available publication text also does not disclose a funding source, which makes independent replication especially important.