The 6 most common myths about plant-based protein (and what science says instead)

On May 19, the NPR Health desk splashed an attention-grabbing headline across its site: “Protein for strength training? Vegan diet matches meat for muscle gains.”

The story summarized a tightly controlled University of Illinois trial in which forty young adults lifted weights for nine days while eating either an omnivorous menu built around whey or an isocaloric vegan plan built around soy-lentil blends.

When researchers biopsied the participants’ muscle fibers, the vegans and the meat-eaters showed identical rates of muscle-protein synthesis—a result that overturns decades of locker-room lore.

Two weeks later, the Department of Health and Human Services released the 2025 Dietary Guidelines Advisory Committee (DGAC) report. In a major pivot, the DGAC proposes re-organizing the protein food group so that beans, lentils, peas, nuts, seeds, and precision-fermented dairy analogues sit at the top of the list—above red meat—because of their fiber, lower saturated fat, and smaller carbon footprint.

In other words, the protein conversation has shifted.

Yet 6 stubborn myths still pop up in workout forums, family dinners, and even on some wellness podcasts. Below, we break down each myth and stack it next to the latest data so you can choose your protein with confidence—and context.

Myth 1

“Plant protein is ‘incomplete,’ so you can’t build serious muscle on it.”

What does the science say?

• Yes, individual plant foods often have less of one or two essential amino acids.
• No, that does not mean plant eaters walk around with half-finished biceps.

A January 2025 systematic review found no meaningful difference in muscle mass, strength, or physical performance between participants assigned to plant versus animal protein, provided total daily protein met or exceeded 1.2 g per kilogram of body weight.

The new Illinois study extends those findings to real-world meal patterns: the vegan group simply ate a mix of soy, lentils, chickpeas, and grains to cover all nine essential amino acids across the day.

Take-home: Think “protein portfolio,” not “perfect food.” A burrito of black beans and brown rice, or a breakfast of oats topped with hemp seeds, delivers a full amino-acid symphony by sundown.

Myth 2

“You must combine two plant proteins in the same bite or the meal ‘doesn’t count.’ ”

This 1970s rule — popularized by the first edition of Diet for a Small Planet — assumed your body needed every amino acid in one sitting. We now know the liver maintains a circulating pool of amino acids for at least 24 hours, allowing different foods to be combined over time.

In the Illinois trial, half the volunteers “back-loaded” most of their protein at dinner while the other half spaced it out evenly; both strategies produced identical muscle-building signals.

Modern dietitians’ rule of thumb: hit your daily target (roughly 0.8–1.2 g/kg for general health, 1.4–2 g/kg for strength athletes), and variety will fill in the gaps.

Myth 3

“Plant protein is harder to digest, so you absorb less of it.”

Digestibility does matter, but so does technology.

New methodologies such as DIAAS (Digestible Indispensable Amino Acid Score) already rate isolated soy, pea, fava-bean, and potato proteins above 0.9—well within “high-quality” territory. Food scientists have pushed the envelope further:

• Precision-fermented whey produced by Dutch startup Vivici earned an FDA “no-questions” letter in March. It’s molecularly identical to bovine β-lactoglobulin but brewed in a tank with 68 % lower carbon emissions.

• A May pilot in Medicine & Science in Sports & Exercise demonstrated that a pea-pumpkin-rice blend enriched with leucine triggers the same anabolic response as whey. (The blend’s digestibility clocked in at 96 %, thanks to an enzyme-assisted processing step.)

Practical fix: choose minimally processed legumes for everyday meals and, if you use shakes, look for blends listing their DIAAS score or added leucine on the label.

Myth 4

“Older adults need meat because plant protein can’t fight age-related muscle loss.”

Sarcopenia—muscle decline past age 60—has fueled protein panic among seniors. But the 2025 meta-analysis mentioned above specifically targeted older adults and still found no animal-protein advantage when intakes were equal.

Meanwhile, longevity researchers are pointing out a different risk: excess animal protein before age 65 can elevate IGF-1, a growth signal linked to higher mortality.

On June 12, longevity physician Dr. Joseph Antoun told reporters that a mainly plant-based pattern in mid-life, shifting to slightly higher total protein—including some animal if desired—after 65, may offer the best trade-off between muscle maintenance and healthy aging.

Bottom line: Older vegans do need to pay attention—aim for 1.2 g/kg, distribute protein over three meals, and add resistance training—but they don’t need steak to stay strong.

Myth 5

“Plant protein is too ‘weak’ for serious athletes.”

Elite sports teams are proving otherwise. The Brooklyn Nets’ performance chef swapped half the roster’s recovery shakes to a soy-pea blend last season with no drop-off in strength metrics.

More rigorously, the Illinois trial showed identical muscle-protein synthesis after weight training, and a parallel study in collegiate runners found equal 5 km times when athletes consumed 2 g/kg/day of either whey or a lentil-quinoa blend for six weeks.

What matters most?

Total grams, leucine threshold (≈3 g per meal), and timing — identical rules apply to both camps.

If you’re training twice daily, an algae-based EPA/DHA capsule plus a fortified plant shake can close the small recovery gap some athletes report.

Myth 6

“Plant protein is more expensive and less accessible.”

Price anxiety is real when a tub of vegan powder costs $49.99. Yet on a per-20-grams-of-protein basis, dried beans and lentils remain the cheapest proteins in the supermarket—often under $0.40 per serving.

Even high-tech options are dropping in price. Vivici projects its precision-fermented whey will hit cost parity with dairy whey by Q4 2025, partly because it uses 86% less water and 50% less energy.

Policy is catching up: the DGAC’s push to foreground beans and lentils is expected to shift procurement guidelines for public schools and SNAP toward lower-cost plant proteins by 2026—a move analysts say could save $1 billion annually in commodity meat purchases.

Tip for your cart: Buy dry legumes in bulk, rotate in tofu (still <$2 per 20 g protein), and reserve specialty powders for convenience moments like post-workout commutes.

Wider impact: why debunking these myths matters

1. Health equity – Misconceptions keep budget-conscious families from the most affordable proteins on the shelf.

2. Climate math – Swapping just 50 % of U.S. beef protein for legumes could cut agricultural emissions by 12 %, according to 2024 modeling from the Lawrence Berkeley Lab.

3. Food innovation – Clear demand for plant protein is accelerating precision fermentation, boosting rural pea and fava-bean farming contracts, and opening new export markets.

4. Policy leverage – The 2025 DGA will guide federal feeding programs for the next five years; busting myths ensures those guidelines rest on evidence, not outdated dogma.

Where we go from here

The protein landscape of 2025 looks nothing like the one that birthed those old myths.

We have algae-based omega-3s, barista-friendly pea milks, GRAS-approved precision-fermented whey, and the strongest evidence yet that plants can power everyone from toddlers to triathletes.

So whether you’re eyeing Meatless Mondays or a full vegan plunge, relax.

The science is on your side— a nd your microbiome, wallet, and the planet will probably thank you, too.