Plant-Based Protein: What You Should Know

The Central Question

Can plant-based proteins compete with animal-based ones? The answer is more nuanced than a simple “yes” or “no.”

Protein Quality: The Basics

Amino Acid Profile

Proteins are made up of 20 amino acids, 9 of which are essential (the body cannot produce them on its own). “Complete” proteins contain all essential amino acids in sufficient quantities.

Animal proteins: Generally complete Plant-based proteins: Often have limiting amino acids

Source	Limiting Amino Acid
Legumes	Methionine
Grains	Lysine
Pea protein	Methionine
Rice protein	Lysine
Hemp protein	Lysine
Soy protein	None (complete)

Bioavailability

The DIAAS (Digestible Indispensable Amino Acid Score) measures how well the body can absorb protein:

Source	DIAAS
Milk protein	~120
Egg	~118
Beef	~112
Soy protein	~91
Pea protein	~82
Rice protein	~59

Important: These values apply to isolated sources. Combinations increase the score.

Combining Different Sources

The classic example: rice + beans. The amino acids complement each other and together form a complete profile.

Modern protein blends use this principle:

• Pea + hemp = a strong combination: pea protein provides plenty of lysine and leucine, while hemp protein complements with methionine, healthy fatty acids, and fibre
• Pea + rice = complete amino acid profile
• Soy alone = already complete

What Does the Research Say?

Muscle Building

A randomised study by Hevia-Larrain et al. (2021) in Sports Medicine compared plant-based and animal protein during resistance training over 12 weeks:

Result: No significant differences in muscle mass or strength — with the same protein intake.

A meta-analysis by Messina et al. (2018) reached similar conclusions: with adequate quantity and quality, plant-based proteins are equivalent for muscle building.

The Leucine Question

Leucine is the most important amino acid for muscle protein synthesis. Plant-based proteins contain less leucine than animal-based ones.

Solution: Consume slightly more plant-based protein or focus on leucine-rich sources:

• Soy protein: ~8% leucine
• Pea protein: ~8% leucine
• Whey: ~11% leucine

A study by Gorissen et al. (2018) showed that 40g of plant-based protein stimulates muscle protein synthesis similarly to 20g of whey.

Long-Term Health

A large prospective study by Song et al. (2016) in JAMA Internal Medicine involving over 130,000 participants found:

• Higher intake of plant-based protein was associated with reduced all-cause mortality
• The effect was particularly pronounced when replacing red meat

Digestibility

Plant-based proteins were long considered harder to digest. Modern processing methods (isolates, enzymes) have largely levelled the playing field.

Some people tolerate plant-based better:

• No lactose
• Often fewer digestive issues (varies individually)
• No casein (which can promote inflammation in some people)

Practical Recommendations

Adjust the Amount

With an exclusively plant-based diet, slightly more protein may be beneficial: 1.8-2.4g/kg rather than 1.6-2.2g/kg.

Vary Your Sources

Don’t rely on a single source. Combine different legumes, grains, nuts, and protein powders.

Focus on Quality

For protein powders:

• Combination of different sources (e.g. pea + hemp)
• At least 70% protein content
• Minimal additives
• No artificial sweeteners

Timing

Research shows no significant difference between plant-based and animal protein when it comes to timing. Total daily intake is more important.

Conclusion

Plant-based proteins can replace animal-based ones for muscle building and health — provided you pay attention to adequate quantities, combine different sources, and choose quality products. Differences in bioavailability can be offset by slightly higher intake.

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Sources:

• Hevia-Larrain V et al. (2021). High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations. Sports Medicine.
• Messina M et al. (2018). No Difference Between the Effects of Supplementing With Soy Protein Versus Animal Protein on Gains in Muscle Mass and Strength in Response to Resistance Exercise. International Journal of Sport Nutrition and Exercise Metabolism.
• Gorissen SH et al. (2018). Protein content and amino acid composition of commercially available plant-based protein isolates. Amino Acids.
• Song M et al. (2016). Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality. JAMA Internal Medicine.