Best Plant-Based Protein Sources Ranked: Completeness, Amino Acids, and Cost Compared (2026)

Soy foods, quinoa, buckwheat, hemp seeds, and nutritional yeast are complete plant proteins, providing all nine essential amino acids. Seitan contains the most protein per serving at about 21 g per 3 oz, but is incomplete due to low lysine. By protein quality scores, soy ranks highest among plant sources with a DIAAS around 0.9.

This ranking evaluates whole-food plant proteins based on protein content, completeness, and cost. It highlights the importance of varying sources to achieve a balanced amino acid profile.

Highest-Protein Plant Foods Per Serving

Most protein per standard serving:

1. Seitan (3 oz): 21 g
2. Tempeh (3 oz): 17 g
3. Tofu, firm (1/2 cup): 10 g
4. Lentils (1/2 cup): 9 g
5. Edamame / hemp seeds (1/2 cup / 3 tbsp): 9 g

Best Complete Plant Proteins (All 9 Amino Acids)

Plant foods with all nine essential amino acids in adequate amounts:

1. Soy (tofu, tempeh, edamame, soy milk)
2. Quinoa
3. Hemp seeds
4. Buckwheat
5. Nutritional yeast

Cheapest Plant Proteins

Most protein for the lowest cost:

1. Lentils (1/2 cup): 9 g
2. Black / kidney beans (1/2 cup): 7.5 g
3. Chickpeas (1/2 cup): 7 g
4. Tofu (1/2 cup): 10 g
5. Oats (1/2 cup dry): 5 g

Highest-Protein Plant Foods: Complete Proteins

The highest-protein plant foods include soy foods, quinoa, buckwheat, hemp seeds, and nutritional yeast, all classified as complete proteins. These sources provide all essential amino acids necessary for optimal health.

Food	Serving	Protein (g)	Complete Protein?	Limiting Amino Acid	Relative Cost
Tempeh	3 oz	17	Yes (soy)	None	$$
Tofu (firm)	1/2 cup	10	Yes (soy)	None	$
Edamame	1/2 cup	9	Yes (soy)	None	$$
Hemp seeds	3 tbsp	9	Yes	None	$$$
Pumpkin seeds	1 oz	8.5	Near-complete	Lysine	$$
Quinoa (cooked)	1 cup	8	Yes	None	$$
Nutritional yeast	2 tbsp	8	Yes	None	$$
Soy milk	1 cup	7	Yes (soy)	None	$
Buckwheat (cooked)	1 cup	6	Yes	None	$
Pistachios	1 oz	6	Near-complete	None	$$$

Soy foods are particularly notable for their high protein quality.

High-Protein Plant Foods: Incomplete (Pair to Complete)

High-protein plant foods that are incomplete include seitan, which has the highest protein content per serving but lacks sufficient lysine. Pairing these with complete proteins throughout the day ensures adequate amino acid intake.

Food	Serving	Protein (g)	Complete Protein?	Limiting Amino Acid	Relative Cost
Seitan	3 oz	21	No	Lysine	$$
Lentils (cooked)	1/2 cup	9	No	Methionine	$
Green peas (cooked)	1 cup	8	No	Methionine	$
Black beans (cooked)	1/2 cup	7.5	No	Methionine	$
Kidney beans (cooked)	1/2 cup	7.5	No	Methionine	$
Chickpeas (cooked)	1/2 cup	7	No	Methionine	$
Peanut butter	2 tbsp	7	No	Methionine	$
Almonds	1 oz	6	No	Lysine	$$
Oats (dry)	1/2 cup	5	No	Lysine	$

Combining incomplete proteins can effectively meet dietary needs.

How to Track Plant Protein and Amino Acids

Eating enough plant protein is less about any single food and more about hitting your daily total from varied sources. Nutrola tracks over 100 nutrients, including protein, from a photo, barcode or voice entry, so you can see your daily total against your target instead of guessing. Nutrola is available from EUR 2.50 per month and shows no ads on any tier.

For related references, see complete protein sources ranked by bioavailability, protein powders ranked by DIAAS and cost, and a dairy-free high-protein meal plan.

How We Compiled These Numbers

Protein is per standard serving from USDA FoodData Central, rounded. Completeness reflects whether a food supplies all nine essential amino acids in adequate amounts, with the main limiting amino acid noted. Protein quality scores (DIAAS, PDCAAS) referenced in the text are published ranges that vary by cooking method and study. Relative cost is general US grocery guidance, not a fixed price.

Frequently Asked Questions (FAQ)

What are the best plant-based protein sources?

The best plant-based protein sources include soy foods, quinoa, buckwheat, hemp seeds, and nutritional yeast. These options provide a good balance of protein and essential amino acids.

Which plant proteins are complete?

Complete plant proteins are those that contain all nine essential amino acids. Examples include soy foods, quinoa, buckwheat, hemp seeds, and nutritional yeast.

Do you need to combine plant proteins?

While it is not necessary to combine plant proteins in the same meal, varying them throughout the day can help ensure you get all essential amino acids. For instance, pairing legumes with grains can fill amino acid gaps.

Which plant protein has the most protein per serving?

Seitan has the most protein per serving, offering about 21 g per 3 oz. However, it is considered incomplete due to its low lysine content.

Is plant protein as good as animal protein?

Plant protein can be as beneficial as animal protein, but it is slightly less digestible. Whole-food eaters may need to consume a bit more to meet their protein needs.

What are DIAAS and PDCAAS?

DIAAS (Digestible Indispensable Amino Acid Score) measures protein quality based on digestibility and amino acid composition. PDCAAS (Protein Digestibility Corrected Amino Acid Score) is another method, but DIAAS is considered more accurate.

Key Takeaways

• Soy foods, quinoa, buckwheat, hemp seeds, and nutritional yeast are complete proteins.
• Seitan offers the highest protein content per serving but is incomplete.
• Protein quality scores show soy is closest to animal protein.
• Most legumes are low in methionine, while grains and nuts are low in lysine.
• Varying protein sources throughout the day helps meet amino acid needs.
• Plant proteins are slightly less digestible than animal proteins.