Protein on a Vegan Diet: Myths, Facts and Real Numbers

Grilled Tofu Salad

Protein is the most questioned nutrient in plant-based nutrition — and also one of the most misrepresented. Most guides on the subject list impressively high protein figures for legumes, repeat the advice to combine proteins at every meal, and leave readers with the impression that getting enough protein as a vegan requires careful, constant management.

Most of those figures are wrong. The combining advice was debunked over four decades ago. And the Academy of Nutrition and Dietetics, in its current position paper, is clear: a well-planned vegan diet meets protein needs. This post covers the actual science — with accurate numbers.

The Complete vs. Incomplete Protein Myth

The idea that plant proteins are "incomplete" — missing essential amino acids — became widely accepted after Frances Moore Lappé's 1971 book Diet for a Small Planet, which argued that plant proteins needed to be strategically combined at each meal to match the amino acid profile of meat. The recommendation made intuitive sense, and it spread quickly.

Lappé herself retracted it a decade later. In the 1981 edition of the same book, she explicitly corrected the record, acknowledging that she had created a "myth" by drawing on flawed mid-century research. Every plant food contains all nine essential amino acids. Some are lower in certain amino acids relative to others — legumes tend to be lower in methionine, grains lower in lysine — but "lower in" is not the same as "absent from."

The body maintains a free amino acid pool, drawing from all the protein consumed throughout the day. Amino acids consumed at breakfast are still available to complement those consumed at lunch or dinner. Combining rice and beans in the same bowl is not nutritionally different from eating them in separate meals on the same day. The Academy of Nutrition and Dietetics' position statement on vegetarian diets confirms this: protein combining at each meal is unnecessary for people who eat a varied diet of plant foods.

The practical takeaway is that the question is not whether vegan protein is "complete" — it is — but whether overall intake is sufficient.

How Much Protein Do Vegans Actually Need?

• The standard recommended dietary allowance (RDA) for protein is 0.8 grams per kilogram of body weight per day. For a 70kg adult, that is 56 grams daily.

• For people eating exclusively plant-based diets, a modest upward adjustment is sometimes recommended — around 0.9 to 1.0g per kilogram — to account for the slightly lower digestibility of plant proteins compared to animal proteins. Plant proteins are typically 70–90% digestible, versus 90–95% for animal proteins, depending on preparation and processing. Cooking, fermenting, and sprouting all improve the digestibility of plant proteins.

• Athletes and people engaged in strength training require more: the American College of Sports Medicine and the Academy of Nutrition and Dietetics both recommend 1.2 to 2.0g per kilogram for people with high training loads, regardless of dietary pattern. Older adults benefit from slightly higher intake — around 1.0 to 1.2g per kilogram — to support muscle maintenance, since muscle protein synthesis efficiency declines with age.

Research published in the Journal of the Academy of Nutrition and Dietetics found that vegans eating varied diets with adequate calories typically consume well over their protein requirements. Protein deficiency in vegans who eat sufficient calories is rare; it is overwhelmingly associated with overall caloric restriction rather than with an absence of protein-rich foods.

Protein in Plant Foods: Accurate Numbers

One of the most persistent problems in vegan nutrition content is the conflation of dry and cooked protein values for legumes. Dried lentils and chickpeas shrink dramatically when cooked — they absorb water, increasing in weight by roughly 2.5x — which significantly dilutes the per-100g protein concentration. Figures quoted from dry weight, if applied to cooked food, overstate the protein content by around two to three times.

The table below uses cooked or ready-to-eat values throughout, sourced from USDA FoodData Central.

Legumes (cooked, per 100g)

Lentils provide approximately 9g of protein per 100g cooked — not 25g, which is the dry weight figure frequently cited. Chickpeas deliver around 8.9g per 100g cooked. Black beans are similar at approximately 8.9g cooked. Edamame (young soybeans, eaten as a snack or in salads) provides 11–12g per 100g. Cooked whole soybeans deliver around 17g per 100g — among the highest of all whole plant foods.

Soy products and wheat-based proteins

Tofu ranges from 8g to 15g per 100g, depending on firmness — firm and extra-firm tofu concentrate more protein as water is pressed out. Tempeh delivers around 19g per 100g, making it one of the most protein-dense whole plant foods; the fermentation process that produces tempeh also improves protein digestibility relative to whole soybeans. Tempeh's PDCAAS (Protein Digestibility-Corrected Amino Acid Score) score is competitive with many animal proteins.

Seitan — made from wheat gluten — is the most protein-concentrated whole plant food in common use, at roughly 25–30g per 100g for the prepared product. The dry vital wheat gluten flour used to make it contains approximately 75g per 100g, which is the figure sometimes cited but rarely reflects what ends up on the plate. Seitan's lysine content is low, which makes it more effective when eaten as part of a varied diet rather than as a sole protein source.

Seeds, grains, and nuts

Hemp seeds are among the most protein-dense seeds at approximately 31g per 100g, and they provide a favourable omega-3 to omega-6 ratio alongside this. Quinoa is notable as a grain with a complete amino acid profile and good relative balance; at around 4–5g per 100g cooked, its protein contribution per serving is modest but its quality is high. Almonds provide approximately 21g per 100g; peanuts around 26g — both raw figures.

Digestibility and Protein Quality

Not all proteins are absorbed with equal efficiency. The PDCAAS and its successor, the DIAAS (Digestible Indispensable Amino Acid Score), are the current tools for measuring protein quality — both account for amino acid composition and digestibility together.

Soy protein achieves a PDCAAS of 1.00, equivalent to eggs and casein, and outperforms most animal proteins on some metrics. Pea protein scores around 0.75–0.89. Beans and lentils are in the 0.60–0.70 range when consumed whole, with fermented and sprouted versions scoring higher.

This means that achieving protein adequacy from plant sources requires either a slightly higher total intake, accounting for lower digestibility, or a greater reliance on high-quality sources like soy, peas, and fermented foods like tempeh. Neither of these is an obstacle to meeting requirements; they are just useful to know when planning.

What a Sufficient Protein Day Looks Like

For a 65kg adult targeting 1.0g per kilogram, the daily goal is 65g. Across a varied vegan diet, this is achievable without protein-specific planning. A day that includes: cooked lentils or chickpeas at one meal (~9g per 100g), tofu or tempeh at another (~10–19g per 100g), whole grains, nuts, seeds, and soy milk will reach or exceed this target without tracking.

Where protein adequacy requires more attention is in diets that are calorie-restricted, very high in refined carbohydrates with limited legumes and soy, or composed primarily of raw fruits and vegetables with minimal protein-dense foods. These patterns are less common but worth knowing about.

Frequently Asked Questions

Can vegans get enough protein without supplements?

Yes. Protein supplements are not needed on a well-constructed vegan diet. Whole food sources — legumes, tofu, tempeh, seitan, soy milk, seeds, and whole grains — provide sufficient protein for most adults meeting their caloric needs. Protein powder can be a convenient addition for athletes with high requirements, but it is not a nutritional necessity for the general population.

Do vegans need to combine proteins at every meal?

No. This recommendation originated in Frances Moore Lappé's 1971 work and was publicly retracted by Lappé herself in 1981. The body draws from a free amino acid pool across the full day, not meal by meal. Eating a variety of plant foods throughout the day provides all essential amino acids without requiring deliberate same-meal pairing.

How much protein do vegans need per day?

The standard RDA is 0.8g per kilogram of body weight, with a modest adjustment to 0.9–1.0g per kilogram recommended for people eating exclusively plant-based diets to account for lower average digestibility. Athletes require 1.2–2.0g per kilogram depending on training load and goals. Older adults benefit from 1.0–1.2g per kilogram to support muscle maintenance.

Are plant proteins inferior to animal proteins?

Not categorically. Soy protein achieves a PDCAAS of 1.00 — equivalent to the benchmark animal proteins — and pea protein scores competitively. Plant proteins as a group are slightly less digestible than animal proteins (70–90% vs 90–95%), and some individual foods are lower in specific amino acids. A varied plant-based diet consuming slightly above the RDA addresses both of these factors comfortably.

Which vegan foods are highest in protein?

By protein density: vital wheat gluten (seitan base, ~75g per 100g dry); hemp seeds (~31g per 100g); tempeh (~19g per 100g); firm tofu (~10–15g per 100g); edamame (~11g per 100g); cooked soybeans (~17g per 100g). Legumes — lentils, chickpeas, black beans — deliver approximately 9g per 100g cooked, which is the figure to use when calculating intake from a prepared meal.

What This Means Practically

Getting enough protein on a plant-based diet is not a problem requiring constant vigilance. It requires a diet with adequate calories and a reasonable variety of legumes, soy products, grains, seeds, and nuts across the day. The main obstacle is not the protein itself — it is misinformation about how plant proteins work, and inflated figures that create false confidence in foods while understating requirements elsewhere.

At The Vegan School, making tofu and seitan from scratch is part of the hands-on curriculum.