Is Tofu the Best Source of Protein?

Tofu offers high-quality protein, a favourable nutritional profile and a fraction of the environmental footprint of most animal foods. Put nutrition and sustainability together and it comes close to being an ideal protein, but it doesn't win every comparison, and the food that beats it may surprise you.

TL;DR

• Tofu's protein quality is measurable, and good. On the DIAAS scale, tofu scores 97, against roughly 108 to 117 for beef, eggs and milk, and 60 for a pea emulsion.
• Animal protein still has advantages. Chicken, eggs, fish and dairy are more protein-dense per gram and provide more leucine, plus B12 and haem iron that tofu lacks.
• For muscle, the practical difference is small. Meta-analyses of resistance training have found similar gains in lean mass and strength from soy and animal protein when total intake is adequate.
• There is no good evidence that soy lowers testosterone in men, though a 2025 analysis found a dose-related rise in oestradiol above typical dietary intakes.
• The environmental gap is large. Tofu produces about 1.98 kg CO₂e per 100g of protein, against 5.7 for poultry and around 25 for beef, and uses 2.2 m² of land against 164 m² for beef.
• Pulses beat tofu on footprint. Peas produce roughly 0.44 kg CO₂e per 100g of protein, about a fifth of tofu's, with considerably more fibre.
• The deforestation objection needs context, but has just got sharper. Around 77% of global soy is fed to livestock and only about 7% becomes food such as tofu, but the Amazon Soy Moratorium collapsed in 2026.

What Would Make a Protein "Best"?

Protein comparisons usually start with grams, which makes chicken breast look formidable and tofu look weak. That framing answers only one question. If we are asking which protein sources people should eat regularly, the relevant criteria include amino acid quality, what else arrives with the protein, effects on long-term health, and the greenhouse gases, land and water used to produce it. Once the question is that broad, tofu becomes unusually competitive, and the fair comparison is per 100g of protein rather than per 100g of food.

How Good Is the Protein?

Soy is not the nutritionally incomplete plant protein of caricature. It contains all nine essential amino acids, and its quality can be quantified rather than asserted. On the DIAAS scale, which measures how much of each essential amino acid is absorbed, a French study using minipigs scored tofu at 97, soy milk at 117, a pea emulsion at 60 and seitan at 28. Animal proteins sit at roughly 108 to 117. Tofu is therefore close to animal protein and far ahead of most other plant foods, though not quite level with meat, eggs or dairy. Its score is also lower than soy milk's because pressing tofu reduces the digestibility of its sulphur-containing amino acids, which is a reminder that the form of a food matters, not just its source.

Protein content varies considerably by product. Firmer tofu contains more protein because more water has been pressed out, while silken tofu contains substantially less, so comparing "100g of tofu" with 100g of chicken means little without specifying which tofu. The general pattern holds: tofu contributes meaningfully to a meal's protein, and chicken, fish and lean meat are still more protein-dense.

If the specific aim is building muscle, there is one further distinction. Animal proteins, and whey in particular, contain more leucine, the amino acid most associated with triggering muscle protein synthesis, so a smaller serving delivers the same stimulus. That has not translated into different outcomes in training studies. A meta-analysis of nine trials involving 266 participants found that soy protein supplementation produced similar gains in strength and lean body mass to whey and other animal proteins over at least six weeks. A larger 2021 review reached a similar conclusion on absolute lean mass and strength, though it did find a small advantage for animal protein on percentage lean mass. So whey wins for extracting maximum stimulus from the smallest serving, while for people eating enough protein across the day, tofu's slightly less favourable profile is not disqualifying.

What Comes With the Protein

Foods are not bags of amino acids. Steak delivers protein alongside haem iron, zinc and B12, but often substantial saturated fat. Oily fish brings EPA and DHA. Dairy provides calcium and B12, and eggs combine digestible protein with choline and several micronutrients. Tofu's package is different: low in saturated fat, containing unsaturated fats, iron and other minerals, and, when set with calcium salts, useful amounts of calcium, though this varies enough between products that the label matters.

Soybeans also contain isoflavones, plant compounds studied heavily because they can interact with oestrogen receptors. That has produced one of the most persistent myths in nutrition, that eating soy feminises men or suppresses testosterone. The testosterone half of that is not supported: a meta-analysis of 38 clinical studies found no effect of soy or isoflavone intake on male hormone levels, and a 2025 dose-response analysis found no relationship between isoflavone dose and total or free testosterone. That newer analysis did find a nonlinear pattern for oestradiol, which rose by around 6.5 pg/mL at about 72 mg of isoflavones a day, and for sex hormone-binding globulin. Those findings rest on only three or four trials each, and the threshold sits above typical dietary intake in Japan of roughly 30 to 50 mg a day, but they are a reason to describe the evidence as "no effect on testosterone" rather than "no hormonal effects at all".

Soy protein's effect on cholesterol is more interesting than it first appears, because it has been contested. A meta-analysis of the 46 trials the US Food and Drug Administration was using to review its soy heart health claim found that soy protein, at a median 25g a day for a median six weeks, lowered LDL cholesterol by 4.76 mg/dL (95% CI −6.71 to −2.80), roughly 3 to 4%. The context is that the FDA was considering revoking its 1999 claim, with the American Heart Association supporting revocation, because most individual trials showed no statistically significant reduction. Both readings are defensible: a small average effect, and an inconsistent one. Worth knowing when weighing these studies: Mark Messina, an author on the hormone, muscle and cholesterol meta-analyses cited here, is executive director of the Soy Nutrition Institute.

The Environmental Difference

This is where the comparison changes scale. The most comprehensive dataset remains Joseph Poore and Thomas Nemecek's analysis of around 38,700 farms in 119 countries, and expressing the results per 100g of protein makes them directly usable. Tofu produces about 1.98 kg CO₂e per 100g of protein. Poultry produces 5.7, farmed fish 5.98, and beef around 25 on average, with beef from dedicated herds far higher than beef from dairy herds. Peas manage about 0.44.

Land tells the same story more starkly: 2.2 m² per 100g of protein for tofu against 164 m² for beef, with pork using roughly five times and poultry three times tofu's land. For beef and lamb, even low-impact production remains substantially above high-impact tofu: the highest-footprint tofu producers emit 3.5 kg CO₂e per 100g of protein, against 9 for the lowest-footprint beef and 12 for lamb. The distributions for tofu and chicken come closer to overlapping, with the best chicken at 2.4. These are global averages across varied farming systems, but the ordering is consistent.

But Isn't Soy Destroying the Amazon?

Soy has a real environmental problem, and 2026 has made it worse rather than better. The Amazon Soy Moratorium, under which traders covering about 90% of Amazon soy refused to buy from land cleared after 2008, collapsed this year: Brazil's competition regulator ordered it suspended from 1 January, the main trade association announced its members' withdrawal on 5 January, and by July no company remained a signatory. Research linked to WWF-Brazil estimates the collapse could mean 1.4 million additional hectares of deforestation over the next decade, equivalent to 745 million tonnes of carbon.

What is misleading is turning that into an argument against tofu specifically. More than three-quarters of global soy, around 77%, is fed to livestock, with 37% going to poultry alone and just 2% to beef and dairy. Only about 7% of global soy becomes food eaten directly, such as tofu, tempeh, edamame and soy milk. The soy footprint hidden in Western diets mostly arrives as meat, not as tofu. That does not give tofu a free pass, since sourcing still matters and the collapse of the moratorium makes traceability harder, but eating soy directly uses far fewer agricultural resources than feeding it to animals first.

Where Pulses Beat Tofu

If we are trying to crown tofu, pulses are an awkward competitor. Lentils, beans and peas have extraordinarily small footprints, with peas producing roughly a fifth of tofu's emissions for the same protein. They also provide something tofu has relatively little of: fibre, along with resistant starch and a range of micronutrients. They are cheap, keep for months and have strong evidence behind their place in healthy diets.

Their weakness is protein density and quality. You need to eat considerably more cooked lentils or beans to match the protein in a portion of firm tofu or chicken, and their amino acid profile is less favourable, as the DIAAS gap between soy and pea protein shows. That creates a real trade-off rather than a winner: pulses may be the stronger environmental whole food, while tofu is the more useful direct substitute for animal protein.

What About Processing?

Tofu is a processed food. Soybeans are soaked, ground and cooked, and the resulting soy milk is coagulated and pressed into blocks. That tells us very little on its own, because "processed" covers everything from frozen peas to confectionery. What matters is what the processing does and what ends up in the final product, and traditional tofu remains recognisably a soybean product with a short ingredient list. That is a different proposition from assuming every plant-based burger or protein bar shares tofu's nutritional profile because its protein started as soy.

What This Actually Means

There is no defensible league table with tofu at number one. For maximum high-quality protein in minimum volume, lean meat, fish and dairy proteins are stronger. For the smallest environmental footprint, pulses beat tofu. For omega-3s, oily fish offers what tofu cannot, and for B12, tofu needs help from elsewhere in the diet.

But change the question to which everyday food delivers substantial high-quality protein, a broadly favourable health profile and relatively little environmental damage per gram of protein, and tofu becomes hard to beat. Its real advantage is that choosing it requires little compromise: protein quality much closer to animal foods than most people assume, with most of the environmental advantage of eating plants. That combination may matter more than winning any single category.

Frequently Asked Questions

Is tofu a complete protein?

Yes. Soy contains all nine essential amino acids, and tofu scores 97 on the DIAAS scale, close to animal proteins at roughly 108 to 117 and well above most other plant foods.

Is tofu as good as chicken for building muscle?

Chicken is more protein-dense and provides more leucine per gram. But training studies have found similar gains in lean mass and strength from soy and animal protein when total protein intake is adequate.

Does tofu lower testosterone?

There is no good evidence that it does. A meta-analysis of 38 clinical studies found no effect on male hormone levels, and a 2025 dose-response analysis found no relationship between isoflavone dose and testosterone. That newer analysis did find oestradiol rising at intakes above roughly 72 mg of isoflavones a day, which is higher than typical dietary intake, on a small number of trials.

Is tofu bad for the environment because soy causes deforestation?

Soy expansion does drive deforestation, and the Amazon Soy Moratorium collapsed in 2026, so sourcing matters more than before. But around 77% of global soy is fed to livestock and only about 7% is eaten directly as food, so most soy-linked deforestation in Western diets arrives through meat.

Is tofu healthier than beans?

Neither needs to win. Beans and lentils provide more fibre and a smaller footprint; tofu provides denser, higher-quality protein. Eating both is better than choosing.

The Bottom Line

Tofu is not unequivocally the best source of protein. It lacks the protein density of chicken, the leucine concentration of whey, the omega-3s of oily fish and the fibre and minimal footprint of pulses. But very few foods perform well across so many criteria at once.

Tofu provides substantial complete protein at a DIAAS of 97, is low in saturated fat, can supply useful iron and calcium, has no convincing evidence behind the testosterone fears attached to soy, and carries a fraction of the greenhouse-gas and land footprint of most animal proteins. If "best" means the highest protein number, tofu loses. If it means the strongest compromise between human nutrition and planetary cost, the case is considerably stronger. The best protein pattern probably isn't built around a single winner at all, and tofu deserves a larger place in the mix than its reputation as a meat substitute suggests.

This article is for general information and does not replace individual medical or nutritional advice.