Appendix

The numbers

Everything the rest of the site computes from, in one place. Click any column heading to sort.

Composition table

Nutrition figures are per 100 g edible portion. “Cooked” is mature seeds boiled in water, drained, no salt added. Rows marked est are literature midpoints rather than a single measured record.

A.1 — Production

What the world actually grows

FAOSTAT primary-crop tonnages for 2022. Note the scale break: soybeans alone outweigh every pulse on earth combined, roughly four times over — but almost all of that goes to oil and animal feed rather than to people.

World production by crop

million tonnes

Dry beans — top producers

million tonnes

India grows almost a quarter of the world's dry beans and still imports them. Brazil and Myanmar follow. The United States is a large producer and a small consumer; Rwanda is the reverse.

Dry bean consumption per person

kg per year

Rwanda and Burundi eat roughly nine times as many beans per head as the United States and twenty times as many as China. In parts of the Great Lakes region beans supply more than a quarter of all dietary protein.

A.2 — Footprint

The cost of a hundred grams of protein

Global medians from Poore & Nemecek's 2018 meta-analysis of 38,700 farms in 119 countries — still the widest like-for-like comparison available. Switch the metric to see how differently the three resources rank.

Greenhouse gas

125×Emissions per 100 g of protein from beef against the same protein from peas

48×Land per 100 g of protein, beef against peas

~1.9kg CO₂eEmitted per kilogram of synthetic nitrogen manufactured — the fertiliser a nodulating legume does not need

The comparison is not entirely fair to livestock, which can graze land that grows nothing edible, and not entirely fair to legumes either, which are usually compared on protein alone rather than on the full nutrient profile. The ratios are large enough that neither caveat changes the ranking.

A.3 — Method

Where each figure comes from

Nutrition

Per 100 g edible portion, from USDA FoodData Central (SR Legacy and Foundation Foods). “Cooked” means mature seeds boiled in water, drained, without added salt. Where a species has no USDA record — tepary, moth bean, rice bean, jack bean, bambara groundnut, hyacinth bean, grass pea — the entry carries a literature midpoint and is flagged est everywhere it appears.

Amino acids and protein scoring

Amino-acid figures are milligrams per gram of protein, computed from USDA per-100 g amino-acid records divided by the protein in the same record. Scores are the ratio against the WHO/FAO/UNU 2007 requirement pattern for adults: His 15, Ile 30, Leu 59, Lys 45, Met+Cys 22, Phe+Tyr 38, Thr 23, Trp 6, Val 39 mg/g. Scores here are uncorrected for digestibility, so they sit above the PDCAAS figures usually quoted.

Energy

Listed energy is the USDA value. The breakdown chart uses Atwater general factors — protein and available carbohydrate at 4 kcal/g, fat at 9 — plus a 2 kcal/g credit for dietary fibre, representing short-chain fatty acids absorbed after colonic fermentation. Because the fibre term is not in the USDA figure, the breakdown total exceeds the listed energy, which is the point of showing it.

Oligosaccharides, phytate, tannin

Literature midpoints in g per 100 g dry seed. These vary by a third or more with cultivar, growing season and analytical method, and are not part of the USDA tables. Every one is flagged est.

Cooking model

Baseline boiling times are for soaked seed at a full boil at sea level. Altitude adjusts the boiling point through the standard atmosphere and the Antoine equation; time then scales as a first-order rate with Q₁₀ = 2.5, which is the range reported for legume texture. Factor multipliers are mid-range effects from the pectin literature rather than measurements of any particular pot.

Gas estimate

Cooked mass converts to dry mass through each species' water-absorption ratio; oligosaccharide content is the midpoint above; preparation multipliers are mid-range values from soaking and processing studies; complete colonic fermentation is taken at 350 mL of gas per gram of fermentable carbohydrate, the middle of the reported 300–400 mL range. Individual variation is larger than every one of those terms.

Production and consumption

FAOSTAT primary-crop production, 2022, rounded to the nearest 0.1 Mt. Per-capita figures are apparent consumption from food-balance sheets — supply divided by population, so they include waste and are systematically higher than what people actually eat.

Environmental footprint

Poore, J. & Nemecek, T. (2018). "Reducing food's environmental impacts through producers and consumers." Science 360(6392):987–992. Global medians per 100 g of protein, covering production through retail. Freshwater withdrawals are weighted for local scarcity in the original and are shown here unweighted.

Taxonomy and genomes

Subfamily classification follows the Legume Phylogeny Working Group (2017), Taxon 66(1):44–77. The common bean reference genome is Schmutz, J. et al. (2014), "A reference genome for common bean and genome-wide analysis of dual domestications," Nature Genetics 46:707–713.

What this site is not

Not medical or dietary advice, and not a food-safety authority. The preparation hazards described are real and well documented, but if you are cooking an unfamiliar legume — particularly lupin, grass pea, jack bean or lima beans from an unlabelled source — check a current food-safety source for your region rather than relying on a web page.