Complete protein
A complete protein is a food source that supplies all nine essential amino acids in proportions adequate for human needs; eggs, dairy, meat, fish and soy qualify, while most single plant sources fall short in one.
"Complete" is a useful label that has been turned into a scare word. It describes the amino acid profile of a single food, not whether a diet works.
What qualifies
Eggs, milk, curd, paneer, meat, fish and soy — including tofu and soya chunks — supply all nine essential amino acids in adequate proportions. Quinoa and buckwheat are the usual plant exceptions people cite, and both are genuinely good, though neither is necessary.
What being incomplete actually costs
Very little, in practice, at normal intakes. A food limited in lysine simply contributes less usable protein per gram than its label suggests. The fix is not exotic: eat more total protein, and eat it from more than one source. A day containing dal, roti, curd and some nuts is not amino-acid deficient in any meaningful sense.
Where it does start to matter
Two situations. First, a very low total protein intake, where a poor profile compounds an already small number. Second, an all-plant diet at high training volumes, where hitting 1.6 g per kilogram from cereals and vegetables alone is difficult; adding soy, dairy if eaten, or a plant protein blend solves it.
For everyone else, the practical rule is: total protein first, variety second, completeness of any single food a distant third.
Sources
- 1.Protein and amino acid requirements in human nutrition (WHO Technical Report 935) — WHO, FAO and UNU
- 2.FoodData Central — USDA Agricultural Research Service
Related reading
- Vegetarian protein worth the calories it costs
Ranked by calories per gram of protein, not by grams per 100 g. Which vegetarian sources are efficient, which are not, and how to build a 130 g day.
- Paneer or tofu: the protein comparison in full
Tofu gives similar protein for half the calories; paneer gives more calcium and better taste to most palates. The full comparison, with the numbers.
- Protein in dal, chana, rajma and the rest
A katori of dal is 7 to 9 g of protein. Useful, and less than its reputation. What each pulse supplies, and where legumes fit in a protein target.
- What macros are, and which ones are worth counting
Protein, carbohydrate, fat and alcohol, what each supplies, and why calories plus protein is the two-number system most people should actually use.