The arithmetic of protein for a real household, an honest verdict on greens powders, and the nutrient almost every kitchen is short of.
~13 min read
Two things are genuinely missing from most kitchens, and they are missing in different ways. One is a shortfall of quantity, the other of variety. Treat them as one problem and you will solve neither.
Protein is the quantity problem. Almost every household eats some at every meal; what is short is the total, and its shape across the day. Which makes it countable: weigh the food, add the grams, compare the sum against a figure that depends on the person.
Vegetables are the variety problem. A household can hit any reasonable weight target on potato, carrot, onion and tinned tomato and still be narrow, because what makes plants worth eating is not spread evenly among them. Pigment classes sit in different plants, the sulphur compounds are particular to the brassicas, and the fibres different organisms ferment are not interchangeable.
Protein — measured in grams
A total to reach, spread across the day. Fixable by arithmetic: find the figure, count what you eat, close the difference.
Vegetables — measured in kinds
A range to widen — not fixable by eating more of what is already on the plate, because the missing compounds are in the plants that are not.
Fibre — short in both senses
Under-supplied in quantity and narrow in kind at once, and almost nobody counts it.
Each gap has a product sold against it, and the two behave differently. One can genuinely close its gap, because a gram of protein from a scoop is a gram of protein. The other cannot. What the body needs sets out the categories; what follows is the arithmetic.
Protein is filed in most people’s heads next to energy, beside carbohydrate and fat. That is the least of what it does. A body burns protein when it must, and the rest of the time it is building with it — because almost everything you are made of, apart from water, bone mineral and stored fat, is protein.
Structure
Collagen is the most abundant protein in a body — roughly a third of the total — and the scaffold of skin, tendon, ligament and the organic framework of bone. Keratin is hair and nail; elastin is what lets a lung spring back.
Enzymes and transport
Every reaction in you is run by a protein catalyst specific to that one reaction. Haemoglobin carries oxygen, transferrin carries iron.
Defence and movement
An antibody is a protein made to a specification written on demand; the immune system manufactures proteins at speed. Actin and myosin sliding past one another is contraction, in the muscles and in the heart.
None of it is permanent. An adult dismantles and rebuilds somewhere near 250 to 300 grams of protein a day, far more than anyone eats, because most amino acids are recovered from tissue taken apart. And there is no depot: fat has adipose tissue, carbohydrate has glycogen, protein has a small free pool and nothing else. When intake falls short the body takes apart something that was doing a job.
Diagram to come
Two loops side by side in the same visual grammar, so the absence of a store is visible rather than stated. Left, fat: an arrow in from diet, a large clearly-drawn storage tank, an arrow out to use. Right, protein: an arrow in from diet, a deliberately tiny pool, and NO tank — instead a large circular recycling loop between working tissue and the pool, drawn much thicker than the dietary arrow so the reader sees that most amino acids are recovered rather than eaten. A small arrow leaves the protein loop permanently, marked as daily loss. A dotted arrow runs from working tissue back into the pool, drawn only on the protein side, marked as what happens when intake falls short.
Protein is the only macronutrient containing nitrogen, at close to 16% by weight, which gives a way to measure it. Convert everything a person eats and everything they excrete to nitrogen, and subtract. More in than out is positive balance — net tissue laid down, as in growth or recovery. Equal is equilibrium, where a healthy adult ought to sit. Less in than out means tissue is being disassembled faster than it is replaced.
Balance can go negative on any day because the loop is not perfectly closed: some amino acids are irreversibly oxidised, some nitrogen leaves as urea from the liver, some goes in shed skin and hair. Those losses run whether or not you eat, which is why the requirement is daily — and why one very large serving cannot carry a whole day, since the rise in synthesis after a meal is limited in size and duration and the surplus is oxidised rather than banked.
The reference figure is grams of protein per kilogram of body weight per day, and depending on the authority it lands between 0.75 and 0.83, commonly rounded to 0.8. Almost everything said about protein in public goes wrong at this figure, because of what people assume it is.
It came from nitrogen balance work in healthy young adults and answers one question: the least intake at which a healthy adult does not lose tissue, with a margin so it covers nearly everyone. That is a floor. No authority publishes a figure for the intake at which a person does best, because there is no agreed method for calculating one.
A floor is not a target
Reading 0.8 g/kg as a goal is the commonest error in this subject. It is the bottom of the range, not the middle. Most published work on adults who are ageing, training, recovering or eating mainly plants points to a working intake between 1.0 and 1.6 g/kg — above the floor, and reachable from food in almost every case.
Four things move the figure, all in the same direction. Age: from around sixty-five the muscle response to a given amount of protein is blunted, and consensus sits nearer 1.0 to 1.2 g/kg. Resistance training: the evidence converges around 1.4 to 1.6 g/kg, with little further benefit above roughly 2.0. Recovery from illness, surgery or injury raises requirements, and belongs with the practitioner managing it. Pregnancy and nursing raise them too — territory for a midwife, doctor or dietitian, and nothing here substitutes for that conversation.
Two worked examples. An adult of 68 kilograms, moderately active, not lifting: the floor is 68 × 0.8, or 54 grams, and a working figure at 1.2 g/kg is 82 grams — around 27 grams at each of three meals. An adult of 82 kilograms who lifts three times a week and is fifty-eight: at 1.6 g/kg the figure is 131 grams, which across four feedings is 33 grams each. Around 25 to 30 grams in a sitting produces most of the response a typical adult gets from one meal, so that fourth feeding is a real one, and it is the one that has to be deliberately added.
| Food | A realistic serving | Protein |
|---|---|---|
| Chicken breast, cooked | 100 g | ≈31 g |
| Tinned tuna, drained | 100 g | ≈25 g |
| Salmon fillet, cooked | 100 g | ≈23 g |
| Cooked lentils | 200 g, a bowl of soup | ≈18 g |
| Chickpeas, tinned and drained | 240 g, one tin | ≈18 g |
| Greek yoghurt | One 170 g pot | ≈16 g |
| Firm tofu | 100 g | ≈15 g |
| Eggs | Two large | ≈12 g |
| Milk | 250 ml | ≈8 g |
| Wholemeal bread | Two slices | ≈7 g |
| Rolled oats | 50 g dry | ≈6 g |
| Almonds | 30 g, a small handful | ≈6 g |
Count for one week and you will not need to count again; the point is to calibrate the eye. A supplement supplements: it does not replace food, and nothing here replaces professional medical care.
Nine of the twenty amino acids cannot be built by a human body and must arrive in food: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Every conversation about protein quality is a conversation about those nine.
A protein is complete when it contains all nine in proportions meeting human requirement, in a form the gut can take up. Eggs, dairy, meat and fish are complete; so are soy and quinoa. Most other single plant foods are not — and not because an amino acid is missing, but because one of the nine sits in too small a proportion relative to the rest. That one is the limiting amino acid: the body builds protein until the scarcest part runs out, then oxidises the remainder.
The pattern is worth memorising. Grains and most cereals are short on lysine; legumes are short on methionine, and nuts and seeds follow the legume pattern. Which is why the traditional pairings of almost every cuisine are a grain and a legume: rice and dal, beans and maize, hummus and flatbread. Nobody designed those from a table.
Then the idea was overstated. A widely read book of 1971 argued that plant proteins had to be combined within the same meal to be usable, and its own author withdrew the strict version in the 1981 edition. The free pool of amino acids, and hundreds of grams of your own protein turning over daily, buffer supply across many hours. What survives is the plainer statement — eat a range of protein sources across a day. The essential amino acids entry holds the nine.
PDCAAS — the Protein Digestibility-Corrected Amino Acid Score — takes the limiting amino acid’s ratio to the human requirement pattern and multiplies it by how much of the protein is digested. Two known faults: digestibility is measured from what comes out at the far end, after the colon’s organisms have altered the nitrogen, and the score is truncated at 1.00, so a protein exceeding requirement in every amino acid scores the same as one that just meets it. DIAAS fixes both, measuring at the end of the small intestine and scoring every amino acid rather than only the limiting one.
Directionally: animal proteins and dairy isolates score near or above 1.0, soy in the high 0.8s to 0.9s, pea protein somewhat below, wheat lowest of the common sources. Both scores compare single ingredients — a blend chosen so one protein supplies what another lacks beats any of its parts, which is what a bowl of rice and dal was already doing.
A plant protein powder is the most food-like thing on a supplement shelf. It is not a concentrate of one active compound; it is ground plant material with most of the water removed, so that what remains is mostly protein by weight.
What TerraMix carries, at the ingredient level, is four things. The nine essential amino acids, which are the reason the product exists. The branched-chain amino acids — a subset of those nine rather than an addition, named separately because they are metabolised in muscle rather than passing through the liver first. Oleic acid, present because the plant sources carry their own fat. And prebiotic fibre, which organisms in the large intestine ferment.
A plant blend reaches completeness the way a kitchen does — by pairing. Any single plant protein is held back by one of the nine, so a formulation is built from more than one source. Which plants, and how much protein per serving, are printed on the pack you own; formulations are revised and are not identical in every market.
Now the honest part. A powder is a convenience, not an upgrade on real food. A scoop and a chicken breast deliver the same nine amino acids to the same bloodstream, and the chicken breast — or the bowl of lentils — arrives with iron, zinc, B vitamins and a reason to sit down. What a powder has is speed, portability and a predictable number, which solves one shape of problem: the gap between training and the next real meal, the travel day with no kitchen. There, the alternative is no protein at all.
It loses the other comparison just as easily: topping up a day that already reaches its figure from food, it is expensive food. Work out your figure, count a week, see whether a gap exists. If not, the money belongs in the vegetable aisle.
A greens powder is a concentrated supply of some plant compounds. That sentence is true, and it is the whole of the claim. It is not a substitute for vegetables, and the reason is what got left behind in the drying room.
Three things make vegetables work and a powder carries only one. Fibre, by mass: a day of vegetables delivers ten grams or more where a scoop delivers one or two. Volume: the bulk that fills a stomach and requires chewing, which a drink bypasses by design. And variety across time: a week of real vegetables rotates through dozens of plants, and that rotation feeds a wide range of organisms in the colon. A powder is the same blend every day.
What a scoop is not
It is not five portions of vegetables in a glass, whatever the front of the tub says. The compounds that survive drying are there; the fibre, the volume and the variety are not — and those are the parts most households are short of. A powder that displaces vegetables leaves a kitchen worse off than before it arrived.
What TerraGreens carries, at the ingredient level, is vitamin C — required for collagen formation, for taking up iron from plant foods and for normal immune function — and potassium. Its two named botanicals are acerola cherry, among the most concentrated natural sources of vitamin C there is, and wolfberry, which carries carotenoid pigments including zeaxanthin.
Who it genuinely helps is narrower than the marketing suggests, and real. Someone whose vegetable intake is close to zero and who is not going to change that this month — a scoop beats nothing. Someone travelling for a fortnight with no kitchen. A person whose appetite is returning, for whom a glass is achievable and a plate is not. In each, the powder is a bridge across a bad stretch rather than a fixture. Use it beside food, never instead of it.
Photograph to come
An honest scale comparison, shot from directly above on a plain worn wooden surface in daylight. Left: a single levelled scoop of green powder in a small white dish — small, and not flattered by the framing. Right, laid out loose and uncomposed, what a day of plants actually looks like: a head of broccoli, a handful of spinach, half a red cabbage, two carrots, a red pepper, a bowl of cooked lentils, a pear, a pile of mixed berries, an onion, a clove of garlic. No props, no branding, no dramatic lighting, nothing styled as a product shot. Both sides must be shot at the same distance so the difference in bulk is the picture rather than an implication of it.
Removing water concentrates whatever survives and destroys the rest. Minerals are elements and cannot be destroyed, so potassium, magnesium and iron survive drying completely — a dried plant is more mineral-dense than a fresh one purely because the water left. Fibre survives too, but milling changes how it behaves: cell walls that would have reached the colon as recognisable structure arrive as fine particles, fermented faster and doing much less of the bulking work. The losses fall among the delicate molecules. Vitamin C is heat-sensitive and readily oxidised, which is why a blend making a vitamin C statement generally includes a source as concentrated as acerola, and the volatile aromatics simply leave — which is why dried herbs smell different from fresh. So a scoop is a good delivery system for minerals and stable pigments, a mediocre one for delicate vitamins, and a poor one for fibre, because there is so little material in a scoop to begin with.
Fibre is plant carbohydrate no human enzyme can break. It passes through much as it arrived, which is exactly why it works: everything fibre does, it does by being present rather than by being absorbed. The useful split is between two behaviours, and most real foods carry some of each.
Soluble and viscous
Pectin in apples and citrus pith, beta-glucan in oats, inulin in chicory and onion. It dissolves into a gel, and a gel does mechanical work: it slows the stomach emptying and slows the rate at which glucose from the same meal reaches the blood.
Insoluble and bulking
Cellulose, hemicellulose and lignin — wheat bran, vegetable skins, nuts. It holds water, adds bulk and shortens transit time.
Fermentable
Cutting across both: the fraction organisms in the colon can eat, broken down into short-chain fatty acids. Digestive support follows that chemistry down.
The figure is 25 to 30 grams a day, and guidelines across countries converge on it. Typical intake runs at about half, which makes fibre the most reliably under-supplied nutrient in an ordinary kitchen.
Here is a day that reaches it. Fifty grams of porridge oats, about 5 grams. A pear eaten with its skin, another 5. Two slices of wholemeal bread, 5. A bowl of lentil soup made with 200 grams of cooked lentils, 8. Eighty grams of broccoli beside dinner, 2. A handful of almonds, 4. That is 29 grams with no supplement and no unusual purchase. Fibre accumulates, four or five grams at a time.
Two cautions. Increase it over two or three weeks rather than in a day, because the population that ferments it takes time to adjust. And drink more water as you do: the bulking fraction works by holding water, and without enough, more fibre makes transit slower rather than easier.
Diagram to come
A cross-section of gut contents split into two halves so the mechanical difference is visible rather than described. Left half, soluble: food particles suspended in a visibly thickened gel, an arrow showing slowed movement, and a small inset showing glucose leaving the gel gradually rather than in a rush. Right half, insoluble: recognisable plant fragments — skins, bran flakes, stalk fibres — holding water droplets, drawn as a bulkier mass, with a wider faster arrow for shortened transit. Underneath both halves, one shared band showing the fermentable fraction reaching the colon with bacteria working on it, so the reader sees this third property cuts across the first two rather than being a third substance.
All of it collapses into one practical question, and the answer differs by household. Pick the one that describes yours.
Which of these is closest to you?
Each answer is a shape for the day rather than a list of things to buy. The shape is the part that matters.
Behind all four answers is the same ranking. Food first, because it carries everything else. Then variety, because it is the one lever that reaches the part of you fibre feeds. Then, only where a counted gap remains, a product to close it. Anything persistent or worrying about appetite or digestion belongs with a healthcare practitioner. Building your stack is where everything from this course is assembled.
Supplements are intended to complement a varied diet, not to replace food, and nothing here replaces professional medical care. Keep supplements out of reach of children, and keep oils away from eyes and inner ears. If you are pregnant, nursing, under medical care or taking medication, speak to your healthcare practitioner before use. Nothing here is intended to diagnose, treat, cure or prevent any disease.
Two products, one nutrient, and a habit of counting that transfers to the rest of the shelf.
Lesson 9 of 12 · Nutrition