Which protein helps build muscle and may extend your lifespan?

Protein isn’t just protein. While gym-goers often focus on rapid muscle gain, many people are asking a different question: which protein sources also support a longer, healthier life? Recent findings from nutrition and ageing research point in a clear direction - with a few surprising nuances.

What researchers mean by “the best” protein

There isn’t a single number that defines “best” protein. Three factors matter most: a complete amino-acid profile, strong digestibility, and enough leucine to trigger muscle protein synthesis. These are assessed using measures such as PDCAAS or the newer DIAAS. Animal proteins often score highly because they deliver all essential amino acids in favourable amounts. Plant proteins are catching up - particularly when combined thoughtfully.

"Without enough leucine per meal, the kick-start for building new muscle is slow to arrive - roughly 2 to 3 grams is considered a practical target."

Portioning matters as well. Instead of one large protein hit in the evening, spreading intake more evenly across the day tends to work better. And as we age, we generally need a bit more protein per kilogram of body weight because muscles respond less readily to stimuli.

How much protein per day - and how should you spread it out?

• Healthy adults: around 0.8–1.2 g of protein per kilogram of body weight.
• Sport and muscle gain: 1.6–2.2 g/kg, depending on training volume and energy balance.
• Older adults: 1.0–1.2 g/kg, aiming for 25–40 g of protein per meal.
• Leucine target: roughly 2–3 g per meal (e.g. 25–30 g of high-quality protein).

A practical day might look like this: breakfast 25–30 g (e.g. Skyr with oats and nuts), lunch 30–40 g (a lentil bowl with quinoa and tofu), snack 20–25 g (a protein shake or cottage cheese with berries), dinner 25–35 g (salmon with potatoes and broccoli). If you eat fully plant-based, pair pulses with grains and, if needed, top up with soy or pea protein.

Muscle: which protein sources provide the strongest stimulus?

Whey, milk, yoghurt and eggs

Whey protein acts quickly, is rich in leucine, and fits well first thing in the morning or straight after training. Greek yoghurt, quark and Skyr are filling and provide “slower” proteins such as casein - a useful choice in the evening. Eggs offer a very balanced profile; two to three eggs already provide a meaningful share of the leucine threshold.

Fish and lean meat

Fish supplies high-quality protein alongside beneficial omega‑3 fatty acids, which can support recovery and inflammatory balance. Lean poultry and beef can be powerful for muscle, but for long-term health they’re best kept in sensible portions and prepared without heavy processing or charring.

Plant-based options: soy, peas, lupin & combinations

Soy protein is one of the few plant-based “complete proteins”. Pea and lupin protein offer solid values, but on their own they less often reach the leucine threshold. When you combine pulses with grains (for example beans with rice, lentils with wholewheat pasta), amino-acid gaps are largely closed. Plant-based protein drinks that blend pea, rice and soy can work well too.

Food (portion)	Protein	Leucine (≈)	Quality (DIAAS/PDCAAS, rough)	Longevity assessment
Whey, 25 g protein	25 g	2.7 g	very high	neutral to good (unprocessed, functional)
Greek yoghurt, 200 g	18–20 g	1.8–2.0 g	high	good (fermented, filling)
Eggs, 2	12–14 g	1.1–1.3 g	high	neutral (amount and context matter)
Salmon, 150 g	30 g	2.7–3.0 g	high	very good (plus omega‑3)
Chicken breast, 150 g	32 g	2.8–3.2 g	high	good if moderate and gently cooked
Tofu, 200 g	24 g	1.9–2.2 g	medium to high (soy)	good (plant-based, versatile)
Lentils cooked, 250 g	18–20 g	1.5–1.8 g	medium	very good, especially when combined

Note: values are rounded and vary by product.

Protein sources for longevity: quality beats quantity - up to a point

Observational studies suggest that replacing part of animal protein with plant sources is associated with a lower risk of death overall. Processed red meat stands out as particularly unfavourable. Fish, fermented dairy, and pulses tend to perform better. Possible reasons range from inflammation markers and gut microbiome effects to accompanying nutrients such as fibre, potassium and plant bioactives.

Even so, older adults shouldn’t eat too little protein “out of fear of mTOR”. Sarcopenia - age-related muscle loss - is a genuine risk factor for falls, loss of independence, and hospital admissions. Many older people benefit from 1.0–1.2 g of protein per kilogram of body weight per day, spread across 2–4 meals, ideally alongside regular strength training.

"For lifespan, it’s not only how much protein is on the plate - but the package it comes in: unprocessed, plant-forward, with fish and fermented milk."

Degree of processing and cooking method make a difference

Highly processed meats (such as many sausages and cured products) are linked in numerous analyses to a higher risk of illness. Better choices include fresh ingredients, short ingredient lists, and gentler cooking methods such as steaming, stewing or baking. If you barbecue, marinading with herbs, oil and lemon juice can help reduce unwanted compounds by limiting burning.

Upgrading plant protein: how to make it work day to day

• Build duos: beans + rice, hummus + wholegrain flatbread, peanuts + soy, lentils + spelt.
• Use leucine boosters: soy, peas, peanuts and chickpeas are relatively leucine-rich.
• Include fermentation: tempeh, miso, yoghurt alternatives with added protein.
• Watch timing: after training, have a protein-rich meal or a shake.

Common questions - briefly explained

Does a high-protein diet strain the kidneys?

In healthy people, large analyses do not show kidney damage from a protein-rich diet. If you already have kidney disease, you need personalised medical guidance. Drink enough fluids and have blood markers checked - especially with long-term higher intakes.

Is collagen a good muscle-building protein?

Collagen contains few essential amino acids and very little leucine. It may be useful for tendons and skin, but on its own it’s not suitable for building muscle. Pair it with a leucine-rich protein.

What role does the gut microbiome play?

Plant proteins come with fibre and plant bioactives that feed the gut microbiome. That can reduce inflammation and, in turn, indirectly support a healthier healthspan.

What you can actually put on your plate

If you want to build muscle and stay fit for longer, three pillars work well: plenty of plant protein from pulses, nuts and wholegrains; fish two to three times per week; and fermented dairy daily - or suitable plant-based alternatives with added protein and calcium. Keep red meat occasional and processed meats as rare as possible.

Two details often make the real difference. First, the overall package: a lentil stew brings protein, fibre, potassium and polyphenols - which is very different from a protein bar heavy in sugar alcohols. Second, the training pairing: without a stimulus, there’s no adaptation. Two to three strength sessions per week make the protein you eat far more effective in the body.