What to check before buying
Before the three criteria, the thing the category will never tell you: whole
food beats powder by default. Greek yoghurt, eggs, tinned fish, cottage
cheese, chicken, lentils and tofu all deliver protein along with the
micronutrients, fibre and chewing that a scoop of isolate does not. Powder is a
convenience product for the gaps — the morning you are running out the door,
the post-training window when you are not hungry, the day your appetite is
simply too small to reach your target. Buy it as a gap-filler and it works.
Buy it as a diet strategy and it usually replaces something better.
With that established, three things.
Cost per 25 grams of protein. Not cost per tub, not cost per serving.
Scoop sizes range from 28 g to well over 40 g and protein per scoop from 20 g
to 30 g, so “servings” is a manufacturer-defined unit and comparing on it is
comparing nothing. Divide the price by the total protein in the container, then
multiply by 25. Once you do, the premium tub that looked expensive sometimes
isn’t, and the plant blend with the large scoop usually is.
Third-party testing, specifically for heavy metals. Protein powders
concentrate whatever was in the source material, and independent testing
programs have repeatedly found lead, cadmium, and arsenic in retail powders —
consistently higher in plant proteins than in whey, because plants draw metals
up from soil, and higher in cocoa-flavoured products than vanilla. This is the
strongest single argument for paying more for a certified product, and it
applies most to exactly the plant-based powders bought by people trying to eat
more carefully. NSF Certified for Sport, Informed Choice, and Clean Label
Project are the marks worth looking for.
Protein quality, which in practice means leucine. Leucine is the amino
acid that triggers muscle protein synthesis, and roughly 2.5–3 g in a single
serving is the amount associated with a maximal response. Whey is about 11
percent leucine, so a 25 g serving clears the bar easily. Pea and rice blends
run nearer 8 percent, which is why a plant serving is often 30–35 g rather
than 25 — the blend is fine, it just needs to be bigger, and the cost
comparison should be made at the size that actually does the job. Casein is a
complete protein that digests slowly, which makes it a reasonable evening
option and a poor post-training one. Collagen, sold everywhere as protein, is
not a muscle protein: it lacks tryptophan and is low in leucine, and it should
not be counted toward your target.
How we evaluated
We compared widely available protein powders on cost per 25 g of protein,
protein as a percentage of scoop weight, leucine density, third-party
certification with heavy-metal coverage, ingredient transparency, and the
mundane practicalities — whether it dissolves in cold water in a shaker, and
whether the flavour is one you will still be drinking in month three.
We have not lab-tested these products. We did not run amino acid profiles,
we did not test for heavy metals, and no sample was sent to a laboratory. Our
assessment is based on supplement facts panels, published certifications,
existing independent testing programs, and user reports. Where a product’s
testing is the manufacturer’s own internal program rather than an outside
certifier, that appears in the cons rather than being quietly rounded up.
Ratings follow the methodology on our How We Test Products page. Some links
earn us commission. Commissions never affect ranking or inclusion, and the
opening paragraph of this guide — telling you food is better — is the clearest
evidence we can offer that the incentive is not driving the copy.
What the evidence supports — and where it stops
Adequate protein combined with resistance training has been shown to help
adults over 40 preserve lean mass and strength, and the combination is
considerably more effective than either alone. Intakes in the range of roughly
1.2 to 1.6 g per kg of body weight per day are where most of the supporting
evidence sits for active adults in this age group — above the minimum
requirement, which was set to prevent deficiency rather than to optimise
anything.
Research suggests that per-meal distribution matters more after 40 than it did
before. Older muscle shows a blunted response to a given dose of protein —
often called anabolic resistance — which is why the per-meal amounts studied in
this population tend to run 30 to 40 g rather than the 20 g that suffices in
younger adults. Spreading protein across three or four meals appears to beat
loading it into dinner, though the effect size in trials is smaller than the
enthusiasm around it.
Where it stops is important. Powder is a delivery vehicle, not an
intervention: no trial has shown that protein from a scoop outperforms the same
protein from food. Protein supplementation without resistance training produces
very little in the way of muscle or strength. And in people already meeting
their target, adding more protein has not been shown to add benefit — the
dose-response curve flattens. The full grading is in the evidence review linked
below.
FAQ
Whey or plant — does it actually matter? Less than the marketing implies.
Whey is more leucine-dense per gram, so it does the job in a smaller serving,
and head-to-head trials favour it modestly. A well-formulated pea-and-rice
blend at a slightly larger serving closes most of the gap. Choose on
tolerance, ethics, and heavy-metal certification rather than on a small
difference in amino acid arithmetic.
Is casein before bed worth it? It is a reasonable habit, not a
breakthrough. Casein digests slowly and pre-sleep protein has been studied with
mildly positive results, but the effect is small and it is doing the same job
that hitting your daily target with any protein does. If you like it and it
helps you reach the target, use it.
Do I need more than one scoop a day? Most people do not. Powder should be
covering the gap between what you ate and what you were aiming for, and for
most readers that gap is one serving on some days and zero on others. If you
are using three scoops a day, the problem is the diet underneath, not the
supplement on top of it.