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I've used concentrate and isolate interchangeably for years and the leucine number per scoop is the only spec that actually matters to me. Anything past 2g leucine per serving clears the threshold; everything else is flavour preference and digestion.
After 40, the conversation around protein shifts. Sarcopenia, the progressive loss of muscle mass that begins in your mid-thirties, accelerates quietly. Resistance training slows it. Adequate dietary protein slows it further ā I've gone into the per-kilogram numbers in detail in my piece on how much protein men over 40 actually need. But the quality and quantity of protein you consume per meal, not just per day, determines how effectively you stimulate muscle protein synthesis (MPS). This is where protein supplementation earns its place for men who train seriously.
This guide covers the physiology you need to understand, the three UK protein powders worth buying in 2026, and the common mistakes that undermine results.
Quick Verdict
For most men, MyProtein Impact Whey remains the best value option on the UK market. At roughly Ā£10 to Ā£13 per kilogram depending on flavour and promotion, it delivers a solid amino acid profile, roughly 21g of protein per serving, and decent leucine content. If you train three or more times per week and want to increase total daily protein without spending serious money, Impact Whey is where to start.
The Leucine Threshold: Why 20g Is Not Always Enough
The mechanism behind protein's muscle-building effect is now well established. When dietary amino acids, particularly leucine, reach a threshold concentration in the blood, they activate the mTOR (mechanistic target of rapamycin) signalling pathway in skeletal muscle, triggering MPS. Below that threshold, the signal is weak. Above it, MPS is maximised.
Drummond and Rasmussen, writing in the Journal of Nutrition in 2008, identified that approximately 2.0g of leucine per meal is required to maximally stimulate this mTOR-mediated MPS response. Standard whey concentrate delivers roughly 2.0 to 2.5g of leucine per 25g serving, which is why a single scoop typically produces a meaningful anabolic response. Underdosing, say 10 to 15g of protein, keeps you below this threshold regardless of overall daily intake.
Equally important is the distribution of protein across the day. A study by Areta and colleagues, published in Nutrients in 2013, found that total 24-hour protein intake matters more than the precise timing window around training. Spreading 150g to 180g of protein across four to six meals, each exceeding the leucine threshold, is more effective for MPS than front-loading protein in two large feeds. This has practical implications: a protein shake is not just a post-workout ritual; it is a convenient way to hit the leucine threshold at meals where whole food protein is impractical. If you train in a gym setting and need a more focused breakdown of post-workout options, see my best gym protein UK guide.
Isolate vs Concentrate: Does the Difference Matter?
The primary distinction between whey concentrate and whey isolate is protein density and lactose content. If you are choosing between dairy and plant sources rather than between whey grades, my whey vs plant protein comparison for men over 40 covers the leucine maths. Concentrate typically provides 70 to 80% protein by weight; isolate delivers 90% or more. Moore and colleagues, in a 2014 paper in the Journal of Applied Physiology, found that whey isolate produced a marginally superior MPS response compared to concentrate, likely attributable to faster digestion and a more rapid rise in plasma amino acids.
In practice, the difference is modest for most men. If you are lactose intolerant or experience digestive discomfort with concentrate, isolate is worth the premium. If your digestion handles concentrate without issue and you are managing supplement costs across a 12-week training block, concentrate delivers sufficient MPS stimulus at meaningfully lower cost per gram. The leucine threshold is what matters most; both forms cross it at standard serving sizes. Stack whey with creatine for men over 40 and you have the two highest-evidence training supplements covered.
1. MyProtein Impact Whey Protein
MyProtein Impact Whey is the most purchased protein powder in the UK for a straightforward reason: it consistently delivers a solid amino acid profile at the lowest price point of any reputable brand.
- Price: approximately Ā£10 to Ā£13 per kg (frequent promotions reduce this further)
- Form: whey concentrate
- Protein per serving: 21g (25g scoop)
- Cost per serving: roughly 60 to 80p
Flavour range is extensive. Chocolate Smooth and Unflavoured both mix well. Leucine content sits at approximately 2.1g per serving, clearing the threshold identified in the Drummond and Rasmussen research. The ingredient list is clean, with no proprietary blends or unnecessary fillers. For men looking to add one to two shakes daily alongside a whole-food diet, this is the rational choice.
2. Bulk Pure Whey Protein
Bulk Pure Whey Protein occupies a slightly different position: a straightforward, unfussy product from a brand that has built its reputation on transparency. Bulk publishes full amino acid profiles, which is more than many competitors do.
- Price: approximately Ā£12 to Ā£15 per kg
- Form: whey concentrate
- Protein per serving: 22g (30g scoop)
- Cost per serving: approximately 75p to Ā£1.00
The higher serving size gives a marginal advantage in leucine delivery per shake. Bulk's sourcing is European, which will matter to some buyers. The unflavoured version is particularly useful for mixing into porridge or smoothies without altering taste. If MyProtein is ever out of stock or a specific flavour matters, Bulk Pure Whey is an equally evidence-sound alternative.
3. Optimum Nutrition Gold Standard Whey
Optimum Nutrition Gold Standard has been the benchmark protein powder globally for over two decades. Unlike the concentrate options above, Gold Standard uses a blend of whey isolate as the primary protein source alongside concentrate and hydrolysed whey.
- Price: approximately Ā£18 to Ā£22 per kg via Amazon UK
- Form: whey isolate and concentrate blend
- Protein per serving: 24g (30g scoop)
- Cost per serving: approximately Ā£1.10 to Ā£1.40
The isolate-first formulation means faster digestion and a quicker amino acid peak, consistent with the Moore et al. findings on isolate's MPS advantage. It is also widely available across supermarkets and pharmacies, which removes friction for men who do not plan ahead with bulk orders. The premium price is justified if bioavailability and convenience are priorities; it is harder to justify on budget alone when concentrate options perform similarly in practice.
Comparison Table
| Product | Form | Protein per serving | Cost per serving | Best For | |---|---|---|---|---| | MyProtein Impact Whey | Concentrate | 21g | 60ā80p | Best value, daily use | | Bulk Pure Whey | Concentrate | 22g | 75pāĀ£1.00 | Transparency, European sourcing | | ON Gold Standard | Isolate blend | 24g | Ā£1.10āĀ£1.40 | Convenience, bioavailability |
What to Avoid
The "200g protein daily" figure circulates widely in gym culture, particularly among men who conflate bodybuilding protocols with evidence-based nutrition. For a moderately active man at 85kg, the research supports 1.6 to 2.2g per kilogram of bodyweight, placing the upper functional limit at roughly 140 to 190g. Chronically exceeding this provides no additional MPS benefit and simply increases food cost and renal filtration load. Protein is one lever ā get the broader testosterone-supportive diet right and the supplement does its job rather than carrying the whole programme.
The post-workout timing window is a persistent myth. The Areta et al. research makes clear that distributing protein consistently across the day is what drives outcomes. Missing a post-workout shake by two hours does not undo your training session. What does matter is ensuring that each protein-containing meal exceeds the leucine threshold, which is where a quality whey product earns its place.
Amino acid spiking, the practice of adding cheap amino acids such as glycine or taurine to inflate a product's total protein reading, is another concern. It appears most often in budget products that advertise protein content well above what the ingredient cost could support. Products with published amino acid profiles, such as those from Bulk, are easiest to verify.
FAQ
Q: When is the best time to take protein powder? A: Whenever it helps you reach your total daily target and clear the leucine threshold across multiple meals. Post-workout timing has marginal benefit at best; consistency across the day matters more, per Areta et al. (2013).
Q: Should I buy isolate or concentrate? A: Concentrate is sufficient for most men. Isolate is worth the premium if you experience lactose intolerance or digestive discomfort, or if you prioritise the slightly faster amino acid delivery supported by Moore et al. (2014).
Q: Is plant protein as effective as whey? A: Plant proteins, particularly pea and soy blends, can match whey's MPS effect when the leucine threshold is met, but this typically requires a larger serving size because plant sources have lower leucine density per gram of protein. Whey remains more efficient per gram, which matters when managing total calorie intake.
Q: How much protein do I actually need daily? A: For men over 40 who train with weights, 1.6 to 2.2g per kilogram of bodyweight is well supported by the research. A 85kg man needs roughly 135 to 185g daily. Whole food should supply the majority; supplementation fills the gap.
Total daily protein at 1.6-2.2g/kg, spread across 4-5 meals, each clearing roughly 2g leucine. Concentrate is fine for most men; isolate only if lactose bothers you. Whey is a tool to hit the threshold conveniently, not a magic anabolic.
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