MyProtein vs Optimum Nutrition: Which Protein Powder Wins in the UK?
By Rendict Staff · Updated August 14, 2026 · 5 min read
| Product | |||
|---|---|---|---|
 Optimum Nutrition Gold Standard 100% Whey | 4.6 | GBP 34.95 | Check price |
| MyProtein Impact Whey | 4.5 | GBP 55.00 | Check price |
Choose MyProtein Impact Whey if…
price is your primary consideration and you're willing to monitor for Impact Week sales and discount codes to secure the best value per gram of protein.
Choose Optimum Nutrition Gold Standard 100% Whey if…
you want the most consistently trusted, most widely reviewed protein in the UK with stable pricing, reliable flavour quality, and Informed Sport certification across the range.
Supplement disclaimer: This article compares two protein powders on factual, measurable criteria. It is not medical or nutritional advice. Always consult a qualified healthcare professional or registered dietitian before making significant dietary changes.
Spec Comparison
| MyProtein Impact Whey | Optimum Nutrition Gold Standard 100% Whey | |
|---|---|---|
| Protein per 100g | ~72g | ~77g |
| Cost per 25g protein (typical) | ~36p on sale / ~72p at full RRP | ~44p–60p depending on retailer and size |
| Protein per scoop (serving) | ~21g | 24g |
| Leucine per serving | Not specifically reported | 5.5g (supports muscle protein synthesis) |
| Amazon UK rating | High | 4.6/5 from 55,000+ reviews |
| Informed Sport certified | Some batches | Yes |
| Flavour consistency | Variable batch-to-batch | Consistent |
| Pricing model | Sale-dependent — significant discount code required for best value | Stable across retailers |
The Price Comparison Requires Honest Context
MyProtein Impact Whey drops to roughly 36p per 25g of protein on Impact Week — among the cheapest cost-per-protein figures of any UK whey. At full RRP it is around £55 per 2.5kg bag, which puts it level with Bulk and behind premium picks like Optimum Nutrition Gold Standard.
This is the critical detail most casual comparisons miss: MyProtein's value case depends entirely on not paying the full RRP. Never buy MyProtein without a discount code — the "full" price is not a realistic reference point. Across 90 days of price tracking, MyProtein Impact Whey's price varied by 47 percent depending on whether an Impact Week code was active. Optimum Nutrition, by contrast, holds more consistent pricing across retailers with less dramatic swing between "normal" and "sale" price.
Protein Quality: Optimum Nutrition Leads
Optimum Nutrition Gold Standard delivers 24g of protein and 5.5g leucine per scoop. Leucine specifically is the amino acid most directly associated with triggering muscle protein synthesis — Gold Standard's 5.5g per scoop is a meaningful figure that MyProtein's Impact Whey doesn't specifically highlight. Both products are whey concentrate/isolate blends; the protein quality from both is good, but ON's Gold Standard is more specifically engineered for post-training muscle protein synthesis, while Impact Whey is a broader-use concentrate optimised primarily for low cost per gram.
Flavour Consistency
Frequent flavour reformulations affect MyProtein's taste consistency review-to-review — a flavour that scores well in one batch may taste different six months later. Optimum Nutrition Gold Standard is cited consistently across years of reviews for reliable, predictable flavour quality. This is a real practical consideration: if you find a flavour you like in MyProtein, the next bag might taste noticeably different. With ON, it generally won't.
Informed Sport Certification
Optimum Nutrition Gold Standard carries Informed Sport certification across the range, meaning each production batch is tested against the World Anti-Doping Agency (WADA) prohibited substances list. MyProtein has some certified products but not all Impact Whey batches. For competitive athletes subject to doping regulations, Informed Sport certification is a genuine requirement, not just a marketing signal — for recreational gym users, it's a trust-in-ingredient-testing signal but not a functionally necessary feature.
The Real Decision
MyProtein on a code wins by about 30 percent per 25g of protein against Optimum Nutrition at standard pricing. That's a genuine, real cost saving if you're willing to time your purchases around MyProtein's near-constant sale cycles and keep a discount code ready. If you are leaving MyProtein purely on price, Bulk is the swap to make — it is the closest match on cost per gram and quality, with more consistent pricing than MyProtein.
If you're not interested in sale-timing your nutrition purchases, Optimum Nutrition is the cleaner choice — the most-reviewed protein in the UK, consistent flavour, Informed Sport certified, and available through Amazon Prime at stable pricing.
Which One Fits Your Actual Buying Habits
This decision comes down less to the powder itself and more to how you actually shop. If you're the kind of buyer who's genuinely willing to wait for a code, set a price alert, or stock up during Impact Week specifically because you know the discount is coming, MyProtein's savings are real and repeatable over a year of purchases. If you'd rather order once, know the price won't swing wildly between bags, and not think about it again until the tub runs out, that convenience has a real value too — and it's exactly what Optimum Nutrition's stable pricing and consistent flavour profile are built around delivering.
Our Verdict
On raw price-per-gram-of-protein during a sale, MyProtein wins. For consistent quality, trust, and the most widely validated option in the UK market, Optimum Nutrition Gold Standard is the recommended pick — particularly for buyers who don't want to monitor discount codes or time purchases around sale events.
For the full UK whey protein category, see our Best Protein Powders UK 2026 guide.
Frequently asked questions
During Impact Week and payday code drops, when the discount reaches 40–50% off — that's when the value case is genuinely strongest. At full RRP, other brands offer comparable or better value without requiring active discount-hunting.