Best Whey Isolate Protein Powder (2026): Transparent Labs
By Erin Rose Updated October 5, 2026 Methodology
Buy Transparent Labs Whey Protein Isolate. It is on two testing lists and uses only stevia, for $1.93 per 25 g of protein. Budget pick: Myprotein Impact, $1.69.
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Our pick
Transparent Labs
- Cost
- $1.93 per 25 g protein
- Testing
- NSF Certified for Sport + Informed Choice
We checked 13 vanilla whey isolates sold on Amazon. 10 of 13 are on a testing list, and 6 are on one that screens for drugs banned in sport. See the ranking.
The best whey isolates on Amazon, ranked
We rank on three things, in this order: a testing list for the tub you buy, the price of 25 g of protein, and what else is in the scoop. Every tub here is a vanilla flavor, so the prices and sweeteners compare fairly.
| Whey isolate | Testing list | Protein | Per 25 g |
|---|---|---|---|
 1. Transparent Labs French Vanilla, 30 servings. Stevia. | NSF Certified for Sport French Vanilla, 1,029 g tub, listing 1809884Informed Choice line: Whey Protein Isolate | 28 g | $1.93 |
 2. Myprotein Impact Vanilla Ice Cream, 65 servings. Sucralose, acesulfame K, stevia, sugar. | Informed Choice line: Impact Whey Isolate (USA) | 25 g | $1.69 |
 3. NOW Sports Vanilla, 1.8 lb. Xylitol, stevia. | Informed Sport line: NOW Sports Whey Protein Isolate | 25 g | $1.82 |
 4. ON Gold Standard 100% Isolate Rich Vanilla, 44 servings. Sucralose. | Informed Choice line: ON Gold Standard Isolate | 25 g | $1.98 |
 5. Dymatize ISO100 Gourmet Vanilla, 3 lb. Sucralose, stevia. | Informed Choice line: ISO100 Hydrolyzed Protein Powder (USA) | 25 g | $2.06 |
 6. Kaged Vanilla, 41 servings. Stevia, sucralose. Adds a protease enzyme blend. | Informed Sport line: KAGED Whey Protein Isolate | 25 g | $2.07 |
 7. Legion Whey+ French Vanilla, 30 servings. Stevia. | NSF/ANSI 173 Whey+ Grass-Fed Whey Isolate French Vanilla | 22 g | $2.23 |
 8. BPN Vanilla, 25 servings. Stevia (Reb M). Adds MCT powder. | NSF Certified for Sport Vanilla, 790 g tub, listing 1778885 | 25 g | $2.60 |
- Transparent Labs ($1.93) is our pick. It is the only one on two lists for the exact tub Amazon sells, has the most protein a scoop (28 g), and uses only stevia.
- Myprotein Impact ($1.69) is the cheapest isolate on a testing list. Informed Choice lists it. It uses three sweeteners plus a little sugar. Its Amazon listing is new (September 2026) and has no reviews yet.
- NOW Sports ($1.82) is the cheapest on a list that tests every batch, Informed Sport. Amazon sells only the 1.8 lb tub today; the 5 and 10 lb tubs had no seller price.
- ON Gold Standard 100% Isolate ($1.98) and Dymatize ISO100 ($2.06) are both on Informed Choice. Both use sucralose. ISO100's 5 lb vanilla tub had no seller price on Amazon, so we priced the 3 lb.
- Kaged is on Informed Sport. Legion Whey+ is on NSF/ANSI 173, which checks the label, not banned drugs. BPN is NSF Certified for Sport but costs more per gram.
Proof for our two picks
NSF Certified for Sport: Transparent Labs
Informed Choice: Myprotein
Why Transparent Labs is our pick
It passes the strictest check for the tub you get. NSF Certified for Sport tests each listed lot for drugs banned in sport and checks that the label is accurate. NSF lists each flavor and size on its own, and its French Vanilla listing names the 1,029 g tub, which is the 30-serving tub on Amazon. Informed Choice also lists the product line.
It has the most protein a scoop of the isolates we ranked: 28 g in a 34.3 g scoop. Price per gram still matters more than scoop size, and at $1.93 per 25 g it sits mid-pack.
It keeps the extras short. The ingredients are whey isolate, natural flavors, stevia, salt and sunflower lecithin.
Why not the cheapest? Myprotein saves about $7.26 a month at one scoop a day. If that matters more than a second testing list and the sweeteners, buy Myprotein. Both are on a list.
What the labels say
Per scoop, Transparent Labs has 28 g of protein and 130 calories. Myprotein has 25 g and 110 calories. Both list whey protein isolate first.
| Transparent Labs | Myprotein Impact | |
|---|---|---|
| Scoop | 34.3 g | 31 g |
| Protein | 28 g | 25 g |
| Calories | 130 | 110 |
| Carbs | 1 g | 3 g |
| Sugar | 1 g | 1 g |
| Fat | 0.5 g | 0 g |
| Sodium | 180 mg | 110 mg |
| Sweeteners | Stevia | Sucralose, acesulfame K, stevia, sugar |
Also checked: tested but pricier, and not on a list
Two more are on NSF Certified for Sport but cost more and hold less protein a scoop. Three are on no testing list we searched, so we do not link them.
| Whey isolate | Testing list | Protein | Per 25 g |
|---|---|---|---|
| Thorne Vanilla, 30 servings. Cane sugar, stevia. | NSF Certified for SportNSF/ANSI 173 | 21 g | $2.58 |
| Klean Isolate Natural Vanilla, 20 servings. Stevia, monk fruit. | NSF Certified for SportNSF/ANSI 173 | 20 g | $4.03 |
| Nutricost Vanilla, 2 lb. Sucralose. | No list found | 30 g | $1.77 |
| Isopure Zero Carb Creamy Vanilla, 3 lb. Sucralose. Adds L-glutamine and a vitamin blend. | No list found | 25 g | $2.04 |
| Naked Whey Isolate Vanilla, 24 servings. Stevia (Reb M). | No list found | 30 g | $2.60 |
Isopure's Low Carb line is on Informed Choice, but its Zero Carb line is not, and the vanilla Isopure tubs we found on Amazon are Zero Carb. Naked's entry on Informed Choice is Naked Whey, its concentrate, not the isolate.
Which whey isolate is best for weight loss?
None of them burns fat. If you are counting calories, compare calories per scoop for the protein you get. ON Gold Standard 100% Isolate has 100 calories and 1 g of carbs for 25 g of protein. ISO100 has 110 calories and 2 g of carbs. Myprotein has 110 calories and 3 g of carbs. Transparent Labs has 130 calories and 1 g of carbs, for 28 g of protein.
All whey isolate is low in lactose. Typical isolate is 0.5 to 1% lactose and typical concentrate is 4 to 8%, according to the U.S. Dairy Export Council's spec sheets. Low is not zero, so it is not safe for a milk allergy.
Who should buy which
- You want the best whey isolateTransparent Labs
NSF Certified for Sport for this tub, on Informed Choice, stevia only. $1.93 per 25 g. Check price.
- You want the lowest price with a testing listMyprotein Impact Whey Isolate
On Informed Choice. $1.69 per 25 g in the 65-serving pouch. Check price.
- You are drug-tested and want to spend lessNOW Sports Whey Protein Isolate
On Informed Sport, which tests every batch. No artificial sweeteners. $1.82 per 25 g. Check price.
- You want the fewest calories a scoopON Gold Standard 100% Isolate
100 calories for 25 g of protein. On Informed Choice. $1.98 per 25 g. Check price.
Not set on isolate? Best protein powder, all types. Head to head: Transparent Labs vs Optimum Nutrition, Isopure vs Optimum Nutrition, Isopure vs Dymatize ISO100 and Optimum Nutrition vs Dymatize ISO100. Every list and lot: third-party tested protein powder.
Questions
What is the best whey isolate protein powder?
Transparent Labs Grass-Fed Whey Protein Isolate. It is the only isolate we found on two testing lists for the exact tub sold on Amazon: NSF Certified for Sport lists the French Vanilla 30-serving tub, and Informed Choice lists the product line. It has 28 g of protein a scoop, is sweetened only with stevia, and costs $1.93 per 25 g of protein.
What is the cheapest third-party tested whey isolate?
Myprotein Impact Whey Isolate, at $1.69 per 25 g of protein in the 65-serving pouch. Informed Choice lists Impact Whey Isolate (USA). It uses sucralose, acesulfame potassium, stevia and a little sugar. If you want a list that tests every batch, NOW Sports Whey Protein Isolate is on Informed Sport for $1.82 per 25 g.
Which whey isolate is best for weight loss?
No protein powder causes weight loss. If you are counting calories, compare calories per scoop. ON Gold Standard 100% Isolate has 100 calories and 1 g of carbs for 25 g of protein. Myprotein Impact has 110 calories and 3 g of carbs for 25 g. Transparent Labs has 130 calories and 1 g of carbs, but more protein: 28 g.
Is whey isolate better than regular whey?
It has less lactose and less fat, and it costs more. Whey isolate is typically 0.5 to 1% lactose, against 4 to 8% for whey concentrate (U.S. Dairy Export Council spec sheets). ON Gold Standard 100% Whey, a blend of isolate and concentrate, costs $1.45 per 25 g of protein on Amazon. The all-isolate version costs $1.98. For muscle, the total protein you eat in a day matters more than the type.
Which whey isolates are NSF Certified for Sport?
Of the 13 isolates we checked, Transparent Labs, BPN, Thorne and Klean Isolate are on NSF Certified for Sport. NSF lists each flavor and tub size on its own. We checked that each listing names the vanilla flavor and the size Amazon sells.
Do any whey isolates add amino acids to the protein?
We read the ingredient list of all 13. None lists glycine or taurine, two amino acids sometimes added to pad a protein count. Isopure Zero Carb lists added L-glutamine and a vitamin blend. Kaged adds a protease enzyme blend. NSF Certified for Sport and NSF/ANSI 173 both check that a product matches its label.
Sources
- Amazon listings, Nutrition Facts images and ingredient lists, read October 5, 2026: Transparent Labs B0CQ3JTR6F, Myprotein B0HHL8HQ4G, NOW Sports B0013P1HVC, ON Gold Standard 100% Isolate B07MMQNXTK, Dymatize ISO100 B00HJR6SNK, Kaged B07DLGPYHN, Legion B00KWL6GNW, BPN B0GV5YHK19, Thorne B0797B27FW, Klean B074XDDRRK, Nutricost B01HOPJ3OC, Isopure B000E95HP0, Naked B0FJHYZZXP.
- NIH Dietary Supplement Label Database: Dymatize ISO100 Gourmet Vanilla 3 lb, label 302413; ON Gold Standard 100% Isolate Rich Vanilla, label 331939.
- NSF Certified for Sport listings, read October 5, 2026: Transparent Labs 1809884, BPN 1778885, Thorne 1513728, Klean 1121764; brand searches for the others.
- Other testing lists, searched October 5, 2026: NSF/ANSI 173; Informed Choice (October 2026); Informed Sport; USP Verified.
- Myprotein: Impact Whey Isolate ingredients by flavor, read October 5, 2026.
- U.S. Dairy Export Council spec sheets: Whey Protein Isolate and Whey Protein Concentrate 80% (typical lactose), read October 5, 2026.