Optimum Nutrition Gold Standard vs Dymatize ISO100 (2026): Which to Buy

 

Gold Standard

10.0/10

Cost

$1.86 per 25 g protein

Testing

Informed Choice

Check price

 

ISO100

Not scored

Cost

Dymatize publishes no price

Testing

Informed Choice

Check price

Is it the same protein?

Close. Both scoops have 120 calories and about the same protein: 24 g in Gold Standard and 25 g in ISO100. The real difference is the kind of whey. ISO100 uses only whey isolate, part of it hydrolyzed (pre-broken into smaller pieces). Gold Standard is a blend of isolate, concentrate and whey peptides.

The protein share is about the same: 78% of ISO100’s scoop is protein and 77% of Gold Standard’s, so ISO100 is a point higher. Being all isolate shows up elsewhere: 0.5 g less fat, 25 mg less cholesterol and 1 g fewer carbs a scoop. In the other direction, ISO100 has more than three times as much sodium in chocolate, 180 mg against 55 mg, so if you watch your sodium, Gold Standard is the better fit.

For muscle, neither label gives a reason to expect a different result if you get the same protein. Dymatize sells its hydrolyzed whey as faster to absorb. That is the brand’s claim, and our advice does not rest on it. How much you need a day: protein dosage guide.

Who checks each tub, and for what

Both powders are on Informed Choice. It screens shop-bought products for banned substances, at least monthly. Informed Choice lists the product line, not a tub size or flavor: Gold Standard as “ON Gold Standard 100% Whey” and ISO100 as “ISO100 Hydrolyzed Protein Powder (USA)”.

ISO100 was not on NSF Certified for Sport when we searched. Gold Standard’s two NSF Certified for Sport listings cover only the 10 lb tubs, not the 5 lb tub compared here. If your sport requires NSF, see which Gold Standard tubs and flavors NSF lists.

Both powders on the Informed Choice list

Gold Standard on Informed Choice

ISO100 on Informed Choice

What the labels say

Both labels list milk and soy, and neither says how much lactose is in the tub. Only Gold Standard adds lactase, the enzyme that breaks down lactose (milk sugar); only ISO100’s label says “Gluten free” and “Contains a bioengineered food ingredient”.

See both labels

Gold Standard’s image is the label NSF keeps, from a 10 lb tub; the per-scoop table uses the 5 lb tub’s figures.

If lactose bothers you, look at the kind of whey. Whey isolate has much less lactose than whey concentrate. Typical isolate is about 0.5 to 1% lactose, and typical 80% concentrate is about 4 to 8%, according to the U.S. Dairy Export Council’s spec sheets (isolate, concentrate). Those are typical values, not the amount in these tubs. Whey is a milk protein, so neither powder is lactose-free or safe for a milk allergy.

The price test: compare the two 5 lb tubs

The two 5 lb tubs hold the same protein, so their prices compare directly. Gold Standard holds 1,776 g (74 scoops, 24 g of protein each) and ISO100 holds 1,775 g (71 scoops, 25 g each).

Optimum Nutrition lists the 5.05 lb tub at $131.99 on its own store (October 1, 2026). That is $1.86 per 25 g of protein. Dymatize publishes no price; it sells ISO100 only through other stores. Same tub size, same protein: buy whichever 5 lb tub costs less where you shop. Smaller Gold Standard tubs cost more per gram: the 0.68 lb tub works out to $2.76 per 25 g.

Stores set their own prices. To check a tub you see, use the grams above and our cost per 25 g check, which also lists every protein powder we price.

Who should buy which

• You want the most protein for your moneyThe cheaper 5 lb tub

  Both hold the same protein, so the tub price decides.

• Lactose bothers you, or you want less fat and cholesterolISO100

  All its protein is isolate, which typically has less lactose than concentrate. It also has less fat and cholesterol a scoop.

• You want Optimum Nutrition’s own all-isolate powderOptimum Nutrition 100% Isolate

  $2.35 per 25 g of protein at list price (3 lb tub).

• You are drug-testedEither

  Check that your sport accepts the list each one is on. The testing section covers both, including NSF.

• You already have a tub, or you would rather get protein from mealsBuy nothing

  Finish the tub you have; switching changes the price, not the result. Powder is a convenient option, not a requirement; food can cover your protein (ISSN 2017).

More protein guides: Ascent vs Gold Standard, Ghost Whey vs Gold Standard and all protein guides.

Sources

1. Labels: Gold Standard 100% Whey, Double Rich Chocolate, from the 5 lb tub’s label, with the image NSF keeps with its Certified for Sport listing (10 lb tub); and the NIH Dietary Supplement Label Database record (ISO100, Gourmet Chocolate).
2. Testing: Informed Choice certified products (both powders) and NSF Certified for Sport (Gold Standard). Searched August 25, 2026 to September 22, 2026.
3. Prices: optimumnutrition.com, list price for every size, checked October 1, 2026. Dymatize sells no tubs on dymatize.com. We print no Amazon prices; Amazon is only where the buy links go.
4. U.S. Dairy Export Council spec sheets: Whey Protein Isolate and Whey Protein Concentrate 80% (typical lactose content).
5. Jäger R, et al. International Society of Sports Nutrition position stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20. PubMed 28642676