Isopure vs Gold Standard Whey: A Comprehensive Comparison

In this review, I’ll be comparing Isopure and Optimum Nutrition Gold Standard Whey across eight key criteria, including taste, mixability, nutritional value, and cost.

My goal is to help you decide which protein powder is the best fit for your fitness goals, budget, and dietary needs by providing a head-to-head comparison of these two very popular proteins.

As a former NFL/CFL athlete, I’ve tried countless protein powders, so I launched a dedicated YouTube channel to review them. I focus on protein powders because there are so many choices and a lot of misinformation out there.

Let’s get into it!

Prefer to watch than read? Watch my full reviews on YouTube:

In This Review:
Summary | Overview | Comparison | Taste | Mixability | Digestibility | Protein Density | Nutritional Value | Third Party Testing | Cost Comparison | How To Save Money | Final Thoughts

Things to Keep in Mind:

As you read this review, remember:

Isopure offers four types of whey protein:

• Zero/Low Carb (Flavored)*
• Zero Carb (Unflavored)
• Natural Flavor
• Natural Flavor Low Carb

Gold Standard offers two types:

• Gold Standard Whey*
• Naturally Sweetened Gold Standard Whey

*These are the flagship products you probably know best.

The regular versions use artificial sweeteners like Sucralose and Acesulfame Potassium, while the natural options use Monk Fruit Extract, Stevia Leaf Extract, or Cane Sugar.

Important note: Gold Standard’s Naturally Sweetened Whey was discontinued in 2024 due to low sales. So, if you’re trying to avoid artificial sweeteners, Isopure is the better choice.

30 Second Summary:

• Taste: Isopure won the taste test, but just barely.
• Protein Purity: Isopure is a much “purer” protein than Gold Standard Whey, reaching up to 100% purity in some cases.
• Isolate vs. Blend: Isopure is made entirely of whey isolate, while Gold Standard is a blend of isolate, concentrate, and hydrolyzed whey protein.
• Cost: Gold Standard Whey is more cost-effective than Isopure, both in Cost Per Serving and Price Per Gram of Protein.
• Flavor Variety: Gold Standard offers 20 different flavors, while Isopure has only 7.
• Calories: Isopure has fewer calories per serving (107 on average) compared to Gold Standard (125 on average).
• Carbs: Gold Standard has more carbs per serving, on average, than Isopure.
• Sugar: Most Isopure products contain no added sugar, unlike Gold Standard Whey.
• Sodium: Isopure has significantly more sodium per serving (240mg) than Gold Standard (55mg).
• Parent Company: Both Isopure and Gold Standard are owned by Glanbia. This is why their return policies, marketing materials, and websites are similar.

The main difference between Isopure and Gold Standard is that Isopure is pure whey isolate, contains more vitamins and minerals, and offers some natural flavors, whereas Gold Standard now only offers artificial sweeteners.

Had a blast testing these!

A Quick Look: Isopure vs Gold Standard

Note: Label specs will vary depending on the flavor you choose.

Head-to-Head Comparison:

Here’s how I rated Isopure vs Gold Standard across 8 categories. To learn more about our testing process, see here.

Note: The Naturally Sweetened Gold Standard flavor was discontinued in 2024 due to low sales.

We’ll update this review once we’ve had a chance to review the original (artificially sweetened) product.

Which One Tastes Better?

In my humble opinion, Isopure tastes better. I tried both Chocolate and Vanilla flavors of Isopure and Gold Standard and Isopure won in both cases.

However, it’s worth noting that I was comparing the Naturally Sweetened Gold Standard Whey, not the artificially flavored one, which might taste better. Also, Gold Standard comes in 20 different flavors, so you’ve got plenty of options.

If you’re okay with the extra calories, you could try adding milk, fruit, or peanut butter to your shake to improve the taste.

Shortly after mixing

Which One Mixes Better?

Both products mixed easily and went down smoothly, with no digestive issues.

Note: I used a shaker bottle and shaker ball to mix these proteins. For even better results, you could try using a fork, hand mixer, or blender.

No clumps and minimal foam

Which One is Higher Purity?

Both products are among the densest whey proteins on the market. In other words, most of their calories come from protein as opposed to other ingredients.

That said, Isopure is a higher-purity protein across the board, regardless of flavor or sweetener type, because it’s 100% whey protein isolate, whereas Gold Standard is a blend of concentrate, isolate, and hydrolyzed whey.

When I asked Gold Standard to break down their blend, they replied, “The exact formula is proprietary. However, the ingredients are listed in predominance (from greatest to least).”

Here’s a complete breakdown of protein density across all the options:

Note: To calculate protein density, we multiply protein per serving by 4 ( because 1 g of protein = 4 calories) and then divide by total number of calories.

So if you’re looking to minimize your calories while maximizing your protein intake and don’t mind paying a premium for it, Isopure is your best bet.

Isopure Zero/Low Carb is the purest option out there, but it tastes worse cause there’s less sugar.

What’s the difference between concentrate, isolate, and hydrolyzed whey?

Whey concentrate is the least processed form of whey protein¹, containing more fat, carbs, and lactose.

Whey isolate is purer, with most fat and carbs removed, while hydrolyzed whey is isolate broken into smaller protein pieces. Isolate and hydrolyzed whey are generally absorbed faster than concentrate.

Which One is More Nutritious?

Vitamins and Minerals

Isopure offers more vitamins and minerals, including Vitamin B12, Biotin, and Chromium. These nutrients help boost energy², support muscle recovery, and maintain healthy blood sugar levels³.

Lactose and Sweeteners

Isopure offers naturally sweetened flavors, while Gold Standard used to—but they discontinued it due to low sales.

Isopure is lactose-free, whereas Gold Standard contains a small amount of lactose since it’s a blend of concentrate, isolate, and hydrolyzed whey, rather than pure isolate like Isopure.

That said, the lactose in Gold Standard is minimal and likely won’t be an issue unless you’re highly lactose intolerant.

Which to Choose?

If you want to keep calories low, use natural sweeteners, or avoid lactose completely, Isopure is your best option.

If you prefer a higher-calorie shake that doubles as a meal replacement or need a budget-friendly option and don’t mind artificial sweeteners, go with Gold Standard.

A lot more vitamins and minerals in Isopure

Which One is More Trustworthy?

Gold Standard has the Informed Choice label, which tests for banned substances, and they’re also approved by ConsumerLab.com, which verifies label claims.

Isopure doesn’t do any third-party testing. This doesn’t mean they’re being dishonest, but it’s not the best look. It’s like saying you make the best burger in town and not letting a food critic try it. Wouldn’t that burger taste better with expert approval?

Important note: Both Isopure and Gold Standard are owned by Glanbia. So even though Isopure doesn’t third party test, it’s good to know their parent company isn’t opposed to it.

Which One Costs More?

Isopure is a higher purity product and therefore costs more. So if price is your main concern, Gold Standard is the clear winner.

Here’s a complete breakdown of Price Per Serving and Price Per Gram of Protein across all products:

Note: Prices change based on when and where you buy the product, and the size of the tub.

How To Save Money:

There are three ways to save money on Isopure and Gold Standard products:

1. Sign up for their newsletters to save 15% on your first order.
2. Follow them on Facebook, Twitter, and Instagram for occasional discount codes
3. Buy a product and leave a review, and once approved, they’ll send you a discount code.

Check price on Amazon: Isopure Whey, Gold Standard Whey

Check price on the website: Isopure Whey, Gold Standard Whey

Final Thoughts: Which is Best for You?

Ultimately, it comes down to your 1) fitness goals, 2) budget, and 3) dietary restrictions.

Isopure is best if you want a higher-quality protein powder that is lactose-free and uses natural sweeteners, though it costs more.

Gold Standard is a better choice if you’re looking for an affordable option and don’t mind a bit of lactose and artificial sweeteners.

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If you still have questions about these two proteins, hit me up on YouTube or Instagram and I’ll do my best to clarify.

Thanks for stopping by! 🙏🏾

References

1. Morr, C., & Ha, E. (1993). Whey protein concentrates and isolates: processing and functional properties.. Critical reviews in food science and nutrition, 33 6, 431-76 . https://doi.org/10.1080/10408399309527643.

2. Lee, M., Hsu, Y., Shen, S., Ho, C., & Huang, C. (2023). A functional evaluation of anti-fatigue and exercise performance improvement following vitamin B complex supplementation in healthy humans, a randomized double-blind trial. International Journal of Medical Sciences, 20, 1272 – 1281. https://doi.org/10.7150/ijms.86738.

3. Asbaghi, O., Fatemeh, N., Mahnaz, R., Ehsan, G., Elham, E., Behzad, N., Damoon, A., & Amirmansour, A. (2020). Effects of chromium supplementation on glycemic control in patients with type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials.. Pharmacological research, 105098 . https://doi.org/10.1016/j.phrs.2020.105098.