# Isopure Protein Powder Review

> Isopure protein powder from the label: Zero Carb, Low Carb, Unflavored and Clear compared on protein, calories, sweeteners, testing and cost per 25 g.

- **URL**: https://www.best-proteinpowder.com/isopure-protein-powder-review/
- **Updated**: 2026-11-02
- **Author**: [Best Protein Powder Editorial Team](https://www.best-proteinpowder.com/authors/editorial-team/)
- **Publisher**: [Best Protein Powder](https://www.best-proteinpowder.com/)

---

Zero Carb, Low Carb, Unflavored and Clear, read off the label: what each Isopure tub gives you per scoop, what the vitamin blend adds, and whether the isolate premium is worth it for you.

**How we rank:** We judge every powder on the label, not the marketing: protein per scoop, cost per 25 g of protein, the full ingredient list and third-party testing. No paid placements, and commission never sets a ranking. [Read our methodology](https://www.best-proteinpowder.com/how-we-test/)

Isopure does one thing and does it cleanly: whey protein isolate, with almost nothing else in the scoop. The flagship Zero Carb gives about 25 g of protein for roughly 100 calories and zero carbohydrate per the label, which is about as lean as protein powder gets. It is an excellent choice for strict low-carb diets and calorie counting. Its weak spots are a sucralose-sweetened flavored range, an added vitamin blend you may not want, and no banned-substance certification we could confirm.

## Our Top Picks

| Award | Product | Why |
| --- | --- | --- |
| Flagship Pick | [Isopure Zero Carb Protein Powder](https://www.best-proteinpowder.com/isopure-protein-powder-review/#isopure-zero-carb) | The best Isopure for cutting and keto, as long as you are not drug tested. |
| Best Classic Flavors | [Isopure Low Carb Protein Powder](https://www.best-proteinpowder.com/isopure-protein-powder-review/#isopure-low-carb) | Pick Low Carb over Zero Carb if you want chocolate or peanut butter that tastes like a shake. |
| Best Clean Label | [Isopure Zero Carb Unflavored Protein Powder](https://www.best-proteinpowder.com/isopure-protein-powder-review/#isopure-zero-carb-unflavored) | The best Isopure for smoothie makers, bakers and anyone who wants nothing but isolate. |
| Best Juice-Style | [Isopure Clear Whey Isolate Protein Powder](https://www.best-proteinpowder.com/isopure-protein-powder-review/#isopure-infusions) | Worth it if milky shakes put you off; otherwise Zero Carb is better value. |
| Alternative: NSF Certified | [Thorne Whey Protein Isolate](https://www.best-proteinpowder.com/isopure-protein-powder-review/#thorne-whey-protein-isolate) | The isolate to buy instead of Isopure if you are drug tested. |

## 1. The Short Verdict

Isopure is worth buying if you want the most protein for the fewest calories and carbohydrates. The flagship **Zero Carb** powder gives about 25 g of protein from whey protein isolate in a single 31 g scoop for roughly 100 calories, 0 g of carbohydrate and about 0.5 g of fat, per the label at the time of writing. Almost 80% of what you scoop is protein. Few flavored powders on the shelf beat that.

It is less convincing if you care about sweeteners or certification. The flavored Zero Carb and Low Carb tubs we checked use sucralose and a mix of natural and artificial flavors, and every flavored tub carries an added blend that Isopure markets as 20 vitamins and minerals. We could not confirm an NSF Certified for Sport or Informed Sport listing for any Isopure powder, so drug-tested athletes should look elsewhere.

Cost lands in the middle of the isolate market. Isopure is not a budget whey, but because each scoop is a full 25 g dose, its cost per 25 g of protein in the large tubs is competitive with other big-name isolates and lower than most boutique grass-fed isolates. It is also widely discounted on Amazon, which helps.

Our verdict: buy Zero Carb if you are on keto, cutting hard or counting every calorie, buy Unflavored if you want an isolate with nothing added, and buy Clear if you want a protein drink that tastes like juice rather than a milkshake. Skip the range if you are tested, avoid sucralose, or already take a multivitamin and do not want to double up.

> **THE ONE-LINE ANSWER**
>
> **One of the leanest flavored isolates you can buy**
>
> About 25 g of protein for roughly 100 calories and zero carbs. Choose Unflavored to avoid sucralose and added vitamins, and a certified isolate if you are drug tested.

## 2. Who Makes Isopure

Isopure began as an independent company, The Isopure Company, LLC, based in Hauppauge, New York, and built its name on pure whey isolate drinks and powders at a time when most gym proteins were concentrate blends. In 2014 the Irish nutrition group Glanbia agreed to buy it for about $153 million, adding it to the performance nutrition division that already held Optimum Nutrition.

That makes Isopure a sister brand of Optimum Nutrition, one of the best-selling wheys on Amazon. Glanbia positions Isopure as its lifestyle protein brand, and it expanded the range into the UK in 2025 with whey and collagen products. Our [Optimum Nutrition review](https://www.best-proteinpowder.com/optimum-nutrition-protein-powder-review/) covers the sister brand if you want to compare Gold Standard against Isopure directly.

Ownership by a large dairy and nutrition group matters in two ways. Glanbia is one of the world's biggest whey ingredient processors, so Isopure has reliable access to isolate at scale, which keeps prices stable. And the brand's quality claims rest on Good Manufacturing Practices and testing by its own quality assurance lab, which is standard for a big manufacturer but is not the same as an independent certification.

The range today is broader than the name suggests. Beyond the classic Zero Carb and Low Carb powders, Isopure sells an unflavored isolate, a clear whey line, naturally flavored and gut health variants, a plant-based powder, collagen, and ready-to-drink protein waters and shakes. This review focuses on the four whey powders most shoppers compare.

## 3. The Range Side by Side

Every powder here is built on whey protein isolate, so the differences come down to carbohydrate, flavor system and texture. The table uses label and retailer figures at the time of writing; carbohydrate in Low Carb varies the most by flavor, from about 1 g to 4 g per scoop.

| Powder | Protein (label) | Calories | Carbs | Sweetener |
| --- | --- | --- | --- | --- |
| Zero Carb (flavored) | About 25 g | About 100 | 0 g | Sucralose |
| Low Carb | About 25 g | About 110-120 | About 1-4 g | Sucralose |
| Zero Carb Unflavored | About 25 g | About 100 | 0 g | None |
| Clear Whey Isolate | About 20 g | About 90 | About 2 g | Stevia |

The flavored Zero Carb is the purest expression of the brand: whey isolate, the vitamin and mineral blend, soy lecithin, flavoring, salt, sucralose and potassium chloride, with about 220 mg of sodium per scoop in the vanilla salted caramel flavor we checked. That sodium figure is worth noting if you drink several scoops a day, though it is modest next to most meals.

Low Carb is the same isolate with a creamier, dessert-style flavor system. The Dutch chocolate version adds cocoa and xanthan gum, which thickens the shake and accounts for the extra carbohydrate and calories. Listings claim about 5.5 g of naturally occurring BCAAs per serving, which is in line with any 25 g dose of whey isolate.

Unflavored is the cleanest powder Isopure makes: whey isolate plus a little sunflower or soy lecithin to help it mix, with no added flavors, colors or sweeteners per the brand. Clear is a different product altogether, a thin, juice-style isolate with about 20 g of protein in a 25 g scoop, sweetened with stevia and flavored with fruit. It is covered in more depth in our [clear protein powder guide](https://www.best-proteinpowder.com/best-clear-protein-powder/).

## 4. The Isopure Powders, Ranked

We ranked the four Isopure powders most buyers choose between on protein per serving, calories, ingredient list and cost per 25 g, then added one clearly labelled alternative from another brand for readers who need an NSF Certified for Sport isolate. All figures are per the label or retailer listing at the time of writing and vary by flavor, so check the tub you buy.

### 1. Isopure Zero Carb Protein Powder

**Award:** Flagship Pick | **Type:** Whey protein isolate, zero carb

- **Protein per serving:** About 25 g (label)
- **Calories:** About 100
- **Third-party testing:** In-house QA; no sport certification
- **Best for:** Cutting, keto

Isopure's flagship gives about 25 g of protein from whey protein isolate per 31 g scoop, for roughly 100 calories, 0 g of carbohydrate and about 0.5 g of fat, per the label at the time of writing. Flavored versions are sweetened with sucralose and include a blend Isopure markets as 20 vitamins and minerals. It is one of the leanest flavored powders on the market, and the 3 lb tub keeps cost per 25 g competitive with other big-name isolates. There is no banned-substance certification we could confirm.

**Bottom line:** The best Isopure for cutting and keto, as long as you are not drug tested.

**Pros:**

- About 25 g of protein for roughly 100 calories
- Zero carbohydrate per the label
- Competitive cost per 25 g in 3 lb tubs
- Mixes thin and fast in water

**Cons:**

- Sucralose and artificial flavors in flavored versions
- Added vitamin blend may double up a multivitamin
- No NSF or Informed Sport listing confirmed

[Check price on Amazon](https://www.amazon.com/dp/B000E95HP0?tag=sktiger-20)

### 2. Isopure Low Carb Protein Powder

**Award:** Best Classic Flavors | **Type:** Whey protein isolate, low carb

- **Protein per serving:** About 25 g (label)
- **Calories:** About 110-120
- **Third-party testing:** In-house QA; no sport certification
- **Best for:** Everyday shakes

Low Carb is the same 25 g of whey isolate per scoop with a creamier flavor system: cocoa and xanthan gum in the Dutch chocolate version, which pushes calories to roughly 110 to 120 and carbohydrate to about 1 to 4 g depending on flavor. It tastes more like a traditional protein shake than Zero Carb, according to buyer feedback, and still suits nearly every low-carb diet. Flavored versions use sucralose and include the vitamin blend.

**Bottom line:** Pick Low Carb over Zero Carb if you want chocolate or peanut butter that tastes like a shake.

**Pros:**

- About 25 g of protein per scoop
- Thicker, dessert-style flavors
- Large tubs keep cost per 25 g reasonable

**Cons:**

- About 1 to 4 g of carbohydrate, so not ideal for strict keto
- Sucralose sweetened

[Check price on Amazon](https://www.amazon.com/dp/B000E8ZJGS?tag=sktiger-20)

### 3. Isopure Zero Carb Unflavored Protein Powder

**Award:** Best Clean Label | **Type:** Whey protein isolate, unflavored

- **Protein per serving:** About 25 g (listing)
- **Calories:** About 100
- **Third-party testing:** In-house QA; no sport certification
- **Best for:** Smoothies, baking

Unflavored is the cleanest powder in the range: whey protein isolate plus a little sunflower or soy lecithin, with no added flavors, colors or sweeteners per the brand. Retail listings show about 25 g of protein for roughly 100 calories and 0 g of carbohydrate per 29 g scoop. It disappears into smoothies, oatmeal, yogurt and baking, and it is the Isopure to buy if you avoid sucralose. It tastes faintly milky on its own in water.

**Bottom line:** The best Isopure for smoothie makers, bakers and anyone who wants nothing but isolate.

**Pros:**

- No sweeteners or flavorings
- About 25 g of protein for roughly 100 calories
- Easy to cook and bake with

**Cons:**

- Bland in plain water
- Usually sold in 1 lb bags, which cost more per gram

[Check price on Amazon](https://www.amazon.com/dp/B00SCO8AA8?tag=sktiger-20)

### 4. Isopure Clear Whey Isolate Protein Powder

**Award:** Best Juice-Style | **Type:** Clear whey protein isolate

- **Protein per serving:** About 20 g (listing)
- **Calories:** About 90
- **Third-party testing:** In-house QA; no sport certification
- **Best for:** Hot days, light drinks

Isopure's clear whey, sold as Infusions on older listings, mixes into a thin, translucent drink rather than a shake. It gives about 20 g of protein for roughly 90 calories and about 2 g of carbohydrate per 25 g scoop, per listings at the time of writing, sweetened with stevia and flavored with fruit. Buyers like it as a summer or post-cardio drink; common complaints are foam after shaking and a protein taste that still comes through. It costs more per gram than the classic tubs.

**Bottom line:** Worth it if milky shakes put you off; otherwise Zero Carb is better value.

**Pros:**

- Light, juice-style drink instead of a milky shake
- Stevia rather than sucralose
- About 90 calories per scoop

**Cons:**

- Only about 20 g of protein per scoop
- Foams when shaken, per buyer feedback
- Higher cost per 25 g

[Check price on Amazon](https://www.amazon.com/dp/B081ZV26B2?tag=sktiger-20)

### 5. Thorne Whey Protein Isolate

**Award:** Alternative: NSF Certified | **Type:** Whey protein isolate, NSF Certified for Sport

- **Protein per serving:** About 21 g (label)
- **Calories:** Check flavor label
- **Third-party testing:** NSF Certified for Sport
- **Best for:** Drug-tested athletes

If you like Isopure's lean isolate formula but need a banned-substance certification, Thorne is the swap. It is NSF Certified for Sport, which is why it turns up in professional and collegiate training rooms, and it gives about 21 g of protein per scoop. You pay more per 25 g and need slightly more powder per dose, but for a tested athlete the certification is the reason to buy.

**Bottom line:** The isolate to buy instead of Isopure if you are drug tested.

**Pros:**

- NSF Certified for Sport
- Short, fully disclosed formula
- Strong reputation for quality control

**Cons:**

- About 21 g of protein per scoop
- Premium cost per 25 g

[Check price on Amazon](https://www.amazon.com/dp/B07978MBRM?tag=sktiger-20&linkCode=ll1)

## 5. Zero Carb vs Low Carb

For most buyers the real decision is between the two classic tubs. Zero Carb gives about 25 g of protein, 0 g of carbohydrate and roughly 100 calories per scoop. Low Carb gives the same 25 g of protein with about 1 to 4 g of carbohydrate and roughly 110 to 120 calories, depending on flavor. The protein is identical whey isolate; the difference is entirely in the flavoring.

Choose Zero Carb if you are on a ketogenic diet, track net carbs to the gram, or want fruit and candy-style flavors. Its flavors tend to be lighter, and it mixes thin in water, which buyers often describe as more like a flavored drink than a shake. That thinness is a strength in a hot post-workout drink and a weakness if you wanted something that feels like a milkshake.

Choose Low Carb if you want chocolate, peanut butter or vanilla flavors that taste closer to a traditional protein shake. The cocoa and gum make it thicker, and the 1 to 4 g of carbohydrate is still low enough for almost any diet short of strict keto. Most people will not notice the 10 to 20 calorie difference.

Either way, both are isolates, which carry less lactose than whey concentrate. That makes Isopure a reasonable choice for many people with mild lactose intolerance, though not a guarantee for everyone. If whey in general upsets your stomach, our [whey vs whey isolate](https://www.best-proteinpowder.com/whey-vs-whey-isolate/) explainer covers what isolate does and does not fix.

## 6. Cost per 25 g of Protein

We compare powders on cost per 25 g of protein: the price of the tub, divided by the total grams of protein inside, multiplied by 25. Because Isopure's scoop is already a 25 g dose, its cost per 25 g is simply its cost per serving, which makes it easy to compare. Prices move constantly, so treat these as approximate ranges at the time of writing.

A 3 lb tub of Zero Carb holds about 44 servings at 31 g per scoop. At the regular and discounted prices we saw on Amazon, that works out to roughly $1.40 to $2.10 per 25 g. The 3 lb Low Carb Dutch chocolate tub holds about 41 servings and sat at roughly $1.85 to $2.20 per 25 g depending on discounts. The 7.5 lb tubs cut the per-gram cost further if you know you like the flavor.

> **Approximate Cost per 25 g**
>
> - **$1.40-2.10**: Zero Carb, 3 lb
> - **$1.85-2.20**: Low Carb, 3 lb
> - **44**: Servings in 3 lb Zero Carb
> - **Higher**: 1 lb bags and Clear

The 1 lb bags are where Isopure gets expensive: about 14 to 16 servings, at a noticeably higher cost per gram than the 3 lb tubs. They make sense for trying a flavor and little else. Clear also costs more per gram of protein, both because juice-style isolates are priced as a premium product and because each scoop gives about 20 g instead of 25 g.

How does that compare? Isopure's big tubs sit roughly level with other mainstream isolates and below most grass-fed or boutique isolates. A whey concentrate blend such as Gold Standard is usually cheaper per 25 g, but gives you more fat, carbohydrate and lactose for the saving. If you want an isolate and you are not paying for certification, Isopure is fair value.

## 7. Testing and Certification

Isopure's quality claims are in-house. Retail listings say the powders are made under FDA Good Manufacturing Practices and tested by the brand's own quality assurance lab, and the labels describe the whey as rBST free and gluten free. Those are reasonable baseline claims for a large manufacturer, and Glanbia's scale suggests mature quality systems.

What we could not confirm is an independent banned-substance certification. We could not confirm an NSF Certified for Sport or Informed Sport listing for Isopure powders at the time of writing, and the US product listings we read did not claim either. One overseas retailer's copy described a Zero Carb flavor as Informed Choice certified, but we could not verify that on the certifier's side, so we do not rely on it.

If you are a drug-tested athlete, that gap matters more than anything else on this page. NSF Certified for Sport screens products for substances banned in sport and checks that the label matches the contents. An isolate with that seal, such as Thorne Whey Protein Isolate, is the safer pick. Our [best whey protein isolate](https://www.best-proteinpowder.com/best-whey-protein-isolate/) ranking lists the certified options.

On heavy metals, dairy isolates are generally the low-risk end of the protein market, because whey is separated from milk rather than grown in soil. That is a category-level point, not a published result for Isopure specifically, and we did not find independent heavy-metal data for these tubs. For how to weigh contaminant testing across brands, see our guide to [whether protein powder is safe](https://www.best-proteinpowder.com/is-protein-powder-safe/).

## 8. Sweeteners and the Vitamin Blend

The flavored Zero Carb and Low Carb powders we checked are sweetened with sucralose and flavored with natural and artificial flavors. Sucralose is approved for use in food in the US and is used across most mainstream protein powders, so this is not a safety red flag. It is a preference issue: some people dislike its aftertaste, and some prefer to avoid artificial sweeteners altogether.

If that is you, you have two Isopure options. Unflavored has no sweetener at all and disappears into smoothies, oatmeal or coffee. Clear is sweetened with stevia instead. Isopure also sells naturally flavored versions, though we did not verify their sweetener panels flavor by flavor, so check the label before buying those.

The vitamin and mineral blend is the more unusual feature. The vanilla salted caramel Zero Carb label we checked lists vitamins A, C and E, a range of B vitamins including about 165 mcg DFE of folate, plus around 370 mg of calcium, 115 mg of magnesium and about 4 mg of zinc per scoop. Isopure markets these as immune and recovery support.

For most people the doses are modest and harmless. If you already take a multivitamin and drink two or three scoops a day, though, you are stacking the same nutrients, particularly folic acid and zinc, and it is worth adding them up. Pregnant readers in particular should check total folic acid and vitamin A with their doctor or a registered dietitian before combining a fortified powder with a prenatal vitamin.

## 9. Who Should Skip It

Skip Isopure if you are drug tested. Without a confirmed NSF Certified for Sport or Informed Sport listing, any protein powder carries a small but real risk of contamination with a banned substance, and the consequences of a failed test are far worse than paying a little more for a certified isolate.

Skip the flavored tubs if you avoid sucralose or artificial flavors, and skip any flavored version if you already take a full-dose multivitamin and do not want to double up. Unflavored solves both problems at the cost of having to flavor it yourself, which is easy in a smoothie and harder in a shaker of water.

Skip Isopure if you want the cheapest protein per gram and do not mind some fat and carbohydrate. A whey concentrate or blend will usually be cheaper per 25 g, and for most people the extra few grams of carbohydrate make no practical difference. Our [best whey protein powder](https://www.best-proteinpowder.com/best-whey-protein-powder/) guide covers the budget end.

Finally, skip it if you are vegan or have a milk allergy, which isolate does not fix. Lactose intolerance is a different matter; many lactose-sensitive people tolerate isolate well. Anyone with kidney disease should get a protein target from their doctor first. Comparing isolates from another big brand? Our [Dymatize review](https://www.best-proteinpowder.com/dymatize-protein-powder-review/) covers ISO100, Isopure's closest rival.

## 10. Matching the Tub to Your Goal

**For cutting and calorie counting:** Zero Carb. About 25 g of protein for roughly 100 calories is one of the best ratios in flavored protein. One scoop after training, or between meals to blunt hunger, adds a big chunk of protein for very little of your calorie budget. Mix with water to keep it lean.

**For keto:** Zero Carb or Unflavored, both at 0 g of carbohydrate per the label. Low Carb's 1 to 4 g is fine for most low-carb diets but may matter on strict keto if you drink several scoops. Remember that excess protein is not a keto problem for most people; total carbohydrate is.

**For cooking, smoothies and coffee:** Unflavored. With no sweetener or flavor, it adds 25 g of protein to oatmeal, yogurt, pancakes or a smoothie without changing the taste much. Isolate can foam when blended hard; blend briefly or stir it in at the end. **For summer and fruit-flavor fans:** Clear, mixed with cold water, tastes more like a sports drink than a shake.

Whichever tub you pick, use it to fill a gap rather than replace meals. Most adults who train hit their protein target with three or four protein-rich meals and one shake. Our [guide to how much protein you need](https://www.best-proteinpowder.com/how-much-protein-do-i-need/) will help you work out whether you need a shake at all.

## 11. Common Mistakes to Avoid

### Buying Low Carb for strict keto

Low Carb sounds keto friendly, but some flavors carry up to about 4 g of carbohydrate per scoop. Over two or three scoops a day that adds up on a 20 g carb budget. If you are on strict keto, Zero Carb or Unflavored, both at 0 g per the label, are the safer choices.

### Doubling up on vitamins

Flavored Isopure includes a blend of vitamins and minerals, including folic acid, zinc and calcium. If you also take a multivitamin or prenatal and drink several scoops daily, add up the totals. Most people are fine, but there is no benefit to doubling doses, and pregnant readers should check with a doctor.

### Assuming a big brand means certified

Isopure is owned by Glanbia, one of the biggest names in sports nutrition, but we could not confirm NSF Certified for Sport or Informed Sport status for its powders. Brand size is not certification. Tested athletes should search the certifier databases for the exact product and flavor before buying.

### Buying 1 lb bags long term

The 1 lb bags hold only about 14 to 16 servings and cost noticeably more per 25 g than the 3 lb tubs. They are good for testing a flavor. Once you know what you like, the larger tubs cut your cost per gram of protein significantly, especially when discounted on Amazon.

### Shaking Clear like a normal shake

Clear whey foams when shaken hard, which is a common buyer complaint. Mix it with cold water, shake gently or stir, and let it sit a minute before drinking. Treating it like a juice rather than a milkshake makes it far more pleasant to drink.

## 12. Frequently Asked Questions

### Is Isopure a good protein powder?

Yes, for the right buyer. Isopure Zero Carb gives about 25 g of whey isolate protein for roughly 100 calories and zero carbohydrate per the label, which is among the leanest ratios in flavored protein. The trade-offs are sucralose in flavored tubs, an added vitamin blend, and no banned-substance certification we could confirm, which rules it out for tested athletes.

### How much protein is in Isopure Zero Carb?

About 25 g of protein per 31 g scoop in the flavored versions we checked, for roughly 100 calories, 0 g of carbohydrate and about 0.5 g of fat, per the label at the time of writing. Unflavored gives about 25 g per 29 g scoop. Figures vary slightly by flavor, so check the panel on your tub.

### What is the difference between Isopure Zero Carb and Low Carb?

Both give about 25 g of whey isolate protein per scoop. Zero Carb has 0 g of carbohydrate and about 100 calories; Low Carb has about 1 to 4 g of carbohydrate and roughly 110 to 120 calories, depending on flavor, because its creamier flavors use cocoa and gum. Low Carb tastes more like a traditional shake, per buyer feedback.

### Is Isopure good for lactose intolerance?

Often, yes. Isopure is whey protein isolate, which is filtered to remove most of milk's lactose and fat, so many people with mild lactose intolerance tolerate it better than concentrate. It is not lactose free for everyone, and it is still a dairy protein, so it is not suitable for anyone with a milk allergy or a vegan diet.

### What sweetener does Isopure use?

The flavored Zero Carb and Low Carb powders we checked are sweetened with sucralose and flavored with natural and artificial flavors. Isopure Clear uses stevia, per retail ingredient lists. Unflavored has no sweetener at all. Isopure also sells naturally flavored versions; check their labels flavor by flavor before buying if sweetener matters to you.

### Is Isopure third-party tested?

Isopure says its powders are made under FDA Good Manufacturing Practices and tested by its own quality assurance lab. We could not confirm an NSF Certified for Sport or Informed Sport listing for Isopure at the time of writing, so we do not treat it as independently certified. Drug-tested athletes should choose a certified isolate such as Thorne.

### Who owns Isopure?

Isopure is owned by Glanbia, the Irish nutrition group that also owns Optimum Nutrition. Glanbia agreed to buy The Isopure Company, based in Hauppauge, New York, for about $153 million in 2014, and runs it as part of its performance nutrition business, where it sits alongside brands such as Optimum Nutrition, Think! and Amazing Grass.

## Related Whey Protein Guides

- [Best Whey Protein Isolate](https://www.best-proteinpowder.com/best-whey-protein-isolate/): Our full ranking of isolates on purity, testing and cost per 25 g.
- [Dymatize Protein Powder Review](https://www.best-proteinpowder.com/dymatize-protein-powder-review/): ISO100, Isopure's closest rival, checked against the rest of the Dymatize range.
- [Best Clear Protein Powder](https://www.best-proteinpowder.com/best-clear-protein-powder/): Juice-style isolates compared, including Isopure Clear.

## The Bottom Line

Isopure makes one of the leanest flavored protein powders you can buy. Zero Carb gives about 25 g of whey isolate protein for roughly 100 calories and no carbohydrate, Low Carb trades a few grams of carbohydrate for richer flavors, Unflavored strips out the sweetener and vitamins, and Clear turns isolate into a juice-style drink.

Its limits are clear too: sucralose in the flavored tubs, a vitamin blend you may not need, and no banned-substance certification we could confirm. If those do not bother you, Isopure is fair value for an isolate. If they do, our [best whey protein isolate](https://www.best-proteinpowder.com/best-whey-protein-isolate/) ranking shows the certified alternatives.

## More in Brand Reviews

Guides in this category that pair with what you just read.

- [Best Low Carb Protein Powder](https://www.best-proteinpowder.com/best-low-carb-protein-powder/)
- [Optimum Nutrition Protein Powder Review](https://www.best-proteinpowder.com/optimum-nutrition-protein-powder-review/)
- [Dymatize Protein Powder Review](https://www.best-proteinpowder.com/dymatize-protein-powder-review/)
- [Transparent Labs Protein Powder Review](https://www.best-proteinpowder.com/transparent-labs-protein-powder-review/)

About the Author

[Best Protein Powder Editorial Team](https://www.best-proteinpowder.com/authors/editorial-team/), Supplements Desk

The editorial team reads the label, the certificate and the price per gram of protein before a powder gets near a ranking -- and says plainly when a cheaper tub does the same job.

[Full profile](https://www.best-proteinpowder.com/authors/editorial-team/) | [How we test](https://www.best-proteinpowder.com/how-we-test/)