Cellucor Iso Pro: The Grass-Fed Whey Protein Debate Continues

Cellucor Iso Pro

Nutrabolt has finally come out with a whey protein isolate in Cellucor Iso Pro… and it’s grass-fed whey. But does that make for better protein powder?

For well over a decade, Cellucor has offered quality supplements. We all know C4, one of the best selling preworkouts of all time. A few years ago, Cellucor COR-Performance Whey introduced the world to how creative a protein flavor can be with flavors like Red Velvet, Cor-Fetti, Chocolate Chip Cookie Dough, and more — literally taking it to Optimum Nutrition in their own front yard.

The brand also has a gainer and casein protein supplement, but neither get that as much fanfare as the COR Whey. It seemed like the only thing missing was a whey protein isolate! If you’ve been around for a decade or so, you might remember Cellucor Super Sport, a pure whey isolate that came and went in a heartbeat.

So what’s a lactose-sensitive Cellucor fan to do?!

Missing no more, the monster brand recently dropped news that it’s bringing a new type of protein isolate to the market named Cellucor Iso Pro. And this time, it’s fruity.

Sign up for deal and coupon alerts below, and let’s see what Cellucor’s up to:

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Yet Another Typical Isolate Protein?

Not necessarily. The first thing that jumps out about Iso Pro, is the label states it is a “grass fed whey isolate.” The next logical question would be, “is grass fed whey superior to ‘normal’ whey?”

You would probably lean towards thinking it is, simply because it sounds “healthier” in theory. But is that the case? For beef, it absolutely is — but what about for the whey??

Grass Fed Beef vs. Grain-Fed Beef

When we evaluate food such as beef, there is no debate that the nutritional value is superior in organic, grass fed, and pasture raised sources.[1]


“You are what you eat” – to an extent, of course. Consider how the foods that a cow eats will impact the nutritional content of its milk and meat. Commercially-raised cows are fed grains for the majority of their life so they can fatten up as quickly as possible.[1] This can lead to meat and milk production that have different fatty acid profiles compared to cows that eat grass, which is richer in nutrients,[1] not to mention the various micronutrient differences.

Beef from these grass-fed cows is higher in Omega 3s than Omega 6s and also carry a higher amount of conjugated linoleic acid or CLA[1] — and theoretically, the raw whey is too!

But what’s that have to do with whey, especially whey isolate?!

Okay, so the fatty acid content of your grass-fed burger is healthier. Good. But when we’re dealing with a whey protein isolatewhich has had its fat filtered out — does it matter much anymore?

Well here we go again — as covered in our NutraBio Natural Series Grass-Fed Whey Protein Isolate and Transparent Labs Grass-Fed Whey Isolate posts, as well as our Onnit Grass-Fed Whey Protein review, we need to have a serious conversation about grass-fed proteins.

And the honest answer is that we don’t know. We are yet to see a single study or amino acid profile on grass-fed whey protein (specifically an isolate) compared to a similar grade whey from grain-fed dairy. All the better if such a lab test would compare pesticide and hormone contents across the two.

Grass Fed Beef Benefits

So grass fed beef has a better fatty acid content,[1] but how’s that help with whey isolate when you’re filtering all the fat out?!

Until we see such data, our stance is that “a leucine molecule is a leucine molecule” – and when it comes to health content, a grass-fed WPI-90 is not going to be strikingly different than a grain-fed WPI-90.

After all, who cares about a “healthier fatty acid profile” when you’re drinking less than a gram of fat anyway?!

Consider the glutathione

Cellucor Cor-Performance Whey

If this grass-fed isolate is a bit much for you, then Cellucor Cor-Performance Whey is a more affordable best-seller with some amazing flavors!

It might be worth mentioning that studies have proven a higher level of Glutathione protein within grass-fed beef, versus grain fed beef.

So what the heck is Glutathione?

Glutathione (GT), is a protein tripeptide composed of cysteine, glutamic acid and glycine and functions as a powerhouse antioxidant and protects cells from oxidized lipids.[1] Oxidized lipids can cause cellular damage, but glutathione can prevent such damage to DNA.[1] It’s found in almost all plant and animal tissue and is absorbed in the small intestine.[1]

Glutathione is elevated in lush green forages, and therefore grass-fed beef is particularly high in this critical antioxidant compared to grain-fed contemporaries.[1] Reports have shown a significant increase in GT molar concentrations in grass-fed beef.[1]

But again, do these benefits transfer to whey?

We can’t say for certain. It stands to reason that milk from more nutritious grass-fed cows may be superior to whey from grain-fed cows but there is no study or date to prove that is the case. Once again, we’re filtering out nearly everything but protein!

A piece of good news though: there are several studies showing that glutathione production increases when supplementing whey. Maybe it’s due to that glutathione being in the whey itself? And if that’s the case, then grass-fed whey would be even better!

But once again, we’re not sure if this is enough to warrant grass-fed whey from a health standpoint. So why are we here?

Ethics. The real reason to buy grass-fed

So if nobody’s given us an honest data-based reason to buy grass-fed whey isolate, why should we care?

Because you do it for the cows.

Black Cows

Grass-Fed Cows provide more glutathione, the powerhouse antioxidant. Does any of that show up after they whey filtration though?

If you’re an animal lover, consider that grass-feeding pastured animals is accepted as being far friendly for the cows — and likely for the environment too. They are healthier, happier, and leaner when fed grass. Makes sense, this is their natural state and they’ve been doing it that way for thousands of generations. That is until “big agri” came along.

PricePlow is based in Texas, and here in Texas, we like our steer. If our lovely bovine friends are providing your post workout shakes, and you have extra cash in the bank, it might not hurt to show them a little love and support the grass-fed cattle industry. But we stress that this should happen when all of your most important bills are taken care of first.

And one final question before we move on: how does one prove that the whey is truly from grass-fed cows? There’s no lab test for that.

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Where Does This Grass Fed Whey Come From?

Cellucor Iso Pro strictly uses Lactalis IngredientsPRONATIV Native Whey Isolate Protein as its only protein source. If you are asking what the heck PRONATIV Native Whey Isolate is, fear not: PRONATIV whey isolates have some interesting elements, and seem to be competitive against other types of isolates.

But first, let’s finally jump into the Cellucor Iso Pro ingredient label itself, then explain the benefits PRONATIV is selling regarding their whey isolate.

Cellucor ISO Pro Ingredients

The Cellucor Iso Pro Ingredients show low cholesterol, passing one of our latest smell tests discussed in our whey isolate guide. But WTF’s up with the artificial colors??? Is that really necessary in a protein powder?

At first glance, Iso Pro’s nutrition label looks like what we would expect to see for an isolate protein. Here is the run down:

This is definitely a classic isolate protein label, and it passes the ‘sniff test’ in terms of cholesterol content, as discussed in the article linked above.

It has a respectable amount of carbs and is almost entirely void of fats. With a common 25g of protein per serving and 0g of sugar, Iso Pro will be a competitive isolate in terms of nutrition and macros.

About The Ingredients:

  • PRONATIV Whey Protein Isolate

    The first ingredient that the label lists is PRONATIV Native Whey Protein Isolate by Lactalis Ingredients. Normally we see a few types of protein on the label (including isolate products) and even traces amounts of whey protein concentrate. You will quickly realize that all of the protein comes from the PRONATIV whey isolate.


    PRONATIV, by Lactalis Ingredients, claims 95% protein by weight and more leucine! This is amazing if proven true!

    In addition to having the benefits of being grass-fed whey, the PRONATIV whey isolate claims to be 95% protein,[2] but further research shows that this isn’t 100% true. We dug a little deeper and it turns out that the raw material is 94% protein on a dry basis, but that is not a realistic, real-world measurement. Instead, on an as is basis (as in, this is how we’ll be consuming it), PRONATIV is 89% protein by weight.[4] Great for an isolate, but nothing we haven’t seen before. PRONATIV also claims that its protein has 15% more leucine than a traditional whey isolate and has zero fats, antibiotics, hormones, or chemical agents.[2]

    PRONATIV-95 Specifications

    Update: It turns out that PRONATIV-95 isn’t 95% protein. Not even close. It’s 94% protein on a dry basis, but in the real world, we like to report as is – since that’s how we consume it. And that number is 89%.[4] Still impressive, but it’s not 95%.

    The PRONATIV whey also undergoes a cold-filtration system rather than a heated ion exchange to separate the whey isolates from milk. A cold filtration system has been shown superior than the ion exchange system, because the heated ion exchange can denature the protein.[3]

    95% Protein by weight and more leucine?!

    If this is indeed the case, then we might really be on to something here. We’ve asked PRONATIV to provide this data for your consumption, as their one-page website is extremely sparse as of Iso Pro’s product launch in March 2018.

    Update: As mentioned above, it’s not 95% protein by weight. It’s 94% protein on a dry basis, but really 89% protein as is,[4] which is the measurement that should be used when realistically talking about protein powder, since we consume it as is.

    PRONATIV-95 Amino Acid Profile

    Despite the lower-than-hyped protein content by weight, the PRONATIV-95 leucine score is quite nice!

    More information on the PRONATIV process

    What’s interesting is that PRONATIV is a native whey protein directly extracted from the milk — it’s not a by-product of cheese as is typical with whey protein!

    PRONATIV Processing

    How PRONATIV gets processed compared to regular whey isolate on the right. Note that there’s no cheese or chemical processing here – just straight from milk to physically-separated whey!

    This means there is less processing than standard whey proteins on the market. They’re using a low-temperature process (only physical separation instead of chemical separation), so this should make the protein easier for your body to use.

    Because of that process, PRONATIV is a complete protein made with naturally occurring bioactive peptides, natural essential amino acids, and antioxidants. PRONATIV contains immunoglobulins and lactoferrin which are typically lost during standard whey processing.

  • Citric Acid

    An organic acid that naturally occurs in citrus fruit. This is commonly used in fruit flavored supplements. We’ll address this later when we hit on flavors. This is an indication that the flavors will include some fruit options.

  • The Rest

    The other ingredients labeled are your basic sweeteners and flavor agents found in most protein powders.

    How about some C16H10N2Na2O7S2 to start your day? Not sure what that is? It’s Disodium 6-hydroxy-5-[(4-sulfophenyl)azo]-2-naphthalenesulfonate, of course, and Cellucor’s adding it to their ‘natural’ grass-fed whey!

    Although Cellucor’s going the “natural” route with the grass-fed whey, they’re sticking with their tried-and-true artificial sweeteners, sucralose and ace-k. Many grass-fed whey proteins move to stevia, but Cellucor is sticking to flavor first, and fact is, artificial sweeteners are still tastier for the majority of consumers.

    77% protein by weight?

    It’s also worth noting that this label’s protein content is just under 77% protein by weight due to the fillers added. This is on the low-side compared to other whey isolates, so it better be thick and tasty! Given that they’re saying to use 16-20oz water per rounded scoop, we’re guessing it will be.

    But why use a 95% 89% protein by weight raw material in PRONATIV if you’re going to add that much filler anyway?

    Artificial colors in protein? Why?

    Of note is the FD&C Yellow #6, also commonly known as Disodium 6-hydroxy-5-[(4-sulfophenyl)azo]-2-naphthalenesulfonate. This is an artificial dye to add coloring. Depending on your stance on artificial coloring, this may change your opinions on the product.

    Seriously, do we really need artificial colors in our protein powder? PricePlow disapproves of this completely unnecessary practice. Other successful brands have gotten away from this, it’s time for Cellucor to be a true industry leader and follow suit.

Iso Pro Flavors

Cellucor Iso Pro

Fruity cereal will be our first pick, since cereal flavors are the hot thing right now. Blame Ghost for that!

Take a look at the three available flavor options and you’ll be surprised – perhaps pleasantly so. There are no chocolate, vanilla, cinnamon, or cookies and cream type flavors!

Instead, Iso Pro is taking a run at the fruit flavored whey isolates and will initially be available in:

  • Fruity Cereal
  • Strawberry Splash, and
  • Orange Citrus

If fruity flavors in a post workout shake seem a bit different than what you are accustomed to, we recommend considering that Cellucor has never put out a COR-Whey flavor that did not meet or exceed expectations. In this case, Cellucor seems to be taking a page out of the MAN Sports ISO-Protein playbook, where the “fruity cereal” flavor hit the head on the spot.

Our bet is that these will be pretty tasty, as expected from Cellucor! They rarely fail you on flavor.

How to use: 16-20oz water?!

One crazy thing here: Cellucor’s website is suggesting 16-20oz water!! This means you’re either going to have the thinnest, runniest protein shake ever, or they truly are bringing some serious thickener game!!

We mentioned above the relatively low protein-by-weight compared to other top-rated whey isolates, so there was definitely some room stolen by the thickeners. We’ll need to review this one on our YouTube channel.

Final Thoughts

Well it’s about time Cellucor reintroduced a pure isolate! How long has it been since COR-Performance Whey shook the industry up? Nobody remembers their previous isolate, Super Sport, but that vanilla flavor was like custard. We honestly expected something like this much sooner!

Cellucor Logo

See our Cellucor page to save on all Cellucor Supplements and get Cellucor news alerts!

Iso Pro looks like it’s climbing the tall mountain of isolates and will offer consumers one of the most clean whey protein isolate options on the market. Utilizing a clean isolate such as PRONATIV will give buyers peace of mind, knowing that they’re getting only the highest quality of protein. But data returned by PRONATIV leaves us a bit less excited, especially regarding the protein-by-weight, but the leucine number is definitely nice and high.

For the time being, we’re happy to be on the grass-fed whey train, so long as you have the budget and are buying it for the right reasons. As it stands, grass-fed whey isolate isn’t a health-choice. It’s an ethical one. If you’re cool with that and are still in, then we’re on the same page.

As for the flavors, they sound interesting for sure, and Cellucor has yet to disappoint in the taste department, so we’ll assume these will be no exception. But we’d be lying if we said we don’t want that amazing COR-Performance cinnamon swirl flavor in isolate form here!

So for a cleaner take on your whey isolate shake, Iso Pro looks like a great option – especially if you want it fruity.

Cellucor IsoPro – Deals and Price Drop Alerts

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Disclosure: PricePlow relies on pricing from stores with which we have a business relationship. We work hard to keep pricing current, but you may find a better offer.

Posts are sponsored in part by the retailers and/or brands listed on this page.

About the Author: Mike Roberto

Mike Roberto

Mike Roberto is a research scientist and water sports athlete who founded PricePlow. He is an n=1 diet experimenter with extensive experience in supplementation and dietary modification, whose personal expertise stems from several experiments done on himself while sharing lab tests.

Mike's goal is to bridge the gap between nutritional research scientists and non-academics who seek to better their health in a system that has catastrophically failed the public. Mike is currently experimenting with a low Vitamin A diet.

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  1. Daley, Cynthia; Abbott, Amber; Doyle, Patrick; Nader, Glenn; and Larson, Stephanie. A Review of Fatty Acid Profiles and Antioxidant Content in Grass-fed and Grain-fed Beef (2010); https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2846864/
  2. PRONATIV, https://pronativ.com/#home-nutrition
  3. Dow Liquid Separations. Dow Chemical Company. DOWEX Ion Exchange Resins – Fundamentals of Ion Exchange. (June 2000); https://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_0032/0901b803800326ca.pdf
  4. PRONATIV-95 Specifications; https://blog.priceplow.com/wp-content/uploads/pronativ-95-specifications.pdf

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