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Does this sound familiar? You crushed your 30-minute workout, then guzzled down a post-workout shake so you don’t miss a single drop of gains. 

But then it happens: You hear your stomach gurgle, feel it start to bloat, then you feel a strong need to stay near a bathroom just. in. case. Phew, no disasters this time, but the next go-round is still up for grabs—until now!

Because you need your tummy to keep up with your muscle gains and recovery, GGR’s team of dietitians and nutrition experts are rounding up and reviewing the best protein powder for sensitive stomachs.

You can trust us to do this; after all, we’ve personally tested more than 100 protein powders in the search for the best protein powders on the market, rating them in categories like formulation, taste, and solubility. We also worked with an independent accredited lab called Ellipse Analytics to perform quality testing on a sample of more than 150 protein powders for label accuracy and purity. We then scored them and chose to feature products that ranked in the top 50% of the samples tested. You’ll see those products designated below as well.

Medical disclaimer: This article is intended for educational and informational purposes only. It is not intended as a substitute for medical advice. For health advice, contact a licensed healthcare provider.

Best Protein Powder for Sensitive Stomachs 

Does Protein Powder Cause Tummy Troubles?

Before hopping into the best protein powders for sensitive stomachs, it’s important to note that a “sensitive stomach” is not a formal medical diagnosis. Instead, it describes digestive issues—like abdominal cramps, bloating, and constipation—but a medical diagnosis often follows after evaluating these symptoms or at least some sort of troubleshooting. 

Some of the most common culprits of a sensitive stomach include lactose intolerance, celiac disease, and irritable bowel syndrome (IBS). Managing these conditions often requires making dietary changes, like evaluating your protein powder of choice, to remedy tummy troubles.

Some ways protein powder may cause digestive upset include:

  • Eating or drinking too fast may cause indigestion, so slugging back that protein shake might be the culprit—and a simple fix is to slow down the chug!
  • Dairy-based protein powders are popular but not always tolerated by people with lactose intolerance and other dairy allergies. Moreover, digestive problems are common whey protein side effects
  • Artificial sweeteners—especially sugar alcohols—enhance the sweetness of protein powder without adding sugars, although they may cause gastrointestinal discomfort like bloating. 
  • Gluten—a protein found in wheat, rye, barley, and triticale—might be in your supplement due to cross-contamination when manufactured. Those managing celiac disease require a gluten-free diet, and people with IBS may also benefit from reducing or eliminating gluten. 
  • Other additives, like inulin and xanthan gum, may also have adverse side effects for the digestive system.

Everyone has different food tolerances; some people are severely intolerant to lactose, while others are ultra-sensitive to gluten. All this to say, our top picks reflect most of the leading causes of digestive issues related to protein powder—so let’s hop into them!

Best Overall Protein Powder for Sensitive Stomachs: Transparent Labs 100% Whey Protein Isolate

Good for: Anyone searching for reputable, high-quality protein 

Best Overall

Transparent Labs 100% Grass-Fed Whey Protein Isolate

GGR Score: 4.2 starstarstarstarstar

Product Highlights

  • High-quality whey protein isolate
  • 28 grams of protein per serving
  • 15 flavors to choose from
  • $1.99 per serving

Pros & Cons

Pros

  • High-quality protein
  • No artificial sweeteners, food dyes, or preservatives
  • Lots of flavors to choose from
  • Good customer reviews
  • Whey isolate may be easier to digest for some people

Cons

  • Price per serving on the high end

Bottom Line

Our testers love Transparent Labs 100% Grass-Fed Whey Protein Isolate because we know exactly what's in it, and almost every flavor we've tried is a 5 out of 5 on taste. Yes, it's a little more expensive than other protein powders but you get what you pay for.

Providing 28 grams of protein with only 1 gram of carbohydrate and 0 grams of fat, Transparent Labs 100% Whey Protein Isolate is the epitome of pure protein. But it’s not just the nutrition profile that makes Transparent Labs’ 100% grass-fed whey protein isolate top our list (again) as the best overall protein powder for sensitive stomachs.

We’ll first point out that all whey protein1 products are considered complete proteins—meaning they supply all essential amino acids, including branched-chain amino acids (BCAAs)—and aid muscle growth. However, whey protein concentrates and isolates offer subtle yet notable differences. 

transparent labs protein bottle in hand

Compared to concentrates, whey protein isolates contain more protein and fewer carbs, fat, and lactose. Being lower in lactose makes whey protein isolates a possible muscle-building2 solution for anyone with lactose intolerance or dairy sensitivities.

And the greatness of Transparent Labs’ whey isolate doesn’t stop with its protein—it sports a tidy ingredient list without using artificial colorings, preservatives, and sweeteners. And you can choose between eight tempting flavors, including Cinnamon French Toast and Oatmeal Chocolate Chip Cookie.

Third-party lab test results for Transparent Labs Whey Isolate Protein Powder
GGR collaborated with Ellipse Analytics, an accredited third-party lab, to test more than 150 protein powder products. We screened for dozens of factors and rated each product against its peers. Excellent indicates the top 10% of products; Above Average is the top 25% of products; and Meets Standard is the top 50% of products tested.

GGR performance editor and product tester Anthony O’Reilly tried this product and said, “I’ve been taking Transparent Labs protein for about a month, and overall I have to say I’m a big fan! I haven’t experienced any stomach or digestive issues after drinking it as I sometimes do with other whey protein powders—several customer reviewers said the same thing. It mixes incredibly well with milk or water, and I can say that I feel full for quite a while after downing a protein shake.”

Transparent Lab products are third-party tested, with their Certificates of Analysis and Composition readily accessible on their website. GGR also worked with Ellipse Analytics, an independent accredited lab, to test Transparent Labs whey isolate and more than 150 other protein powders for protein content and purity. Overall, Transparent Labs whey isolate ranked as an Above Average product, and you can read more about exactly what we tested for in our Independent Supplement Testing Glossary.

If you want a more in-depth guide to this grass-fed whey protein isolate, check out our complete Transparent Labs Protein Review.

Type of ProteinGrass-fed whey protein isolate 
Protein Content (per serving)28 g per 1 scoop
Flavor(s)Chocolate Peanut Butter, Cinnamon French Toast, French Vanilla, Milk Chocolate, Mocha, Oatmeal Chocolate Chip Cookie, Strawberry, Vanilla Peanut Butter
Cost$59.99/30 servings = $2.00/serving

Best Natural Protein Powder for Sensitive Stomachs: Legion Whey+

Good for: Those who prioritize natural ingredients and animal welfare 

Best Natural

Legion Whey+

GGR Score: 4 starstarstarstarstar

Product Highlights

  • Sourced from small dairy farms in Ireland
  • Over 5 g of BCAAs per serving
  • Non-GMO and animal welfare approved
  • Third-party tested for banned substances

Pros & Cons

Pros

  • Low in carbs and fat
  • Natural ingredients
  • Money-back guarantee
  • Made with ethically-sourced milk
  • Lots of flavor options

Cons

  • Comparably high cost per serving
  • May be clumpy when mixed
  • Some flavors have mixed reviews

Bottom Line

Legion Whey+ is a clean, sustainable protein powder that also is macro-friendly and a great option for anyone looking for a clean protein supplement. Many of our testers have brought this with their own money because they love the taste and easy mixability.

Only containing all-natural ingredients without artificial ingredients and “chemical junk,” Legion Whey+ naturally lands as a top pick. And while we’ve done a top-to-bottom Legion Whey+ protein review, we’ll share the cliff notes here.

legion whey protein bag bottle

The first thing to note about Legion Whey+ is that it provides whey protein isolate, which may be better tolerated by those with dairy sensitivities like lactose intolerance. But this isn’t just any whey protein isolate—Legion makes it known its non-GMO protein supplement is Truly Grass Fed and Animal Welfare Approved certified, meaning the dairy cows live in optimal and natural conditions. 

Legion whey+ protein lab result scorecard
GGR collaborated with Ellipse Analytics, an accredited third-party lab, to test more than 150 protein powder products. We screened for dozens of factors and rated each product against its peers. Excellent indicates the top 10% of products; Above Average is the top 25% of products; and Meets Standard is the top 50% of products tested.

We also welcome the invitation to try 15 exciting and nostalgic flavors (Cinnamon Cereal, anyone?), although some options contain ingredients like xanthan gum3 and stevia that may cause tummy troubles for some people. But if you don’t love Whey+, Legion will give you a full refund on the spot.

Legion Whey+ is certified to contain no banned substances by Labdoor, an independent third-party testing company. This strengthens the confidence of consumers, especially competitive athletes, that the supplement contains what it claims to and not what it shouldn’t. 

It’s also manufactured in National Sanitation Foundation (NSF)-certified, Food and Drug Administration (FDA)-inspected, Good Manufacturing Practices (cGMP)-compliant facilities. 

Further adding to Legion Whey’s cred, GGR worked with independent and accredited lab called Ellipse Analytics to perform our own testing on label accuracy and purity, and Legion Whey achieved a Meets Standard rating overall. Learn more about these purity metrics in our Independent Supplement Testing Glossary.

Type of ProteinNon-GMO whey protein isolate 
Protein Content (per serving)22-24 g per scoop
Flavor(s)Apple Pie, Banana Bread, Birthday Cake, Chocolate Peanut Butter, Cinnamon Cereal, Cocoa Cereal, Cookies & Cream, Dutch Chocolate, French Vanilla, Fruit Cereal, Honey Cereal, Mint Chocolate, Mocha Cappuccino, Pumpkin Pie, Salted Caramel, Strawberry Banana, Unflavored
Cost$59.99/30 servings = $2.00/serving

Best Low-Carb Protein Powder for Sensitive Stomachs: Jacked Factory Authentic ISO

Good for: Low-carb and keto dieters looking for a whey protein isolate 

Best Low-Carb

Jacked Factory Authentic ISO Grass-Fed Whey Protein

GGR Score: 3.5 starstarstarstarstar

Product Highlights

  • Three flavors
  • 25g per scoop
  • 110 calories per serving
  • Under 1g of fat per scoop

Pros & Cons

Pros

  • 25g of protein
  • Only 110 calories per scoop
  • No added sugars
  • Under 1g of fat per serving

Cons

  • Reviewers state the taste is not the best
  • Doesn't mix well

Bottom Line

A protein powder that comes very close to being pure protein, at a reasonable price.

Jacked Factory Authentic ISO provides 25 grams of protein with only 1 gram of carbs and 0.5 grams of fat, making it suitable for low-carb and keto dieters. And you can enjoy delicious flavors—like Blueberry Muffin and Cinnamon French Toast—without added sugars!

The grass-fed whey protein isolate mostly contains natural ingredients, including Himalayan rock salt and stevia extract. However, it’s also formulated with artificial flavors and the artificial sweetener sucralose. Both stevia and sucralose have been known to cause GI distress in some people, so it’s helpful to know if you are sensitive to either of these sweeteners while looking for the best protein powder for you.

An image of a woman using Jacked Factory Authentic Iso protein powder

The vanilla flavor also contains a gum blend, so you might opt for a different flavor if you’re sensitive to guar gum, gum acacia, or xanthan gum. If you want to avoid any additional ingredients beyond whey protein isolate, Authentic ISO comes in a single-ingredient Unflavored option. 

Jacked Factory Authentic ISO manufactured in the U.S. in a cGMP, FDA-registered facility. And if you aren’t satisfied with the product, Jacked Factory offers a 100% hassle-free, money-back guarantee. Read more in our full Jacked Factory Authentic Iso Whey review.

Type of ProteinGrass-fed whey protein isolate 
Protein Content (per serving)25 g per 1 scoop
Flavor(s)Blueberry Muffin, Cinnamon French Toast, Unflavored, Vanilla, Vanilla Oatmeal Cookie
Cost$39.99/30 servings = $1.33/serving

Best-Tasting Protein Powder for Sensitive Stomachs: XWERKS Grow

Good for: Fitness enthusiasts with a savvy palate 

Best-Tasting

XWERKS Grow

GGR Score: 4 starstarstarstarstar

Product Highlights

  • Natural, healthy, convenient, and tasty way to get protein
  • Uses a microfiltration process to preserve critical biological nutrients in raw whey
  • Removes unwanted fats and carbohydrates
  • All flavors are naturally sweetened
  • Nicely flavored, easily digested, and low-carb protein powder
  • Promotes muscle growth and repair

Pros & Cons

Pros

  • Keto-friendly
  • Naturally sweetened
  • Sourced from naturally raised grass-fed cows
  • Has a smooth and creamy taste
  • Soy- and gluten-free
  • Convenient

Cons

  • Expensive

Bottom Line

XWERKS Grow whey protein isolate provides a solid blend of amino acids, vitamins, and minerals in a whey protein isolate. Our testers have said this is one of the best-tasting protein powders they've tried, and they've had more than 100.

Xwerks Grow proves great-tasting protein powder doesn’t have to be fancy. It sticks to the basics by offering four classic flavors—Chocolate, Vanilla, Peanut Butter, and Strawberry—without artificial sweeteners, flavors, or coloring.

Depending on the flavor, each scoop provides 23 to 25 grams of protein with little to no carbs and fat. The whey protein isolate is sourced from pasture-raised cows in New Zealand, regarded as one of the strictest countries in the world regarding dairy standards and quality, so you need not worry about hormones, antibiotics, or pesticides passed on to you. 

Xwerks also claims their protein powder is free of lactose due to the microfiltration process it undergoes, making it easily digestible without the bloat. The microfiltration process also helps keep amino acids and other beneficial nutrients intact—including alpha lactalbumin4 and immunoglobulins5—to support metabolic, immune, gut, neurological, and overall health.

Xwerks Grow 1

Each Xwerks Grow flavor is also free of gluten and soy, but they do contain xanthan gum which could cause tummy troubles in some consumers. But if you’re unsatisfied with your order, Xwerks offers a 100% money-back guarantee.

Anthony O’Reilly, GGR performance editor and expert product tester, tried Xwerks Grow and enjoyed the chocolate flavor, describing it as a “protein Yoo-hoo.”

Read our full XWERKS Grow whey protein review for more expert thoughts about this product.

Type of ProteinGrass-fed whey protein isolate
Protein Content (per serving)25 g per 1 scoop
Flavor(s)Chocolate, Peanut Butter, Strawberry, Vanilla,
Cost$59.00/30 servings = $1.97/serving

Best Plant-Based Protein Powder for Sensitive Stomachs: KOS Vegan Protein Powder

Good for: Dairy-free and plant-based consumers 

Best Plant-Based

KOS Vegan Protein Powder

GGR Score: 4 starstarstarstarstar

Product Highlights

  • Multi-source vegan protein powder 
  • USDA-certified organic, soy-free, gluten-free, dairy-free, non-GMO
  • Digestive support via DigeSEB to help maximize absorption

Pros & Cons

Pros

  • Manufactured in the USA
  • Superfood-infused
  • 20 g protein per serving
  • Chocolate flavor is rich
  • Enhanced with digestive support enzymes
  • Under $1.50 per serving

Cons

  • Customers say it has a gritty/chalky flavor
  • Some users reported protein gave them stomach issues
  • Reports of strong sweetness and bad aftertaste

Bottom Line

KOS is a vegan protein with a lot of positive reviews, but a number of people experienced stomach issues using this protein powder.

KOS Vegan Protein Powder is a great plant-based protein powder for sensitive stomachs, especially for people intolerant to dairy products. Each two-scoop serving provides 20 grams of protein sourced from organic peas, chia seeds, flaxseed, pumpkin seeds, and quinoa.

Pea protein6 is a complete protein since it provides all essential amino acids, although it’s relatively low in methionine and cysteine compared to other plant- and animal-based proteins. However, combining other plant-based sources—like pumpkin seeds7 and chia seeds8—enhances the amino acid profile and provides beneficial nutrients like omega-3 fatty acids and antioxidants.

The organic plant-based protein also contains an “organic fruit and veggie blend” with superfood properties and a digestive enzyme blend called DigeSEB for digestion support. These enzymes may reduce discomforts like bloating and gas, especially if you are sensitive to any of the ingredients in the protein powder.

kos vegan protein review

KOS plant protein blend comes in an Unflavored option and offers six flavors—like Blueberry Muffin and Chocolate Peanut Butter—naturally sweetened with monk fruit, stevia, and coconut sugar. This said, while it’s free of artificial sweeteners and sugar alcohols, the plant protein does contain added sugars, unlike others on our list. 

Amanda Capritto, GGR senior staff writer and expert product tester, tried this product and said, “It’s one of the only vegan protein powders I can tolerate as someone who primarily drinks whey.” This might not sound like a ringing endorsement, but for someone who usually only drinks whey protein, it actually is.

Our KOS vegan protein review details more if you’re interested.

Type of ProteinOrganic pea protein, organic chia seed, organic pumpkin seed protein, organic flaxseed, organic quinoa
Protein Content (per serving)20 g per 2 scoops
Flavor(s)Blueberry Muffin, Chocolate, Chocolate Chip Mint, Chocolate Peanut Butter, Salted Caramel Coffee, Vanilla, Unflavored
Cost$55.99/28 servings = $2.00/serving

Best Budget Protein Powder for Sensitive Stomachs: Bulk Supplements Whey Protein Isolate

Good for: Supporting muscle gains without losing out on (much) money

Best Budget

Bulk Supplements Whey Protein Isolate

GGR Score: 3.8 starstarstarstarstar

Product Highlights

  • Unflavored whey protein isolate
  • 26 g of protein per serving
  • 110 calories per serving

Pros & Cons

Pros

  • Only two ingredients
  • 26 g of protein per serving
  • Really affordable
  • Suitable for those with a sensitive stomach

Cons

  • Unflavored, which some people may not care for
  • Some complaints about the packaging
  • Some complain it's foamy when mixed

Bottom Line

This whey protein isolate from Bulk Supplements is a great budget pick. It's unflavored and offers 26 grams of protein per scoop. There are only two ingredients—whey protein isolate and sunflower lecithin—so you don't have to worry about any fillers.

Bulking, slimming down, or simply getting enough protein doesn’t have to be costly, thanks to Bulk Supplements Whey Protein Isolate. Also, as a gluten-free whey protein isolate, it’s a viable option for sensitive tummies—unless you’re strictly dairy-free or vegan. 

Protein data testing from third-party lab for Bulk Supplements whey protein isolate
GGR collaborated with Ellipse Analytics, an accredited third-party lab, to test more than 150 protein powder products. We screened for dozens of factors and rated each product against its peers. Excellent indicates the top 10% of products; Above Average is the top 25% of products; and Meets Standard is the top 50% of products tested.

The whey protein isolate is unflavored, so there’s no worry about any added sugars, artificial sweeteners, and other additives and fillers. And providing 26 grams of protein with virtually no carbs and fat, it’s a great option to sneak in extra protein, whether blended as a protein shake or mixed into your favorite baked goods. We like this versatility! Although, if you’re used to shaking a protein shake with water as a convenient to-go option, this probably won’t be your best bet.

All Bulk Supplements are manufactured according to cGMP Standards to ensure the highest quality for manufacturing, packaging, labeling, and holding operations. Products are also third-party tested throughout production to ensure compliance, standards, and consistency.

GGR’s own testing of more than 150 protein powders with independent accredited lab Ellipse Analytics also showed great results for Bulk Supplements whey protein isolate, providing it with an overall rating of Excellent. This means it was in the top 10% of products we tested for label accuracy and purity. Find out more about what we tested for in our Independent Supplement Testing Glossary.

Type of ProteinWhey protein isolate
Protein Content (per serving)26 g per 4 Tbsp
Flavor(s)Unflavored 
Cost$33.96/33 = $1.03/serving

Best Organic Protein Powder for Sensitive Stomachs: Transparent Labs Vegan Protein Powder

Good for: Anyone who prefers organic and/or vegan supplements

Best Organic

Transparent Labs Organic Vegan Protein Powder

GGR Score: 3.4 starstarstarstarstar

Product Highlights

  • A rice and pea protein powder 
  • Rated with 4.3 stars on their website
  • Comes in 2 flavors 
  • 24 g of protein per serving
  • Organic product with minimal ingredients

Pros & Cons

Pros

  • No artificial sweeteners, colors, or preservatives
  • Organic and vegan
  • Only 5-7 ingredients
  • Reviewers love the taste
  • 24 g of protein per serving

Cons

  • Only 2 flavors
  • Stevia can cause GI issues for some
  • Expensive

Bottom Line

This organic rice and pea protein powder is a good choice for people who want a clean plant-based protein option with minimal ingredients.

Not only is Transparent Labs the best organic protein powder for sensitive stomachs, but it’s the best organic protein powder all around. It sports the USDA Organic Seal, showing us it meets strict organic standards set by the United States Department of Agriculture. 

Transparent Labs also already topped our list for its grass-fed whey protein isolate powder, but this go-round welcomes a vegan alternative formulated with rice and pea protein. And if you’re worried about the plant-based blend lacking protein integrity, let’s discuss why you shouldn’t be. 

While vegan proteins are often low in lysine, an essential amino acid, rice protein has some of the highest lysine contents. Research9 also tells us organic brown rice protein isolate can be used instead of animal and dairy-based options without losing essential nutrient value. Also, compared to other animal-derived and commercially available proteins, a study in the Nutrition Journal10 suggests rice protein isolate can improve body composition and exercise performance.

Transparent labs Vegan Protein 1

Moreover, research11 supports that pea and rice proteins are promising allergen-friendly proteins. Rice protein12 is also considered an easily accessible protein source and an alternative to animal-based and gluten-containing protein.

And recall all Transparent Lab products are free of “artificial junk” like artificial sweeteners, coloring, and preservatives. You can also view the Certificate of Analysis, conducted by a third-party lab, of any Transparent Labs product conduct.

One downside is the flavor, which product tester and GGR editor Frieda Johnson says tastes kind of artificial—at least the French Vanilla flavor she tried. She thinks it may be the stevia that she’s tasting, as she’s known to be sensitive to it and dislikes the flavor. 

Check out our full Transparent Labs vegan protein review for our comprehensive thoughts on this protein powder option.

Type of ProteinRice protein, pea protein isolate 
Protein Content (per serving)24 g per 1 scoop
Flavor(s)Chocolate, French Vanilla
Cost$49.99/30 = $1.67/serving

Best Protein Powder for Athletes with Sensitive Stomachs: Onnit Grass-Fed Whey Protein

Good for: Competitive athletes (and any consumers, really) who need a trusty protein without questionable substances 

Best for Athletes

Onnit Whey Protein

GGR Score: 4 starstarstarstarstar

Product Highlights

  • Sourced from New Zealand grass-fed cows
  • Made with whey protein isolate to filter out fats and carbs
  • Offers a complete amino acid profile
  • Website offers a subscription option to save money and auto-ship

Pros & Cons

Pros

  • Low in carbs
  • High in leucine
  • Whey isolate gets to muscles faster
  • Non-GMO

Cons

  • High cost per serving
  • Can cause digestive issues for some people
  • The Mexican Chocolate flavor has mixed reviews

Bottom Line

Onnit Whey Protein is a great protein option for those looking for a grass-fed protein, however there are cleaner grass-fed protein powders on the market that are lower in cost.

Calling all athletes with sensitive stomachs! (Or really anyone searching for a grass-fed whey protein isolate powder…) Onnit Grass-Fed Whey Protein is Informed-Sport certified, meaning it’s been rigorously tested for banned substances before being available to purchase by athletes and the masses. 

Whether you opt for Vanilla or Mexican Chocolate, each scoop of Onnit provides 20 grams of protein sourced from whey protein isolate. The virtually lactose-free and gluten-free protein may make it easier to digest.

Moreover, Onnit sources their dairy from New Zealand cows (like Xwerks Grow) that can freely roam and graze the pasture. Also, rest any concerns about hormones and antibiotics in the dairy. 

In addition to high-quality protein, Onnit’s whey isolate provides a digestive enzyme blend to aid digestion. It also supplies probiotics to support immune and gut health, although we still recommend checking out the best probiotics to address your targeted needs.

An image of Onnit grass-fed whey

GGR staff writer and expert product tester Amanda Capritto says, “The Mexican Chocolate actually tastes different from other chocolate protein powders, which I honestly wasn’t expecting. It’s rich when mixed with whole or oat milk.”

Our Onnit grass-fed whey isolate review will provide more of our thoughts on this product if you’re intrigued.

Type of ProteinGrass-fed whey protein isolate
Protein Content (per serving)20 g per 1 scoop
Flavor(s)Mexican Chocolate, Vanilla
Cost$59.95/30 servings = $2.00/serving

Best Unflavored Protein Powder for Sensitive Stomachs: Now Sports Whey Protein Isolate

Good for: Sneaking in tasteless protein without committing to one flavor

Best Unflavored

NOW Sports Whey Protein Isolate

GGR Score: 4.03 starstarstarstarstar
Community Score: 5 starstarstarstarstar

Product Highlights

  • 25 g of whey protein isolate per serving 
  • NPA A-rated GMP certified 
  • No artificial colors, flavors, or additives
  • Packaged in the USA

Pros & Cons

Pros

  • No additives
  • Pure protein isolate
  • Budget friendly
  • Mixes well

Cons

  • Some reports of a sour aftertaste
  • Some users complained of missing scoopers

Bottom Line

NOW Sports Whey Protein Isolate is an unflavored protein which delivers 25 grams of protein per serving along with a good profile of BCAAs.

If you’re searching for a reputable, unflavored whey protein isolate, your hunt stops now! NOW Sports Whey Protein Isolate provides 25 grams of protein with less than 1 gram of carbs and fat.

The unflavored powder is free of added sugars and artificial ingredients, making it a great option for those sensitive to artificial sweeteners. But we must point out that NOW Sports whey protein isolate also comes in Chocolate and Vanilla flavors that contain xanthan gum and xylitol, which could spark some tummy troubles. 

Formulation aside, the protein powder is Informed-Sport certified, telling us it’s free of over 220 banned substances by many major athletic organizations. It’s also packaged and quality tested in U.S.-based, GMP-certified facilities.

An image of NOW sports whey protein isolate

While the protein powder is not manufactured with common food allergens, like wheat and gluten, it is also important to note that it is produced in a GMP facility that processes other products with these ingredients. This is important for anyone allergic or sensitive to certain allergens, as there’s a risk for cross-contamination. 

This protein made our list of best-tasting protein powders, which is pretty impressive for an unflavored protein. You can read more details about this protein powder in our comprehensive NOW Sports whey protein isolate review.

Type of ProteinWhey protein isolate
Protein Content (per serving)25 g per 1 scoop
Flavor(s)Unflavored 
Cost$72.81/81 servings = $0.90/serving 

Best Whey Protein Powder for Sensitive Stomachs: Kaged Whey Protein Isolate

Good for: Anyone searching for an ultra-pure whey protein powder 

Best Whey

Kaged Whey Protein Isolate

GGR Score: 4.5 starstarstarstarstar

Product Highlights

  • Whey protein isolate
  • 25 grams of protein per serving
  • Available in 3 flavors
  • Third-party tested

Pros & Cons

Pros

  • Affordable
  • Good macro profile
  • Reviewers claim it's easy on the stomach
  • Tastes good

Cons

  • Clumpy when mixed
  • Certain flavors out of stock frequently
  • Only 3 flavors available

Bottom Line

Kaged Whey Protein Isolate is a fast-digesting protein available in five flavors with 25 grams of protein per serving.

If you’re looking for “the clean way to build muscle,” Kaged Whey Protein Isolate is ready to be unleashed. The whey protein isolate is ultrafiltered, so what’s left is a pure protein with minimal fat and lactose. 

kaged protein powder

The whey protein isolate also contains ProHydrolase®, a digestive enzyme blend, to aid digestion and absorption. Moreover, a 2020 study published in Sports13 found that adding ProHydrolase® to whey protein may elevate amino acids 30 and 180 minutes post-ingestion compared to whey alone. 

The scorecard for third-party testing of Kaged whey isolate protein
GGR collaborated with Ellipse Analytics, an accredited third-party lab, to test more than 150 protein powder products. We screened for dozens of factors and rated each product against its peers. Excellent indicates the top 10% of products; Above Average is the top 25% of products; and Meets Standard is the top 50% of products tested.

There are four flavors to choose from (GGR editor and expert product tester Nicole Davis said the chocolate flavor reminded her of a Carnation Instant Breakfast mix—in a good way), all free from gluten, GMOs, and artificial flavors and colors. However, they contain a gum blend and non-nutritive sweeteners, which may cause digestive distress in some individuals—keep that in mind.

But to end on a high note, Kaged Whey Protein Isolate is third-party tested and banned substance free by Informed Sport. To boot, GGR did its own independent testing with third-party accredited lab Ellipse Analytics to test for label accuracy and purity, and Kaged whey isolate achieved a Meets Standard rating overall. This means it was in the top 50% of the products we tested and met our rigorous quality standards.

We gave you the cliff notes here, but you can read more about this product in our full Kaged Whey Protein Isolate review.

Type of ProteinWhey protein isolate
Protein Content (per serving)25 g per 1 scoop
Flavor(s)Chocolate, Chocolate Peanut Butter, S’mores, Vanilla
Cost$59.99/44 servings = $1.36/serving

Other Protein Powder for Sensitive Stomachs We Tried

Curious about other protein powders for sensitive stomachs? We also tried the below options and think they’re worth trying out, even though they didn’t make this list:

How We Picked and Tested the Best Protein Powder for Sensitive Stomachs

When searching for the best protein powders for sensitive stomachs, our team of dietitians and nutrition experts reviewed the following: 

  • Protein content: While it goes without saying, we’ll say it anyway… A solid protein powder should be high in protein, and our top picks contain at least 20 grams of protein with little to no carbs and fat. 
  • Protein source options: Here’s the thing about protein powder for sensitive stomachs—one product may spark digestive distress for one person but not for the next. So whether you’re looking for a low-lactose, gluten-free, or plant-based product, we included various protein sources in hopes there’s an option for all. 
  • Additional ingredients: If the protein powder contains additional ingredients, we’re always inspecting their logic—like adding digestive enzymes and fruit and veggie blends. We also strive to find protein powders without belly-bloating ingredients like artificial sweeteners.
  • Flavor variety: From Blueberry Muffin to Cinnamon French Toast to Chocolate, we aimed to capture a flavor favorite to tickle everyone’s fancy, and unflavored options for those who’d prefer a stealthy way to sneak in protein. 
  • Cost: Because we truly believe everyone should have access to supplements if they can help them reach their fitness and health goals, our top pick lists accommodate a range of budgets. 
  • Third-party testing: We always prioritize products that undergo rigorous third-party testing—like being Informed-Sport or NSF Certified for Sport certified. 
  • Brand transparency and loyalty: We pride ourselves on our honest reviews, and we build trust in brands that are transparent and loyal, as well. This said, we analyze the brand behind the product from top to bottom and side to side—like reviewing their company’s mission statement, customer support access, and any available customer reviews. 

Benefits of Protein Powder for Sensitive Stomachs

Some benefits are obvious *cough* being gentle on the belly *cough* but others, not so much. Here are the many ways protein powder for sensitive stomachs can benefit your health and lifestyle:

  • Ensures adequate protein intake, especially if you aren’t consuming a diet rich in high-protein foods
  • Lowers the risk of digestive distress
  • Helps build lean muscle mass while aiding muscle recovery
  • Supports body composition goals, including weight loss and muscle growth
  • Offers the ultimate convenience since it’s shelf-stable and requires no refrigeration like other common sources of protein 
  • Promotes overall health and wellness, as protein is an essential macronutrient needed in large amounts

Dosing and Interactions 

Benefits of protein top of mind, you might now wonder, “How much protein do I need?” 

While daily protein needs vary based on age, birth sex, activity level, and other factors, the recommended dietary allowance (RDA) for adults is 0.8 grams of protein per kilogram of body weight per day (g/kg/d). For someone who weighs 170 pounds, or 77 kilograms, this amounts to about 60 grams of protein per day. 

However, credible organizations—like the Academy of Nutrition and Dietetics, American College of Sports Medicine, and International Society for Sports Nutrition—encourage adults to consume 1.2 to 2.0 g/kg/d to support muscle recovery and performance. Using the same 170-pound individual, their daily protein target could range from 92 to 154 grams per day. 

A man standing in a gym is drinking from a shaker bottle.

It’s also important to note that if you already get enough protein through high-protein whole foods, you probably don’t need to supplement. If not, you might consider supplementing with protein powder that aligns with your tummy tolerance.

Moreover, protein powders are generally considered safe with little risk of interactions. However, especially if you’re taking medication and/or managing a health condition, you should ensure that the protein powder of choice will not lead to any interactions or adverse effects. For instance, whey protein may interfere with the absorption of Levodopa and some antibiotics.

We recommend consulting with a dietitian or another healthcare professional to guide your protein needs and possible interactions. Their expertise can help you find a safe and effective protein powder that best aligns with any dietary restrictions and/or preferences.

Third-Party Testing

The FDA might not tightly regulate dietary supplements, but it does establish Current Good Manufacturing Practices (cGMPs) standards for quality assurance we recommend looking out for. 

Companies can also voluntarily have their supplement undergo third-party testing, which helps verify the products’ purity and overall safety. Reputable, third-party testing stamps we trust include: 

  • Informed-Sport 
  • Labdoor
  • National Sanitation Foundation (NSF)
  • NSF Certified for Sport

Supplements may also have certifications related to specific dietary restrictions and preferences, like being USDA Organic. If you ever doubt third-party certifications, consider contacting the company for more information or select another trusted product—there are many great ones on this very list!

Buying Guide: What to Look for in Protein Powder for Sensitive Stomachs

While all the protein powders we reviewed are great options, finding the best one for you is nuanced based on your dietary needs. Before checking out your online cart, ensure it factors in and checks most (if not all) of these boxes:

  • Protein content: Choose a protein powder that supplies at least 20 grams of protein per serving. Also, plant-based protein powders tend to be naturally lower in protein than whey-based options, although you can always bump up the portion (as tolerated) to meet your needs.
  • Protein source: Go with a protein source that best suits your dietary needs and preferences, including a whey protein isolate or plant-based option if you’re sensitive to dairy and a gluten-free product if managing celiac disease. 
  • Additional ingredients: While the protein source and content should be the highlight, some protein powders contain ingredients—like digestive enzymes and probiotics—to enhance the digestibility and overall benefit of the blend. Also steer clear of artificial sweeteners, along with other preservatives and fillers, particularly if you have a sensitive stomach. 
  • Dietary restrictions and preferences: Choose a product that factors your dietary restrictions and preferences, such as lactose-free, gluten-free, vegan, or organic. 
  • Third-party certifications: Prioritize third-party products tested by reputable organizations such as USP and NSF International. Also double-check to see if the product is third-party tested and manufactured in NSF-certified, FDA-inspected, and/or cGMP-compliant facilities. 
  • Flavor: Grab a flavor that suits how you’ll enjoy it most, whether that’s Strawberry blended into a fruit smoothie, Vanilla baked into treats, or Cinnamon Cereal to sip on its own. If you’d prefer a sneaky protein boost, an unflavored option might suit you best.  
  • Budget: Evaluate how much you’re willing to spend on protein powder. And pro tip: Take advantage of subscribe and save deals (if you’re confident in the product, that is).
  • Brand integrity: Of course, how you feel about a brand is completely personal, but we recommend reviewing the brand of interest before supporting them with your hard-earned dollars. Areas to check out include a company’s mission statement, core values, and any available reviews on its main side or third-party sellers like Amazon. 

FAQs About Protein Powder for Sensitive Stomachs

What protein powder is easiest on the stomach?

While no universal protein powder is best for sensitive stomachs, one free of artificial sweeteners and other additives is generally less likely to cause digestive issues. You should choose a protein powder that suits your dietary restrictions and preferences. For instance, a whey protein isolate or plant-based protein might be better tolerated than whey protein concentrate or casein in individuals with lactose intolerance.

What kind of protein powder is best for IBS?

While dietary needs are individualized for those living with IBS, general recommendations include limiting or avoiding products with sugar alcohols, dairy, and gluten. Therefore, a gluten- and lactose-free protein powder—like whey protein isolate or a plant-based option—without sugar alcohols or other artificial sweeteners might be best for IBS.

Why do protein shakes upset my stomach?

A protein shake can cause an upset stomach based on many factors, including drinking too quickly or consuming a protein powder that doesn’t accommodate your dietary restrictions. Trial another protein powder that best suits your needs—like one without artificial sweeteners, lactose, and gluten—and consult a healthcare professional for additional guidance.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any diseases.

References

  1. Kadam B, Ambadkar R, Rathod K, et al. Health Benefits of Whey: A Brief Review. Int J Livest Res. 2018;8(5):31. doi:https://doi.org/10.5455/ijlr.20170411022323
  2. Duarte NM, Cruz AL, Silva DC, et al. Intake of whey isolate supplement and muscle mass gains in young healthy adults when combined with resistance training: a blinded randomized clinical trial (pilot study). J Sports Med Phys Fitness. 2020 Jan;60(1):75-84. doi: 10.23736/S0022-4707.19.09741-X. Epub 2019 Sep 23. PMID: 31565912.
  3. EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS), Mortensen A, Aguilar F, et al. Re-evaluation of xanthan gum (E 415) as a food additive. EFSA J. 2017;15(7):e04909. Published 2017 Jul 14. doi:10.2903/j.efsa.2017.4909
  4. Layman DK, Lönnerdal B, Fernstrom JD. Applications for α-lactalbumin in human nutrition. Nutr Rev. 2018;76(6):444-460. doi:10.1093/nutrit/nuy004
  5. Justiz Vaillant AA, Jamal Z, Patel P, et al. Immunoglobulin. 2023 May 26. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan–. PMID: 30035936.
  6. Berrazaga I, Micard V, Gueugneau M, et al. The Role of the Anabolic Properties of Plant- versus Animal-Based Protein Sources in Supporting Muscle Mass Maintenance: A Critical Review. Nutrients. 2019;11(8):1825. Published 2019 Aug 7. doi:10.3390/nu11081825
  7. Dotto JM, Chacha JS. The potential of pumpkin seeds as a functional food ingredient: A review. Sci Afr. 2020;10:e00575. doi:https://doi.org/10.1016/j.sciaf.2020.e00575
  8. Grancieri M, Martino HSD, Gonzalez de Mejia E. Chia Seed (Salvia hispanica L.) as a Source of Proteins and Bioactive Peptides with Health Benefits: A Review. Compr Rev Food Sci Food Saf. 2019;18(2):480-499. doi:https://doi.org/10.1111/1541-4337.12423
  9. Kalman DS. Amino Acid Composition of an Organic Brown Rice Protein Concentrate and Isolate Compared to Soy and Whey Concentrates and Isolates. Foods. 2014;3(3):394-402. Published 2014 Jun 30. doi:10.3390/foods3030394
  10. Joy JM, Lowery RP, Wilson JM, et al. The effects of 8 weeks of whey or rice protein supplementation on body composition and exercise performance. Nutr J. 2013;12(1). doi:https://doi.org/10.1186/1475-2891-12-86
  11. Zhao H, Shen C, Wu Z, Zhang Z, Xu C. Comparison of wheat, soybean, rice, and pea protein properties for effective applications in food products. J Food Biochem. 2020;44(4). doi:https://doi.org/10.1111/jfbc.13157
  12. Jayaprakash G, Bains A, Chawla P, et al. A Narrative Review on Rice Proteins: Current Scenario and Food Industrial Application. Polymers (Basel). 2022;14(15):3003. Published 2022 Jul 25. doi:10.3390/polym14153003
  13. Townsend JR, Morimune JE, Jones MD, et al. The Effect of ProHydrolase® on the Amino Acid and Intramuscular Anabolic Signaling Response to Resistance Exercise in Trained Males. Sports (Basel). 2020;8(2):13. Published 2020 Jan 22. doi:10.3390/sports8020013

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