REVIEW: ONE Bars Protein Bar

February 27, 2024
REVIEW: ONE Bars Protein Bar

In my quest to find the best protein bar on the market, today I’m breaking down ONE Bars Peanut Butter Cup Protein Bar.

But first things first…

Who is ONE Bars?

According to their website:

It seems like every day a new better-for-you snack pops up on the market, but we weren’t born yesterday. And we’re not jumping on some new protein or energy bar fad. ONE Brands, formerly known as Oh Yeah! Nutrition, was founded in 1999 by Ron McAfee. With roots in sports nutrition, ONE has always been a protein snack bar pioneer with a singular mission: exceptional taste, texture and ingredients with zero compromises and even fewer regrets. Learning from one project to the next, Ron ultimately developed what has become known as the ONE Bar.

Doesn’t it feel like almost every company has the same core beliefs? Every single one of them focuses on taste, texture and “quality” ingredients. Some even say stuff like no HFCS and no ingredients that you can’t pronounce. (And then add corn syrup to their bars.)

And yet their ingredient lists look like they only care about their bottom line. I think I’m giving too much away in the intro.

So, does ONE Bars make high quality, clean protein bars?

Well… only one way to find out.

ONE Bars Ingredients 

ONE Bars says: 

“Two more great things [the bar] combines? 20 grams of protein with just 1 gram of sugar. It’s made to power your workouts, mornings, all-day meetings or afternoon slump pick-me-ups.” 

But is that really the case?

Probably. But their ingredient list will tell us the true story.

Let’s ignore the Nutrition Facts for a… wait why do they have a marketing message in their nutrition label? 

I mean I know this is part of their product slides but still. My guess is to distract us from the truth we’re about to uncover in the small print just below the large marketing jargon. Anyway, let’s just focus on the long list of ingredients. 

I immediately see milk protein isolate, vegetable fiber, and… is that glycerin? Why is glycerin the third ingredient in a protein bar? Usually brands chuck it in at the end because of how little glycerin they use. I guess that’s not the case here.

If only there were a better way to create protein bars that aren’t just candy bars in disguise. (Foreshadowing)

So, let’s break these ingredients down into an easy to read list.

  1. Protein Blend (Milk Protein Isolate, Whey Protein Isolate)
  2. Soluble Vegetable Fiber
  3. Vegetable Glycerin
  4. Isomalto-Oligosaccharides (Vegetable Source)
  5. Palm Kernel Oil
  6. Maltitol
  7. Peanut Flour
  8. Peanut Butter
  9. Milk Protein Concentrate
  10. Peanuts
  11. Natural Flavors
  12. Cocoa Powder (Processed With Alkali)
  13. Calcium Caseinate
  14. Soy Lecithin (An Emulsifier)
  15. Sea Salt

As might already know, the FDA requires food manufacturers to list their ingredients in order by weight.

Which means that the ONE Bars Peanut Butter Cup Protein Bar is filled with protein! 

That’s a great start, but what about the rest of the ingredients?

ONE Bars Milk Protein Isolate

Milk protein isolate is a blend of casein and whey proteins in the ratio of cow’s milk. So, most of it is casein (around 80%).

The only reason to use milk protein isolate over whey protein or other protein sources is because it’s cheap — likely sourced from industrial dairy cows pumped full of synthetic hormones, treated inhumanely, and with an unnatural diet — all of which are a problem for both your health and planetary wellness.

Milk protein isolate isn’t for people with a cow’s milk protein allergy. It’s also not for people who are lactose intolerant.

Neither is it for vegans or people on plant based diets.

So, is it the best option?

Not really.

But still better than soy protein.

Where Did The Fiber Go, ONE Bars?

This is the first time we’re gonna go into fiber.

Because ONE Bar is using fiber twice, but has nothing to show for in their label.

Let me explain.

The second ingredient in the ONE Bar is Soluble Vegetable Fiber. This is used just to add fiber to packaged food by manufacturers. There’s no nutritional value, except they should feed your gut bacteria and keep you full for longer.

But where does this fiber come from? Which vegetable is ONE Bar getting their fiber from?

This mystery source of fiber is just one part of the problem with ONE Bar.

They also use Isomalto-Oligosaccharides (IMO) — which can be used either as fiber or as a sugar substitute (or both) because it is digested slowly by our body. And this is the fourth ingredient in the list.

So much fiber!

But not really.

Before the FDA changed the regulation on how IMOs are labeled, brands used to be able to just hide them on the label and count them as fiber. But the science finally caught up to the marketing.The body actually treats this like sugar instead of having the gut-boosting benefits of fiber.

The second and fourth ingredient in the label being fiber means that there should be a LOT of fiber in the bar. But… we don’t see that.

We see 24 grams of carbs with 8 grams of fiber. 

24 grams is almost half the protein bar (60 grams). So, if the 8 grams of fiber comes from the vegetable fiber, where do the rest of the 16 grams of carbs come from?

I’m going to guess it’s a combination of the vegetable fiber, glycerin, and the IMO. But that’s still a lot of carbs considering ONE Bars’ entire marketing message is 20 grams of protein and 1 gram of sugar.

There’s 16 grams of sugar in this bar.

Just because they call it carbohydrate, doesn’t mean it doesn’t break down into sugar. It also doesn’t mean that these are high quality sources of carbs. They’re not.

So Much Glycerin in ONE Bars

The third ingredient is… glycerin? 

Why is there so much glycerin in this protein bar? 

You might have heard of glycerin as a skin care ingredient, which it is. But it’s also used as a food additive.


Well, glycerin helps preserve moisture, prevents sugar crystallization, and adds bulk, smoothness, softness, sweetness, and texture to foods. And it’s also a sugar alcohol just like maltitol. Which means it can also give you gut problems like maltitol if you eat too much of it.

I’m going to assume there’s at least 7 grams of glycerin in this bar considering there’s at least 8 grams of fiber — which is TOO MUCH glycerin!

ONE Bars Palm Oil

Palm oil is the cheapest oil you can buy. This is the reason why almost all long shelf life packaged food has palm oil as the source of fat.

Growing palm oil is destroying the habitat of endangered species such as Orangutan, pygmy elephant and Sumatran rhino. Which is why sustainable sources of palm oil are so important — to prevent deforestation and ensure quality.

But ONE Bar doesn’t use sustainable palm oil. They’d mention it on the label if they did.

With 9 grams of fat, there’s at least 5 grams of palm oil in this bar. Because there’s 5 grams of saturated fat in this bar.

The point is, that there are so many better choices of fat out there, that using the cheapest one you can find while you say that your bars are “super nutritious and totally delicious” doesn’t exactly make sense.

They could have chosen to go the extra mile to source organic MCT oil (from coconuts) which would have been a healthier and more sustainable alternative to palm oil.

Sugar Alcohol in ONE Bars 

Did you notice the ingredient after palm oil?

I’ll give you a hint: 

It’s sugar (alcohol)!

Maltitol is a sugar alcohol that companies use to sweeten their products without using sugar. It has fewer calories and a lower GI than sugar but just like sugar, it doesn’t have any nutritional value. 

Basically junk.

But maltitol has another problem: diarrhea.

According to this 2019 paper: “the excessive consumption of polyols causes gastrointestinal symptoms and laxative effects in healthy patients.”

So, eating a little bit of maltitol might be fine. But eating too much will definitely cause a lot of gas, and maybe diarrhea.

Bottom line: not great for your gut.

The bigger problem with sugar alcohols is really with regular, recurring use. They have been shown to disrupt the good bacteria in your gut, which in turn disrupts health…a healthy microbiome is key to a highly functional immune system and plays a central role in overall health.

ONE Bars Final Verdict

ONE Bars Peanut Butter Cup Protein Bar contains ingredients in never before seen compositions. How is there so much vegetable fiber and glycerin in just one protein bar? These are ingredients you should see at the bottom of the label.

Plus eating so much of them is a huge problem. 

Even though the milk protein is cheap it’s still the best ingredient on this protein bar.

Which is exactly why I can’t recommend ONE Bars to you. 

But if you’re looking for a real protein bar without sugar alcohols and sourced from 100% real food ingredients, see below. 👇

Tejesh Reddy

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