Optimum Nutrition Put 8 Grams of Fiber in a 30-Gram Protein Shake. For Once, the Label Checks Out
A new Optimum Nutrition shake appeared on Amazon this month with no press release: 30 grams of protein, 8 grams of fiber, 190 calories. We read the carton the way we read David’s and Genius Gourmet’s. The fiber dose sits inside the range its trials used, the “lactose free” claim has the enzyme to back it, and the two things worth knowing are about evidence quality, not the label.
Optimum Nutrition Ultra-Filtered Milk Protein Shake + Fiber (chocolate, vanilla, strawberry) was on sale on Amazon at $12.99 per four 11 fl oz cartons as of September 18, 2026, with no press release and no listing on the brand's own site. Per 325 mL carton the label images show 190 calories, 2 g fat, 200 mg sodium, 12 g carbohydrate (14 g in chocolate), 8 g dietary fiber (29% DV), 4 g total sugars including 1 g added, 30 g protein and 700 mg calcium; ingredients are ultra-filtered low fat milk, soluble corn fiber, heavy cream, natural flavor, cane sugar, salt, potassium citrate, lactase, cellulose gel and gum, and steviol glycosides. The fiber is soluble corn fiber, a slow-fermenting fiber tolerated in trials at 40 g in a single dose and 65 g across a day; 12 g a day produced mild to moderate symptoms and 20 g a day more flatulence and rumbling. One carton's 8 g is inside the 6 to 18 g a day studied for prebiotic effects, but that evidence is thin: eight adults per group for 14 days, manufacturer-funded, with bifidobacteria rising more at 6 g than at 12 or 18 g. "Lactose free (contains lactase)" is listing language backed by lactase on the ingredient list; at most 3 g of the sugars are milk-derived, against the 12 to 15 g of lactose most people with malabsorption tolerate. Cellulose gum is carboxymethylcellulose, which at 15 g a day for 11 days modestly increased abdominal discomfort and reduced microbiota diversity in a seven-person feeding study; the carton states no amount and rival shakes list the same stabiliser. The listing markets to GLP-1 users while the carton carries the required "Do not use for weight reduction" notice for products that get most of their calories from protein; the two are not in conflict. Educational, not medical advice.
Optimum Nutrition, one of the biggest names in protein powder, has put out a new ready-to-drink shake with almost no noise. There is no press release. It is not on the brand’s own website. A supplement trade site flagged it in late August as coming soon, and within the past month three flavours appeared on Amazon, chocolate, vanilla and strawberry, at $12.99 for four 11-ounce cartons. The front of the pack reads “30G Ultra-Filtered Milk Protein Shake + Fiber,” with a callout for “8g gut-friendly fiber.”
We have spent the month reading protein-shake labels, and most of those reads have turned on a gap: a “lactose-free” claim with no lactase on the list, a fat engineered not to digest, a prebiotic at one thirty-fifth of its studied dose. This one is different, and it is worth saying so plainly. The fiber dose is inside the range that has actually been tested. The lactose claim is backed by the enzyme that makes it true. The sweeteners are declared. There are still things worth knowing, about how thin the evidence for the fiber’s gut benefits is, about a stabiliser that has made headlines, and about a marketing line aimed at people on GLP-1 drugs. But this is a label that mostly does what it says.
The panelWhat one carton contains
| Per container | ON Shake + Fiber | Genius Gourmet | Core Power 26 g | Premier Protein |
|---|---|---|---|---|
| Calories / protein | 190 / 30 g | 170 / 30 g | 170 / 26 g | 160 / 30 g |
| Fiber | 8 g (29% DV) | 0 g | 2 g | 2 g |
| Total / added sugars | 4 g / 1 g | 5 g / 4 g | 5 g / 0 g | 1 g / 0 g |
| Sodium | 200 mg | 380 mg | 260 mg | 230 mg |
| Lactase on the ingredient list | yes | no | yes | no |
| Sweeteners | cane sugar, steviol glycosides | cane sugar, Reb M | sucralose, acesulfame K | sucralose, acesulfame K |
Per 325-millilitre carton, the label images on the listing give 190 calories, 2 grams of fat, 200 milligrams of sodium, 12 grams of carbohydrate (14 in chocolate), 8 grams of dietary fiber, which is 29 percent of the Daily Value, 4 grams of total sugars of which 1 is added, 30 grams of protein, and 700 milligrams of calcium, half a day’s worth. The vanilla ingredients, in order: ultra-filtered low fat milk, soluble corn fiber, heavy cream, natural flavor, cane sugar, salt, potassium citrate, lactase, cellulose gel and gum, and steviol glycosides. Chocolate adds alkalised cocoa; strawberry adds lycopene for colour. Fiber is the second ingredient by weight, ahead of the cream. Set beside its shelf-mates, the difference is that one line: Core Power and Premier Protein each list 2 grams, and Genius Gourmet lists none.
The fiberEight grams of soluble corn fiber, inside the tested range
Soluble corn fiber is corn starch rebuilt so that most of it escapes digestion and reaches the colon, where bacteria ferment it slowly. Slow is the useful word. The reason inulin-based products cause complaints is that inulin ferments fast; this family of fibers does not, and the tolerance data are unusually generous. In a 2012 trial, healthy adults tolerated 40 grams as a single dose and 65 grams spread over a day. A University of Minnesota crossover giving 12 grams a day for two weeks found it “well tolerated, with mild to moderate GI symptoms,” and a trial at 20 grams a day reported more flatulence and stomach rumbling alongside “a mild laxative effect with nominal gastrointestinal tolerance issues.” At 8 grams in one carton, most people will notice nothing. It counts as fiber on the panel under the FDA’s allowance for “resistant maltodextrin/dextrin,” the category the leading manufacturer says its soluble corn fiber falls under.
Most label reads turn on a gap between the claim and the dose. This one does not: 8 grams is inside the range the trials used.
The “gut-friendly” half of the claim, which the listing’s artwork expands to “prebiotic fiber to support gut health,” rests on thinner ground, and the gap here is about evidence quality rather than dose. The main dose-ranging study, published in 2016, gave healthy adults 6, 12 or 18 grams a day for two weeks, with eight people in each group. Bifidobacteria rose at 6 grams, and, oddly, rose more at 6 grams than at 12 or 18; the authors themselves called it “a possible prebiotic effect.” The study was funded by Tate & Lyle, which makes the branded version of the ingredient, as was part of the Minnesota trial. The better-powered work is on something else entirely: two Purdue trials in adolescents found 10 to 20 grams a day improved calcium absorption. Optimum Nutrition does not say who supplies its fiber and does not claim the calcium effect. The fair summary is that the fiber is real, gentle and at a sensible dose, and that “supports gut health” is a reasonable hope rather than a demonstrated result.
The lactaseWhy this “lactose free” is easy to believe
The listing says “Lactose free (contains lactase),” and the ingredient list agrees. That matters because ultra-filtration on its own does not finish the job: removing more than 95 percent of milk’s lactose by filtration takes repeated washing steps, which is why fairlife adds lactase to Core Power and why we asked the question of a shake that did not list it. Lactase splits whatever lactose remains into glucose and galactose, which show up on the panel as sugar. Here that is 3 grams: 4 grams of total sugars minus the 1 gram of added cane sugar. Even if all 3 grams were still lactose, most adults with lactose malabsorption tolerate 12 to 15 grams in a sitting. With the enzyme on the list, it will be far less than 3.
Two things to knowThe stabiliser, and the GLP-1 line
“Cellulose gel and gum” keeps the protein and cocoa from settling. Cellulose gum is carboxymethylcellulose, the emulsifier in a widely covered 2022 feeding study in which seven healthy adults ate 15 grams of it a day for eleven days and showed “modestly increased postprandial abdominal discomfort,” less diverse gut bacteria and lower short-chain fatty acids than nine controls. That trial dosed at a level chosen to test the question, many times what a stabiliser contributes; the carton does not state an amount, and we will not guess one. Premier Protein and Core Power list the same pair. It is a reason to keep an eye on the research, not a reason to pour out a shake.
The listing also pitches the shake as “nutrition support made simple for GLP-1 users,” while the carton itself carries the notice federal rules require on many high-protein products: “Use this product as a food supplement only. Do not use for weight reduction.” The two are not in conflict. The notice is boilerplate triggered by getting more than half of its calories from protein (here, 120 of 190), and the listing promises nutrition, not weight loss. For what it is worth, last year’s joint medical-society advisory on eating during GLP-1 treatment does prioritise protein and fiber, prefers them from food, and notes that high-fiber foods can worsen constipation early in treatment; we walk through that in our guide to fiber on a GLP-1.
So: 30 grams of protein, a fiber dose that matches its studies, an enzyme that backs its lactose claim, 1 gram of added sugar, no artificial sweeteners, and a little less sodium than its rivals, for about $3.25 a carton. Eight grams is more than a quarter of a day’s fiber; our calculator will show you what the rest of your day needs to supply, ideally from plants. Optimum Nutrition had no involvement in this article, which is educational, describes what the cited labels and trials say, and is not medical advice.