Why Protein Drinks Need Sweeteners

Protein, in its unsweetened form, ranges from neutral to actively unpleasant in taste. Whey protein has a slightly milky, sometimes chalky flavor. Collagen peptides are relatively neutral but can have faint savory notes. Neither tastes like something you would voluntarily drink on its own.

To make protein drinks palatable and enjoyable enough for daily consumption, manufacturers must add flavoring and sweetness. The options are limited:

• Sugar: Provides familiar sweetness and mouthfeel but adds significant calories (4 calories per gram), spikes blood glucose, and undermines the health and fitness goals that drive most people to protein drinks in the first place.
• Non-nutritive sweeteners: Provide sweetness with zero or near-zero calories and minimal to no blood sugar impact. These include both artificial sweeteners (sucralose, acesulfame potassium) and natural zero-calorie sweeteners (stevia, monk fruit).
• Sugar alcohols: Provide sweetness with fewer calories than sugar and reduced glycemic impact. Erythritol is the most common in protein drinks.
• Rare sugars: Allulose is a naturally occurring sugar with approximately 10 percent of the calories of regular sugar and negligible glycemic impact.

For a protein drink targeting health-conscious consumers who want zero sugar and low calories, non-nutritive sweeteners are not optional. They are the only viable path to a product that tastes good enough to drink daily while maintaining the nutritional profile that makes it functional.

The Major Sweeteners in Protein Drinks

Sucralose

Sucralose is a modified sugar molecule that is approximately 600 times sweeter than sugar. It is made by replacing three hydroxyl groups on a sucrose molecule with chlorine atoms, creating a compound that the body largely does not metabolize. Approximately 85 percent of consumed sucralose passes through the body unchanged.

Sucralose is the most widely used sweetener in protein drinks due to its clean taste profile, heat stability, and lack of bitter aftertaste. It provides zero calories and does not raise blood sugar or insulin levels in most studies.

The research profile on sucralose is extensive. It has been reviewed and approved by the FDA, European Food Safety Authority, World Health Organization, and over 80 other regulatory bodies. More than 110 safety studies were reviewed prior to its original FDA approval. Concerns raised in some recent studies about gut microbiome effects have been noted by researchers, though the doses used in these studies often far exceed typical human consumption levels. At the amounts found in one or two protein drinks per day, the evidence base supports safety.

Stevia (Steviol Glycosides)

Stevia sweeteners are extracted from the leaves of the Stevia rebaudiana plant, native to South America. The sweet-tasting compounds are steviol glycosides, with rebaudioside A (Reb A) and stevioside being the most commercially significant. Stevia is approximately 200 to 300 times sweeter than sugar.

Stevia is popular among consumers seeking “natural” sweetener options. It provides zero calories, does not raise blood sugar, and some studies suggest it may have mild blood-pressure-lowering effects. The primary drawback is taste: stevia can have a bitter or licorice-like aftertaste, particularly at higher concentrations. This is why many products use stevia in combination with other sweeteners to achieve a more balanced flavor profile.

Stevia has GRAS (Generally Recognized as Safe) status from the FDA for high-purity steviol glycosides. The European Food Safety Authority has set an acceptable daily intake of 4mg per kilogram of body weight, well above what typical consumption of stevia-sweetened beverages would provide.

Monk Fruit (Luo Han Guo)

Monk fruit extract comes from the Siraitia grosvenorii fruit, cultivated in southern China for centuries. The sweet compounds are mogrosides, with mogroside V being the primary sweetening agent. Monk fruit extract is approximately 150 to 200 times sweeter than sugar.

Monk fruit is increasingly popular as a natural, zero-calorie sweetener with a relatively clean taste profile. It does not raise blood sugar and has no known adverse effects at typical consumption levels. Some research suggests mogrosides may have antioxidant and anti-inflammatory properties, though these findings are preliminary.

Monk fruit extract has GRAS status from the FDA. Its primary limitation is cost, as it is significantly more expensive than sucralose or stevia, which is why it appears more often in premium products or in combination with other sweeteners.

Erythritol

Erythritol is a sugar alcohol naturally found in small amounts in fruits and fermented foods. It provides approximately 70 percent of the sweetness of sugar at about 0.2 calories per gram (compared to sugar’s 4 calories per gram). Unlike other sugar alcohols (sorbitol, maltitol, xylitol), erythritol is absorbed in the small intestine and excreted largely unchanged by the kidneys, which means it rarely causes the digestive distress associated with other sugar alcohols.

Erythritol has a cooling sensation in the mouth and is often combined with high-intensity sweeteners like stevia or monk fruit to provide bulk and mouthfeel while the other sweetener provides the primary sweetness. It does not raise blood sugar or insulin levels.

A 2023 study published in Nature Medicine raised concerns about erythritol and cardiovascular risk markers. However, the study was observational and measured blood levels of erythritol (which the body produces naturally) rather than directly linking supplemental consumption to adverse outcomes. The research community has noted significant limitations in the study design, and regulatory bodies have not changed their safety assessments. At the amounts typically found in protein drinks, erythritol remains within established safe consumption guidelines.

Acesulfame Potassium (Ace-K)

Acesulfame potassium is approximately 200 times sweeter than sugar. It is often used in combination with other sweeteners because it has a rapid onset of sweetness that can mask the slower onset of other sweeteners, creating a more sugar-like taste experience. On its own, Ace-K can have a slightly bitter aftertaste at high concentrations.

Ace-K is calorie-free, does not raise blood sugar, and is not metabolized by the body. It has been approved by the FDA since 1988 and has been reviewed by numerous international regulatory bodies. Over 90 studies were evaluated as part of its safety assessment.

Allulose

Allulose is a rare sugar naturally present in small quantities in figs, raisins, wheat, and maple syrup. It has approximately 70 percent of the sweetness of sugar but provides only about 0.2 to 0.4 calories per gram. What makes allulose unique among sugars is that it is absorbed by the body but not metabolized for energy, meaning it has a negligible effect on blood glucose and insulin.

Allulose has attracted significant interest because it behaves like sugar in terms of taste and cooking properties while having minimal metabolic impact. Some research suggests it may even have beneficial effects on blood glucose regulation. The FDA does not require allulose to be listed as a sugar on nutrition labels, recognizing its distinct metabolic profile.

Sweetener Combinations: Why Brands Blend

Most protein drinks use combinations of sweeteners rather than a single sweetener. This is not about cutting costs. It is about taste optimization. Each sweetener has a distinct sweetness profile (onset speed, peak intensity, duration, aftertaste) and combining them creates a more balanced, sugar-like sweetness that no single sweetener achieves alone.

Common combinations include:

• Sucralose + Ace-K: Clean taste with rapid onset and no aftertaste.
• Stevia + erythritol: Natural sweetener profile with added bulk and mouthfeel.
• Monk fruit + erythritol: Natural pairing with complementary sweetness profiles.
• Stevia + monk fruit + erythritol: Triple blend for complex, rounded sweetness.

The sweetener blend a brand chooses reflects both its flavor goals and its positioning in the market. Products marketed as “natural” tend to use stevia, monk fruit, and erythritol. Products prioritizing clean taste above all else often include sucralose. There is no universally “best” sweetener, only trade-offs between taste, naturalness perception, cost, and individual tolerance.

Common Concerns Addressed

Do sweeteners spike insulin? The majority of research shows that sucralose, stevia, monk fruit, and erythritol do not significantly raise insulin levels when consumed in isolation. Some studies have found that consuming sweet-tasting beverages alongside carbohydrate-rich meals may modestly amplify the insulin response, but this effect is inconsistent across studies and sweetener types. In the context of a zero-sugar protein drink consumed on its own or as a snack, the insulin concern is not supported by the evidence.

Do sweeteners affect gut bacteria? This is an area of active research. Some animal studies have shown changes in gut microbiome composition at very high sweetener doses. Human data is more limited and less consistent. The doses used in animal studies often correspond to daily consumption levels far exceeding what you would get from one or two protein drinks. Monitoring this research is reasonable, but the current evidence does not support avoiding sweeteners at typical consumption levels based on microbiome concerns.

Do sweeteners increase cravings for sweet foods? The “sweetness without calories tricks the brain into craving more sweets” hypothesis has been studied extensively. Results are mixed. Some studies find no effect on subsequent food intake; others find a modest increase in sweet cravings in certain populations. The practical reality is that replacing a 27g-sugar energy drink with a zero-sugar protein drink reduces total sugar intake dramatically, regardless of any theoretical cravings effect.

How Prox Approaches Sweetening

Prox achieves its 0g sugar, 90-calorie profile through careful sweetener selection designed to deliver clean, enjoyable taste without compromising the functional nutrition that defines the product. The sweetener approach is calibrated to complement the sparkling format and fruity flavor profiles, creating a drinking experience that feels like a premium soda rather than a medicinal protein supplement.

This matters for compliance. The best protein drink in the world is useless if you do not enjoy drinking it. By investing in flavor development and sweetener optimization, Prox ensures that hitting your protein goals with a zero-sugar, 90-calorie beverage is something you look forward to rather than endure.

The Bottom Line

Sweeteners in protein drinks are a necessary component that enables zero-sugar, low-calorie formulations to taste good enough for daily consumption. The major sweeteners used, including sucralose, stevia, monk fruit, erythritol, and allulose, have been extensively studied and approved by regulatory bodies worldwide. No sweetener is perfect, and individual preferences and tolerances vary, but at the consumption levels found in one or two protein drinks per day, the evidence supports safety across the board. The more important question is not which sweetener a protein drink uses but whether the drink effectively delivers on its core promises: high-quality protein, low calories, zero sugar, and a taste profile you will actually stick with.

Try Prox →