Coke Zero Vs. Diet Coke: Flavor, Nutrition, Benefits, Downsides

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Evidence BasedCoke Zero vs. Diet Coke: What’s the Difference?

Medically reviewed by Marie Lorraine Johnson MS, RD, CPT — Written by Shavonne Morrison, MS, RD, LD — Updated on June 20, 2025

Nutrition and ingredients
Taste
Considerations
Which is better?
Tips for cutting back
Bottom line

There isn’t much difference between Coke Zero and Diet Coke. You can drink either coke if you want to reduce your sugar intake, as both of them contain artificial sweeteners.

You’ve likely heard that limiting the amount of added sugar in your diet is important for your health.

People who regularly consume sodas may try switching to sodas made with artificial or non-nutritive sweeteners to reduce their added sugar intake.

These alternatives make products taste sweet but don’t lead to the blood sugar increases that traditional sugar may cause.

Diet drinks are a way to avoid added sugars in beverages, but more recently, sodas with “zero” in their name have hit the market alongside them. Coca-Cola is a popular example of a brand with both “diet” and “zero” varieties.

If you’re wondering about the differences between Coke Zero and Diet Coke — and how to determine which is a better choice for you — read on.

A can of Coke Zero with a dark pink circular background on the left and a can of Diet Coke in the same dark pink circle on the right. The circles are against a lighter pink background.

Nutrition facts and ingredients of Coke Zero and Diet Coke

Below are the ingredients and nutrition facts for both Coke Zero and Diet Coke. In this section, we’ll break down some of the key differences and similarities you may want to consider.

Coke Zero nutrition facts

Coke Zero’s ingredients include:

carbonated water
caramel color
phosphoric acid
aspartame
potassium benzoate (to protect taste)
natural flavors
potassium citrate
acesulfame potassium
caffeine

It also contains the amino acid phenylalanine, so people with phenylketonuria (PKU) should avoid it.

A 12-ounce (355-mL) serving of Coke Zero provides:

Calories: 0
Total fat: 0 grams (g)
Sodium: 40 milligrams (mg)
Total carbohydrates: 0 g
Total sugars: 0 g
Protein: 0 g
Potassium: 60 mg
Caffeine: 34 mg

Coke Zero contains no added sugars since it uses artificial sweeteners instead. It comes in a variety of flavors, including cherry, cherry vanilla, orange vanilla, and vanilla. Coke Zero also has less caffeine than Diet Coke. Caffeine-free Coke Zero is also available.

Diet Coke nutrition facts

Diet Coke’s ingredients include:

carbonated water
caramel color
aspartame
phosphoric acid
potassium benzoate (to protect taste)
natural flavors
citric acid
caffeine

Like Coke Zero, Diet Coke contains the amino acid phenylalanine, so people with PKU should avoid it.

A 12-ounce (355-mL) serving of Diet Coke provides:

Calories: 0
Total fat: 0 g
Sodium: 40 mg
Total carbohydrate: 0 g
Total sugars: 0 g
Protein: 0 g
Caffeine: 46 mg

Diet Coke contains no added sugars since it uses artificial sweeteners instead. Regular Diet Coke uses aspartame, but you can also purchase a variety of Diet Coke that’s made with Splenda, a brand of sucralose.

Flavor varieties of Diet Coke include ginger lime and feisty cherry. Like Coke Zero, Diet Coke also comes in a caffeine-free version.

Key differences between Coke Zero and Diet Coke

These products are essentially the same, especially regarding their main selling point: not containing sugar.

What differs between the two is the type of sweetener they contain, as well as their caffeine content, although these two differences are still unlikely to be significant to most people.

While Diet Coke uses aspartame as its sweetening agent, Coke Zero uses both aspartame and acesulfame potassium, also called “Ace K” or “acesulfame K.”

Acesulfame potassium is another calorie-free sweetener that passes through the body without raising blood sugar levels.

Per Diet Coke’s ingredient label, its primary sweetener is aspartame, and since ingredients are listed in order by weight, it’s reasonable to assume that it contains much less acesulfame potassium. This means that these drinks are quite similar in terms of ingredients.

The other key difference is caffeine content. Coke Zero has less caffeine than Diet Coke. However, both beverages are well below the recommended daily caffeine limit of 400 mg per day for adults.

One debatable difference is the taste of these two drinks. Some say they cannot taste a difference, while others swear by either Diet Coke or Coke Zero as tasting closest to the “real deal.”

Taste comparison

As of late, Coca-Cola writes on its website and in its most recent marketing materials that it has developed a new recipe for Coke Zero. The company doesn’t go into detail about how it has changed but maintains that it “has more real Coca-Cola flavor, still without any sugar”.

Coke Zero has a slightly different aftertaste than Diet Coke, likely due to its acesulfame potassium. Diet Coke tastes more like regular Coke to many people. However, for some, it’s the reverse.

Neither tastes just like the original Coca-Cola. Depending on multiple factors — like whether you get it from a beverage fountain, in a can, or in a bottle — each type may have a slightly different taste.

Potential side effects

For most, not many harmful side effects come from drinking carbonated beverages in moderation.

However, caffeine and artificial sweeteners may negatively affect some people, even at moderate intake levels.

The United States Department of Agriculture (USDA) recommends that adults have no more than 400 mg of caffeine per day.

That’s about 4 cups of coffee, or nine or eleven 12-ounce (355-mL) cans of Diet Coke or Coke Zero, respectively. So, you’re unlikely to exceed the limit by drinking these sodas in moderation.

If you’re highly sensitive to caffeine, though, you may want to watch your intake of these beverages. Otherwise, they contain a relatively low amount of caffeine.

Aspartame may cause headaches for some people, according to the American Migraine Foundation. While this effect may vary, it’s good to know ahead of time so you can connect the dots if you start experiencing headaches after drinking these beverages.

In addition, some research has indicated that aspartame may be carcinogenic. More long-term, high quality human studies are necessary before we can connect aspartame to cancer.

A concluded that products containing aspartame are safe to consume by the general population at current levels. However, it may pose certain health risks for certain populations, such as:

people with seizures
neurological conditions
people with phenylketonuria
people who are pregnant

Those who take a more cautious approach to ingredients in foods may want to avoid aspartame, and that’s OK. However, it’s worth noting that the Food and Drug Administration (FDA) considers aspartame safe.

Similar to aspartame, acesulfame potassium has been evaluated for potential carcinogenic effects. Again, however, the evidence is unclear, and more long-term, high quality human studies are necessary.

Acesulfame potassium is FDA approved.

Which is a better choice?

There are very few differences between Diet Coke and Coke Zero. As such, there is no concrete, measurable reason to suggest that one is superior to the other.

Nutritionally, there are no significant differences. Their ingredient and caffeine contents are similar as well, so neither is healthier than the other.

Remember that diet soda is not considered a healthy drink. It’s a fun treat that can be consumed in moderation — and switching from original sodas to diet ones is a great starting place if you’re trying to cut back on added sugars.

Whichever you choose will depend largely on which tastes better to you. Coke Zero has been said to taste more like regular Coke, but some people feel differently and even prefer Diet Coke over regular Coke.

Tips for reducing diet soda intake

With the conflicting evidence surrounding artificial sweeteners, you may be wondering how you can get your fizzy fix while limiting your artificial sweetener intake.

Here are some ideas you can try:

Flavored waters: Calorie-free flavored waters can be refreshing and hydrating. Consider them as a healthy addition to your fridge or cooler.
Kombucha: Kombucha is a probiotic-filled beverage that promotes healthy gut bacteria and is naturally fizzy due to the fermentation process. Most kombuchas have less sugar than regular sodas, but compare labels to ensure you’re not overdoing it on added sugars.
Probiotic sodas: Some brands of probiotic “soda” are similar to kombucha. They’re designed to taste similar to soda but have far less sugar. Their benefits are similar to those of kombucha due to the probiotics.
Stevia sodas: Several brands of fizzy drinks mimic popular soda flavors and contain no artificial sweeteners. Instead, these sodas use plant-based alternative sweeteners like stevia or monk fruit. They still taste similar to soda but have no sugar or artificial sweeteners.
Sparkling water: If it’s fizz you’re after rather than the sweetness, sparkling waters may come to your rescue. While they’re not always sweet, they still provide carbonation without any sugar or artificial sweeteners.

The bottom line

If you want to limit added sugars, sodas made with artificial sweeteners — like Diet Coke and Coke Zero — may seem like a good choice.

While some of the artificial sweeteners in these two drinks have faced controversy over their potential negative health effects, consuming either beverage in moderation should not be a concern, especially when compared with the negative effects of their sugar-laden alternative.

Coke Zero and Diet Coke are essentially the same nutritionally. They differ mostly in their flavor.

If you decide you want to limit added sugars and non-nutritive sweeteners, kombucha or a probiotic soda may be good alternatives.

How we reviewed this article:

SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

Aspartame and other sweeteners in food. (2025). https://www.fda.gov/food/food-additives-petitions/aspartame-and-other-sweeteners-food
Haighton L, et al. (2019). Evaluation of aspartame cancer epidemiology studies based on quality appraisal criteria. https://pubmed.ncbi.nlm.nih.gov/30716379/
Harpaz D, et al. (2018). Measuring artificial sweeteners toxicity using a bioluminescent bacterial panel. https://pubmed.ncbi.nlm.nih.gov/30257473/
How to read food and beverage labels. (2022). https://www.nia.nih.gov/health/healthy-eating-nutrition-and-diet/how-read-food-and-beverage-labels
Shaher SAA, et al. (2024). Aspartame safety as a food sweetener and related health hazards. https://pmc.ncbi.nlm.nih.gov/articles/PMC10459792/#sec5-nutrients-15-03627
Spilling the beans: How much caffeine is too much? (2024). https://www.fda.gov/consumers/consumer-updates/spilling-beans-how-much-caffeine-too-much
Top 10 migraine triggers and how to deal with them. (2017).https://americanmigrainefoundation.org/resource-library/top-10-migraine-triggers/

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Evidence Based

This article is based on scientific evidence, written by experts and fact checked by experts.

Our team of licensed nutritionists and dietitians strive to be objective, unbiased, honest and to present both sides of the argument.

This article contains scientific references. The numbers in the parentheses (1, 2, 3) are clickable links to peer-reviewed scientific papers.

Medically reviewed by Marie Lorraine Johnson MS, RD, CPT — Written by Shavonne Morrison, MS, RD, LD — Updated on June 20, 2025

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Nutrition

Nutrition

Nutrition facts and ingredients of Coke Zero and Diet Coke

Coke Zero nutrition facts

Diet Coke nutrition facts

Key differences between Coke Zero and Diet Coke

Taste comparison

Potential side effects

Which is a better choice?

Tips for reducing diet soda intake

The bottom line

How we reviewed this article:

Evidence Based

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