Is Diet Coke Gluten Free?

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Stop the presses!

If you are gluten sensitive and continue to drink Diet Coke, you will NOT get well.

I’m sorry.  I know I’m not making any friends with this post.  Diet Coke is not my enemy…but it might be yours!  I want you to be well, and if Diet Coke is in your way…let’s find a way out of it!

[bctt tweet=”Diet Coke is NOT #glutenfree. If you’re gluten sensitive & drink it, you WON’T get well. ” username=”stuffed_pepper”]Diet Coke is NOT gluten free.

(Disclaimer:  I was not able to verify this statement from a lab experiment. Often, the body is the best indicator of the presence of gluten, and many times I’ve experienced a gluten response myself and in clients that drank it.  That lead me to consult with a physician, and then take a closer look at the ingredients and dig a little deeper.) 

I went to the website to get some nutritional information to share with you…but when I click on the link at the bottom of the US Coca-Cola Home Page that says Nutrition information, it takes me to a page about America’s Favorite Park.  What?

I’m sure this is a programming error.  I’m sure that someone at the corporate office is scrambling to fix this link promptly.  So, I’ll tell you what I know and have learned, and you can make your decision from there.

Diet Coke ingredientsSince I couldn’t link to the ingredients on the website, I went searching and found an old can out in my garage.  Yep.  I was never the Diet Coke addict, never even much of a soda drinker.  On one of those hot days when you just mowed the lawn though…there was something about pouring it over the ice clinking in the glass and the fizzy foamy sweetness cooling you down, head to toe.  Wait, wasn’t that a Diet Coke commercial from my childhood?

Yes.  And it’s a mental image that still makes me a little bit thirsty!

So, now that you know I’m not a “soda saint”…I have a past…now you know I’m human and relatable.  I have fought the soda battle and I have won.  I haven’t touched the stuff in over three years.  This was part of my own journey to health.  Since I wasn’t a daily soda drinker, I didn’t pay much attention to it when I went gluten free.  However, during that time I got the idea in my crazy head that since my “craving time” was when I got home from work, I could drink a Dr. Pepper on the way home so I wouldn’t want something sweet upon entering the kitchen after my long work day.

That experiment lasted less than a week.  My body was pretty unhappy about my experiment…but just like everything else, I had to try a few more times before convincing myself that it contained gluten.  And now it became a challenge, because I wasn’t a soda addict before…so it made me want it more!  Each time I drank it, though, it was like a reality check I didn’t need to have!  It didn’t make me sick or give me an upset stomach, but the next morning I would be blown up like a puffer fish.

In the last several months, I’ve had three “die-hard” soda drinkers give up the stuff.  One drank regular Coke – and it kept landing her in the hospital (although she was sure it was something else).  The other two drank diet Coke.

Why did they give it up?  Here is a list of the ingredients:

The ingredients are:  Carbonated water, Caramel Color, Aspartame, Phosphoric Acid, potassium Benzoate, Natural Flavors, Citric Acid, Caffeine

The three ingredients in red are the reasons I ask my clients to give it up.

  1.  First, caramel color often contains gluten as a source, and it doesn’t have to be disclosed on the label.  According to Wikipedia, caramel color “is manufactured by heating carbohydrates, either alone or in the presence of acids, alkalies, and/or salts. Caramel is produced from commercially available nutritive sweeteners consisting of fructosedextrose (glucose), invert sugarsucrosemalt syrupmolasses, starch hydrolysates and fractions thereof.”

In other words, caramel color is manufactured based on sugars that can come from corn or malt or other sugar types.  Until Coca-Cola decides to tell us what their source of caramel color is, I have to assume it contains gluten to be safe.

  1.  Aspartame is not what I consider a gluten ingredient.  However, the use of aspartame causes other issues in your body as an artificial sweetener.  First, it “tricks” your body by dulling your sense of sweet.  This “dulling of your senses” can lead you to crave more sweet items.  Things that are naturally sweet, like fresh strawberries or other fruit may no longer meet your desire for something sweet.  It can also “trick” your pancreas into producing more insulin than needed…leading your body into a pre-diabetic state.  Aspartame has even been linked as the cause of headaches and memory problems as long ago as 1994 (see the study here).
  2.  Natural Flavors is a term that food manufacturers can use to describe a host of ingredients.  Directly from the FDA website’s food labeling guide:

How are spices, natural flavors or artificial flavors declared in ingredient lists?

Answer: These may be declared in ingredient lists by using either specific common or usual names or by using the declarations “spices,” “flavor” or “natural flavor,” or “artificial flavor.”

[EXAMPLE] “INGREDIENTS: Apple Slices, Water, Cane Syrup, Corn Syrup, Modified Corn Starch, Spices, Salt, Natural Flavor and Artificial Flavor”

However, products that are spices or spice blends, flavors or colors must list each ingredient by name.

Do you think that’s confusing, vague, and leaves a lot to interpretation?  You bet.  I’ve recently been manufacturing my own gluten free goodies, and I’ve learned a lot about where manufacturers can cut corners in cost by using the cheapest option and listing it under one of the above terms.  I not only take the time to research each ingredient and source, I often pay more for what I consider “safe” ingredients.  Many manufacturers are so squeezed on profit margin that they don’t have that luxury.  Add to that, the products available in restaurant supply shops are meant to save costs and cooking time…so they are often laden with gluten-based ingredients.  I just looked at a box of restaurant French Fries, for example…it said “Natural Cut Potatoes” on the box.  A closer look at the ingredients, and the potatoes are rolled in corn starch, maltodextrin, and natural flavor.  Doesn’t sound too “natural” to me.  This is why I encourage you to stay away from “Natural Flavor” whenever you can.  Unless the product states specifically what the source of the flavor is, it could be anything, sourced from a host of gluten based ingredients.

So, as sorry as I am to disappoint any of the Diet Coke drinkers, I’m not sorry if this has helped you take a step in your journey to better health!  My clients have lost weight, stabilized their blood sugar, and reduced inflammation by eliminating both regular and diet sodas.

Need more convincing?  Read this article posted by Fox News about the ten reasons to give up diet soda.

Give it a try!  For the next ten days, give it up.  Write down how you feel each day (know that at first, you may have caffeine withdrawal which can cause headaches and anxiety-type feelings).  If you don’t feel any different, I would love to know!

~GGF Gourmet

(Jen Cuevas of The Gluten & Grain Free Gourmet at:

2 Responses so far.

  1. Bridie says:


    Ive tried the green stevia coke a few times and it doesnt seem to agree with me. Do you think its a gluten issue or could the stevia also be a problem? Im coeliac and sensitive to wheat derivatives (i.e. less than 20ppm gluten).

  2. Hello Bridie,
    Thanks for reaching out! I had to look up what the green stevia Coke actually contained in the ingredients. This is what I found: Carbonated Water, Sugar, Colour (Caramel E150d), Natural Flavourings Including Caffeine, Phosphoric Acid, Sweetener (Steviol Glycosides). The issues that I wrote about in the article centered around the caramel color and the natural flavorings in the original Diet Coke, and it appears that despite the change in marketing and type of artificial sweetener, those ingredients have remained the same. The caramel color and natural flavoring may contain gluten or wheat derivatives. Here is some more information about the caramel coloring (which is why I steer clear every time I see it): “Caramel coloring can be made from a variety of carbohydrates including: dextrose (corn), invert sugar, malt syrup (barley), molasses, lactose (sugar in milk), starch hydrolysates (corn or wheat). Since the source of caramel color is generally not known, people with food allergies should avoid caramel coloring.” For the direct reference to this, see more at: You can also try contacting Coca-Cola to inquire as to whether those ingredients are derived from gluten. I hope this helps! Please let me know if you have further questions. -Jen

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