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Decoding the Dilemma: Is it Safe to Drink a Diet Coke?

One question often arises when it comes to beverages: Is it acceptable to indulge in a diet soft drink? Artificial sweeteners, have sparked numerous debates and concerns over the years. But is the concern warranted? In this article, we'll delve into the world of artificial sweeteners, focusing particularly on aspartame, and explore whether enjoying a diet soft drink can coexist with a healthy lifestyle.

Understanding Sweeteners: The Three Categories

Before we dive into the artificial sweetener debate, here is a quick summary of the different type of sweeteners available in Australia at this time:

1. Artificial Sweeteners: Zero Calories, Maximum Sweetness

Artificial sweeteners are calorie-free and can be found in a wide array of food and drink products, often labeled as 'diet,' 'low joule,' or 'no sugar.' Examples include Aspartame (951), Saccharin (954), and Sucralose (955).

2. Nutritive Sweeteners: Less Calories than Sugar

Nutritive sweeteners, while providing a sweet taste, are not calorie-free. They contain fewer calories than sugar and products with these sweeteners may be labeled as 'carbohydrate modified.' Examples include Erythritol, Xylitol, and Sorbitol.

You may have seen these types of sweeteners on food labels, particularly with the rise of 'low carb' products. One thing to note, if you have a sensitive stomach or IBS, these sweeteners may cause symptoms such as bloating or loose bowels.

3. Natural Intense Sweeteners: Nature's Sweet Surprises

Recent additions to the sweetener market include natural intense sweeteners like Stevia and Monk Fruit extract. Stevia is around 200-300 times sweeter than regular sugar and contains no calories. Monk Fruit extract is equally sweet, at 250-400 times the sweetness of sugar, and also contains no calories.

Aspartame: Unraveling the Recent Controversy

Aspartame, a well-known artificial sweetener, made headlines in recent months when the International Agency for Research on Cancer (IARC), a branch of the World Health Organization, reclassified it as a class 2B carcinogen.

The IARC categorizes cancer risk into four groups:

1: Causes cancer.

2A: Probably causes cancer.

2B: Possibly causes cancer.

3: No evidence available on cancer risk.

According to the IARC, "this category (2B) is used for agents for which there is limited evidence of carcinogenicity in humans and less than sufficient evidence of carcinogenicity in experimental animals."

So what does this mean for aspartame? To be categorised in class 2B, no human evidence of carcinogenicity is required. It is interesting to note that aspartame shares this category with numerous things such a aloe vera, ginkgo biloba extract, and coconut oil products. All of which are generally applauded in the the health and wellness space. I did read one article that pointed out the consumption of diet soda is far greater than the use of products such as aloe vera, so therefore a direct comparison of risk cannot be made. This is a reasonable point, however, I do think the world has a love / hate relationship with sweeteners and as such, aspartame always receives massive media attention whenever there is something new to discuss.

Aspartame has been studied in multiple conditions in meta-analyses, reviews, randomised control trials, case-control studies, cohort studies & others. Multiple studies conducted since the 1980's have failed to demonstrate links between aspartame and cancer. While occasional studies have found an increased risk, this evidence is typically not supported when considering the broader scientific landscape.

It's worth noting that alcohol, is categorised as a Group 1 carcinogen by the IARC, indicating there is sufficient evidence in humans to link it to cancer. Yet, we spend more time arguing over the health effects of a can of Diet Coke than pointing out that the drinking habits of adult Australians is are likely to significantly more harmful to our health.

So is it Safe to drink Coke Zero or Diet Coke?

So, where does this leave Diet Coke or Coke Zero? Is it safe to drink Coke Zero or Diet Coke? (or your diet drink of choice!)

If you are looking to lose weight, there is evidence to suggest that swapping full-strength soft drinks for their diet counterparts can have a positive impact on body weight.

When it comes to health concerns with sweeteners such as aspartame, it is important to look at the amount and the frequency of consumption. In Australia, the Acceptable Daily Intake (ADI) of aspartame is set at 0-40mg per kilogram of body weight per day. For a 70kg person, this translates to roughly 20 cans of diet soft drink per day—far more than anyone would typically consume. So having the occasional Diet Coke or Coke Zero means you are consuming amounts of aspartame that are far below the levels that have been deemed safe for humans.

So what do I recommend?

  1. Water is always the preferred beverage of choice

  2. Feel free to enjoy an occasional diet soft drink as part of a diverse, and well-balanced diet

  3. If you are looking to lose weight, there is evidence to suggest that swapping full strength soft drinks for their diet counterparts will be beneficial for both your health and your weight - but don't use diet drinks as a replacement for meals and snacks in order to facilitate weight loss


Nutrition is an evolving science. So it is important to "watch this space" as I have no doubt there will be more research findings about sweeteners in the years to come. This article has mainly focused on aspartame and the claims relating to its cancer risk. However, there are plenty of broader discussions to be had about sweeteners that are beyond the scope of this particular blog post.

In the end, moderation and balance are key. At this point, I am of the opinion that artificial sweeteners, including aspartame, can be a part of a healthy lifestyle when consumed sensibly and as part of a well-rounded diet. Remember, it's essential to make informed choices and not let sensationalised headlines overshadow the scientific evidence. Your health journey is about finding what works best for you and your unique needs.


REFERENCES (In case you want to do a bit of nerding out!)



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