Does Diet Coke really cause cancer?


As concerns over health and well-being grow, the safety of artificial sweeteners, particularly aspartame found in products like Diet Coke, has come under scrutiny. The International Agency for Research on Cancer (IARC), a specialized cancer agency of the World Health Organization (WHO), has classified aspartame as a possible carcinogenic hazard to humans. But before we jump to conclusions, let’s delve deeper into the evidence and its implications.

What is aspartame, and where is it found?

Aspartame is an artificial sweetener that is approximately 200 times sweeter than sugar, yet contains no kilojoules. It is commonly used in various products, including carbonated drinks like Diet Coke, Coke Zero, Pepsi Max, and some store-brand offerings. Identifying aspartame in products can be done by looking for the additive number 951 on the label. Additionally, certain food items like yogurt and confectionery may also contain aspartame, though it is not suitable for use in baked goods due to its instability at warm temperatures.

Understanding the risk vs. hazard distinction

Before we explore the evidence surrounding aspartame, it’s essential to grasp the difference between risk and hazard. A hazard refers to an agent capable of causing cancer, while risk measures the likelihood of it causing cancer.

The evidence behind the aspartame cancer concern

The IARC arrived at its assessment after analyzing data from various observational, experimental, and animal studies worldwide. Limited evidence was found in human studies linking aspartame consumption to liver cancer, supported by some animal studies. Moreover, lab-based biological mechanism studies suggested how cancer could potentially develop from aspartame consumption.

In particular, three human studies investigated the association between cancer and aspartame intake, using soft drink consumption as a proxy for aspartame intake. While all three studies found a positive correlation between artificially sweetened beverages and liver cancer, they could not rule out the influence of other factors on the results.

IARC’s group classification for carcinogens

The IARC classifies potential cancer-causing agents into four groups:

Group 1: Carcinogenic to humans – Agents with convincing evidence from human studies on how they cause cancer, such as tobacco smoking and alcohol.

Group 2a: Probably carcinogenic to humans – Agents showing positive associations with cancer in humans, though other explanations may not be fully explored, such as red meat and night shift work.

Group 2b: Possibly carcinogenic in humans – Agents with limited evidence of causing cancer in humans, often based on animal studies or well-understood mechanisms, such as ginkgo biloba and lead.

Group 3: Not classifiable as a carcinogen – Agents lacking sufficient evidence from humans or animals, with limited mechanistic evidence, such as 500 substances, including aloe vera and certain chemicals.

Does diet Coke pose a cancer risk?

For the average person weighing 70 kilograms, it would be practically impossible to consume the recommended acceptable daily intake of aspartame (0 to 40mg per kilo of body weight) by drinking Diet Coke alone. Additionally, aspartame may be present in other foods consumed, but in realistic amounts, the risk remains low.

However, it’s essential to consider the broader picture. Aspartame is predominantly found in processed and ultra-processed foods, which research has recently shown to have detrimental health effects. Moreover, artificial sweeteners, including aspartame, might lead to increased sugar cravings, potentially promoting overeating and weight gain.

While consuming the occasional or even daily diet soft drink is generally safe and likely not a cancer risk, it is crucial to be cautious about the overall intake of artificial sweeteners. They offer no health benefits and may have some adverse effects. A balanced and mindful approach to diet and lifestyle remains key to maintaining overall well-being.


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