Understanding Nutrition: What is the most unhealthy soda to drink?

October 4, 2025 •

4 min read

According to a study published in Nature Medicine in January 2025, sugar-sweetened beverages like soda are linked to over 3 million new cases of diabetes and heart disease each year. Understanding what is the most unhealthy soda to drink? is crucial for making informed choices about your nutrition and overall wellness.

Quick Summary

This article evaluates the primary factors contributing to a soda's unhealthiness, including sugar content, acidity, and artificial additives. It ranks some of the leading contenders for the most unhealthy soft drink and explores the long-term health consequences of regular consumption.

Key Points

Mountain Dew is a top contender for the most unhealthy soda, packed with extremely high levels of sugar (46g per 12oz can) and high acidity from citric acid.
Dark colas like Coke and Pepsi are also highly detrimental due to large sugar quantities and damaging phosphoric acid, which erodes tooth enamel and can affect bone health.
High sugar content in sodas is strongly linked to obesity, metabolic syndrome, fatty liver disease, and type 2 diabetes.
Diet sodas are not a guilt-free alternative, as they still contain high acidity and artificial sweeteners, which may pose their own health risks and affect gut bacteria.
Better beverage choices include plain or flavored sparkling water, unsweetened tea or coffee, and herbal infusions to satisfy cravings without the health drawbacks.
Limiting intake is key, as even a single soda per day significantly increases risks for chronic diseases like heart disease and diabetes.

The Primary Culprits: What Makes a Soda Unhealthy?

Several ingredients conspire to make certain soft drinks significantly more damaging to your health than others. While all sugary sodas are best consumed in moderation, understanding the specific components that make them harmful is the first step toward making healthier dietary choices.

Excessive Sugar and High-Fructose Corn Syrup

One of the most obvious factors is the sheer volume of sugar. Many popular sodas are loaded with high-fructose corn syrup (HFCS), a highly concentrated sweetener with no nutritional value beyond calories.

Mountain Dew, for example, is frequently cited as one of the worst offenders due to its exceptionally high sugar content. A 12-ounce can contains 46 grams of sugar, exceeding the American Heart Association's recommended daily limit for both men and women in a single serving.
Fanta Grape is another sugar bomb, often containing over 40 grams per serving. This massive sugar load leads to rapid spikes in blood sugar, increasing the risk of insulin resistance, weight gain, metabolic syndrome, and type 2 diabetes.

Destructive Acids

Sodas are notoriously acidic, a quality that severely damages dental enamel. Two of the most common acids are citric and phosphoric acid.

Phosphoric acid, found in darker colas like Coke and Pepsi, is particularly harmful to dental health and can interfere with calcium absorption, potentially affecting bone density.
Citric acid, common in citrus-flavored sodas like Mountain Dew and orange soda, also contributes significantly to tooth erosion. This acidic attack on your teeth is a major cause of cavities and tooth decay, especially when consumption is frequent.

Artificial Additives and Stimulants

Beyond sugar and acid, some sodas contain other questionable ingredients:

Artificial Dyes: Sodas get their bright colors from artificial dyes. Mountain Dew's Yellow 5 and cola's caramel coloring are potentially carcinogenic in high doses, adding another health concern.
Brominated Vegetable Oil (BVO): Historically, citrus-flavored drinks like Mountain Dew and Fanta contained BVO to prevent flavoring from separating. While many major brands have now removed it, BVO was previously linked to neurological issues.
Caffeine and Other Stimulants: Energy drinks, often sold alongside sodas, contain excessive caffeine and other stimulants like taurine and guarana, which can lead to rapid heart rate and high blood pressure, especially when combined with high sugar.

Head-to-Head: A Comparison of Unhealthy Sodas

Here is a comparison of some of the most commonly criticized sodas, highlighting their key unhealthy components.


Soda Brand	Key Unhealthy Factors	Primary Health Risks
Mountain Dew	Extremely high sugar content (46g/12oz), high acidity (citric acid), artificial Yellow 5 dye	Obesity, Type 2 diabetes, severe dental decay, potential metabolic issues
Coca-Cola / Pepsi	High sugar (39-43g/12oz), high acidity (phosphoric acid), caffeine, caramel coloring	Obesity, Type 2 diabetes, dental enamel erosion (due to phosphoric acid), bone density issues
Orange Soda (e.g., Fanta)	High sugar (43g/12oz), high acidity (citric acid), artificial coloring and flavoring	Obesity, dental erosion, Type 2 diabetes
Root Beer (e.g., Mug)	High sugar (43g/12oz), caramel coloring, high-fructose corn syrup	Weight gain, blood sugar spikes, low nutritional value

Health Implications Beyond the Calories

Regular soda consumption contributes to a host of health problems that extend far beyond weight gain.

Heart Disease: The excess sugar and resulting high triglycerides from soda consumption significantly increase the risk of heart disease and premature death. Studies show a strong link between daily sugary drink intake and increased cardiovascular risk.
Liver Damage: The liver converts excess fructose from soda into fat. This can lead to non-alcoholic fatty liver disease (NAFLD), a condition often diagnosed in people who regularly consume soda.
Kidney Stones: The high phosphate content in colas can be detrimental to kidney health and has been linked to an increased risk of developing kidney stones.
Addiction and Brain Health: The combination of sugar and caffeine can be addictive, creating a cycle of cravings. Over time, this can lead to metabolic dysfunction, mood swings, and a higher threshold for sweetness.
Diet Soda Risks: It's important to note that diet sodas are not a perfect solution. While they contain no sugar, their artificial sweeteners and high acidity pose their own set of risks. Some studies link artificial sweeteners to potential metabolic dysfunction and changes in the gut microbiome. Therefore, even diet sodas should be limited.

Conclusion: Making Healthier Choices

While identifying a single definitive "most unhealthy soda" is challenging due to varying factors, it's clear that Mountain Dew stands out for its high sugar content, high acidity, and specific artificial dyes. Dark colas are also major contenders due to their sugar, caffeine, and particularly damaging phosphoric acid. Ultimately, the unhealthiest soda is the one you consume regularly and in large quantities.

To improve your nutrition diet, consider healthier alternatives to soda:

Water: Plain or infused with fruit and herbs is the best choice for hydration.
Sparkling Water: For those who crave carbonation, naturally flavored sparkling water without added sugar or artificial sweeteners is an excellent option.
Unsweetened Tea or Coffee: Provides flavor and caffeine without the harmful effects of sugar.
Kombucha: A fermented tea that offers probiotics with less sugar than most sodas.

Making a conscious effort to replace sugary and acidic drinks with healthier options is one of the most impactful steps you can take for your long-term health and wellness. For more on healthier beverage choices, visit The Nutrition Source at Harvard T.H. Chan School of Public Health.

Frequently Asked Questions

The primary reasons are the high content of added sugars, particularly high-fructose corn syrup, which leads to weight gain and chronic diseases, and the high acidity from citric and phosphoric acids, which severely damages dental health.

Yes, Mountain Dew is widely regarded as one of the most unhealthy sodas. It contains a very high sugar content (46 grams per 12 ounces), high levels of citric acid, and artificial yellow dyes, all of which contribute to serious health risks.

No, but they are not entirely healthy either. While diet sodas contain no sugar, they are still highly acidic, which can erode tooth enamel. Some studies also suggest that the artificial sweeteners may negatively impact the gut microbiome and metabolic health.

Both the sugar and high acid content in soda attack tooth enamel. The acid softens the enamel, while the sugar feeds bacteria that produce more acid, leading to rapid decay and cavities. Using a straw can help reduce contact with teeth.

Yes. Sodas contain 'empty calories' from sugar that don't provide a feeling of fullness. This can lead to consuming more calories throughout the day and contributes significantly to weight gain and obesity over time.

Both are bad, but in different ways. Cola's phosphoric acid is very erosive, while citrus sodas use citric acid, which can also cause significant damage. Some studies suggest citrus sodas might be even more damaging to enamel over time.

Opt for beverages like plain water, naturally flavored sparkling water, unsweetened tea or coffee, or infused water with fresh fruit and herbs. These alternatives satisfy the desire for a flavorful drink without the negative health impacts of soda.