Diet sodas, like Diet Coke, are popular alternatives to sugar-sweetened beverages for individuals aiming to reduce their sugar or calorie intake. These drinks utilize artificial sweeteners to replicate the sweet taste without the added calories. While they may seem like a healthier choice, the health effects of diet drinks and artificial sweeteners remain a topic of debate. This article delves into the pH level of Diet Coke and its potential impact on health, particularly dental health, while also exploring other broader health implications associated with diet soda consumption.
What is Diet Coke?
Diet Coke is a mixture of carbonated water, artificial or natural sweeteners, colors, flavors, and other food additives. It typically contains very few to no calories and offers no significant nutrition. For example, a 12-ounce (354-mL) can of Diet Coke contains no calories, sugar, fat, or protein, and 40 mg of sodium. However, not all sodas that use artificial sweeteners are low in calories or sugar-free, as some may use sugar and sweeteners together.
Common Ingredients in Diet Soda:
- Carbonated water: Most sodas are made by dissolving carbon dioxide into water under pressure.
- Sweeteners: These include artificial sweeteners like aspartame, saccharin, sucralose, or herbal sweeteners like stevia, which are significantly sweeter than regular sugar.
- Acids: Acids like citric, malic, and phosphoric acid are used to add tartness to soda drinks and are linked to tooth enamel erosion.
- Colors: The most commonly used colors are carotenoids, anthocyanins, and caramels.
- Flavors: Many different kinds of natural juices or artificial flavors are used in diet soda, including fruits, berries, herbs, and cola.
- Preservatives: These help diet sodas last longer on the supermarket shelf, with potassium benzoate being a commonly used preservative.
- Vitamins and minerals: Some manufacturers add vitamins and minerals to market their products as healthier no-calorie alternatives.
- Caffeine: Many diet sodas contain caffeine, with a can of Diet Coke containing 46 mg of caffeine, while Diet Pepsi contains 35 mg.
The pH Scale and Acidity of Beverages
The pH scale measures the acidity or basicity of a food or drink based on a number from 0-17, with 7 being completely neutral. Anything with a number under 7 is more acidic, and anything with a number higher than 7 is more basic. For each number that is below the next (4 below 5), the acidity or basicity increase by 10 times. Therefore, a substance with a pH of 4 is 10x more acidic than that with a pH value of 5.
pH Level of Diet Coke and Dental Erosion
Both regular and diet soft drinks contain phosphoric and citric acid, which contributes to the total acidic challenge potential on enamel. Dental erosion (DE) is the chemical dissolution of tooth structure in the absence of bacteria when the environment is acidic (pH < 4.0). The pH of extrinsic solutions (dietary beverages) coming into contact with the dentition appears to be the major determinant of dental erosion; the hydrogen ion concentration [H+] or acidity, as measured in pH, is primarily responsible for the immediate dissolution and softening of surface tooth structure (erosive potential) by acidic beverages composed of weak acids. Teeth erode in the pH range of 2.0 to 4.0, although surface enamel starts to demineralize as the pH drops below 5.5 when the external milieu of the oral cavity becomes under-saturated for hydroxyapatite.
A study involving subjects aged 12-15 measured plaque pH after exposure to regular Coke and Diet Coke. The results showed that regular Coke had significantly more acidic plaque pH values at the 5-, 10- and 20-minute intervals compared to Diet Coke, (P = < .001), when subjected to a t test. The mean pH at 5 minutes for Coke and Diet Coke was 5.5 +/- 0.5 and 6.0 +/- 0.7, respectively. At 10 minutes, the pH for Coke and Diet Coke was 5.6 +/- 0.6 and 6.2 +/- 0.7, respectively. These data suggest that regular Coke possesses a greater acid challenge potential on enamel than Diet Coke.
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A comprehensive pH assessment of beverages available for human consumption found that the majority are potentially erosive to the dentition. The pH of commercial non-dairy beverages range from 2.1 (lime juice concentrate) to 7.4 (spring water). Acids are added to beverages and compose a flavor profile giving the beverage a distinctive taste. Phosphoric acid is added to cola drinks to impart tartness, reduce growth of bacteria and fungi, and improve shelf-life. Citric acid, a substance naturally occurring in citrus drinks and added to many others, imparts a tangy flavor and functions as a preservative.
Previous investigations have indicated pH, not titratable acidity, is the critical determinant of beverage erosive potential. Knowledge of beverage pH is essential for the development of preventive strategies for patients with clinical erosion. The elimination of extremely erosive drinks (pH < 3.0), minimizing erosive drinks (pH 3.0 - 3.99), and substituting drinks with a (pH ≥ 4.0) would be prudent advice for the prevention of erosion.
Potential Health Effects of Diet Soda
Weight Management
Observational studies have found that using artificial sweeteners and drinking high amounts of diet soda is associated with an increased risk of obesity and metabolic syndrome. Scientists have suggested that diet soda may increase appetite by stimulating hunger hormones, altering sweet taste receptors, and triggering dopamine responses in the brain. Given that diet soft drinks have no calories, these responses may cause a higher intake of sweet or calorie-dense foods, resulting in weight gain. However, evidence of this is not consistent in human studies.
Experimental studies do not support the claim that diet soda causes weight gain. In fact, these studies have found that replacing sugar-sweetened drinks with diet soda can result in weight loss.
Type 2 Diabetes and Heart Disease
Research has found that just one serving of an artificially sweetened drink per day is associated with an 8-13% higher risk of type 2 diabetes. A study in 64,850 women noted artificially sweetened drinks were associated with a 21% higher risk of developing type 2 diabetes. However, this was still half the risk associated with regular sugary drinks.
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Diet soda has also been linked to increased risks of high blood pressure and heart disease. A review of four studies including 227,254 people observed that for each serving of artificially sweetened beverage per day, there is a 9% increased risk of high blood pressure.
Kidney Disease
Drinking diet soda has been linked to an increased risk of chronic kidney disease. A recent study analyzed the diets of 15,368 people and found that the risk of developing end-stage kidney disease increased with the number of glasses of diet soda consumed per week. Compared with those who consumed less than one glass per week, people who drank more than seven glasses of diet soda per week had nearly double the risk of developing kidney disease.
Pregnancy
Drinking diet soda while pregnant has been linked to some negative outcomes, including preterm delivery and childhood obesity. A Norwegian study in 60,761 pregnant women found that intake of artificially sweetened and sugar-containing drinks was associated with an 11% higher risk of preterm delivery. Furthermore, consuming artificially sweetened drinks while pregnant is significantly associated with an increased risk of childhood obesity.
Other Potential Health Effects
- May reduce fatty liver: Some studies have shown that replacing regular soda with diet soda can reduce fat around the liver.
- No increase in reflux: Carbonated drinks have not been found to make reflux or heartburn worse.
- No strong links to cancer: Most of the research on artificial sweeteners and diet soda has found no evidence it causes cancer.
- Changes to the gut microbiome: Artificial sweeteners may alter the gut flora, leading to reduced blood sugar control and potentially increasing the risk of type 2 diabetes.
- Increased risk of osteoporosis: Diet and regular cola is associated with bone mineral density loss in women, but not in men.
- Tooth decay: Like regular soda, diet soda is associated with dental erosion due to its acidic pH level.
- Linked to depression: Observational studies have found higher rates of depression among those who drank four or more diet or regular sodas per day.
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