Effects of Diet Soft Drinks on Your Health: How Caffeine, Phosphoric Acid & Artificial Sweeteners in Diet Soda Affect Health

Effects of Diet Soft Drinks on Your Health: How Caffeine, Phosphoric Acid & Artificial Sweeteners in Diet Soda Affect Health
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Exposing Myths

The effects of diet soft drinks on your health are varied, and go beyond popular beliefs that artificial sweeteners are dangerous. (The jury’s still out on that.) Drinking diet soda in even moderate amounts can have effects on your teeth, bone density, and weight, among other things.

We look beyond the headlines to the real research, answering several common questions about how diet soft drinks can affect your health, often with surprising answers:

  • Am I getting too much caffeine from drinking diet sodas?
  • Doesn’t diet pop have the same effect on teeth as coffee?
  • Is the carbonation in diet soft drinks leaching calcium from my bones?
  • Does this Diet Coke make me look fat?

Image credit: garytamin, https://www.sxc.hu/photo/641292


Many diet soft drinks contain caffeine; 45 milligrams or so per twelve ounces. Caffeine in moderate doses has not been shown to have adverse effects on the body, although the research is careful to indicate that this doesn’t prove that caffeine isn’t harmful.

One negative health effect of caffeine, however, is that it’s addictive. The more you regularly consume, the more affected you’ll be if you remove the caffeine, suffering withdrawal symptoms such as lethargy or headaches.

However, if you keep your caffeine consumption below 300 mg per day (the highest recommended amount for optimum health), you likely won’t suffer adverse health effects.


Erosion of tooth enamel is one adverse effect that diet soft drinks have on your health. Diet soft drinks are very acidic, and that acid bathing the teeth makes the enamel more vulnerable to bacterial attack.

Coffee, another popular acidic drink, has been vindicated in recent years due to studies finding that coffee’s acids have a protective effect on tooth enamel. The acids in diet soft drinks, however, do not share this protective benefit and expose the teeth to decay.

Drinking diet soft drinks will lead to increased tooth decay, if you’re not careful.


What gives soda its fizz? Phosphoric acid does. While it’s been theorized that phosphorus will leach calcium from your bones, actual scientific studies have shown that this is not the case. Any correlation between increased diet soft drink consumption and reduced bone density is more likely due to a lack of calcium in the diet. Diet soft drinks have no calories or nutritive value, so drinking diet soda as a replacement for something else — say, milk — will indeed lead to lower calcium intake.

However, there is no direct correlation between phosphoric acid in diet soft drinks and calcium depletion. The “pop” in your pop isn’t going to lead to osteoporosis on its own.

Artificial Sweeteners

The artificial sweeteners used in diet soft drinks today are aspartame and sucralose (sold under the brand name Splenda). Aspartame has a long history of health concerns, most of them lacking any science to back them up. Many of the worries may arise from the fact that one compound that aspartame breaks down into is phenylalanine, an essential amino acid that a small percentage of the population cannot metabolize and must avoid. However, studies for more than two decades have consistently shown aspartame to have no known health effects — carcinogenic, neurological, or otherwise. Recent studies showing a correlation between aspartame and increased cancers in rats are intriguing, but scientific reviewers claim they are flawed. Sucralose, commonly known as Splenda, is also demonstrated to be safe so far, with the majority of studies showing no or weak links between sucralose and disease. The situation is similar to aspartame’s, with recent studies showing potentially troubling results — e.g., that sucralose may trigger migraines in those susceptible to them — but researchers say more studies must be done before drawing conclusions.

What are some commonly accepted health effects of artificial sweeteners in diet soft drinks, then? Well, research suggests that consumption of artificial sweeteners is strongly correlated with weight gain and obesity:

  • The taste of sweetness, whatever the source, is mildly addictive. Tasting something sweet may make you crave sweeter tastes, thus leading to seeking out desserts or other foods you may not have desired otherwise.
  • Drinking diet soft drinks might actually make you hungrier. The exact way this effect works is unknown, and the literature is divided as to whether the effect is real or not. Some scientists theorize that the brain is not fooled by diet soft drinks so your belly may be full of liquid, but your brain knows that liquid has no calories and no nutritive value and may urge you to seek out more nutritional fuel sources.
  • Drinking diet soft drinks is correlated with the development of obesity. A University of Texas epidemiological study found that drinking diet soft drinks was strongly correlated with normal or overweight people becoming obese over time.


The most troubling effects of diet soft drinks on your health are that they will almost certainly make you more disposed to gain weight, and that they will weaken your tooth enamel’s defenses against bacteria, leading to tooth decay. You don’t need to worry about calcium depletion arising directly from diet sodas, or about caffeine in moderation, but that doesn’t make the real effects any less troubling. You’d be much better off putting down the diet soft drinks and choosing water, juices, or even coffee or tea instead.


Harvard School of Public Health, https://www.hsph.harvard.edu/nutritionsource/healthy-drinks/sugary-vs-diet-drinks/

UT Health Science Center, https://www.uthscsa.edu/hscnews/singleformat2.asp?newID=1539

Hughes, Julie. “Does diet soda cause weight loss… or weight gain?” https://healthpsych.psy.vanderbilt.edu/2009/DietSodaWeight.htm

Go Ask Alice!, https://www.goaskalice.columbia.edu/5358.html

Go Ask Alice!, https://www.goaskalice.columbia.edu/1485.html

Payne, Hannah. “Artificial Sweeteners: The Truth About Diet Soda” https://dujs.dartmouth.edu/winter-2008/artificial-sweeteners-the-truths-and-lies-behind-diet-soda