Diet soda, often marketed as a healthier alternative to sugary soft drinks, has gained popularity among individuals seeking to reduce their sugar intake or manage their weight. While it's low in calories and sugar, diet soda lacks nutritional value and contains artificial sweeteners, leading to questions about its potential health effects, including its impact on digestion and potential contribution to constipation.
The Appeal and Composition of Diet Soda
Many people are drinking less sugary soft drinks than in the past. This is a great win for public health, given the recognised risks of diets high in sugar-sweetened drinks. But over time, intake of diet soft drinks has grown. Diet soft drinks are designed to taste similar to regular soft drinks but without the sugar. Instead of sugar, diet soft drinks contain artificial or natural sweeteners. The artificial sweeteners include aspartame, saccharin and sucralose. Many artificial sweeteners are much sweeter than sugar so less is needed to provide the same burst of sweetness. Diet soft drinks are marketed as healthier alternatives to regular soft drinks, particularly for people who want to reduce their sugar intake or manage their weight.
Potential Side Effects of Diet Soda
While diet soda is often marketed as healthier than regular soda because it contains no added sugar, it's important to consider its potential side effects. Below, we'll explore the possible health effects of drinking too much diet soda and the symptoms you might have. These may include gut symptoms, sleep problems, and sugar cravings.
Impact on Gut Health
The artificial sweeteners found in diet soda might negatively affect your gut microbiome, which is the community of beneficial bacteria in your digestive tract. According to researchers, the gut microbiome plays a key role in many aspects of health, including immune function, nutrient absorption, heart health, and more.
Aspartame is one of the most common nonnutritive sweeteners in diet soda. One in vitro study of 13 individuals found that aspartame decreased production of Isobutyric acid, a type of short-chain fatty acid. Short-chain fatty acids play a role in preventing inflammatory diseases and regulating body weight.
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Some scientists believe that artificial sweeteners might affect your gut bacteria. Still, a lot of the research so far was laboratory-based, or it involved animals, not people. And, of course, what happens inside a rat won’t necessarily happen inside a person.
Turning to studies with human participants, not all have found the same effects. It’s likely that the health effects of artificial sweeteners vary from person to person, depending on the composition of their microbiome and the type of sweetener.
Some studies in humans have found that consuming artificial sweeteners can lead to changes in the gut microbiome. But others haven’t. Beyond artificial sweeteners, diet sodas often contain other additives, like coloring and flavoring, which may also affect the gut microbiome. At this point, we don’t know how these changes might influence overall health, but scientists continue to look into the issue.
There is some early evidence artificial sweeteners may irritate the lining of the digestive system, causing inflammation and increasing the likelihood of diarrhoea, constipation, bloating and other symptoms often associated with irritable bowel syndrome. However, this study noted more research is needed.
Weight Management
For people trying to lose weight, there’s some evidence that switching from regular soda to diet soda may help, to some degree. But other studies have suggested that drinking diet soda may lead to weight gain.
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Take one study, which tracked people for over 9 years. It found that those who regularly drank diet soda tended to have higher levels of fat around their middles, compared with people who didn’t. But it’s important to keep in mind that weight maintenance is complex, and many factors are involved.
Despite the word “diet” in the name, diet soft drinks are not strongly linked with weight management. In 2022, the WHO conducted a systematic review (where researchers look at all available evidence on a topic) on whether the use of artificial sweeteners is beneficial for weight management. Overall, the randomised controlled trials they looked at suggested slightly more weight loss in people who used artificial sweeteners. But the observational studies (where no intervention occurs and participants are monitored over time) found people who consume high amounts of artificial sweeteners tended to have an increased risk of higher body mass index and a 76% increased likelihood of having obesity. In other words, artificial sweeteners may not directly help manage weight over the long term. Studies in animals have suggested consuming high levels of artificial sweeteners can signal to the brain it is being starved of fuel, which can lead to more eating. However, the evidence for this happening in humans is still unproven.
Metabolic Health
It’s normal for your blood sugar levels to rise after you eat or drink anything that contains sugar, like regular soda. But for some people, these rises are pronounced, and they feel tired and hungry. Over the years, these blood sugar spikes can increase the risk of heart disease.
Because diet soda contains no sugar, you won’t experience large spikes and dips in blood sugar. So, switching to diet soda might seem like a good way to help your metabolic health. However, some experts believe that drinking diet soda with artificial sweeteners can affect the gut microbiome and negatively impact the blood sugar response.
This, they argue, may increase the risk of developing metabolic syndrome. There’s also evidence linking artificial sweeteners with a greater risk of heart disease and type 2 diabetes. Scientists need to do more research into the links between artificial sweeteners, gut bacteria, and metabolic health.
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One 2021 study found that regularly consuming artificial alternative sweeteners, which are present in diet soda, is associated with a risk of developing cardiovascular complications. This includes glucose intolerance and type 2 diabetes. Another study found that consumption of these sweeteners is associated with an increased risk of metabolic syndrome. Metabolic syndrome is a group of factors that, if left untreated, may increase the likelihood of developing heart disease.
Blood Pressure
Some studies suggest that diet soda may increase blood pressure. For instance, a meta-analysis from 2015 linked this effect to both regular and diet soda. However, other studies identified a link between standard soda and higher blood pressure but didn’t see the same relationship with diet soda. So, the jury is out. Still, it’s worth noting that many sodas contain caffeine. In fact, some have as much or more than a regular cup of coffee. And too much caffeine can also increase blood pressure.
Many factors influence your blood pressure, including what you eat, how much physical activity you do, and how stressed you are. It’s a complex topic, and we still don’t understand whether diet soda plays a part.
Gut Symptoms
A lot of diet soda may leave you feeling bloated. This is because sodas tend to be carbonated, and drinking them can lead to gas getting trapped in your system. Also, if you have a sensitive gut, the caffeine in some diet sodas may cause diarrhea. This is because caffeine activates contractions in your digestive tract, causing food to move through your gut more quickly. Plus, some sweeteners in diet sodas - such as sorbitol, mannitol, and xylitol - are known to worsen gut symptoms for some people.
For example, if you have irritable bowel syndrome, eating or drinking a lot of certain sweeteners may cause bloating and diarrhea.
Sleep Problems
Small amounts of caffeine - usually up to 400 mg - don’t cause problems for many people. This amount works out to about 4 cups of regular coffee or 5-6 cups of tea. But if you drink a lot of diet soda, the amount of caffeine in your day can easily add up. And too much caffeine has a well-established reputation for affecting sleep quality and quantity. Meanwhile, studies in mice have shown that artificial sweeteners can disturb sleep-wake cycles, though researchers haven’t confirmed whether this happens in humans.
Headaches
For some people, drinking multiple servings of diet soda per day could cause headaches. This may be due to certain artificial sweeteners found in diet soda, such as aspartame. One review noted that aspartame caused symptoms like headaches and migraines in those who took aspartame pills, particularly in those with neurological or psychiatric conditions. However, the review notes that some of the studies used aspartame pills, which release more aspartame into the body than you would get from drinking it in liquid form.
A handful of older studies, including a randomized controlled trial and a cohort study have found that artificial sweeteners may cause headaches in people who are already prone them. But other studies have found no effect of artificial sweeteners on headache frequency. Looking specifically at migraine headaches, a recent review concluded that other dietary factors, such as caffeine, were most likely to be triggers.
Some studies have also found that caffeine, which is present in some diet sodas, could cause headaches for a small percentage of people.
Food Cravings
Some research suggests that the artificial sweeteners found in diet soda may have the same effect on the food reward pathway in the brain as regular sugar. One study found that it can make food more palatable. This could lead to increased hunger and food intake. Additionally, because artificial sweeteners are significantly sweeter than regular sugar, researchers have suggested they might increase sugar cravings and dependence, making it much harder to reduce your intake. Nevertheless, research on this topic is mixed. Additional studies on diet soda and sugar cravings are needed.
Some studies suggest that artificial sweeteners may play tricks on your brain and increase your food cravings. But scientists still need to do more research. In one study, researchers gave participants a 300-ml drink containing either sugar, artificial sweetener, or plain water. Two hours after participants had the drink containing artificial sweetener, the team found increased activity in the brain region responsible for food cravings and appetite. And they found that after the artificial sweetener, female participants ate more at the buffet. They didn’t find this in males. Still, it’s worth noting that all the participants had fasted overnight before the study, so they were probably hungrier than usual.
In another study, researchers gave people standard or diet soda, then showed them pictures of food. The researchers spotted differences in brain activity between the two groups. After diet soda, there was increased activation of the brain’s reward system and decreased activity in control-related regions. Although the researchers call for more studies, they conclude that diet soda may lead to reduced inhibition and a greater desire for high-calorie foods.
Diet Soda and Constipation: The Direct Link
While scientists have not yet specifically looked into whether aspartame can cause constipation, some research indicates it may affect a person’s gut microbiota. However, the results are conflicting.
Aspartame is an artificial sweetener that manufacturers include in many low calorie beverages, foods, and other products. Manufacturers widely use it today, and the Food and Drug Administration (FDA) has approved its use as a food additive. The FDA and other similar administrations worldwide have also established acceptable and safe daily intake levels of aspartame.
Several studies have investigated how sweeteners affect a person’s gut microbiota, which describes the trillions of bacteria and other microbes that live in their gut. Doctors refer to problems with a person’s gut microbiota as dysbiosis. These issues may lead to gut problems, which may include chronic constipation.
Scientists have studied how aspartame affects a person’s gut microbiota. However, several human and animal studies found different and conflicting results. Some studies found that aspartame did not affect the gut microbiota. Conversely, others found that it could influence how the gut worked and may affect the gut microbiota.
Another 2019 review of studies investigated research into the effects of several sweeteners on a person’s gut microbiota. However, the researchers could not find any data on these effects. They also noted that a person’s body rapidly breaks down and absorbs aspartame in the small intestines before it has a chance to reach the large intestine, which is where most of the gut microbiome resides. For this reason, they stated it is hard to understand how aspartame influences a person’s gut microbiota. However, they noted that the artificial sweeteners saccharin and sucralose may affect the gut microbiota according to findings from several animal studies.
Aspartame also contains high levels of phenylalanine. Those with PKU need to avoid aspartame to help prevent harmful levels of phenylalanine from building up in their bodies.
Acceptable Daily Intake of Aspartame
The FDA establishes and monitors acceptable daily intake (ADI) levels for many food additives. An ADI is the amount of a substance a person can safely consume daily over their lifetime. Health experts usually express ADIs in milligrams (mg) of the substance a person can consume daily for each kilogram (kg) of their body weight.
The FDA’s ADI for aspartame is 50 mg for every kg of someone’s body weight. For someone weighing 60 kg, or 132 pounds (lb), this ADI equates to 75 packets of aspartame sweetener per day. In 1984, the European Food Safety Authority established an ADI for aspartame of 40 mg per kg of a person’s body weight. A person with a body mass of 70 kg (154 lb) would need to drink at least 9-14 cans of diet soda every day to exceed this limit, according to the ACS.
Addressing Constipation: Lifestyle Adjustments
If you've ever been constipated, you know that it’s uncomfortable. But making a few changes to your daily life can relieve the problem, even keep it away for good.
The Role of Exercise
If you don't exercise or you spend a lot of time just sitting, you can get constipated. It can be a problem for people who have to stay in bed a lot or just can't move much because of a health problem.
The answer: Try to exercise every day. It doesn’t have to be an intense workout. It's just important that you move on a regular basis. Even a 15-minute walk can help.
Fiber Intake
Fiber keeps more water and bulk in your intestines. That makes stools softer and easier to pass. But if you don’t have enough in your diet, you can get constipated.
The answer: Add lots of high-fiber foods to your meal plans, including fruits, vegetables, beans, and whole-grain breads and cereals. But add it in slowly. If you start eating too much all at once, that can cause constipation.
Hydration
Fluids, especially water, keep everything moving in your digestive tract. The answer: You don't have to focus on drinking a certain number of glasses of water a day. Instead, keep a bottle of water with you and remember to drink from it all day. Juice is OK, too, but watch other drinks. Fluids that have caffeine -- like coffee and soft drinks -- may make you dehydrated and make your constipation worse. And milk can make some people constipated.
Responding to the Urge
If you ignore the urge to poop, you may eventually stop feeling the need to have one. Maybe you don't go because you're busy or you don't want to use a bathroom outside your home. But doing this a lot can lead to constipation. The answer: No matter where you are, use the bathroom as soon as you feel the urge to go.
Establishing a Routine
The longer stool stays in your intestines, the harder it gets. And that makes it harder to pass. The answer: Try to have a bowel movement at the same time every day. It could help you to be more regular. Eating helps waste move through your colon. So you might try going to the bathroom 15-45 minutes after breakfast. Make sure you give yourself plenty of time so you don't feel rushed.
Medications and Supplements
Some drugs and supplements that you take for other conditions can cause constipation. This can include antacids, narcotics, antidepressants, and drugs that treat high blood pressure, as well as iron supplements. The answer: Don't stop taking any medication without talking to your doctor. Instead, try other habits to ease constipation. Drink plenty of water, move 15-20 minutes twice a day, and eat plenty of fiber-rich foods. Ask your doctor if you should take a laxative or other medicine to help ease your constipation.
Avoiding Overuse of Laxatives
Laxatives can help with constipation every once in a while. But if you rely on them, your bowels may start to depend on them to function. When you use them for a long time, it can actually make constipation worse. The answer: Think before you reach for a laxative. First, try drinking water, adding more fiber to your diet, and exercising. If those don't work, talk to your doctor. They may suggest trying a laxative for a little while if lifestyle changes aren't helping.
Alternatives to Diet Soda
Having diet soda every once in a while is unlikely to harm your overall health. But it’s important to remember that diet soda gives you very few nutrients, and there are healthier options. If you’re stuck for inspiration, here are some alternatives:
- Infuse water with fresh fruit, like lemon, lime, melon, or berries.
- Try fermented drinks, like kombucha.
- Have a fruit or herbal tea.
- Go for other teas or coffee, and you might opt for decaf.
- Try some homemade iced tea.
- Stick to plain water - it’s cheap, simple, and it does the job.
There are plenty of simple steps you can take to decrease your intake of diet soda. Start by slowly swapping it for other drinks in your diet. Here are a few alternative drinks to consider: flavored water, herbal tea, coconut water, seltzer water, kombucha. Look for versions of these drinks that either are unsweetened or have a lower sugar content. You can also try adding a splash of juice to water or seltzer. You can make flavored water by adding cucumber slices, fresh or frozen fruit, herbs like basil and mint, or citrus fruits like lime or lemon to plain or sparkling water for a hint of flavor without added sugar.
It may also help to buy less soda when you go grocery shopping and stock up on healthy alternatives instead. This will make it much easier to reach for a different drink in place of diet soda when you feel thirsty. Finally, it may be easier to gradually decrease your diet soda consumption instead of cutting it out all at once. Reducing the amount of diet soda that you drink each week to make long-lasting, sustainable changes may be easier to stick with over time.
People who usually consume synthetic sweeteners such as aspartame may wish to use natural sweeteners, such as stevia and monk fruit, which both have FDA approval for consumption. Another option is honey. However, while it has a slightly lower glycemic index score than sugar, it can still raise a person’s blood sugar levels. In contrast, research indicates that stevia and monk fruit are unlikely to affect a person’s blood sugar levels.