Nutritionists do not like diet soda, and there is not a single official recommendation from any association or state that would support it. Although added sugar is one of the main problems of the modern “Western” diet, soda on sweeteners is constantly met with something between disbelief and hostility, and the ratio of hostility to evidence of harm is not quite right. Is Diet Soda Harmful?
In short: no, sweeteners are not harmful if the recommended norms are observed and help to lose weight by reducing the calorie intake.
The most important thing to know about low-calorie sweeteners is that you consume them in tiny amounts. Take Sucralose: The US Food and Drug Administration has set an acceptable daily intake (determined by determining a safe level and dividing by 100) at 5 mg/kg of body weight. If you weigh 70 kg, you can eat 350 mg daily – that’s how much Sucralose is in ~ 30 standard serving packets of this sweetener. Of course, some substances are harmful even in tiny amounts, but science figures it out pretty quickly, and no one will allow them to be sold in a supermarket.
The bad reputation of sweeteners began with saccharin when it was linked to bladder cancer in the 1970s. Then it turned out that this is not related to people, and subsequent studies have confirmed this.
There are also concerns that the body is experiencing a gap between the sweet taste of food that does not provide energy, as it does with sugar, and what it manifests. It is hypothesized that this may alter feelings of hunger and satiety, decrease the awareness of calories taken from food, adversely affect the gut microbiota, increase glucose intolerance, and lead people to consume more calories from other foods. To date, none of these claims against sweeteners have been proven.
First, tiny amounts of anything are unlikely to mess with the gut microbiota. The microbiota has become a nutritional conspiracy theory: that’s where people go to prove something is dangerous when there’s no evidence for it. Scientists in research are overfeeding people with fiber to change the makeup of the microbiota—with limited success. And research on probiotics, which are specifically designed to change gut bacteria, shows that it’s hard to do, even when you purposefully try.
While gut bacteria and gut dysbiosis are probably the most common problems, there is exactly one human study. Seven people were fed saccharin in large quantities for a week, and four had “poorer glycemic responses,” that’s all—pure saccharin in large quantities, seven people. The rest of the studies were done on mice. It isn’t easy to conduct a pure controlled experiment on humans. Then, in a sense, chaos in the human intestine and the changes must be very powerful to be meaningful and affect different body systems.
You also must understand that even laboratory-controlled studies are not always similar (and sometimes not similar) to real life. For example, a recent study concludes:
Sucralose may have adverse effects on glucose metabolism in obese individuals. These studies also highlight the physiological role of sweet taste perception in glucose homeostasis, supporting the idea of moderate consumption of all sweets, regardless of their calorie content.
The study involved ten people with normal weight and nine with obesity. None used sugar substitutes regularly and had diabetes or significant insulin resistance. Each day of testing differed only in what solution people took on an empty stomach 10 minutes before the oral glucose tolerance test: water (control group), oral Sucralose (with a perception of a sweet taste by a person), or Sucralose in the form of injections – without a perception of a sweet taste.
Results: “Sucralose differentially affects hormonal responses to oral glucose loading in obese and normal weight individuals. Taking Sucralose (not just because of its sweet taste) increases insulin secretion and transiently lowers glucose in obese but not normal weight individuals. These data support the hypothesis that Sucralose may harm glucose metabolism in obese people, the group most commonly consumed with sugar substitutes for weight control. These data also highlight the physiological role of sweet perception in glucose homeostasis, supporting the idea of moderate consumption of sweets, regardless of their calorie content.
This useful scientific study helps to understand better what happens to glucose metabolism. But taking high doses of pure Sucralose on an empty stomach, including injections, is not something that occurs in real life (although, in any case, drinking liters of diet soda in the morning on an empty stomach is not a good idea). A similar story is with fructose. Rodent studies show that solutions with high doses of pure fructose lead to obesity and other problems in rodents. But experimental doses are so high that they have nothing to do with human consumption of fruits – during the day, on an empty stomach, or at night.
This is not a call to switch to sweeteners. But if there is any evidence that they can help with weight loss a little (and there is no evidence of harm for legal sweeteners at recommended dosages), it makes no sense to oppose them so hostilely.
Most likely, the fact is that sweeteners represent almost everything that is wrong with our nutrition:
- they are mostly synthetic;
- they play on people’s love of sweets, which manufacturers use to sell us more and more;
- they are found mainly in ultra-processed foods, which are recommended to be eaten less often.
If we summarize all the official recommendations for proper nutrition and translate them into human language: you should not eat too much, mostly plants. Eat home-cooked food and drink water. But given how far people are from this, should we let the “perfect” be the enemy of the “normal”? The fact is that many people do not want to drink water. They want to drink soda.
Consider the most recently published meta-analysis in the British Medical Journal. There was insufficient proof of benefit, but the possibility of harm cannot be ruled out. However, the inverse is also true: there is no definitive evidence of harm, and a benefit cannot be ruled out. The meaning is the same, but it sounds more positive. Almost similar can be found for any substance. For example, take caffeine: everyone wants to find out what is wrong with it. Go to PubMed, a repository of scientific articles, and look at human studies. Ignore anything that is sponsored by the industry. You’ll find a lot of lists of potential harm, but once you weed out the speculation and focus on the evidence, you won’t find anything to worry about.
And here is a comprehensive literature review published in Food and Chemical Toxicology in 2017. Conclusions:
- There is no negative effect of long-term use of Sucralose in healthy and diabetic patients on health or glycemic indicators.
- The allowed daily intake of Sucralose remains well below the allowable daily values.
- The review confirms the conclusions of regulators worldwide that Sucralose is safe for its intended use as a non-caloric sweetener.
Sugar consumption has declined since 1999, but obesity continues to rise. When we look at population-based observational studies, we see that sugar substitute drinkers tend to weigh more and have poorer health. But today, all studies that show the relationship between sweeteners and obesity in humans are observational, not controlled. This means that there is only an association between two variables: Obese people drink Diet Coke more and more, but such studies do not prove that Diet Coke is the cause of obesity.
Diet soda drinkers are more likely to be overweight due to poor eating habits and other factors. For example, some people drink Diet Coke to whiten their poor diet, leading to obesity. Others believe they can afford more calories with food because they drink Diet Coke and overeat. There is a connection, but not causation. Diet Coke doesn’t make you fat. It’s just that obese people tend to drink Diet Coke.
Conversely, the fact that using sweeteners in a healthy lifestyle is not encouraged may mean that people who are health conscious and have good habits do not use them. Almost the same as with vitamins in jars: health is associated with more healthy lifestyle habits, and dietary supplements and vitamins, like a bottle of clean water with you everywhere, are the attributes of a healthy lifestyle.
When we look at controlled studies, we see that replacing sugar with non-caloric sweeteners, people consume fewer calories and lose weight over time. The results are not very significant, but to date, there is not a single dietary intervention known that would have a wow effect on the treatment of obesity on its own, in isolation, not in combination with other interventions.
Suppose the nutrition community encouraged people with obesity and very poor eating habits to switch from sugary soda to a few liters of pure water to a non-caloric soda. In that case, it might be more effective and viable.
The US Department of Health is monitoring people who have lost more than 15 kg and have been able to maintain the new weight for at least a year. Only 10% report drinking sugar-sweetened beverages regularly, while 53% drink diet soda regularly. Compare that to the general population, where 61% drink sugary soda daily, and only 15% drink the diet version. Everyone knows that drinking clean water is good, but soda is not. But people still drink soda, so the lesser evil is to drink non-calorie soda.
