A review of 17 studies involving 1733 adults found that substituting artificially sweetened drinks for sugared drinks is associated with slightly reduced body weight, body fat percentage, and measures of fatty liver disease (JAMA Netw Open, 2022;5(3):e222092). However, artificially-sweetened drinks are less healthful than drinking water or unsweetened coffee or tea. Sugar-sweetened beverages are least healthful, increasing risk for diabetes, high blood pressure, weight gain, and heart attacks.

Research on Artificial Sweeteners and Inflammation
Artificial sweeteners can harm you by altering the bacteria in your colon (Nutrition Today, May 6, 2021;56(3):105-113). Some artificial sweeteners may cause inflammation, a condition in which your own immune system, which is supposed to kill invading germs, stays active all the time to attack you (Int J Mol Sci, May 15, 2021;22(10):5228).  These authors found that just two cans of diet drinks that contain the most widely used artificial sweeteners (saccharin, sucralose, and aspartame) increased growth and colon invasion of Enterococcus faecalis (harmful colon bacteria that invade the colon cells to turn on your immune system), and decrease the healthful E. Coli bacteria that do not invade your colon cells.

You have more than 100 trillion bacteria in your colon. Some are healthful, while others can harm you. The types of bacteria in your colon are determined far more by what you eat than by your genetics (Nature, 2018;555(7695):210-215), and some types of bacteria can turn on your immune system to cause inflammation that increases risk for heart attacks, dementia, auto-immune diseases and certain cancers (J Alzheimers Dis, 2017;58:1-15).

Colon bacteria eat the same foods that you do. The healthful bacteria are content to eat what you eat, so they stay in your colon and do not try to cross into your cells and bloodstream, but the harmful bacteria seek different foods by invading the cells lining your colon. Your immune system tries to defend you by producing huge amounts of white blood cells and chemicals that work to destroy the invading bacteria by punching holes in their outer membranes and trying to kill them. This constant invasion of your colon cells by harmful bacteria can cause your immune system to stay on all the time and attack you in the same way that it kills germs. It can punch holes in your arteries to start plaques forming and then cause the plaques to break off from an artery to cause a heart attack. Inflammation can also change the DNA in cells so they become cancerous, and if your immune system does not recognize and kill these cancer cells, they can spread to and damage other parts of your body.

How Artificial Sweeteners Work
Artificial sweeteners are components of food that cause a sweet taste in your mouth without causing the gain in calories or rise in blood sugar that you get when you eat sugars. They do this by being so sweet that you can get the taste of sugar by using only a very small amount. For example:
• Aspartame (NutraSweet, Equal) – 180 time as sweet as sugar
• Saccharin (Sweet’N Low, Sweet Twin, Sugar Twin) – 350 time as sweet as sugar
• Stevia (Truvia and other brands) – 250 times as sweet as sugar
• Sucralose (Splenda) – 660 times as sweet as sugar

As far as I know, only saccharin, sucralose and stevia have been shown specifically to change the composition of the gut microbiota, but many other artificial sweeteners, such as isomalt, maltitol, lactitol, and xylitol, may increase the numbers of bacteria that have been associated with weight gain (J Neuroendocrinol, Jun 2015;27(6):424–434).

Artificial Sweeteners Can Increase Risk for Weight Gain and Diabetes
You may have to take in large amounts of artificially-sweetened drinks to suffer significant health consequences, but many studies show that artificial sweeteners make you hungry so that you eat more food, increasing your risk for weight gain and diabetes. A review of 30 studies showed that artificial sweeteners are associated with weight gain, increased waist circumference, and higher incidence of obesity, hypertension, metabolic syndrome, type II diabetes and heart attacks (Can Med Assoc J, Jul 17, 2017;189(28):E929-E939).

Sugar is Worse Than Artificial Sweeteners
We have known for many years that eating too much sugar can harm you by causing high rises in blood sugar, which can damage cells throughout your body. Sugar-sweetened beverages cause the highest rises in blood sugar to increase risk for diabetes (BMJ, 2015;351:h3576), high blood pressure (Am J Clin Nutr, 2015;102(4):914-921), weight gain (Am J Clin Nutr, 2013;98(4):1084-1102), and heart attacks (Br J Nutr, 2015;113(5):709-717).

Dietary sugar is supposed to be absorbed in the upper intestinal tract, but research from Yale suggests that taking in excessive amounts of sugar can cause some of the sugar to pass through the intestines unabsorbed. This sugar arrives in your colon where it can harm you by keeping healthful bacteria from growing in your colon and encouraging the overgrowth of harmful bacteria (PNAS, Dec 17, 2018). The safest drink for quenching thirst is water. Unsweetened coffee and tea appear to be safe also.

My Recommendations
• Restrict or avoid foods and drinks with added sugar. Most of the medical community now agree that sugar added to foods and drinks can increase your risk for weight gain, heart attacks and certain cancers.
• Artificial sweeteners appear to be safer than sugared foods and drinks, but increasing numbers of scientific papers show that artificial sweeteners can change the bacteria in your colon to increase risk for gaining weight and developing diabetes.
• If you are overweight and want to lose weight, I recommend adopting an anti-inflammatory diet that restricts sugar-added foods and drinks, mammal meat, processed meats, fried foods and refined grains (foods made from flour). Also try to exercise every day.
Drink Water Instead of Sweetened Drinks
Artificial Sweeteners Are Not Benign