Note: This report is an update of the one originally posted on 3/31/19. New studies referenced here were published since my original report.
The Nurses' Health study and The Health Professional's Follow-Up study, two of the largest studies on the subject, show that sugar-sweetened beverages are associated with increased risk for heart attacks, diabetes, obesity and high blood pressure, and the more sugar-sweetened beverages you take in, the more likely you are to suffer from these diseases (Circulation, April 30, 2019;139:2113–2125). Sodas are the highest source of added sugar in the North American diet, and it is sobering to learn that 50 percent of North American adults drink at least one sugared beverage each day.
However, people who drink a lot of sugar-sweetened beverages have lots of other unhealthful habits. They are:
• less likely to exercise
• more likely to smoke
• more likely to have high blood pressure
• likely to eat an unhealthful diet
The authors of this study tried to correct for these additional unhealthy lifestyle practices and have presented the most comprehensive long-term data ever on sugared and artificially sweetened beverages and their association with diseases and deaths. A recent review of the world's literature shows the same results (JAMA Netw Open, May 19, 2019;2(5):e193121).
Evidence Against Artificial Sweeteners
If you want to take sweetened drinks, you are safer with artificially-sweetened beverages, but they also are associated with increased risk for heart attacks and death in women (Circulation, 2019;139:2113–2125), and for obesity, strokes, dementia, diabetes and pre-diabetes.
• Drinking two or more artificially sweetened drinks per day is associated with an increased risk of strokes, heart attacks, and early death, particularly in overweight women over 50 (Stroke, Feb 14, 2019). More than 80,000 healthy post-menopausal women were followed for almost 12 years. Those who consumed two or more 12-ounce artificially sweetened beverages each day were 31 percent more likely to have a clot-based stroke, 29 percent more likely to have heart disease and 16 percent more likely to die from any cause during the study period, compared to women who drank diet beverages less than once a week or not at all. Obese women were twice as likely to suffer clotting strokes, but non-obese women were not at increased risk.
• A review of 56 studies showed that adults and children gain weight on artificial sweeteners and gain even more on sugared drinks (BMJ, Jan 7, 2019).
Why Sugared Drinks are Particularly Harmful
Sugar in a drink causes more than double the rise in blood sugar than the same amount of sugar eaten in a cookie. Solid food is not allowed to pass from your stomach into your intestines, so when you eat sugar-added solid foods, the pyloric sphincter at the end of the stomach closes and does not allow the food to pass into the intestines until it is converted into a liquid soup. On the other hand, liquid sugar is allowed to pass immediately into your intestines, where it is quickly absorbed into your bloodstream.
All sugared drinks, including fruit juices, can cause as high a rise in blood sugar. A high rise in blood sugar can cause sugar to attach to cells and damage them. People who take a lot of sugared drinks are at increased risk for:
• High triglycerides: Your body converts extra sugar almost immediately to a type of fat called triglycerides, so a high rise in blood sugar causes a high rise in triglycerides.
• Low HDL (good) cholesterol: High triglycerides can cause clots to form in your blood vessels, so your HDL cholesterol works to protect you by carrying the triglycerides from your bloodstream to your liver.
• Fatty liver: Triglycerides moved from your bloodstream into your liver cause the liver to fill up with fat and
• Diabetes: A fatty liver can cause diabetes. People who are genetically susceptible to having high triglycerides are at very high risk for diabetes (Nutrigenet Nutrigenomics, Oct 2017;10(3-4):75-83).
How to Tell if You Have a Fatty Liver
• blood sugar greater than 140 an hour after eating
• fasting triglyceride level greater than 150 mg/dl
• systolic blood pressure greater than 120 just before going to bed
• HDL cholesterol below 40 mg/dl
• waist circumference greater than 40 inches in a man or 35 inches in a woman
• more than three inches of fat underneath your skin when you pinch near your belly button
If any of these apply to you, your doctor can order an inexpensive and harmless sonogram of the liver which will demonstrate whether you have excess fat there.
The most important prevention and treatment for type II diabetes is to get the fat out of your liver so your liver can do its job of lowering blood sugar by removing sugar from your bloodstream. Some people who are genetically susceptible to diabetes will need to lose excess fat from the rest of their bodies before it will come out of the liver. High triglycerides can be lowered by exercising, losing excess weight and avoiding foods that cause high rises in blood sugar (all sugared drinks including fruit juices, sugar added foods and other refined carbohydrates such as bakery products and pasta).
Unless you are in the midst of a long, vigorous exercise session, I recommend that you drink only water or unsweetened coffee or tea. For my recommendations on use of sugared drinks during intense exercise, see Sugar for Prolonged Hard Exercise