A serving of 100 percent fruit juice contains the same amount of sugar as a sugared soft drink. Eight ounces of fruit juice contains the same 30 grams of sugar (eight teaspoons) that is found in eight ounces of soda, because that is the concentration at which sugar tastes best in drinks.
A review of 17 studies of children and 25 studies of adults found that drinking 100 percent fruit juice regularly is associated with gaining extra weight (JAMA Pediatr, January 16, 2024:e236124). A review of 73 meta-analyses that included 8,601 studies showed that adding sugared drinks to your diet was associated with significantly higher risks of 45 negative health outcomes (BMJ 2023;381:e071609). The Nurses’ Health Study and The Health Professional’s Follow-Up Study have shown 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 conditions (Circulation, April 30, 2019;139:2113–2125).
Sugar in Drinks Can Cause High Rises in Blood Sugar
Sugar in a drink causes more than double the rise in blood sugar as the same amount of sugar eaten in a cookie. When you eat 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. Sugar in a drink is allowed to pass immediately into your intestines, where it can be absorbed into your bloodstream. When you drink fruit juice or any other sugared drink, you are at increased risk for:
• High triglycerides: Your body can convert extra sugar almost immediately to a type of fat called triglycerides, so a high rise in blood sugar causes a rise in triglycerides.
• Low HDL (good) cholesterol: High triglycerides can cause clots to form in your blood vessels, and 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 can cause your liver to fill up with fat.
• Diabetes: A fatty liver can lead to diabetes. If you are genetically susceptible to storing fat in your liver, you are at increased risk for diabetes (Nutrigenet Nutrigenomics, Oct 2017;10(3-4):75-83).
Sugared Drinks and Disease
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. A study of nearly 100,000 postmenopausal women followed for an average of more than 20 years found that compared to women who had fewer than three sugar-sweetened drinks per month, those who drank one or more sugar-sweetened beverages per day had an 85 percent increased risk for liver cancer and 68 percent increased risk for death from chronic liver disease, such as liver scarring, cirrhosis, alcoholic liver diseases, fatty liver and chronic hepatitis (JAMA, 2023 Aug 9, (6):537-546).
A study of more than 28,000 North American adults found that those who ate 25 percent or more of their daily calories from added sugars had the highest rate of kidney stones (Front Nutr, Aug 4, 2023). Kidney stones contain calcium, and many studies have shown that a high-sugar intake markedly increases the loss of calcium in the urine. Sugar added to foods and drinks contributes to weight gain, high blood pressure, insulin resistance and diabetes, all of which are associated with increased risk for kidney stones.
How Sugared Drinks Increase Risk for Heart Attacks
• Taking in sugar-added foods and drinks causes a high rise in blood sugar.
• A high rise in blood sugar causes sugar to stick to the outer membranes of cells and destroys them.
• To prevent blood sugar from rising higher, the pancreas releases insulin which lowers blood sugar by driving sugar from the bloodstream into the liver.
• As soon as the liver fills up with sugar, it can store no more sugar, so the extra sugar is converted by your liver into fatty triglycerides, so blood levels of triglycerides rise too high.
• To prevent blood triglyceride levels from rising too high and causing clots, your good HDL cholesterol carries the triglycerides into the liver, so your HDL cholesterol goes down and you store extra fat in your liver to cause a fatty liver.
• As the liver collects extra fat, it cannot respond to insulin that lowers blood sugar by driving sugar from the bloodstream into the liver, so your blood sugar rises even higher, which can lead to type II (insulin-resistant) diabetes.
• As the cycle continues, extra fat is deposited in the liver and the belly, which gives you a big belly.
• Then your liver takes large numbers of triglyceride molecules and combines them with lesser numbers of cholesterol molecules to make the bad LDL cholesterol, which causes plaques to form in arteries (arteriosclerosis), which can break off to lead to a heart attack.
Why Sugar-Sweetened Drinks are Harmful
Fatty Liver Can Cause Diabetes, Heart Attacks and Cancers
My Recommendations
Many scientific studies show that eating a few sugar-rich whole fruits each day is healthful, even for people who are diabetic (Annals of Int Med, June 16, 2020;172(12):826-827). However, it now appears that drinking fruit juice regularly is associated with excess weight gain (Diabetes Obes Metab, Jan 2024;26(1):180-19). Unless you are in the midst of a long, vigorous exercise session where you need some extra sugar, I recommend that you avoid fruit juices and quench thirst only with water. Unsweetened coffee or tea are also OK.
