For all of human history, the natural sugars in fruits, vegetables and other plants have served us well. They have provided essential fuel for our body’s most important processes.
But now that sugars have been processed into more potent forms and added to so many foods and drinks — sodas, candies, breakfast cereals, salad dressings, breads — most of us are getting more sugar than our bodies were meant to handle.
Over time, excess consumption of these added sugars can increase the risk of health problems. Here’s how that may play out in various parts of your body.
The Mouth
The potential issues from added sugars start in your mouth. Here, certain bacteria break sugars down and produce acids, which can eventually erode your tooth enamel.
Your saliva is able to neutralize these acids, but if you keep consuming sugary foods and drinks throughout the day, it won’t be able to keep up. Acid levels will remain high, increasing your risk for cavities.
A diet high in sugary drinks like soda and juice can also change your mouth’s microbiome — increasing the number of acid-producing bacteria and decreasing the beneficial ones. That may make you even more susceptible to cavities.
The Gut
Most sweet foods contain several types of sugars. In the small intestine, they are broken down into simple sugars — mainly glucose and fructose.
Your body can easily absorb glucose from your intestine, but some people have trouble absorbing fructose, which is found in high amounts in many fruit juices, sweeteners like agave syrup, and drinks sweetened with high fructose corn syrup, like sodas. If fructose lingers in your gut, bacteria can ferment it, which may cause gas, bloating and abdominal pain.
Young children tend to have more difficulty absorbing fructose than adults, but it can contribute to irritable bowel syndrome symptoms in people of all ages.
The Pancreas
When your blood sugar rises, your pancreas releases insulin, a hormone that helps glucose enter your cells to be used for energy. As your cells pull in the glucose, your blood sugar returns to normal.
Eating foods high in added sugars can cause large blood sugar spikes. When this happens repeatedly, over years, your cells can become less responsive to insulin. This is called insulin resistance. Your pancreas compensates by making more insulin, but eventually, it may not be able to make enough to keep your blood sugar levels in check. This is how Type 2 diabetes develops.
The Brain
Glucose provides essential fuel for your brain. When your blood sugar rises, glucose molecules cross into your brain, where brain cells use them for energy.
But if you have a big blood sugar spike and a surge of insulin, your glucose levels may plummet an hour or two later. That can leave you feeling irritable, tired and hungry — and perhaps craving something sweet again.
Sugar — its taste in your mouth, its absorption in your gut and even the sight or smell of a sweet food that you love — causes dopamine to surge in your brain. That’s an evolutionary signal that propels you to keep eating easy sources of calories.
Some research suggests that frequent doses of sugar can alter the brain’s reward system, increasing our cravings for sweetness and sometimes making it hard to cut back.
The Liver
Consuming too much added sugar can cause the liver to convert extra sugars, especially fructose, into fat. That fat may then accumulate in the organ.
Over time, this can contribute to what used to be called nonalcoholic fatty liver disease, now known as metabolic dysfunction-associated steatotic liver disease, or MASLD. An estimated four in 10 people worldwide have the condition — many of whom don’t know it, since it typically doesn’t cause symptoms until it’s advanced. It’s the fastest growing reason people need liver transplants in the United States.
Fat Storage
Consuming too much sugar can also increase your risk for obesity. This is especially true if you drink a lot of “liquid calories,” like from sodas or sugary coffee drinks, which tend to leave you feeling less sated than solid food. That makes it easy to consume more calories than your body needs, leading to weight gain.
Some studies suggest that the extra fat manufactured from fructose by your liver is especially prone to accumulating around the organs in your belly. This type of fat, called visceral fat, causes inflammation and insulin resistance and is strongly linked with cardiovascular disease.
The Heart
Excessive sugar consumption has also been linked to high blood pressure. And some of the extra fat made from sugars in the liver can be released into the blood, increasing levels of triglycerides and LDL, or “bad,” cholesterol. Over time, this can clog your blood vessels. High blood pressure and high cholesterol — along with excess weight that may come from consuming sugary foods and drinks — can increase your risk of heart disease.
The Joints
Consuming a lot of sugar can also increase your risk of gout — a complex form of arthritis that causes painful inflammation of the joints, especially in the fingers, toes and ankles. When fructose is broken down in the liver, it creates uric acid, which can accumulate in the joints and cause this kind of inflammation.
How much sugar is too much?
If you’re concerned about the occasional sugary treat, don’t be. Gorging on Halloween candy once a year won’t cause a chronic condition (though it may cause a stomach ache). But years of consuming more added sugars than recommended — along with other aspects of your diet, genetics, sleep and stress levels — may contribute to your risk.
Federal health officials recommend that no more than 10 percent of your daily calories come from added sugars. If you consume 2,000 calories per day, this works out to no more than 50 grams of added sugars per day.
That leaves plenty of room for sweetness, like a teaspoon of honey in your tea (about five grams) or Ghirardelli dark chocolate (three grams per serving of their Intense Dark 86 percent cacao version). But some products, like sugary drinks, can quickly put you over the limit. A 20-ounce bottle of Coca-Cola contains 65 grams of added sugars, for example, and a 16-ounce Caramel Swirl Latte from Dunkin’ has 35 grams.
The American Heart Association sets a stricter limit of 6 percent of calories consumed — or no more than about 25 grams per day for women and 36 grams per day for men.
On average, people in the United States consume about 67 grams of added sugars per day.
Nearly two-thirds of that amount comes from sugary drinks, sweet snacks, desserts and candy. But added sugars are also found in many packaged products like condiments, pasta sauces, sliced breads, granola and sweetened yogurts. You can check the “added sugars” line on nutrition labels to see if any are present. You may be surprised by what you find.
Sources
We consulted Dr.Miriam Vos, a hepatologist at Emory University School of Medicine; Dr. Frank B. Hu, a professor of nutrition and epidemiology at Harvard T.H. Chan School of Public Health; Kimber L. Stanhope, a research nutritional biologist at the University of California, Davis; Ashley Gearhardt, a professor of psychology at the University of Michigan; Michael Goran, a professor of pediatrics at the Keck School of Medicine of USC; Paula Moynihan, an adjunct professor at Adelaide Dental School in Australia; Vasanti Malik, an assistant professor of nutrition and chronic disease prevention at the University of Toronto; and Alexandra G. DiFeliceantonio, an assistant professor of human nutrition, foods and exercise at Virginia Tech.
