Does Sugar Cause Inflammation?

While the sweet treats you enjoy throughout the day (some M&Ms here, a biscuit there) and your after-dinner dessert (hello, ice cream!) taste absolutely delicious, sweet tooths everywhere should know that they’re probably packed with added sugar—and that consuming too much food (or drink) with added sugar can pose potential health risks, like unexpected weight gain.

Many people also wonder, “Does sugar cause inflammation?” It’s a great question, and the answer isn’t so simple. We asked experts to help us discuss the side effects of eating too much added sugar (which has historically been studied the most).

Before we dive into the possible relationship between added sugar and chronic inflammation, it’s important to understand what inflammation means—as well as the difference between natural and added sugar.

What is chronic inflammation, and what’s the difference between natural and added sugar?

Inflammation is the body’s immune system defending against foreign substances, such as viruses and bacteria. Acute inflammation occurs quickly and is caused by tissue damage, while chronic inflammation is slow, long-term, and can be caused by genetic predispositions, diet, and stress.

The Cleveland Clinic says chronic inflammation can cause abdominal pain, fatigue, joint stiffness, fever, skin rash, or chest pain.

“Inflammation is a crucial part of your body’s healing process.” says integrative medical GP Dr Dana Cohen. “Your body sends out inflammatory cells (white blood cells) to attack the unfamiliar matter or mend the damaged tissue. If these inflammatory cells stay too long, it may lead to chronic inflammation which has been described as a fire (in-flame) going out of control.”

Now, on to sugar. Natural sugars can be found in fruit (fructose) and dairy (lactose). Dr Cohen says that too much added sugar can affect your health. Added sugar is when when sugar or kilojoule-heavy sweeteners are manually included when the food or drink is processed. Most major studies done on the relationship between inflammation and sugar are specifically about added sugar, which what we'll focus on here.

Brown sugar, corn syrup, cane sugar, fructose, maple syrup, high-fructose corn syrup, and sucrose are common added sugars.

Read on for the details on the correlation between added sugar and inflammation.

Does added sugar cause inflammation?

There needs to be more research to definitively state the relationship between sugar and chronic inflammation, but Dr Deena Adimoolam, a specialist in diabetes and endocrinology, says there is data suggesting overconsumption of added sugars can increase inflammation.

“The cause for this is unclear, but it may be related to how these added sugars are metabolised,” Dr Adimoolam says. “Many foods with added sugars also have added ingredients like preservatives, food colorings, etc, which may also increase inflammation.”

Some research has shown that a diet high in refined sugars is associated with a higher production of pro-inflammatory molecules. “Excessive consumption of added sugars may cause inflammation in the body by promoting insulin resistance, fat storage, elevated triglycerides, changes in gut microbiota, and the formation of pro-inflammatory compounds,” says dietitian Mascha Davis. “This can all contribute to chronic inflammation.”

Endocrinologist Dr Maria Teresa Anton also says the overconsumption of added sugar can cause an increase in the production of inflammatory markers in the body, which are indicators in blood tests used to detect inflammation caused by diseases or conditions.

One study found that people with a high-sugar diet tend to have higher levels of C-reactive protein in their blood, which is a type of inflammatory marker.

Further research is needed to fully understand added sugar’s relationship with inflammation, but current studies suggest that eating or drinking too much added sugar is not recommended.

“It is still unclear whether different kinds of sugar like fructose, sucrose, glucose, or high fructose corn syrup contribute to inflammation, but it is clear that added sugars in general can lead to obesity and promote inflammation that leads to cardiovascular disease and high blood pressure,” Dr Cohen says.

Do natural sugars cause inflammation?

Again, much of the research available focuses on added sugar. Added sugar and natural sugar both cause blood sugar spikes (which can lead to inflammation), but it is much easier to overconsume the former than the latter. Foods with natural sugars (such as fruit and milk), have a much lower percentage of sugar than foods like doughnuts, cookies, and fizzy drinks. Plus, natural sugar is typically found in anti-inflammatory foods, such as berries and oranges.

Free sugars refer to monosaccharides (such as glucose, fructose) and disaccharides (such as sucrose or table sugar) added to foods and drinks by the manufacturer, cook or consumer, and sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates. It does not include the sugars in fresh fruits and vegetables, and sugars naturally present in milk.

The World Health Organization recommends that adults and children reduce their daily intake of free sugars to less than 10% of their total energy intake. A further reduction to below 5% or roughly 25 grams (6 teaspoons) per day would provide additional health benefits.

Other foods that cause inflammation

Cookies, ice cream, doughnuts, and sweet snacks are not the only offenders when it comes to inflammation. Dr Anton says red meats, refined carbohydrates, and fried foods have been linked to causing inflammation too. Along with those food choices, Dr Cohen also says full fat dairy products, excess omega-6 fatty acids (which can be found in corn oil, sunflower oil, and vegetable oil) can cause inflammation.

Chronic inflammation may occur when you’re eating too much of one or more of these foods, so this doesn’t mean you have to cut out hamburgers and french fries completely. “Inflammation is rarely caused by one food alone, but excess consumption of fried, processed and packaged items that contain high amounts of additives (as well as salt and sugar), may increase risk of chronic inflammation,” Davis says.

While selecting healthy options to put on your plate is helpful, it’s important to remember that drinks can cause inflammation, too. Research shows that excessive amounts of alcohol can lead to systemic inflammation because it impairs the gut and liver’s defences against bacteria.

Dr Cohen advises against focusing on specific foods to avoid, and instead suggests looking at your overall diet. “If someone is eating mostly a whole food diet, some red meat and dairy is okay,” she says.

What other effects does added sugar have on the body?

Beyond causing inflammation, the overconsumption of added sugar can contribute to weight gain, may lead to cavities in your teeth, and is a risk factor for heart disease.

The negative effects of eating or drinking an excessive amount of food and drinks with added sugar are not limited to just your physical health.

“Some of the immediate effects of consuming too much sugar include fatigue, irritability, and/or depression,” Dr Anton says. One study found that consuming added sugars increases the risk of mood disorders in men, and another study found sugar intake increases the need to sleep and lowered energy levels.

“The liver converts sugar to fat,” Dr Cohen says. “And when the liver becomes overloaded with added sugar, this can lead to an accumulation of fat which can result in fatty liver disease (a potential contributor to type 2 diabetes) and heart disease.”

Luckily for those with a sweet tooth, it’s not all bad. Glucose is a type of sugar that is necessary for our survival and it’s made from eating carbohydrates, proteins, and fats. Just keep track of how much you eat (see World Health Organization recommendations above).

How can I reduce inflammation?

Before you consider anything drastic, like a no-sugar diet, there are other lifestyle and diet changes you can make first to safely lower your sugar consumption. Obesity can be linked to chronic inflammation in fat tissue, so Dr Cohen suggests following a Mediterranean diet, getting regular exercise, and sleeping well to help reduce stress and maintain a healthy weight.

Avoid some of the worst foods for inflammation and opt for anti-inflammatory foods for prevention and reduction, such as leafy greens, almonds, walnuts, tomatoes, olive oil, berries, and oranges.

Davis recommends prioritising balance and moderation in your diet, rather than stressing about eating no sugar.

“One approach is to be aware of sneaky sources of added sugars and make substitutions,” she says. See this list of sugar swaps from That Sugar Movement.

Check food labels for added sugars. Keep in mind there are lots of different names for sugar - here's a list to check against.

Dr Adimoolam suggests focusing on weight loss as needed, reducing stress, improving sleep habits, including exercise in your routine, and limiting added sugars to less than 10% of your total daily kilojoules. She also says to eat more beans, fruits, nuts, and cook with extra virgin olive oil for antioxidant benefits.

Dr Anton and Davis also recommend making lifestyle changes and following a holistic approach to reduce and prevent inflammation, such as exercising regularly and limiting stress.

“Addressing inflammation requires a holistic approach that involves focusing on all aspects of health, including nutrition, sleep, physical activity, and mental wellbeing,” Davis says. “It is recommended to aim for at least 150 minutes of exercise each week and to integrate stress management tools like meditation, journalling, or yoga to help prevent and lower inflammation in the body.”

If you are experiencing chronic inflammation, it is always best to speak with your doctor to determine the root of the problems.