Sugar, in all forms, is a simple carbohydrate that the body converts into glucose and uses for energy. But the effect on the body and your overall health depends on the type of sugar you’re eating, either natural or refined.
We wanted to explore the difference between these sugar types as a follow-up to our post about whether sugar drives the growth of cancer, which has received several comments. We again turned to one of our clinical oncology dietitians for expertise on the issue.
Natural sugars are found in fruit as fructose and in dairy products, such as milk and cheese, as lactose. Foods with natural sugar have an important role in the diet of cancer patients and anyone trying to prevent cancer because they provide essential nutrients that keep the body healthy and help prevent disease.
Learn more about how nutrition may help cancer patients manage side effects.
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Refined sugar comes from sugar cane or sugar beets, which are processed to extract the sugar. It is typically found as sucrose, which is the combination of glucose and fructose. We use white and brown sugars to sweeten cakes and cookies, coffee, cereal and even fruit. Food manufacturers add chemically produced sugar, typically high-fructose corn syrup, to foods and beverages, including crackers, flavored yogurt, tomato sauce and salad dressing. Low-fat foods are the worst offenders, as manufacturers use sugar to add flavor.
Most of the processed foods we eat add calories and sugar with little nutritional value. In contrast, fruit and unsweetened milk have vitamins and minerals. Milk also has protein and fruit has fiber, both of which keep you feeling full longer.
How the body metabolizes the sugar in fruit and milk differs from how it metabolizes the refined sugar added to processed foods. The body breaks down refined sugar rapidly, causing insulin and blood sugar levels to skyrocket. Because refined sugar is digested quickly, you don’t feel full after you’re done eating, no matter how many calories you consumed. The fiber in fruit slows down metabolism, as fruit in the gut expands to make you feel full.
But there’s a caveat. Once the sugar passes through the stomach and reaches the small intestine, it doesn’t matter if it came from an apple or a soft drink.
How much sugar is already in your blood will determine how the body uses the sugar,. If you already have a lot of sugar in your system, then what you just digested will form either fat or glycogen, the storage form of glucose that’s used for quick energy. It doesn’t matter if it’s junk food or fruit.
We eat more refined sugar today than our parents and grandparents did three decades ago, which has resulted in increasing obesity rates among adults and children. Obesity has been associated with certain cancers, including breast, prostate, uterine, colorectal and pancreatic. On the flip side, fruits high in antioxidants—blueberries, blackberries, raspberries, strawberries and apples—may reduce your cancer risk. The fiber in fruit, found mainly in its skin, suppresses your appetite to prevent overeating and weight gain.
Our clinical oncology dietitians recommend eating whole foods that are low in refined sugars. Whole foods refer to foods that are either unprocessed, such as fruit and vegetables, or minimally processed, such as whole grains.
The big picture is being a healthy weight and making healthy food choices. It’s about eating a diet with whole foods, lean proteins, complex carbohydrates like quinoa rather than white bread, and non-starchy vegetables. Focus on making good food choices every day on a consistent basis, not on the one piece of cake you had as a treat.
Learn about the benefits of good nutrition during cancer care.