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  • Writer's pictureDerrick W. Spell, MD FACP

Sugar – The True Bad Carb

Updated: Feb 12, 2020

Most Americans eat large quantities of simple, refined carbs (sugars) and small amounts of complex carbs and fiber. In fact, over half of the calories in the typical American diet now come from three sources that were non-existent centuries ago: refined sugars (like table sugar and high fructose corn syrup), bleached flour (like white bread and pasta) and vegetable oils. Unfortunately, these three sources are largely devoid of the essential proteins, vitamins and minerals that our bodies need. Today, let’s focus our discussion on the hazards of refined or simple sugar.

Sugar is sweet and alluring. However, there are no proteins, essential fats, or vitamins in refined sugar. Since sugar has a lot of energy but no basic nutrients, its calories are often referred to as “empty” calories. We have known for some time that sugary foods promote tooth decay. There is now evidence that excessive consumption of sugar not only leads to obesity, but also leads to a variety of chronic illnesses including diabetes, heart disease, and even cancer! (We’ll return to some of the cancer evidence shortly!) There is also a growing body of evidence regarding sugar and food addiction. We have known for some time that sugar has addictive properties in rats. Whenever sugar is given generously to rats and then taken away, they exhibit anxiety and aggressive behaviors. Research shows that some people have brains that react differently than others do when they eat refined sugar. Sugar can stimulate the release of dopamine in the reward center of the brain. In this regard, sugar is more like a drug to some people than it is a food.

But why is sugar so bad for us if it tastes so good? After we eat foods containing lots of sugar, our blood levels of glucose rise very rapidly. This triggers our pancreas to release insulin, thereby enabling glucose to enter our cells. Once glucose enters a cell, it can be rapidly metabolized into energy. (Remember, glucose is the main source of fuel for cells in our body.) The secretion of insulin is also accompanied by the release of another hormone called insulin-like growth factor, or IGF. The main role of IGF is to stimulate cell growth. Simply put, sugar fuels our cells and tissues and helps them grow faster. This growth applies to fat cells as well as all other cells in the body. Insulin and IGF also promote components of inflammation. This encouragement of growth and inflammation is how experts think excess sugar leads to unhealthy conditions like diabetes and cancer.

Most people are completely unaware of the amount of sugar in their diet. In fact, the average American adult consumes about 22 teaspoons of sugar each day. This leads to over seventy pounds of sugar consumption per year! Most of this sugar comes from items like candy and desserts. However, there are many processed foods that have added sugar to help improve flavor. (For example, many “low-fat” versions of products actually contain more added sugars than the normal versions!) This is one of the many reasons why it is helpful to eat foods in their closest to natural form as possible. I recommend reading the list of ingredients before you buy any pre-packaged food. Common sources of added sugar include high fructose corn syrup, cane sugar, and corn sweetener or syrup. Make sure that added sugars like these are not hiding in the list of ingredients. Everyday products that frequently contain added sugar include pasta sauces, barbeque sauces, ketchup and “low-fat” salad dressings.

Other overlooked sources of added sugar include sweetened drinks like regular carbonated beverages, fruit juices and energy drinks. The consumption of sugary drinks has increased substantially over the last several decades. It is no coincidence that incidence of obesity has also increased drastically over the same time frame. We are now learning that there may be a link between the consumption of sweetened drinks and cancer!

In May 2019, a paper published in the British Medical Journal suggests there is a link between higher consumption of sugary drinks and an increased risk of cancer. Researchers in France observed and studied over 100,000 people for nearly a decade. The researchers concluded that a 100 mL per day increase in the intake of sugary drinks was associated with an 18% increased risk of overall cancer and a 22% increased risk of breast cancer! In other words, drinking 4 ounces of sugary drinks per day increased cancer risk by 18%! That is less than three 12 ounce drinks per week! The French researchers suggest that sugary drinks should be limited since they represent a modifiable risk factor for cancer prevention. I would suggest that drinks with added sugar be avoided as much as possible!

My recommendations on sugar consumption are straightforward. Unquestionably, fruit should be part of your diet. Fruits may contain a lot of simple sugars, but most fruits have a favorable glycemic index and therefore, your body manages the sugar more smoothly. Fruits are also a good source of vitamins, minerals and fiber. Fresh fruit is always best, though frozen fruit is acceptable. Canned or dried fruit with added sugars should be avoided. Most food items with lots of added sugars should be minimized or avoided. Examples of these food items include candy, cookies, and cakes. Once again, I recommend avoiding sugary drinks as much as possible. If you would like to eat a sweet treat, make sure it is a small portion. Don’t forget to use the “postponed pleasure ploy” to your advantage! (“Not now, but later” is much less taxing to the brain than “NO!”) For more details, please refer to The Bite-Sized Guide to Getting Right-Sized.

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