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Sugars and the Brain

In this science post, we are taking a closer look at sugar and non-nutritive sugars (NNS), alternatively known as artificial sweeteners. We already examined sugar quite closely, discussing all the reasons why it is beneficial to minimize the intake of it, especially if maximizing the program. However, let’s take a closer look at how sugar and NNS affect us, more specifically our brain, and how they may influence our bodies, and even the choices we make!

Why do we like sugar?

Sugar provides energy to our bodies in the form of calories, so humans, like most other creatures, have evolved to enjoy it. Our primitive ancestors were scavengers. Sugary foods are excellent sources of energy, so we have evolved to find sweet foods particularly palatable. Foods with unpleasant, bitter and sour tastes can be unripe, poisonous or rotting. These foods could cause sickness, so we are more likely to avoid those foods.

We need food to survive, and we need the amount that nature has provided for us in the perfect package, which is food in its whole form. This often includes fibre or other substances that allow for a slower digestion, and does not usually facilitate a fast rise in blood sugar, as well as it is more likely to create a feeling of satiety.

Therefore, to maximize our survival as a species, this innate brain system has us seeking out these foods.

Sugar comes in a variety of forms. To recap, glucose is the simplest form of carbohydrates and only has one sugar molecule, which is called a monosaccharide. Other monosaccharides that may sound familiar include fructose, galactose, and ribose, which the body also processes or may produce for energy.

We have discussed the importance of how our body breaks down our food into these simple sugars in order to provide energy to the body in the science post on Insulin. There was also discussion on how added sugar affects our bodies. But let’s take a deeper dive into how added sugar affects our brain and nervous system, after a refresher on how our body processes these added sugars.

What is added sugar or free sugars?

The World Health Organization (WHO) has been cautioning people to reduce their intake of “free sugars” to less than 10 percent of daily calories since 1989. The WHO states that doing so can lower the risk of becoming obese or overweight, or experiencing tooth decay. Free sugars include both the sugars naturally found in honey and fruit juice, and sugar added to food and drinks. On food labels, added sugars include words such as glucose, fructose, corn syrup, brown sugar, dextrose, maltose, and sucrose, as well as many others.

As we had discussed in previous posts, the most significant sources of added sugar in today’s diet consists primarily of the simple sugar fructose. Fructose is a fairly sweet, naturally occurring sugar. It comes from most fruits, and even some vegetables.

However, the majority of sources of fructose that people tend to consume are table sugar (which is called sucrose, made from sugar cane or beets, is composed of 50% glucose and 50% fructose), honey, agave nectar, fruit juices, palm sugar and (HFCS) high fructose corn syrup (HFCS is a highly processed and inexpensive substitute for cane sugar that was introduced in the 1970s, which is made from corn. It’s used to sweeten a variety of processed foods, including soda, candy, baked goods, and cereals). Today’s sugars are often refined and concentrated.

After we ingest food, the stomach and small intestine go right to work in breaking the food down into its simplest form of glucose, which is absorbed and then released into the bloodstream. Once in the bloodstream, glucose can be used immediately by the cells for energy, or stored in our bodies to be used later. However, glucose and fructose are metabolized very differently by the body. Before it can be used by the body, fructose needs to be converted into glucose, which is conducted by the liver. While every cell in the body can use glucose, the liver is the only organ that can metabolize fructose when ingested in significant amounts!

Before the mass production of refined sugar, humans rarely consumed fructose in high amounts. But as food science has developed over the years, our food has greatly changed from its very simple former self. When people eat a diet that is high in calories and high in fructose, the liver is thought to become overloaded and starts turning the fructose into fat. Many scientists believe that excess fructose consumption may be a key driver in many of the most serious diseases today. These include obesity, type 2 diabetes, insulin resistance, heart disease, and even cancer. However, more human evidence is needed. Although, researchers debate the extent to which fructose contributes to these disorders, there is a considerable mounting body of evidence justifying the concerns.

The data behind sugar

In 2015, the WHO further suggested reducing free sugar daily intake to less than 5 percent of calories, about 6 teaspoons, for optimizing health. In the United States In 2017–2018, the average daily intake of added sugars was 17 teaspoons for children and young adults aged 2 to 19 years, as well as in adults over 20 years of age. Added sugar also accounts for 14 percent of the average person’s daily calorie intake. Most of this comes from beverages, including energy drinks, alcoholic drinks, soda, fruit drinks, and sweetened coffee and teas.

Other common sources are snacks. These don’t just include the obvious, like brownies, cookies, doughnuts, and ice cream. You can also find large quantities of added sugar in bread, salad dressing, granola bars, cereals, and even fat-free yoghurts to name a few.

In Canada, a health report released on October 20, 2021 from Statistics Canada, found that in a 2015 Canadian Community Health Survey (CCHS), the total sugar intake in Canada per person was estimated at 105.6 g/day. While this was down from the 110.0 g/day reported in a CCHS conducted in 2004, it was concluded that the apparent reduction between 2004 and 2015 may actually be caused by misreporting as a result of changes in survey methodology. They also reported that total sugar consumption from foods actually increased between 2004 and 2015, while total sugar intake from beverages decreased.

The Office of Disease Prevention and Health Promotion in the Dietary Guidelines for Americans 2020-2025, suggest cutting the consumption of added sugars to less than 10 percent of calories per day. This is actually in line with WHO's older recommendations, that were stated earlier back in 1989!

However, to help consumers, the Food and Drug Administration (FDA) has developed a new food label that lists added sugars separately, which manufacturers are required to use (though some smaller manufacturers had until 2021 to comply).

Canada has also updated their food labels, which now identifies the total percentage of sugars in a product. This change was imposed by the Canadian