Chapter 1: Energy Demands of the Brain

Our brains, much like any other organ in our body, require a significant amount of energy to function properly. According to a report in Time, Dr. Marcus Raichle, a prominent professor of medicine at Washington University School of Medicine in St. Louis, explains:

"The brain is the most energy-intensive organ we possess," noting that while it comprises only about 2% of total body weight, it utilizes approximately 20% of the body's energy.

The brain primarily relies on glucose and fats as energy sources. As stated in the book Nutrition and Traumatic Brain Injury: Improving Acute and Subacute Health Outcomes in Military Personnel:

In a typical metabolic process, carbohydrates are broken down into glucose, the body's favored source for energy. However, during periods such as fasting when carbohydrate intake is low, the body shifts to burning fat. The liver transforms fats into fatty acids and ketone bodies, which serve as an effective energy alternative for brain cells. This conversion creates three important ketone bodies: β-hydroxybutyrate, acetoacetate, and acetone. Although fatty acids cannot cross the blood-brain barrier, these ketone bodies can enter the brain and provide energy.

While carbohydrates are the preferred choice for metabolism, the brain can also utilize ketones derived from fats, which can cross the blood-brain barrier, unlike fatty acids. This ability of ketones to serve as energy for brain cells is a fundamental principle behind the ketogenic diet.

Section 1.1: What Are Carbohydrates?

Carbohydrates, as the name implies, are compounds made up of carbon (carbo) and water (hydrate). A prime example is glucose, a simple carbohydrate represented by the formula C6H12O6, indicating that it consists of six carbon atoms and six water molecules.

Long chains of glucose molecules can polymerize to form cellulose. These cellulose polymers are classified as dietary fiber, which our digestive system cannot break down, allowing them to pass through our intestines largely intact.

Herbivorous animals like cows possess a digestive system that includes Ruminococcus bacterial species, which produce cellulase enzymes capable of breaking down cellulose into glucose for energy.

As such, carbohydrates may be digestible or indigestible. A straightforward method to assess carbohydrate content in a sample is to burn it and measure the amount of carbon dioxide released. This information is typically reflected on nutritional labels. For instance, oats are rich in carbohydrates, but not all of them are digestible.

Subsection 1.1.1: Understanding Fats

A fatty acid is a carboxylic acid characterized by a long chain of carbon and hydrogen atoms, which can be either saturated or unsaturated. When three fatty acids bond with a glycerol molecule, they form a triglyceride. Health professionals often monitor triglyceride levels in the bloodstream, as high levels indicate that the body is not efficiently breaking down these compounds for energy.

Cells do not directly use glucose or fatty acids for energy. Instead, they utilize the tricarboxylic acid cycle (TCA, also known as the Krebs cycle) to generate energy from a molecule called acetyl-coenzyme A (acetyl-CoA), which can be derived from glucose or ketones consumed through diet.

Acetyl-CoA is oxidized in the mitochondria to produce adenosine triphosphate (ATP), the energy currency of cells. While the body prefers glucose for producing acetyl-CoA, it can switch to ketones when carbohydrate intake is low. ATP is then subjected to oxidative phosphorylation, where breaking phosphate bonds releases energy that cells can convert into other useful forms.

Chapter 2: The Impact of Overconsumption

In our current era, marketing often leads to an excessive intake of energy sources. An overabundance of carbohydrates can result in elevated glucose and fructose levels in the bloodstream, which may convert into reactive aldehyde molecules. These aldehydes have the potential to interact with amino groups on proteins or even DNA, potentially impairing their functions. For example, the glycation of hemoglobin to form HbA1c is a concern for individuals with diabetes.

Moreover, when excessive sugar consumption occurs, the body's ability to eliminate mutated cells diminishes, increasing the risk of cancer.

Fats are not immune to similar issues; unsaturated fats can also undergo oxidation and lipid peroxidation, producing harmful lipid peroxides comparable to aldehydes.

It is essential to discern the truth behind years of misleading marketing claims. Many still believe that saturated fats are unhealthy while unsaturated fats are beneficial, despite evidence to the contrary.

Revisiting these misconceptions requires a solid understanding of the underlying biochemistry to make informed dietary choices, rather than relying on misleading advertisements. After all, it is our brains that we are nurturing.

We must strive to make rational decisions about our health, avoiding manipulation by those primarily interested in profit.

This video explores the biochemistry of carbohydrates and sugars, providing a foundational understanding of their roles in the body.

Richard J. Wood discusses the impact of carbohydrates on health, shedding light on their effects and implications for well-being.