Did you know the brain’s main source of energy is glucose? We can think of glucose as currency for the brain, eating too little can cause brain fog, and an inability to focus!
It has been know by physiologists that the brain’s primary source of energy is the glucose we derive from food. Grains, fruits, dairy, meat, and vegetables all contain some amount of glucose. Grains and fruits contain glucose at it’s highest amount per gram of weight. It has been well documented that the excess consumption of glucose (sugar) can lead to a host of metabolic disorders in the liver, kidneys and heart. However if we do not consume enough sugar (carbohydrates) we can develop brain fog, irritability and mood swings; The body may also go into starvation mode and start to develop ketones from fat and protein for the brain to fuel on. Despite the recent popular trend of “going keto” or becoming “fat adapted”, the research isn’t there yet to prove unequivocally the diet’s effectiveness for weight lose or promotion of longevity in the general population.
So back to the brain. In a recent study published by the Journal of Clinical Investigation, researchers investigated whether the brain can produce fructose from ingesting an excess amount of glucose. Fructose’s most infamous form is HFCS which has been implicated in the rise of the obesity epidemic, and has been shown to alter eating behavior in humans through a change in appetite sensing hormones. However, the mechanism for this has been unknown since fructose can not cross the blood brain barrier. Researchers recruited a group of healthy adults to undergo a hyperglycemic clamp, meaning their blood glucose is held at a high range for a set amount of time, to determine insulin response. The results after specialized brain scanning indicated the brain can produce fructose from glucose.
So why does this matter? This study gives a possible pathway of effect where excess glucose, and maybe not fructose or HFCS, is a causative agent in the metabolic diseases of the brain, liver, eyes and peripheral nervous system. A secondary effect of fructose generation in the brain is the decrease in glutathione production. Glutathione can be viewed as the primary antioxidant produced in the body that aides the immune system in combating inflammation by extinguishing free radical production. Free radical production damages cells, tissues, and organs if our own innate antioxidant producing system is inhibited.
Now this certainly doesn’t change the global effort of limiting consumption of highly processed sugar laden foods, but it does give greater insight in understanding what exactly may be going on in the body when too much sugar is ingested too often for years. The fructose being generated in the brain can cause the body to crave sugar and sweet foods and create a sense of “always being hungry”. This is one key reason why overweight and obese individuals continue to gain weight, and why restrictive eating practices are doomed to fail. Best practice is to focus on nutrient dense food that contains bountiful amounts of nutrients, with few calories, as the volume of food will create a sense of fullness without the additional calories. A plant based eating plan filled with starchy vegetables such as yams, sweet potatoes, broccoli, cauliflower, beets, carrots, squash, beans, peas, and lentils will help to curve the brain off its sugar rush!