How sugar may damage the brain

Most people have heard that sugar is unhealthy, but how exactly does it work against your good mental health?

When you eat concentrated sources of rapidly-digestible carbohydrates such as sugar, flour, fruit juice, and processed cereal products, your blood sugar (glucose) can spike sharply, immediately triggering an equally strong spike in insulin, in an effort to bring blood glucose back down to normal.

These dramatic fluctuations in glucose occur inside the brain as well, because brain glucose rises and falls in proportion to blood glucose.2 These steep spikes and drops in glucose and insulin levels can wreak havoc with your brain and body chemistry in the following three critical ways.

Refined carbohydrates can destabilize hormones and mood

The problem with unstable insulin levels is that insulin isn’t simply a blood sugar regulator. Insulin is a master metabolic hormone that orchestrates the levels of numerous other hormones throughout the body, including sex hormones like estrogen, the blood pressure regulating hormone aldosterone, and the stress hormones cortisol and adrenaline.3 Every time insulin peaks and plummets, these hormones follow suit, which can place you on an invisible internal hormonal roller coaster.

Let’s say you start off your morning with a food rich in refined carbohydrates — like orange juice, a bagel, or a bowl of corn flakes. Within a half hour, your blood sugar spikes, and your pancreas immediately releases insulin into your bloodstream to pull the extra sugar (glucose) out of your blood and squirrel it away into your cells. At about the 90-minute mark, as your blood sugar is dropping, you may experience a “sugar crash” and feel tired, unfocused, and hungry.

The body perceives plummeting glucose as an emergency, so it releases a mixture of hormones to keep glucose from falling below normal. This mixture includes the stress hormones cortisol and adrenaline — our “fight-or-flight” hormone. Adrenaline peaks between two and five hours after eating sugar, causing some to experience physical and emotional distress between meals, including panic symptoms such as anxiety, shakiness, and difficulty concentrating.

Many people consume refined carbohydrates at every meal and as snacks, which can place their hormones on a seesaw all day long and even well into the night. Age, metabolism, gender, genetics, and activity level all influence what your personal internal roller coaster feels like. Fluctuating energy levels, difficulty concentrating, mood swings, binge eating, irritability, anxiety attacks, and insomnia are all possibilities, depending on the individual.

Yet, even if you aren’t aware of any symptoms on the outside, this chaos may still be occurring on the inside, disrupting normal rhythms in ways that can slowly and silently lead to health problems down the road.

Refined carbohydrates can promote oxidation and inflammation

Unnaturally high spikes in blood sugar can be powerful promoters of oxidation and inflammation, which are features of many chronic diseases, including psychiatric disorders.

What is oxidation?

Oxidation happens. The chemical reactions our cells rely upon to turn food into energy require oxygen molecules that can break apart into reactive “free radicals” during glucose processing. Free radicals are like little bulls in a china shop — left unchecked, they bump into and react with neighboring structures and DNA, damaging cells from the inside out (oxidation). Since some amount of oxidation is normal and natural, Mother Nature has armed us with a variety of our very own internal antioxidants to mop up pesky free radicals. Under normal circumstances, these built-in antioxidants are sufficient to keep oxidation and anti-oxidation forces in balance and prevent cellular damage.4

The problem with high-sugar foods and beverages is that they can flood chemical pathways with too much glucose at once, generating more free radicals than our internal antioxidants can neutralize.5 Excess free radicals are then free to randomly destroy whatever they encounter. Depression, bipolar disorder, schizophrenia and obsessive-compulsive disorder are all associated with excess oxidation.6 We are often told that the solution to our oxidation problem is to consume colorful, anti-oxidant-rich fruits and vegetables to bring our systems back into balance, but the truth is that most plant “superfood” antioxidants, when consumed in their natural form, are very poorly absorbed by the human body and are therefore of little use to us.7

It is not the lack of superfoods that tilts our cells too far towards oxidation, it is the presence of refined carbohydrates that deplete our natural antioxidants and make it appear as if we need more antioxidant power than we already have. Instead of buying antioxidants, wouldn’t it make a lot more sense to simply stop eating pro-oxidants?

What is inflammation?

Our immune system reacts to oxidative damage sugar can cause by mounting an inflammatory response. This isn’t the kind of inflammation that makes your brain swollen, red, or sore — it’s inflammation on a microscopic level. Multiple lines of evidence point to a strong connection between inflammation and many cases of depression, bipolar disorder, and schizophrenia. 8

When cells are in distress, they release tiny cries for help in the form of “inflammatory cytokines” such as IL-6 and TNF-alpha that can be measured in the blood. Levels of these molecules are often higher in people with mood and psychotic disorders. Inflammatory cytokines can trigger damage to nearby brain cells and cause chemical imbalances in the brain by disrupting normal production of serotonin, dopamine, and glutamate — key neurotransmitters involved in psychiatric disorders. While we don’t yet have clinical studies cementing a causal relationship, paths leading from sugar to oxidation to inflammation may help to connect the dots between modern diets and mental illnesses.

Refined vegetable oils like soybean and sunflower oil may also contribute to excess inflammation, because they are unnaturally high in omega-6 fatty acids. Industrially-produced seed oils are found in all kinds of processed foods — from high-carbohydrate foods like chips and baked goods to popular low-carbohydrate foods like mayonnaise and salad dressings. Omega-6 fatty acids are responsible for mounting the inflammatory response to oxidative damage, injuries and infections, whereas omega-3 fatty acids are responsible for initiating the healing response that follows.

These two forces work best when they are roughly in balance. Unfortunately, modern diets are not only extremely high in omega-6 fatty acids, they are also often too low in omega-3 fatty acids, tilting our immune system too far towards inflammation and away from healing.9 Imbalances in these essential fatty acids are seen in most psychiatric disorders.

by Dr. Georgia Ede, MD

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