Sweet buzz

An article by the editor-in-chief of the ScienceSeeker website about why sugar is a drug of the 21st century

ScienceSeeker editor-in-chief, neurologist and PhD candidate Jordan Lewis wrote a column about why sugar is a drug like cocaine and heroin. On March 1, it was published on the website of the news aggregator Quartz .

TJ publishes a translation of this material.

Photo Urban Camper

Anyone who knows me can say with confidence: I have a rare sweet tooth. And always has been. My friend and fellow graduate student, Andrew, also suffers from this “disease.” And the fact that we live in Hershey, Pennsylvania, the “Chocolate Capital of the World,” helps a lot.

But Andrew was braver than me. Last year he gave up sweets for the entire Lent. I can't say I'm going to repeat his experiment this year, but if you're going to abstain from sweets this Lent, here's what's in store for you over the next 40 days.

Sugar: natural reward, unnatural dose

We neuroscientists call food a “natural reward.” The fact that things like eating, having sex, and raising our own kind turned out to be pleasurable to our brains was key to our survival as a species.

As a result of evolution, the so-called mesolimbic pathway appeared - a brain system that “deciphers” natural rewards for us. When we do something pleasant, a group of neurons called the ventral area uses the neurotransmitter dopamine to send an impulse to a region of the brain called the nucleus accumbens. The connection between the nucleus accumbens and the prefrontal cortex is responsible for our motor skills, including decisions like whether to take another bite of that delicious chocolate cake.

The frontal cortex also activates hormones that tell our body, “Hey, this cake is really good. I should remember this."

Of course, not all food is a reward. Most of us prefer sweets to more sour and bitter foods because our mesolimbic pathway has evolved to believe that sweet things provide a healthy source of carbohydrates for our bodies. When our ancestors were in the foraging stage, a sour fruit taste meant “not yet ripe,” while a bitter taste meant “warning, poison.”

However, fruit is one thing, and modern diets are completely different. Ten years ago, it was estimated that the average American consumed twenty-two teaspoons of excess sugar per day, the equivalent of three hundred and fifty calories; it is possible that these numbers have increased since then. A few months ago, one expert suggested that the average Briton consumes two hundred and thirty-eight teaspoons of sugar a week.

Today, when convenience has become one of the most important criteria when choosing food, it is almost impossible to find canned or semi-finished products that do not have sugar added for taste or preservation (or both).

This extra sugar is insidious: many of us are not even aware that they are added. Compare this to the way drugs—nicotine, cocaine, or heroin—hijack the brain's reward pathway and make their users addicted. Increasing neurochemical and behavioral evidence suggests that sugar is similarly addictive.

Sugar addiction is not a myth

“The first few days it is very difficult. It's a bit like detoxing from some kind of drug. I even found that I was eating a lot more carbs to compensate for the lack of sugar.”

There are four main components of drug addiction: chronic use, withdrawal, dependence, and cross-sensitization, a phenomenon in which a person becomes addicted to one substance and then becomes dependent on another, stronger substance. All of these components have been observed in animal models of addiction, both sugar and drug addiction.

The average American consumes twenty-two teaspoons of excess sugar per day.

A typical experiment went like this: every day the experimental rats were deprived of food for 12 hours. After this, they had free access to regular food and food with added sugar for 12 hours. After a month of such a diet, the rats showed behavior similar to the behavior of drug addicts. When choosing food, they were more likely to lean toward sugared foods. When they were deprived of such foods during the fasting stage, they began to experience attacks of anxiety and depression. Moreover, unlike normal rats, they became accustomed to common drugs such as cocaine and opiates much more quickly.

As with many drugs, consuming sugar results in a surge of dopamine. Over the long term, regular sugar consumption actually significantly alters gene expression and reduces the availability of dopamine receptors in the midbrain and frontal lobe. Specifically, sugar increases the concentration of the D1 type of nerve receptor, but decreases the concentration of another type of receptor, D2, which is an inhibitor. Regular consumption of sugar also inhibits the action of the dopamine transporter: this protein pumps dopamine out of the synapse and back into the neuron after an action potential.

In short, this means that frequent sugar consumption interferes with dopamine signaling, desensitizes brain pathways, and increases the amount of sugar needed to activate midbrain dopamine receptors. The brain becomes tolerant to sugar. A person has to consume it in ever-increasing quantities to get that “sweet high.”

Photo by lauren s_

Sugar withdrawal also exists

Although these studies were conducted on rodents, it cannot be said that similar processes do not occur in the human brain. “The desire to eat something sweet almost never disappeared, but it was somewhere on a psychological level. But within a week or so I felt better,” Andrew told me.

In a study conducted by Carlo Colantuoni and his colleagues at Princeton University in 2002, rats that were made addicted to sugar also went through sugar withdrawal. It could be alleviated either by food deprivation or by injections of naloxone, a drug used to treat opioid addiction. Both methods led to complications: the rats began to chatter their teeth and shake their heads, and they developed tremors. Naloxone treatment also made the rats more anxious, fearful of being on elevated platforms that had no boundary walls.

Similar withdrawal experiments by other researchers also describe depression-like behavior and an inability to cope with tasks such as forced swimming.

Rats that were in a state of sugar withdrawal were more likely to behave passively when placed in water and did not try to get out of the aquarium, creating the impression of helplessness

A new study published by Victoria Mangabeira and her colleagues in the latest issue of the journal Physiology & Behavior reports that sugar withdrawal is also associated with impulsive behavior. First, the rats were taught to use a drinking bowl by pressing a lever. After training, the animals returned to their home cages and had access to a solution of water and sugar or simply clean water. After 30 days, when the rats were again given the opportunity to press a lever to get water, the sugar-addicted rats pressed the lever significantly more often, which can be considered an example of impulsive behavior.

Of course, these experiments go to extremes. We humans don't deprive ourselves of food for 12 hours and consume soda and donuts at the end of the day. But these studies in rodents may give us insight into the neurochemical underpinnings of sugar addiction, sugar withdrawal, and the behavior of people affected by these illnesses.

For decades filled with strict diets and best-selling books, we've toyed with the concept of "sugar addiction." There are many reports from sugar withdrawal sufferers describing addiction to food, which sometimes caused relapse and impulsive eating of sweets. Don't forget about the countless articles and books about boundless energy and newfound happiness from authors who have given up sugar for good. But despite the ubiquity of sugar in our diets, the concept of “sugar addiction” is still classified as taboo.

Do you still want to give up sugar for your next fast? You may ask: How long does it take to be free from addiction and side effects? I cannot answer this question: all people are too different. In addition, no human studies have been conducted on this topic. But after forty days, it was clear that Andrew had overcome the worst of it and was even able to reverse some of the changes in dopamine signaling: “I remember eating my first piece of candy after a long break and thinking it was too sweet. I needed to restore my previous level of tolerance."

And I can assure you: as a regular visitor to one of the local bakeries, he has already done this.

This material is a translation of the article “Here's what happens to your brain when you give up sugar for Lent ” on Quartz .

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