Sweetness is perhaps the most revered and coveted taste by all. That’s why all paediatric medications are so palatable.
A bite of processed chocolate elevates our mood in seconds. And who is responsible for all this: the pristine white crystals of sugar!
However in this article we are using the term ‘sugar’ to cover all sweet substances that is even sugar substitutes.
Sugar seems to find its way in every next food item we consume. Approximately 75% of the packaged food in US has sugar. At least half of the sugar we consume comes from soft drinks, fruit drinks, and sports drinks.
One average can of regular soda contains 40g sugar – that’s 10 teaspoons.
Many so called ‘healthy foods’ are laden with sugar. 1 serving of yogurt contains 29 grams or 7 teaspoons of sugar, a breakfast bar made from real fruit and whole grain has 15 g of sugar while instant flavoured oatmeal is packed with around 20-30g of sugar.
So even if we skip dessert, sugar is creeping in our diet in some way or the other.
The American Heart Association (AHA) recommends that we limit our daily sugar consumption to 7% or less of our daily calorie intake—that’s about 6 teaspoons (100 calories) for women and 9 teaspoons (150 calories) for men.
But do we ever stop biting into glazed doughnuts (6 teaspoons of sugar) or ice cream ( 4 g added sugar per serving).
Well sugar has around 61 different names in the nutrition label presented by manufacturers. Since the manufacturers are asked to write only about total sugar, it’s hard to determine where the added sugar comes from. Here is a list of few of the names:
Corn syrup solids
Grape juice concentrate
Apart from being omnipresent, there must be a reason why we can’t get enough of sugar. It just a mere habit of eating highly palatable food items or is it beyond that.
Gluttony for White Crystals: How sugar hijacks our brain?
Yep its beyond that. To a certain extent, it’s a matter of choice and if you are able to identify it at this stage then you are safe. But if it has developed into a full blown addiction, there are chances that you might need help.
Yes sugar addiction is as strong as substance abuse. Food is necessary for our survival unlike recreational drugs but anything in excess is unhealthy.
Our brain is designed to reward and motivate us for when we do something pleasurable. In neuroscience, food is considered a ‘natural reward’.
In order for us to survive the brain reinforces and makes us repeat pleasurable activities. Mesolimbic pathway is a system prevalent in our brain that rewards us for such activities.
When we do something pleasurable, our brain cells located in a specific part of the brain called ‘ventral tegmental area’ release some ‘feel good’ chemicals.
These chemicals signal another part of the brain called nucleus accumbens which controls our next bite- whether or not should we have another slice of the lemon pie and also stores this as a pleasant memory which we can recreate in future.
This is how the reward circuitry normally works. But like drugs of abuse, sugar hijacks this pathway and leads to abnormal functioning such as loss of control on food intake.
It makes us dependent on sugar rich foods and its withdrawal causes the same symptoms you would see in rehab patients. In fact animal studies demonstrate that sucrose is far more rewarding than cocaine.
Glycemic index is the effect a food item has on our blood glucose levels. A study was conducted to compare the effects of high glycemic index foods and low glycemic index food items on brain activity.
Interestingly the high glycemic index meal increased hunger and stimulated brain activity in regions linked with reward and craving. This study points out that sugars rich in food have a long lasting effect on our brain’s pleasure centre.
And these lasting effects can seriously hamper our reward circuitry. A study conducted on rats demonstrated that rats that were exposed to sugar in adolescence developed reduced motivation towards sacharrin and sugar like substance maltodextrin in adulthood.
This showed that they had developed tolerance to dopamine rush caused by sucrose consumption.
However these rats had increased preference for cocaine in adulthood indicating that sucrose tolerance perpetuated the brain’s reward circuitry to look for a different alternative.
Sugar overconsumption at a developmental stage can increase risk of developing reward seeking psychiatric disorders.
For those who are intrigued to know which chemicals bring about these activities in the brain, here are the details.
Dopamine- The main guy who helps you become a sugar junkie
Dopamine is one of the feel good chemicals that is released in response to addictive drugs. It is responsible for the rewarding feeling and behaviour reinforcement.
To evaluate the role of dopamine in sugar addiction a study was conducted where dopamine antagonists were fed to animals prior to sucrose feeding.
This resulted in decreased intake of sucrose thus indicating that release of dopamine is essential for the reward stimulating effect of sucrose.
There is also a reverse theory proposed called reward deficiency hypothesis. In this case, individuals who are low on dopamine need to eat excess of sugar or the addictive substance to achieve the same pleasurable state.
It works as a self medication to boost a sluggish dopamine system.
An alternative interpretation is that increased consumption of sugar rich or highly palatable food items dulls the dopamine response.
This makes food less satisfying and motivates even more consumption to achieve a higher or pleasurable experience.
Opiods- Our natural painkillers and addictive substances
Opiods are a set of neurotransmitters or chemicals secreted by brain whose primary function is to relieve pain. They are linked with dopamine’s activity in reinforcing behaviour or habit. Opiods have rewarding effects similar to morphine and heroin.
An experimental study was conducted wherein rats were food deprived for 12 hours and then given access to 25% glucose. They were then treated with naloxone, an opiod antagonist or inhibitor. The treatment caused symptoms such as teeth chattering and anxiety.
The study demonstrated that intermittent but excessive sugar consumption led to a state of opiod dependence such that treatment with opiod inhibitors caused withdrawal symptoms.
Sugar even modifies opiod receptors (proteins that bind with opiods to mediate its activity) so as to increase sensitivity to sugar intake.
Sucrose consumption stimulates opiod release which in turn increases appetite for sweet items. This strong rewarding effect of sucrose is seen reflected in the fact that alcoholics have an increased liking for sweets. However insulin reverses this effect.
Alcohol and food use the same reward circuitry and when this pathway is occupied by one it would block the other. That is why when naloxone is administered binge eaters reduce consumpution of sweet and high fat foods while alcoholics reduce consumption of alcohol.
As BMI increases, alcohol consumption decreases indicating that addiction prone individuals now use food to reach a pleasurable state.
Acetylcholine- The brain chemical that acts against sugar addiction
Acetylcholine is another neurotransmitter whose function is implied in food and drug intake. Withdrawal from drugs or alcohol increases acetylcholine levels and creates a state of depression and aversion.
However excessive sugar intake reduces acetylcholine levels while increasing dopamine levels. Dopamine and acetylcholine balance is essential in feeding and satiety.
Repeated exposure to sugar reduces acetylcholine satiety effect. Studies show that after regular bingeing on sucrose solution, withdrawal can lead to imbalance of dopamine and acetylcholine levels and this causes anxiety.
Ghrelin- Role of our ‘hunger’ hormone in sugar addiction
It is known as the hunger hormone and it stimulates appetite.
It also interacts with dopamine and acetylcholine and hence regulates the food reward response.
Ghrelin interacts with opiod receptors to increase sucrose motivated behaviour and administration of opiod antagonists can inhibit this activity.
Is sugar as addictive as drugs of abuse?
Researchers have found many similarities between patterns of drug abuse and sugar addiction. They are classified as follows.
Bingeing- You just can’t get enough of those sweet crystals
Bingeing is escalation of intake which is characteristic of drug abuse. It occurs as a result of tolerance where you have to eat in excess to achieve the euphoric state or sensitization where eating in intermittent excess amounts yields high levels of pleasure.
A study was conducted where rats were given intermittent access to sugar and chow (rat food).
Interestingly the rats increased their sugar intake over the time especially in the first hour of access. One group was given 24 hours access to sucrose while the other was given 12 hour access.
Both groups elevated their intake. The rats given limited access consumed the same amount of sucrose as the other rats did in 24 hours.
Rats fed daily intermittent sugar and chow regulate their caloric intake by decreasing their chow intake to compensate for the extra calories obtained from sugar.
Daily bingeing on sucrose increases dopamine levels. Intermittent bingeing on sucrose can cause alterations at genetic level in the reward circuitry of the brain thus increasing risk for addiction and eating disorder.
Withdrawal- Abstaining from sugar leads to anxiety and depression
As mentioned previously, excess sugar consumption causes opiod dependence and abstaining from sugar consumption leads to signs of withdrawal.
Naloxone treatment, an opiod antagonist, causes reduction in sugar consumption and promotes signs of withdrawal like tremors, teeth chattering and anxiety.
Craving- Sugar in excess can give crazy thoughts to eat more sweet stuffs
This is enhanced motivation to procure and consume an abused substance. Increased abstinence from sugar intake increases the desire to procure and consume it.
A study was conducted to understand the deprivation effect of sugar. After 12 hours daily access to sugar, rats were abstained from sugar for 2 weeks. After the period of abstinence, their intake increased by 23%.
Guess that’s the reason why dieting leads to weight gain eventually!?
Cross-sensitization and “Gateway” effect- Sugar increases the risk of developing other addictive disorders
Repeated exposure to drugs of abuse, increases its stimulant effects and also increases sensitivity to other drugs. This is known as cross sensitization.
Gateway effect is when consumption of one drug leads to motivation to consume another.
Consumption of legal drug ‘nicotine’ acts as a gateway to illegal drug ‘cocaine’. An experimental study demonstrated that rats exposed to intermittent sugar intake and forced to abstain , subsequently showed enhanced intake of alcohol.
Bingeing on sugar can increase your susceptibility to consumption of alcohol.
Excess sugar consumption can have harmful consequences such as obesity, cardiovascular diseases, dental and metabolic disorders. And the worst of the lot, it can develop into an addiction.
In this case it may require medical treatment in the form of drugs to reduce the activity of brain chemicals and counselling or behavioural therapy. Even will power and change in diet habits can help cure this addiction.
It is pretty interesting to know that our tendency to eat sweet or hyperpalatable foods is not only a matter of choice but is a result of complicate network of chemicals acting in our brain.
So next time you reach for the fourth glazed doughnut, ponder over the thought that is your habit phasing into an addiction.