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Is Sugar Bad for Your Health?

Sugar is present in many of the foods we consume every day. Although it has been a staple in our diet for millennia, today we see it as one of the worse ingredients that can make its way to our table. The cause of this change of perspective is the harmful effect that sugar has on our organism and its contribution to the appearance of different serious diseases.

“Over the past 50 years, consumption of sugar has tripled worldwide. In the United States, there is fierce controversy over the pervasive use of one particular added sugar — high-fructose corn syrup (HFCS). It is manufactured from corn syrup (glucose), processed to yield a roughly equal mixture of glucose and fructose. Most other developed countries eschew HFCS, relying on naturally occurring sucrose as an added sugar, which also consists of equal parts glucose and fructose. Authorities consider sugar as ‘empty calories’ — but there is nothing empty about these calories. A growing body of scientific evidence is showing that fructose can trigger processes that lead to liver toxicity and a host of other chronic diseases 1. A little is not a problem, but a lot kills—slowly (see ‘Deadly effect’). If international bodies are truly concerned about public health, they must consider limiting fructose — and its main delivery vehicles, the added sugars HFCS and sucrose — which pose dangers to individuals and to society as a whole.

Excessive sugar consumption affects human health beyond simply adding calories. Importantly, sugar induces all of the diseases associated with metabolic syndrome. This includes: hypertension (fructose increases uric acid, which raises blood pressure); high triglycerides and insulin resistance through synthesis of fat in the liver; diabetes from increased liver glucose production combined with insulin resistance; and the ageing process, caused by damage to lipids, proteins and DNA through non-enzymatic binding of fructose to these molecules.

Some early studies have also linked sugar consumption to human cancer and cognitive decline. Sugar also has clear potential for abuse. Like tobacco and alcohol, it acts on the brain to encourage subsequent intake. There are now numerous studies examining the dependence-producing properties of sugar in humans. Specifically, sugar dampens the suppression of the hormone ghrelin, which signals hunger to the brain. It also interferes with the normal transport and signaling of the hormone leptin, which helps to produce the feeling of satiety. And it reduces dopamine signaling in the brain’s reward center, thereby decreasing the pleasure derived from food and compelling.”1

There are a variety of types of sugars. The major ones are monosaccharides, such as glucose, fructose and galactose. The other major types are disaccharides, like sucrose, lactose, and maltose, among others. The one we consume the most is sucrose, which is a carbohydrate that is found naturally in various plants, mainly in sugar cane. It is a molecule composed of two monosaccharides, 50% fructose and 50% glucose.

Some of the main issues caused by sugar are:

Added sugar affects the teeth and doesn’t provide essential nutrients.

This is one of the aspects that we hear about the most and is worth remembering. Added sweeteners such as sucralose or high fructose corn syrup contain a high percentage of empty calories, they do not provide any essential nutrients. Recall that our body requires proteins, vitamins and minerals, but sugar only contains energy.

When we consume between 10-20% of calories in the form of sugar, we can develop serious health problems and nutrient deficiency. In addition, teeth are negatively affected since sugar contains digestible energy particles that encourage the appearance and growth of bacteria along the digestive tract.

“Dental caries is a chronic disease that has many causes. Sugar is involved in tooth decay, but it is one of many factors, including oral bacteria, saliva, tooth enamel, food substrate, and host susceptibility. All fermentable carbohydrates are potentially cariogenic. Other dietary factors such as the retention of food in the mouth affect cariogenic potential. Even starches, which may not taste sweet, are chains of glucose and are broken down to glucose in the mouth.”2

High in fructose options can damage the liver

To understand the damage that sugar causes, we must first understand its composition. When sugar enters the digestive system, it is broken down into glucose and fructose. Glucose is vital for our cells, and even if we don’t add it to our diet, our body can produce it naturally in the required amounts via gluconeogenesis thanks to glycogen reserves in our liver. However, fructose cannot be produced naturally and is not necessary for our body. Because of this, it’s difficult for us to metabolize it when it’s ingested in large quantities. When we eat a small portion of fructose, such as piece of fruit, it does not affect us. The liver accumulates fructose and converts it into glucose. Glucose is then stored as glycogen in the liver, to be used when we need it. The problem begins when the liver has too much glycogen accumulated, so if the ingestion of fructose continues, it turns into fat, generating various health problems.

Remember, the fructose that we find in fruits does not cause damage, since the quantity is minimal and its origin is natural. We must also take into account that people who live a healthy and active life can tolerate sugar better than those who don’t. Overloading the liver with fructose can also cause nonalcoholic fatty liver disease (NAFLD), or hepatic steatosis. This has become a very serious problem and it’s associated with metabolic diseases.

  • “Sugar consumption is linked to a rise in non-communicable disease
  • Sugar’s effects on the body can be similar to those of alcohol


Excessive Consumption of Fructuose
Fig. 1. Excessive Consumption of Fructuose Problems


It can also be argued that fructose exerts toxic effects on the liver that are similar to those of alcohol. This is no surprise because alcohol is derived from the fermentation of sugar.”1

Sugar can cause insulin resistance, which eventually develops into metabolic syndrome and diabetes

Insulin is a vital hormone for the functioning of our body since it allows glucose to enter the cells, where it’s metabolized. Excess glucose generates a toxic reaction that manifests itself as diabetes complications such as blindness and amputations.

A characteristic of metabolic dysfunction is that insulin stops functioning properly when the cells become resistant to it. This is known as insulin resistance and can result in obesity, cardiovascular disease, and metabolic syndrome, among others. Consuming too much sugar promotes and facilitates insulin resistance.

Insulin resistance can progress into diabetes type II

High blood glucose levels can give rise to serious and irreversible damages. With the passing of time, insulin resistance becomes stronger and the pancreas can no longer produce the amount of insulin needed to keep blood sugar levels under control. This is when the diagnosis of diabetes type II is made.

“While experimental and observational studies suggest that sugar intake is associated with the development of type 2 diabetes, independent of its role in obesity, it is unclear whether alterations in sugar intake can account for differences in diabetes prevalence among overall populations. Using econometric models of repeated cross-sectional data on diabetes and nutritional components of food from 175 countries, we found that every 150 kcal/person/day increase in sugar availability (about one can of soda/day) was associated with increased diabetes prevalence by 1.1% (p <0.001) after testing for potential selection biases and controlling for other food types (including fibers, meats, fruits, oils, cereals), total calories, overweight and obesity, period-effects, and several socioeconomic variables such as aging, urbanization and income. No other food types yielded significant individual associations with diabetes prevalence after controlling for obesity and other confounders. The impact of sugar on diabetes was independent of sedentary behavior and alcohol use, and the effect was modified but not confounded by obesity or overweight. Duration and degree of sugar exposure correlated significantly with diabetes prevalence in a dose-dependent manner, while declines in sugar exposure correlated with significant subsequent declines in diabetes rates independently of other socioeconomic, dietary and obesity prevalence changes. Differences in sugar availability statistically explain variations in diabetes prevalence rates at a population level that are not explained by physical activity, overweight or obesity.

Differences in sugar availability statistically explain variations in diabetes prevalence rates at a population level that are not explained by physical activity, overweight or obesity.”3

It can generate cancer

Cancer has caused countless deaths worldwide and is characterized by the uncontrolled growth and multiplication of cells. Insulin is one of the main hormones in the regulation of this growth. Many scientists believe that high and constant insulin levels caused by the consumption of sugar contributes to the onset of cancer. This is also aggravated by the fact that sugar facilitates inflammation, another determining factor for the development of cancer. Of course, the consumption of products with sugar will not exclusively determine whether we will suffer from cancer or not, but it is a factor that we should not overlook.

Due to its effects on hormones and the brain, it has a unique effect that promotes obesity

Although we have been taught that the consumption of high calorie foods is unhealthy, the truth is that not all of them cause damage. Each food has particular effects on the brain and hormones. Several studies have shown that the effects of fructose and glucose are very different. Foods that contain fructose generate lethargy and does not produce satiety in the cerebral areas that dictate hunger, causing a greater need to eat more foods rich in sugar. The main problem is that it turns into a vicious cycle from which it is difficult to get out. The more sugar is consumed, the more lethargic our body becomes and the more we feel the need to consume higher amounts.   

It is highly addictive due to the release of dopamine that its ingestion produces

Artificially sweetened foods have ingredients that our body cannot control. Sugar can be extremely addictive for many people. Like drugs, it promotes the release of dopamine from within our brain. Many people believe that this addiction is less dangerous or less serious than other addictions and don’t pay much attention to its effects. This attitude is counterproductive, which is why it’s recommended to abstain from consuming artificially sweetened products. Although it can be difficult to adopt a healthier diet, it’s the only way to avoid falling into addiction.

Those who live with sugar addiction should seek medical and nutritional attention to modify these habits. In some cases, psychological care is also necessary for a complete treatment.

It’s the main factor of obesity in children and adults

Sugar affects hormones and the brain in an ideal way for obesity. It decreases satiety and causes addicts to lose control over their diet. It is not surprising that people who consume more sugar are also more likely to be overweight or obese, no matter the age.

“The worldwide consumption of sugar-sweetened beverages is very high. According to observational studies, intake of sugar-sweetened beverages is associated with metabolic diseases such as metabolic syndrome, obesity, kidney diseases, and others. Based on the observed associations authorities try to regulate intake of sugar-sweetened beverages, especially in adolescents. However, there is a lack of experiments supporting these associations and proving their causality, some even show the opposite.”3

According to research, children are the most affected by the consumption of sugar. Moreover, their body is less prepared to deal with the issues that sugar excess can cause. Statistics indicate that the consumption of sweets increases the risk of obesity in children by 60%.

“At a population level, however, obesity does not fully explain variations and trends in diabetes prevalence rates observed in many countries. Several countries with high diabetes prevalence rates have low obesity rates, and vice versa. High diabetes yet low obesity prevalence are observed in countries with different ethnic compositions. About 20% of obese individuals appear to have normal insulin regulation and normal metabolic indices (no indication of diabetes) and normal longevity, while up to 40% of normal weight people in some populations manifest aspects of the ‘metabolic syndrome.’”3

Excessive sugar causes higher levels of cholesterol and heart problems

For decades, we have lived believing that saturated fats are the main cause of heart problems. However, new studies have shown that sugar is the one that causes veins to clog, thereby decreasing blood flow. This is one of the most dangerous effects of fructose on the metabolism.

Fructose can decrease good cholesterol (HDL), increase triglycerides, raises glycemia and insulin levels in just 10 weeks. All these problems end up increasing the chances of suffering a heart attack or other heart disease.

Most of the time, we do not even realize we are consuming sugar. Unfortunately, we can find it in all types of products, such as: commercial salad dressings, juices, cheeses, yogurt, cereals, breads, etc. To avoid the consumption of unwanted sugar, read food labels and avoid or limit the consumption of those products.


Mean intake of added sugars
Fig. 2. Mean intake of added sugars

“The adverse health effects of sugar have long been a matter of much public and scientific interest. For decades, it has been thought that a high intake of sugar is associated with the development of obesity, type 2 diabetes, and cardiovascular disease (CVD). Given the distinct metabolic fates that differentiate fructose from glucose, recent attention has focused on fructose as having a unique role in the etiology of these conditions. Fructose is found in sucrose or common table sugar, which is a disaccharide composed of 1 glucose molecule and 1 fructose molecule linked via an a1-4 glycoside bond, and is obtained from either sugar cane or beets. Fructose and glucose are also both found as naturally occurring monosaccharides that exist in fruit, honey, and some vegetables. Sweeteners such as high fructose corn syrup (HFCS), which is produced from corn starch through industrial processing, contain free fructose and free glucose in relatively equal proportions and have progressively replaced the use of sugar in the United States since their appearance in the market in the late 1960s primarily due to their low cost.”4



(1) Lustig, R. H., Schmidt, L. A., & Brindis, C. D. (2012). Public health: The toxic truth about sugar. Nature482(7383), 27. Available online at

(2) Mardis, A. L. (2001). Current knowledge of the health effects of sugar intake. Family Economics and Nutrition Review13(1), 87-87. Available online at 

(3) Basu, S., Yoffe, P., Hills, N., & Lustig, R. H. (2013). The relationship of sugar to population-level diabetes prevalence: an econometric analysis of repeated cross-sectional data. PloS one8(2), e57873. Available online at  (4) The

(4) Malik, V. S., & Hu, F. B. (2015). Fructose and cardiometabolic health: what the evidence from sugar-sweetened beverages tells us. Journal of the American College of Cardiology66(14), 1615-1624. Available online at


Robert Velasquez
13 October, 2018

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Hello everyone, my name is Robert Velazquez. I am a content marketer currently focused on the medical supply industry. I studied Medicine for 5 years. I have interacted with many patients and learned a more:

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