Health impact of Sugar

The health impact of sugar refers to the ways that ingesting sugar affects the human body. Sugar is derived from natural sources and occurs naturally in many foods. However, it is also present in a number of processed foods such as candies, soda, and desserts, as well as in foods that are not thought of as sweet, such as breads. As a result, researchers have investigated the ways that consuming sugar affects health as well as the effects of various types of sugars.

Background

The island inhabitants of New Guinea were the first to notice that chewing on a piece of raw sugar cane caused the release of a sudden sweet taste in the mouth. Eventually sugar was carried to other islands and to Asia. Muslim warriors carried it to the lands where they fought; Europe was introduced to sugar during the Crusades, when Christians fought against the Muslims. When European explorers set sail for new lands, they carried sugar plants with them to establish crops. Everywhere it went, sugar was in high demand.

The white crystalline substance familiar as sugar has been processed from the sugar plant for centuries. These plants only grow in certain climates, however, which limited the availability of sugar. Later, it was also discovered that sugar beets could be processed to produce sugar, and growers learned ways to increase sugar cane crops. This increased the availability of sugar, but demand also continued to grow. Industrialization added to the number and types of food produced commercially, many of which included sugar. Where people once had to take time from a busy day to make cookies, cakes, or candy, commercially processed and packaged versions became readily available. This, along with sweetened beverages such as soda, increased the amount of processed sugar people consumed.

Not all sugar is bad. The human body needs the glucose that is contained in sweet foods to generate energy: glucose is the most important fuel source for the brain and a key nutrient for the rest of the body as well. However, processed sugar contains sixteen calories per teaspoon and has no other nutrient value. On the other hand, sugar from fruit and other natural sources contains the same number of calories and provides the same energy but these natural sources provide other nutrients such as fiber, vitamins, and minerals, which also benefit the body. Experts have raised concerns about what happens to the body when a great many of one’s daily calories come from sugar in processed foods as opposed to natural sugar sources such as fruit. The concerns center on two areas: the negative effects of sugar on the body, and the fact that a person eating sugary foods has less capacity to consume foods with greater nutritional value. In 2023, the Centers for Disease Control and Prevention (CDC) warned that three in five Americans ages two and older consume more than the recommended amount of added sugars.

Overview

Connections between sugar and health were first made in the seventeenth century when, in the absence of sophisticated medical tests, British physician Thomas Willis (1621–75) noticed the sweet taste of the urine of people with diabetes. During the nineteenth century, physicians began to notice that people who ate more sugar had a greater chance of being overweight and having high blood pressure and diabetes. Subsequent research has indicated the extent to which sugar may play a role in health.

For example, a study published in 2014 in the Journal of the American Medical Association reported that the average American eats more sugar than the recommended daily amount, which is 5 to 15 percent of daily calories. Assuming an average calorie intake of two thousand calories a day, this would mean about one hundred to three hundred calories a day, less than the amount in one to two cans of soda. Most Americans, according to the researchers, get about one tenth of their calories from sugar. However, the study found about 10 percent of the population consumes an average of 25 percent of its calories from sugar. Some of this sugar comes from obvious sources, especially sugar-sweetened sodas and energy drinks. Others are less obvious, such as breads, sauces, condiments, and even some processed meats.

A number of studies over the years, especially in the twenty-first century, have shown a correlation between sugar consumption and negative health effects, such as increased weight and elevated blood sugar, blood pressure, and cholesterol. One study showed dramatic drops in levels of all these important health measures in as few as nine days when children were put on a diet that reduced sugar without reducing calories.

Sugar’s effects

The 2014 JAMA study found that people who consumed 21 percent or more of their calories each day from sugar had double the chance of dying from heart disease of someone who did not. This held true even if the person ate mostly healthy food otherwise. The study did not determine exactly why sugar had such a negative effect on heart health, but researchers noted that sugar causes arteries to grow thicker and more tense, which raises blood pressure, creating a known risk factor for heart disease. They also theorized that excessive amounts of sugar might cause the liver to release more fat into the blood stream, which is another known risk factor.

Sugar is known to increase the amount of fat that accumulates around the internal organs, especially the liver. A high-sugar diet also increases the likelihood of diabetes by straining the body systems that process and remove sugar from the body. The way the body processes sugar can also lead to energy crashes, when the body quickly burns through the energy from the sugar in a candy bar or soda and then becomes tired from the decrease in easily accessible fuel from sugar.

A 2017 study on mice found some evidence that sugar acts as an addictive substance. Sugar affects the release of dopamine and natural opioids in the body, chemicals that increase feelings of happiness and well-being, and the study suggested that these feelings could lead to addiction-like behaviors. However, that study's design has been criticized for various reasons, including that only mice who were limited to having sugar within a specific two-hour window each day displayed addiction-like behaviors, while mice who were allowed to have sugar whenever they wanted—as is generally the case for human consumption of sugar—did not.

In addition, it is thought that sugar interferes with the body’s natural system for regulating appetite, causing the body to not release enough leptin, an appetite-regulating hormone. Without enough leptin, the body continues to send out hunger signals even when enough food has been consumed. This can lead to excess weight, which is also a risk factor for heart disease and diabetes.

A study at Swinburne’s Centre for Human Psychopharmacology in Australia found some evidence that greater sugar consumption is correlated with poorer memory function by looking at self-reported consumption of juice and soft drinks in relation to brain health markers in MRI scans. According to that study's findings, consuming two sugary drinks per day ages the brain two years relative to someone who does not drink fruit juice. However, since the study looked exclusively at beverages and not at total sugar consumption levels or other lifestyle factors, the findings were not considered conclusive. Studies in New Zealand in 2016 and Baltimore in 2017 undertook postmortem brain autopsies and found that people with Alzheimer's disease displayed high levels of glucose in the brain, with the areas of greatest damage having the greatest concentration of glucose, although it has not been concretely proven that consuming large amounts of glucose is what leads to glucose being found in the brain.

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