Sugar forms a major component of our daily diet. It is present in large quantities in soft drinks, fruits, vegetables and a number of different food products that we consume on a daily basis. While the consumption of sugary food can no doubt be a pleasant and rather satisfying experience, there has been much concern in the last couple of decades regarding the harmful and negative effects of sugar on different physiological processes and organs in the body. In fact, research that dates back to the early 1900’s has demonstrated detrimental effects of sugar on the cardiovascular system. In the 1960’s, Yudkin et al demonstrated that a high intake of sugar was directly related to the higher incidence of cardiovascular disease.1
But the detrimental effects of high sugar consumption are not just limited to the heart. There are a number of different organ systems that depend on sugars for normal functioning, but can be dramatically affected if exposed to excessive amounts of sugar over a prolonged period of time. There is an obvious link between sugar intake and the future development of diabetes, though this is often multifactorial and is a component of the insulin resistance syndrome. Here, we shall explore these effects in a bit more detail.
Negative Effects of Sugar
Sugar intake and coronary artery disease
Coronary artery disease refers to the development of narrowing of the arteries within the heart that leads to the development of heart attacks. The intake of sugar and its effect on the development of cardiovascular disease and coronary artery disease has been a subject of debate. While some studies have shown that people who consume high amounts of sugar in their diet are at risk of developing coronary disease1, other studies have no clear relationship between these two parameters.2 However, it appears a majority of the studies have demonstrated that sugar intake does play a role in development of coronary artery disease, though a combination with a high fat diet also contributes to this. In other words, consuming a diet high in sugar and fat can lead to heart disease.
Sugar intake and obesity
Obesity is defined by the World Health Organisation as an elevated body mass index (BMI) above 30. A BMI above 25 is defined as being overweight. Obesity is a well recognised cause of morbidity and mortality from cardiovascular diseases3, particularly as it can lead to a variety of complications including insulin resistance, diabetes and hypertension. Obesity can also result in a number of mechanical health problems such as arthritis, which makes performing exercise difficult and maintaining one’s independence a lot harder as the weight increases. In a systematic review of the available evidence, Malik et al demonstrated a positive correlation between the consumption of sugar sweetened beverages and weight gain.4 This link has now been proven beyond doubt.
Sugar intake and brain function
There has been a fair bit of research been conducted on the effect of excessive sugar consumption on the brain. It has been suggested that high intake of sugar in children makes then excessively hyperactive, cranky and even moody. This has been suggested to be either due to some sort of an allergic reaction, or that hyperactive children have some sort of hypoglycemia. However, in an article published in the New England Journal of Medicine, an increased intake of sugar or sweeteners did not result in a change in children’s behaviour or cognitive function.5 More advanced studies in rats have shown that excessive consumption of sugar can result in the reduced brain neurotrophic factor in the hippocampus, a factor that is responsible for learning. In other words, high sugar intake may have a direct link to brain structure and function.6
Sugar intake and plasma cholesterol
Elevated levels of plasma cholesterol, especially low density lipoproteins are directly linked to coronary artery disease and stroke. A high dietary sugar (sucrose) intake has been demonstrated to bear an inverse relationship to the levels of high density lipoprotein (also commonly called ‘good cholesterol’) in the blood. 7 In addition to this, consuming high amounts of sugar in the daily diet can result in elevated levels of triglycerides in the blood, which again is a risk factor for coronary disease.8
Sugar intake and the development of cancer
It may be rather surprising to hear that a high sugar intake has been linked to different forms of cancer. In a study looking at the effects of sugar added to coffee and other similar hot beverages, suggestions were made linking sugar intake to proliferation of bowel epithelium, resulting in the development of colon cancer.9 In combination with risk factors such as obesity and gall stones, high sugar intake has also been linked to the development of cancer of the biliary tract.10 It is clear that high dietary sugar can have a tremendous negative impact on the gastrointestinal system by inducing the development of cancer.
Sugar intake and dental caries
The consumption of excessive amounts of sugar can feed oral bacteria, resulting in the formation of dental caries.11 Maintaining good oral health is key in such a situation, and if bad caries develops, tooth decay may warrant teeth extraction.
It is clear from the above brief discussion that increased consumption of sugar can bring about negative effects of sugar, affect a number of different physiological processes and result in clinical conditions that bear significant mortality and morbidity. Monitoring one’s sugar intake is essential to maintain health and prevent a number of different illnesses that can impact one’s life significantly.
1. Yudkin J. Sugar and ischaemic heart disease. Practitioner. 1967; 198: 680–683.
2. Jacobs DR Jr, Meyer KA, Kushi LH, et al. Whole-grain intake may reduce the risk of ischemic heart disease death in postmenopausal women: the Iowa Women’s Health Study. Am J Clin Nutr. 1998; 68: 248–257.
3. Eckel RH, Krauss RM. American Heart Association call to action: obesity as a major risk factor for coronary heart disease. AHA Nutrition Committee. Circulation. 1998; 97: 2099–2100.
4. Malik, Vasanti S., Matthias B. Schulze, and Frank B. Hu. “Intake of sugar-sweetened beverages and weight gain: a systematic review.” The American journal of clinical nutrition 84.2 (2006): 274-288.
5. Wolraich, Mark L., et al. “Effects of diets high in sucrose or aspartame on the behavior and cognitive performance of children.” New England Journal of Medicine 330.5 (1994): 301-307.
6. Molteni, Raffaella, et al. “A high-fat, refined sugar diet reduces hippocampal brain-derived neurotrophic factor, neuronal plasticity, and learning.” Neuroscience 112.4 (2002): 803-814.
7. Ernst N, Fisher M, Smith W, et al. The association of plasma high-density lipoprotein cholesterol with dietary intake and alcohol consumption. The Lipid Research Clinics Prevalence Study. Circulation. 1980; 62: 41–52.
8. Parks EJ, Hellerstein MK. Carbohydrate-induced hypertriacylglycerolemia: historical perspective and review of biological mechanisms. Am J Clin Nutr. 2000; 71: 412–433.
9. Vecchia, Carlo La, et al. “Refined‐sugar intake and the risk of colorectal cancer in humans.” International journal of cancer 55.3 (1993): 386-389.
10. MOERMAN, CLARA J., H. BAS DE MESQUITA, and SYTSKE RUNIA. “Dietary sugar intake in the aetiology of biliary tract cancer.” International journal of epidemiology 22.2 (1993): 207-214.
11. Woodward, M., and A. R. Walker. “Sugar consumption and dental caries: evidence from 90 countries.” British Dental Journal 176.8 (1994): 297-302.