What is Sugar?
Sugar is the generalised name for a class of sweet-flavored substances used as food. They are carbohydrates and as this name implies, are composed of carbon, hydrogen and oxygen. There are various types of sugar derived from different sources. Simple sugars are called monosaccharides and include glucose (also known as dextrose), fructose and galactose. The table or granulated sugar most customarily used as food is sucrose, a disaccharide. Other disaccharides include maltose and lactose.
Sugars are found in the tissues of most plants but are only present in sufficient concentrations for efficient extraction in sugarcane and sugar beet. Sugarcane is a giant grass and has been cultivated in tropical climates in the Far East since ancient times. A great expansion in its production took place in the 18th century with the setting up of sugar plantations in the West Indies and Americas. This was the first time that sugar became available to the common people who had previously had to rely on honey to sweeten foods. Sugar beet is a root crop and is cultivated in cooler climates and became a major source of sugar in the 19th century when methods for extracting the sugar became available. Sugar production and trade has changed the course of human history in many ways. It influenced the formation of colonies, the perpetuation of slavery, the transition to indentured labour, the migration of peoples, wars between 19th century sugar trade controlling nations and the ethnic composition and political structure of the new world.
The world produced about 168 million tonnes of sugar in 2011. The average person consumes about 24 kilograms of sugar each year (33.1 kg in industrialised countries), equivalent to over 260 food calories per person, per day. Sugar provides empty calories.
Since the latter part of the twentieth century, it has been questioned whether a diet high in sugars, especially refined sugars, is bad for health. Sugar has been linked to obesity and suspected of being implicated in diabetes, cardiovascular disease, dementia, macular degeneration and tooth decay. Numerous studies have been undertaken to try to clarify the position but the results remain largely unclear, mainly because of the difficulty of finding populations for use as controls that do not consume sugars.
Some studies involving the health impact of sugars are effectively inconclusive. The WHO and FAO meta studies have shown directly contrasting impacts of sugar in refined and unrefined forms and since most studies do not use a population who are not consuming any "free sugars" at all, the baseline is effectively flawed. Hence there are articles such as Consumer Reports on Health that said in 2008, "Some of the supposed dietary dangers of sugar have been overblown. Many studies have debunked the idea that it causes hyperactivity, for example." Despite this, the article continues to discuss other health impacts of sugar. Other articles and studies refer to the increasing evidence supporting the links between refined sugar and hyperactivity. The WHO FAO meta-study suggests that such inconclusive results are to be expected when some studies do not effectively segregate or control for free sugars as opposed to sugars still in their natural form (entirely unrefined) while others do.
Blood glucose levels
It used to be believed that sugar raised blood glucose levels more quickly than did starch because of its simpler chemical structure. This has been disproved and there is no longer a reason to segregate these two substances when controlling blood glucose levels in diabetics. This has led to carbohydrate counting, a method used by diabetics for planning their meals. However, studies have shown that the consumption of sugar and starch have different impacts on oral health with the ingestion of starchy foods and fruit causing low levels of dental caries.
Obesity and diabetes
Studies on the link between sugars and diabetes are inconclusive, with some suggesting that eating excessive amounts of sugar does not increase the risk of diabetes, although the extra calories from consuming large amounts of sugar can lead to obesity, which may itself increase the risk of developing this metabolic disease. Other studies show correlation between refined sugar (free sugar) consumption and the onset of diabetes, and negative correlation with the consumption of fiber. These included a 2010 meta-analysis of eleven studies involving 310,819 participants and 15,043 cases of type 2 diabetes. This found that "SSBs (sugar-sweetened beverages) may increase the risk of metabolic syndrome and type 2 diabetes not only through obesity but also by increasing dietary glycemic load, leading to insulin resistance, ?-cell dysfunction, and inflammation". As an overview to consumption related to chronic disease and obesity, the World Health Organization's independent meta-studies specifically distinguish free sugars ("all monosaccharides and disaccharides added to foods by the manufacturer, cook or consumer, plus sugars naturally present in honey, syrups and fruit juices") from sugars occurring naturally in food. The reports prior to 2000 set the limits for free sugars at a maximum of 10% of carbohydrate intake, measured by energy, rather than mass, and since 2002] have aimed for a level across the entire population of less than 10%. The consultation committee recognized that this goal is "controversial. However, the Consultation considered that the studies showing no effect of free sugars on excess weight have limitations."
A number of studies in animals have suggested that chronic consumption of refined sugars can contribute to metabolic and cardiovascular dysfunction. Some experts have suggested that refined fructose is more damaging than refined glucose in terms of cardiovascular risk. Cardiac performance has been shown to be impaired by switching from a carbohydrate diet including fiber to a high-carbohydrate diet. Switching from saturated fatty acids to carbohydrates with high glycemic index values shows a statistically-significant increase in the risk of myocardial infarction. Other studies have shown that the risk of developing coronary heart disease is decreased by adopting a diet high in polyunsaturated fatty acids but low in sugar whereas a low fat, high carbohydrate diet brings no reduction. This suggests that consuming a diet with a high glycemic load typical of the "junk food" diet, is strongly associated with an increased risk of developing coronary heart disease.
The consumption of added sugars has been positively associated with multiple measures known to increase cardiovascular disease risk amongst adolescents as well as adults. Studies are suggesting that the impact of refined carbohydrates or high glycemic load carbohydrates are more significant than the impact of saturated fatty acids on cardiovascular disease. A high dietary intake of sugar (in this case, sucrose or disaccharide) can substantially increase the risk of heart and vascular diseases. According to a Swedish study of 4301 people undertaken by Lund University and Malmö University College, sugar was associated with higher levels of bad blood lipids, causing a high level of small and medium low-density lipoprotein (LDL) and reduced high-density lipoprotein (HDL). In contrast, the amount of fat eaten did not affect the level of blood fats. As a side note, moderate quantities of alcohol and protein were linked to an increase in the good HDL blood fat.
It is suggested that Alzheimer's disease is linked with the western diet, which is characterised by high intakes of red meat, sugary foods, high-fat foods and refined grains. It has been hypothesized that dementia could be prevented by taking mono-supplements of specific vitamins or drugs, but studies have shown that this approach does not show appreciable results.
Dietary pattern analysis considers overall eating patterns, comparing diets of people with Alzheimer's disease to diets of healthy controls using factor analysis. This analysis shows a major eating pattern for those with Alzheimer's characterised by a high intake of meat, butter, high-fat dairy products, eggs, and refined sugar, while the major eating pattern for those without Alzheimer's was characterised by a high intake of grains and vegetables.
One group of experimenters compared a normal rodent diet (19% protein, 5% fat and 60% complex carbohydrate) with free access to water against the same diet but with free access to a 10% sucrose solution. The experimental results underscore the potential role of dietary sugar in the pathogenesis of Alzheimer disease and suggest that controlling the consumption of sugar-sweetened beverages may be an effective way to curtail the risk of developing the disease.
There are links between free sugar consumption and macular degeneration in older age.
In regard to contributions to tooth decay, the role of free sugars is also recommended to be below an absolute maximum of 10% of energy intake, with a minimum of zero. There is "convincing evidence from human intervention studies, epidemiological studies, animal studies and experimental studies, for an association between the amount and frequency of free sugars intake and dental caries" while other sugars (complex carbohydrate) consumption is normally associated with a lower rate of dental caries. Lower rates of tooth decay have been seen in individuals with hereditary fructose intolerance.
This definition may contain information from Wikipedia.