Abstract
Carbohydrates, comprised of sugars, starches, and dietary fibers, are a macronutrient that is critical to human health. They are responsible for a significant portion of one’s dietary energy intake. Excessive consumption of carbohydrates due to overreliance on added sugars and refined grains is a major cause of obesity and other health problems. Furthermore, sugars play a critical role in the body’s energy metabolism. Carbohydrates are strongly related to diabetes, contributing to causing it and requiring special management in patients with diabetes. Therefore, monitoring their consumption is critical for a healthy diet, even in non-diabetics.
Introduction
Carbohydrates are one of the major nutrient groups that are necessary for healthy nutrition. This group is divided into three subgroups: dietary fibers, starches, and sugars. These nutrients are present in a majority of food items and represent up to 50% of the caloric intake in the US (Center for Disease Control and Prevention [CDC], 2018). Carbohydrates’ primary nutritional function is as a source of energy, while dietary fiber is also crucial for digestive health.
Carbohydrates are abundant in fruit, pastry, cereals, and highly processed foods. Food low in carbohydrates includes oils, meat, fish, and eggs. Although not directly toxic, an excess of carbohydrates (specifically, sugars) has been linked to obesity and diabetes, which affect up to 46% and 10% of the adult US population, respectively (Hales, Fryar, Carroll, Freedman, & Ogden, 2018; Xu, Liu, Sun, Du, Snetselaar, Hu, & Bao, 2018). A deficiency in starch or sugar, often related to diabetes medication, is called hypoglycemia and can cause weakness, dizziness, and confusion. Dietary fiber is important for digestive processes, and its deficiency can lead to constipation. Therefore, a balanced intake of carbohydrates is necessary to maintain health.
Carbohydrate Functions
Table 1. Functions of three primary types of carbohydrates.
Sugars and Starches
Sugars and starches are a necessary source of energy, possessing an energy value of 4kcal per gram. Indigestion is broken down into three saccharides: glucose, fructose, and galactose, which are then primarily catabolized into adenosine triphosphate (ATP), which is used for cellular energy (Sanders, 2016). The remainder can be stored as glycogen or converted into body fat for longer-term energy storage (Slavin & Carlson, 2014). Sugars, or monosaccharides and disaccharides, take the shortest amount of time to digest and provide a short-term release of energy. Starch is a polysaccharide that takes longer to digest and, therefore, releases its energy over a longer period. Glucose, a sugar, is crucial for the brain’s function, and its deficiency can cause lasting harm.
Dietary Fiber
Dietary fibers are carbohydrates that cannot be effectively broken down by the human body. They possess little to no energy value but are necessary for digestion. Fiber provides one with a feeling of fullness, helping to regulate overall food intake by preventing overeating. Soluble fibers, which can be dissolved in water, primarily contribute to this feeling while also aiding in the regulation of blood cholesterol levels (Threapleton et al., 2013). Insoluble fibers, which cannot be dissolved, provide bulking and are fermented further in the digestive tract, aiding the passing of stool.
Carbohydrate Deficiency
Since the primary function of carbohydrates is providing energy, their general deficiency in the diet causes the body to derive its energy from other sources: fat and protein. This, in turn, leads to muscular deterioration and loss of weight. Furthermore, breaking down fat for energy releases ketones, causing a condition called ketosis. It is common in diabetes but can also be caused by lactation and increased physical activity, particularly when these factors are combined with low carbohydrate, high fat (LCHF) diet (Van Geijer & Ekelund, 2015). In extreme cases, the ketone content is sufficient to increase the blood’s pH balance, causing a life-threatening condition called ketoacidosis.
A low blood sugar content, called hypoglycemia, can cause significant discomfort and, in more extreme cases, be life-threatening, as the brain does not receive the glucose it requires to operate. Symptoms include headaches, palpitations, decreased cognition, aberrant behavior, and, in extreme cases, coma and death (Martín-Timón, del Cañizo-Gómez, 2015; Ortiz, 2017; see Table 2). Since its management relies on heavy restrictions to one’s carbohydrate intake, hypoglycemia is a common complication of diabetes.
Furthermore, it is significantly more common in blacks than whites with diabetes (Lee, Warren, Lee, Huang, Richey Sharrett, Coresh, & Selvin, 2017). Owing to this connection, the two conditions are primarily examined together. It can also be caused by a variety of other factors, such as heavy alcohol consumption.
Table 2: Symptoms of hypoglycemia. (From from Connelly, Yan, Leiter, Bhatt, & Verma, 2015).
Carbohydrate Toxicity
Carbohydrates are not toxic in quantities that are consumed by humans. However, excess energy metabolized from them can be stored as fat, which is a key factor in obesity, cardiovascular disease, and diabetes (Evans, 2016; Jung, Kaplan, Mossavar-Rahmani, Viswanathan, Wylie-Rosett, Beasley, 2014). This bears particular importance in low-income patients who may be unable to afford healthier foods and have to rely on processed food and beverages (Ferdinand, Mahata, 2017). Therefore, guidelines and suggestions exist to limit the consumption of carbohydrates.
An excessive level of blood sugar is called hyperglycemia and is closely related to diabetes, as well. It can be caused by a variety of factors, including stress; however, it is a strong indicator of diabetes (Grove et al., 2017). Its symptoms include increased thirst, frequent urination, fatigue, and headaches. In diabetic patients, hyperglycemia can cause ketoacidosis due to the sugar not being absorbed by cells.
Screening, Assessment, and Monitoring
Carbohydrate malnutrition is closely related to diabetes; therefore, monitoring techniques for these conditions are related, as well. Since overweight and obesity are known risk factors, they are the anthropometric measures to be observed. Blood and urine tests will reveal excessive or deficient concentrations of sugar, and a mixed meal tolerance test can be administered to verify the diagnosis (Paglialunga, Guerrero, Roessig, Rubin, & Dehn, 2016). Clinical observations include taking a medical history for such comorbidities as diabetes, liver and thyroid diseases, and tumors. Dietary factors, taken from a 24-hour recall or a food group questionnaire, should include the amount of fruit and vegetables, as well as highly-processed foods rich in added sugars or refined grains and alcohol.
Table 3. Nutrition Assessment of Carbohydrate Deficiency and Toxicity.
Implications for Health Promotion and Disease Prevention
Carbohydrates are a key source of energy necessary for the human body to operate. The current recommendation is that between 45% and 65% of total caloric intake should come from them (Kroemer, López-Otín, Madeo, & de Cabo, 2018). However, sugars are often added to processed foods to improve their taste. These added sugars contribute to excessive consumption of carbohydrates and cardiovascular disease, particularly in children and adolescents (Vos et al., 2016). Similarly, refined grains contain a high amount of carbohydrates with significantly fewer other nutrients compared to their whole counterparts, presenting another risk of excessive consumption (Mozaffarian, 2016). Current guidelines suggest restricting foods that are rich in refined grains or added sugars.
Conclusions
Carbohydrates are a macronutrient that is critical to producing the energy necessary for the human body and brain. Dietary fiber, while providing no nutritional value, is essential for digestion and aids in regulating blood cholesterol levels. Excessive consumption of carbohydrates is known to lead to cardiovascular disease, obesity, and diabetes; diabetes is closely related to hyperglycemia and hypoglycemia. Although current guidelines suggest that at least half of one’s daily caloric intake should come from carbohydrates, products with refined grains and added sugars can be dangerous if not consumed carefully.
References and Notes
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