Carbohydrate, protein, and fat are the essential dietary components of food, responsible for the growth, reproduction, health maintenance, immunity, and healing of the human body. Deficits or excesses of any of the nutrients may interfere with these physiological processes. Depending on the nutrient in question and the age of the person, nutritional imbalances can result in poor health outcomes.
In the past, researchers focused their efforts on problems resulting from inadequate nutritional intake. Today, however, scientists are turning their attention to the health issues associated with the excess of macronutrients common in developed countries and in many developing nations.
Because of this shift in dietary needs, healthcare professionals are revisiting nutrition and learning how the over-consumption of these nutrients affects the health of their patients. Many are taking courses and workshops to enhance and develop their knowledge of nutrition. There is a nutrition science online short course that informs your ability to provide sound nutritional guidelines.
Overview of Nutrients
Carbohydrates, protein and fat are the basic components of nutrition. All provide energy in the form of calories, with carbohydrates and protein supplying 4 kcal/g and fat providing 9 kcal/g. While not an essential nutrient, alcohol is the other nutrient that supplies energy, at 7 kcal/g.
Consisting of sugars and starches, carbohydrates are the main sources of energy in the human diet, typically providing 50 percent or more of total calories. Nutritionists classify carbohydrates in several ways.
Simple vs. Complex Carbohydrate
Nutrition scientists classify carbohydrates as simple or complex, based on the length of the sugar molecule chains, with complex carbohydrates containing longer chains than simple carbohydrates. The body turns the sugar chains of both simple and complex carbohydrates into energy, but complex carbohydrates are higher in fiber and take longer to digest.
Simple carbohydrates include monosaccharides and disaccharides. Glucose and fructose are common monosaccharides, while sucrose and lactose are common disaccharides. Fruit, table sugar, and milk are examples of foods high in simple carbohydrates.
Complex carbohydrates are polysaccharides; this group of nutrients includes starch, glycogen, and fiber. Plant-based foods contain varying amounts of starch and fiber; cellulose and amylose are examples of fiber and starch, respectively. Grains, legumes, and starchy vegetables are high in starch and fiber. Animal-based foods, particularly muscle and liver tissue, contain trace amounts of glycogen.
Protein supports the growth and maintenance of body tissues. Protein is also the second-largest energy store, second to adipose tissue.
The body breaks down proteins into amino acids, which it uses to synthesize nucleic acids, cell membranes, hormones, neurotransmitters, and plasma proteins. While the body synthesizes both essential and nonessential amino acids, people of all ages must obtain nine amino acids from food to maintain health. These nine essential amino acids for people of all ages are:
Other amino acids are indispensable during childhood and adolescent growth, and in various disease states. These amino acids include arginine, glutamine, cysteine, proline, glycine, and tyrosine. Dietary protein requirements may change to reflect the need for these amino acids under special circumstances, such as prematurity in infants and severe catabolic stress in adults. Certain health conditions can change protein requirements. These health conditions include acute illness, burn injury, chronic illnesses involving infection and inflammation, and end-stage renal disease. Protein deficiency is often a concern among nursing home residents who are not eating normal amounts of food.
Both plant and animal foods provide protein. The main difference between diets supplying the two types of proteins is that, while plants provide all the essential amino acids, some plants provide limited lysine or sulfur-containing amino acids.
Dietary fat aids in the absorption of fat-soluble vitamins, provides energy, and supports cell growth. Compared with carbohydrates and proteins, dietary fats are the least-required macronutrients – the body needs only a few grams of dietary fat per day to function.
The four main dietary fats are:
- Saturated fats
- Trans fats
- Monounsaturated fats
- Polyunsaturated fats
Food contains saturated and unsaturated fats. The main difference between the two is that the chemical structure of saturated fat contains as many hydrogen atoms as possible; in other words, they are saturated with hydrogen. These extra hydrogen atoms keep saturated fat solid at room temperature. Dairy products, eggs, meats, and tropical oils, such as palm oil and coconut oil, contain saturated fat.
Vegetable oils and other liquid fats predominantly contain unsaturated fats. Nutritionists categorize unsaturated fat as monounsaturated fats and polyunsaturated fats. Avocados, olive oil and canola oil contain monounsaturated fats, while nuts, seeds, and seed oils contain polyunsaturated fats.
Of these, only polyunsaturated fatty acids (PUFA) are essential to human nutrition, as the body cannot synthesize these. PUFA function as signaling molecules and as structural components of cell membranes. Essential fatty acids include linoleic acids and alpha-linolenic acid, which are an omega-6 fatty acid and an omega-3 fatty acid, respectively. Sources of polyunsaturated fatty acids include vegetable oils, avocados, walnuts and other nuts, seeds, oils, and fish.
Over the past few years, quite a bit has changed in the American diet – people are eating larger quantities of nutrient-poor foods – and this change in eating habits is causing an uptick in obesity and other disease states. To optimize the care that they provide to patients, healthcare professionals can take advanced courses in nutrition.