GD 1.2 - principles of human nutrition

c) A composite mixture of various nutrients in varying proportions, together with water

Macronutrients are essential components of the human diet, providing the body with energy and supporting various physiological functions. Carbohydrates serve as the primary source of energy, with examples including grains, fruits, and vegetables. Proteins are crucial for tissue repair, muscle growth, and enzyme function, with sources such as meat, fish, dairy, and legumes. Fats provide concentrated energy, insulation, and cell membrane structure, with examples including oils, butter, nuts, and avocados.

Digestion is a complex process involving mechanical and chemical breakdown of food to extract nutrients for energy and bodily functions. It begins in the mouth with chewing and saliva production, continues in the stomach with acid and enzyme secretion, and proceeds in the small intestine where nutrients are absorbed into the bloodstream. Digestive organs such as the liver, pancreas, and gallbladder also contribute enzymes and bile to facilitate digestion. Ultimately, nutrients are transported to cells for energy production, growth, and repair, highlighting the crucial role of digestion in overall health and well-being.

Saturated fats are solid at room temperature and primarily found in animal products such as meat, dairy, and butter. They are associated with increased LDL cholesterol levels and cardiovascular disease risk. Unsaturated fats, on the other hand, are liquid at room temperature and found in plant-based oils, nuts, seeds, and fish. They can be further classified into monounsaturated and polyunsaturated fats, which have been linked to lower LDL cholesterol levels and reduced risk of heart disease.

Proteins are macronutrients composed of amino acids essential for numerous physiological functions, including muscle repair, enzyme catalysis, and immune system function. There are nine essential amino acids that must be obtained through the diet since the body cannot produce them. Complete proteins, found in animal products and some plant-based sources like quinoa and soy, contain all essential amino acids in adequate amounts. Incomplete proteins, found in most plant foods, can be combined to form complete proteins.

Cholesterol is a type of lipid synthesized by the liver and obtained through dietary sources, primarily animal products. It plays a crucial role in cell membrane structure, hormone synthesis, and bile acid production. Cholesterol is transported in the bloodstream by lipoproteins, with high levels of LDL (low-density lipoprotein) cholesterol associated with an increased risk of cardiovascular disease. Dietary choices, including consumption of saturated and trans fats, can impact cholesterol levels

Fiber is a type of carbohydrate found in plant foods that provides numerous health benefits, including improved digestion, weight management, and reduced risk of chronic diseases such as heart disease and diabetes. There are two main types of fiber: soluble fiber, which dissolves in water and helps regulate blood sugar and cholesterol levels, and insoluble fiber, which adds bulk to stool and promotes regular bowel movements. Examples of fiber-rich foods include fruits, vegetables, whole grains, legumes, and nuts.

Calories are units of energy derived from macronutrients in food and beverages. Carbohydrates and proteins provide approximately 4 calories per gram, while fats provide approximately 9 calories per gram. Alcohol also contributes calories but is not considered a macronutrient. The body utilizes calories for metabolic processes, physical activity, and maintaining essential bodily functions. Excessive calorie intake can lead to weight gain and obesity, increasing the risk of chronic diseases such as diabetes, heart disease, and certain cancers. Therefore, it is important to balance calorie intake with energy expenditure to support overall health and prevent weight-related complications.

Essential nutrients are those that the body cannot produce in sufficient amounts and must be obtained through the diet. Examples include essential amino acids, essential fatty acids, vitamins, and minerals. Non-essential nutrients, on the other hand, are those that the body can synthesize in adequate amounts from other sources. While non-essential nutrients may still be important for overall health, they are not considered essential dietary components.

Micronutrients are essential vitamins and minerals required in small amounts for various physiological functions, including metabolism, immune function, and cell signaling. Examples include vitamins A, C, D, E, K, and B-complex vitamins, as well as minerals such as calcium, iron, magnesium, and zinc. Deficiencies in micronutrients can lead to a range of health problems, including weakened immune function, impaired growth and development, and increased risk of chronic diseases.