ABSTRACT

Macronutrients are nutrients required in large amounts and used for producing energy to the body activity. They include carbohydrates (sugars), proteins and lipids (fats).

Carbohydrates are classified into four main groups: monosaccharides (glucose, fructose, galactose), disaccharides (sucrose, lactose, maltose), oligosaccharides (α-glucans), and polysaccharides (starch, soluble dietary fibers like β-glucan, gum, mucilage and insoluble fibers like cellulose, etc.).

Proteins are polymers of different amino acids linked together by peptide bonds in the form of long filaments. Different types of human proteins include albumins, globulins, enzymes, hormones, antibodies, collagens, lipoproteins, glycoproteins, keratins, and so on. There are 20 amino acids in human proteins. A peptide is a mini-protein with the number of amino acids linked varied between 2 to 50.

Lipids, including fats and oils, are essential and nonessential macronutrients. Lipids serve as structural components of cell membrane, function as energy stores within cells and as important signaling molecules. Lipids are divided into 4 main categories: fatty acids, triglycerides, phospholipids and sterols. Fatty acids comprise saturated and unsaturated ones. Well-known unsaturated fatty acids include omega-3 and omega-6 fatty acids, and both are essential. Sterols are lipid compounds and include cholesterol, phytosterols, steroids such as sex hormones, adrenocortical hormones, vitamin D3, and bile.