What do candle wax, steroid hormones and butter have in common? They are all composed of biomolecules called lipids. Small lipid building blocks stacked together form lipid polymers -- bigger, more complex structures. Lipids play an important role in human health and should be included in a healthy diet. Consult your health-care provider or dietitian to find ways to include fat into your nutritious diet.
Lipids are biomolecules that are insoluble in water and play an essential role in human biology and physiology. Lipids provide the body with an energy reserve that can support body functions for about 30 to 40 days without food, as long as water is available. Lipids form cell membranes, insulate the body from cold, cushion and protect organs from injury, prevent the skin from drying out and are involved in hormonal regulation of various body systems.
Monomers and Polymers
Imagine a necklace with beads strung together on a strand of ribbon. In nature, the individual "beads" are small molecules strung together to make a larger, more complex structure called a polymer. For instance, starch is composed of small, polymerized glucose monomers. Unlike amino acids, carbohydrates and nucleic acids, lipids do not form large polymers. Unlike carbohydrates, which often consist of hundreds of joined monosaccharides, lipid polymers are usually only a few monomers long.
Types of Lipids
There are several classes of lipids, including steroids, fats, waxes and phospholipids. Steroids are precursors to sex hormones and keep cell membranes fluid and flexible. Waxes form a protective layer and prevent dessication for plants, bacteria and insects. Phospholipids form a bilayer that surrounds and contains cells. Fats from both plant and animal sources comprise an essential part of the human diet.
Despite their bad reputation, fats are a very important part of a healthy, well-balanced diet. The key is to limit your consumption of dietary fat to 20 to 35 percent of your daily caloric intake. Get your fat from healthy sources like nuts, fish, avocado and olive oil and avoid saturated fats like butter, red meat and whole milk dairy products.