Nutrition Tuesday: Overview of Macronutrients and Micronutrients

Last week we discussed the basics of metabolism. Now it’s important to discuss what nutrients fuel the body to not only get us through exercise, but our day-to-day activities for survival. Our bodies require two different types of nutrients: macronutrients and micronutrients. 
Macronutrients are carbohydrates, fats, and proteins, which ultimately provide the energy necessary to maintain body functions at rest and during physical activities and maintain the body’s structural and functional integrity1
Micronutrients are vitamins and minerals. As their names imply, macronutrients comprise most of a person’s dietary intake, while micronutrients are essential in much lower quantities. With the deficiency of micronutrients, athletic performance in addition to normal physiologic function will suffer. However, with a well-balanced diet, a person should not have to worry about any imbalances. 
Today’s post will give an overview of each type of nutrient required by the human body. The next few days this week I will post a more in-depth look at carbohydrates, fats, and proteins. Next week I will discuss vitamins and minerals.
The Macronutrients
Carbohydrates
Carbohydrates often get a bad name, but without question, wholesome forms of carbohydrates are the best choices for fueling your muscles and promoting good health. Carbohydrates, as their name suggests, are carbon-, hydrogen-, and oxygen-based molecules that are abundant in most plant foods, especially fruits and grains1. Not all forms and sources of carbohydrates are alike. The carbohydrate family includes both simple and complex carbohydrates2. Simple carbohydrates are monosaccharides (structurally the simplest form of carbohydrates) and disaccharides (two monosaccharides). Glucose, fructose, and galactose are monosaccharides or sometimes referred as the simple sugars2. The three most common disaccharides are sucrose (table sugar), lactose (milk sugar), and maltose (malt sugar)2
Complex carbohydrates are formed when sugars link together to form long complex chains, similar to a string of pearls. Plants store extra sugar in the form of starch, which is a complex carbohydrate. Humans store extra glucose mostly in the form of muscle glycogen and liver glycogen. This glycogen will become available for energy during exercise. 


The main functions of carbohydrates are:
  • The primary function is to provide energy to the cells of the body, particularly the brain
  • Facilitate the body’s metabolism of fat
  • Spare muscle protein
Fat
Lipid is the collective name given to a vast variety of water-insoluble chemicals, including fats and oils. Fat or lipids are made up of carbon, hydrogen, and oxygen atoms. The ratio of oxygen to carbon and hydrogen is much lower in lipids than in carbohydrates, and thus lipids are a more concentrated source of energy1. There are three major types of fatty acids that can be distinguished by their molecular bonds and number of hydrogens. Fats can be saturated (the maximum number of hydrogens), monounsaturated (having one carbon-carbon double bond), or polyunsaturated (having two or more carbon-carbon double bonds)1


The main functions of fats:
  • Fats provide many of the body’s tissues and organs (including the heart) with most of their energy. Fat is the ideal fuel because it contains almost twice the energy as glucose, weighs less, and is easily transported and stored1.
  • Essential for the transmission of nerve signals that generate muscle contraction.
  • Serve as a transporter for vitamins A, D, E, and K.
  • Provide cushioning for the prevention of vital organs and insulation from thermal stress of cold environments.
Proteins
Proteins are essential nutritionally because they are comprised of amino acids, which the body needs to synthesize its own proteins and nitrogen-containing molecules that make life possible1. Amino acids are the building blocks of proteins. There are 20 amino acids. Of these 20 amino acids, 9 are considered to be essential because the human body cannot synthesize these amino acids. The remaining 11 amino acids are considered nonessential because the human body can synthesize them. 


The main functions of proteins:
  • Produce antibodies for the immune system
  • Produce enzymes that are required for various chemical reactions in the body
  • Component of structural hormones:
    • Contractile proteins for muscle tissue (i.e. actin and myosin)
    • Fibrous proteins in connective tissues (i.e. collagen, elastin, and keratin)
  • Component of transport proteins (i.e. hemoglobin)
  • Component of peptide hormones (i.e. insulin, thyroid hormone, etc.)
  • Source of fuel when muscle glycogen levels are low due to prolonged intense exercise 
The Micronutrients
Vitamins     
Vitamins are metabolic catalysts that regulate biochemical reactions within the body2. They are found in plants that we eat and are created by the plants themselves. Vitamins are categorized into either water-soluble or fat-soluble vitamins. Water-soluble vitamins are found in the fluid portion of our bodies and do not accumulate to a large degree in the body1. Fat-soluble vitamins are stored in the lipid (fat) portion of our bodies and can accumulate in the cells1. Some vitamins include: Vitamin B6, Vitamin C, Vitamin D, and Vitamin A.
Minerals
Minerals are natural substances that plants must absorb from the soil2. The human body uses minerals for many different jobs, including building bones, making hormones, and regulating the heartbeat. There are two kinds of minerals: macrominerals and trace minerals3. Macrominerals include calcium, phosphorus, magnesium, sodium, potassium, chloride and sulfur3. Trace minerals include iron, manganese, copper, iodine, zinc, cobalt, fluoride and selenium3

References
  1. Antonio J et al. Essentials of Sports Nutrition and Supplements. Totowa NJ: Human Press, 2008.
  2. Clark N. Nancy Clark’s Sports Nutrition Guidebook, 4th Ed. Champaign, IL: Human Kinetics, 2008.
  3. MedlinePlus. Minerals. Available at: http://www.nlm.nih.gov/medlineplus/minerals.html. Accessed May 28, 2012. 
(Disclaimer: This is for your information. If you need help with your diet and developing healthy lifestyle choices then I suggest seeking out professional help from your medical professional or registered dietitian. If you see any errors, please let me know!)
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