By: Amelia Lamb

Macronutrients are the basic substances that are needed for energy purposes and for proper functioning of the body. There are three basic types: lipids (commonly called fats), proteins, and carbohydrates. Each of these types are consumed in large quantities and have different but equally important jobs to perform in the body.
Fats, also called lipids, are a crucial energy source. They also aid in vitamin absorption and are needed for other structural roles such as membrane formation (Clement, 2015). This nutrient provides 9 calories per gram and can be found in many different foods such as dairy products, oils, avocados, nuts, and cold-water fish. There is a lot of confusion involving fat whether it is good or bad for you. Fat is necessary for a healthy life, but different types of fats affect the body differently.
Two common types of fats are saturated fat and unsaturated fat. An easy way to determine the difference between them are that saturated fats are generally solid at room temperature while unsaturated fats tend to be liquid. Saturated fats, in general, are considered less healthy than unsaturated fats. Diets high in saturated fat have been linked to a number of negative health outcomes, including increased LDL cholesterol in your blood. This is the “bad” type of cholesterol and can deposit plaque on your artery walls, leading to atherosclerosis. Contrarily, unsaturated fats lower overall cholesterol as well as increase the “good” type of cholesterol, high density lipoprotein or HDL. HDLs carry lipids and cholesterol to your liver for processing, protecting your arteries against the build-up of fatty deposits.
Fat is insoluble and therefore needs to be broken down before it can be absorbed in the intestines. This is achieved by the gallbladder which releases bile into the small intestine when fat is present; the bile emulsifies or breaks-down the fat with the help of other proteins called lipase to make the lipid water-soluble (Choose My Plate, 2016). Fat, unlike proteins and carbohydrates, enter the lymphatic system before entering the blood stream.
Protein is another macronutrient commonly found in poultry, red meat, fish, dairy, eggs, and legumes, among other sources. Protein provides 4 calories per gram and the Recommended Daily Allowance, or RDA, is at least 0.8 g of protein per kilogram of body weight (Choose My Plate, 2016). For athletes, the requirement can be higher depending on the type of intensity and training. The American College of Sports Medicine in conjunction with the Academy for Nutrition and Dietetics claim that athletes should consume anywhere from 1.2 to 2.0 grams of protein per kilogram of body weight (Caspero 2016). Proteins are required for many different structural functions along with the production of hormones and other enzymes, making the consumption of this macronutrient vital (Mercola 2014).

Protein is made up of long strains of amino acids. There are 21 types of amino acids found in humans, and they can be broken down into two main categories; essential and nonessential. Essential proteins have to be obtained from one’s diet meaning they are not synthesized inside the body. The amino acids that are essential are isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Non-essential acids are produced by the body and are therefore do not have to be ingested. The nonessential amino acids are alanine, arginine, asparagine, aspartate, cystine, glutamic, glycine, ornithine, proline, serine, and tyrosine (“What Are Essential and Non-Essential Amino Acids?” 2015). Proteins, unlike lipids, are broken down by acids in the stomach and are absorbed in the small intestine directly into the blood stream. Proteins are not used for energy as much as fats and carbohydrates. Instead, they are constantly synthesizing and degrading to regulate structures and repair muscles in a process called protein turnover (Choose My Plate, 2016).

The third macronutrient is carbohydrates which supplies 4 calories per gram just like protein. Carbohydrates are the main energy source of the body.  Once broken down into glucose, the body can utilize it right away or store excess in the form of glycogen. Glucose is also important for proper brain functioning. Carbs are found in an abundance of food such as bread products, potatoes, fruits, vegetables, whole grains, and candy. Carbohydrates can be simple or complex. Simple sugars are found in soda, cookies, and other processed foods whereas complex sugars are present in fruits, whole grains (quinoa), and vegetables (Cheney 2015). Carbohydrates, like proteins, are also taken directly into the bloodstream after being denatured in the stomach. Once in the blood stream, cells are able to take in the glucose and use it for energy.

Alcohol, though not a macronutrient, provides 7 calories per gram of basically empty calories because no nutrients is being supplied to the body. That is more calories per gram than carbohydrates or proteins! The high amount of calories present in alcohol can lead to weight gain and many other health problems. Fats, proteins, and carbohydrates, unlike alcohol, are macronutrients and are important for daily functioning of a healthy individual. It’s crucial to consume foods containing these essential nutrients; it is equally as crucial to not over consume any one macronutrient because it can have negative consequences as well. Balancing all of the macronutrients in your diet is paramount.

 

References

Absorption of Lipids. (2007, August 8). Retrieved October 13, 2016, from http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/smallgut/absorb_lipids
Carbohydrates. (2016). Retrieved October 13, 2016, from https://www.hsph.harvard.edu/nutritionsource/carbohydrates/
Caspero, A. (2016, July 19). Protein and the Athlete – How Much Do You Need? Retrieved October 18, 2016, from http://www.eatright.org/resource/fitness/sports-and-performance/fueling-your-workout/protein-and-the-athlete
Cheney, K. (2015, March 30). Simple Carbohydrates vs. Complex Carbohydrates. Retrieved October 13, 2016, from http://www.healthline.com/health/food-nutrition/simple-carbohydrates-complex-carbohydrates#7
Choose My Plate. United States Department of Agriculture. 2016. https://www.ChooseMyPlate.gov
Clement, A. (2015, May 08). What Are Functions of Proteins, Carbohydrates, Fats, Water, Vitamins and Minerals? Retrieved October 18, 2016, from http://www.livestrong.com/article/355090-what-are-functions-of-proteins-carbohydrates-fats-water-vitamins-and-minerals/
Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients). (2002). Retrieved from https://www.nap.edu/read/10490/chapter/12
Digestion and absorption of fats. (n.d.). Retrieved October 13, 2016, from https://courses.washington.edu/conj/bess/fats/fats.html
Mercola, J., Dr. (2014, September 3). The Very Real Risks of Consuming Too Much Protein. Retrieved October 13, 2016, from http://articles.mercola.com/sites/articles/archive/2014/09/03/too-much-protein.aspx
Roberts, S. (n.d.). Saturated Vs. Unsaturated Fats in Lipids. Retrieved October 13, 2016, from http://healthyeating.sfgate.com/saturated-vs-unsaturated-fats-lipids-8611.html
What Are Essential and Non-Essential Amino Acids? (2015, April 13). Retrieved October 18, 2016, from https://www.sproutliving.com/what-are-essential-and-nonessential-amino-acids/
Winston, C. (n.d.). How Are Carbohydrates Digested, Absorbed & Eliminated? Retrieved October 13, 2016, from http://healthyeating.sfgate.com/carbohydrates-digested-absorbed-eliminated-6163.html