Protein is an essential nutrient composed by units known as amino acids. Amino acids are referred to as “building blocks” or the “raw” material that make up proteins. Protein holds several functions in the body including but not limited to:
- Making and repairing proteins/cells which aid in building muscle and body tissues
- Synthesizing and maintaining enzymes and hormones that help speed up many chemical processes in the body
- Fighting infections and participating in clotting blood, playing a part in body’s defense mechanism
- Carrying fat, vitamins, minerals and oxygen around the body by acting as transport carries
- Balancing body fluids
The body needs 20 amino acids to maintain normal functioning. Nine of these are known as “essential” because the body cannot synthesize them and they must be obtained through food. The others are not considered essential because the body can produce them in sufficient amounts. When food contains an adequate amount of these 9 essential amino acids, it is considered a complete protein.
COMPLETE VS INCOMPLETE PROTEIN
As I mentioned previously, a protein is considered complete when it contains all 9 amino acids in adequate amounts. Animal based proteins such as meat, poultry, fish, eggs and milk products are the most commonly known complete proteins; however, plant based proteins should not be discredited as there are also unique plant based complete proteins available such as soy beans, quinoa, and tarwi.
Most other plant based proteins such as grains, legumes, nuts and seeds are considered “incomplete” because they don’t typically supply all 9 amino acids in adequate amounts. Personally, I find the terms incomplete and complete somewhat misleading when referring to the quality of proteins because all plant based proteins (even fruits!-although the amounts are considered insignificant) contain essential amino acids just not in optimal amounts; not on their own anyway.
Plant based proteins can complement each other to create complete proteins. It was once believed that these foods had to be eaten together to provide all nine essential amino acids in one meal… FALSE! Research has shown that you can enjoy these foods dispersed throughout the course of the day and it will still be appropriate. Mixing these in the same meal can simply be a more practical way to ensure long term adequacy when protein intake has the potential to be low.
“It is the position of The Academy of Nutrition and Dietetic that appropriately planned vegetarian diets containing vegetables, fruits, whole grains, legumes, nuts and seeds are healthful, nutritional adequate and may provide health benefits in the prevention and treatment of certain diseases while being more environmentally sustainable than diets rich in animal products”
A vegetarian diet typically meets or even exceeds recommended protein intakes when caloric intakes are adequate. When consumed from a variety of plant based foods during the course of a day, plant based proteins supply enough amino acids to provide adequate nutrition and optimize health.
Although protein can provide energy, it is not the body’s preferred fuel source. Ideally, carbohydrates and fat will provide enough energy so that proteins are able to focus on the previously mentioned bodily functions. Muscle loss can be an unintended consequence when carbohydrate and fat intake is too low; and on the other side of the spectrum, your body can not store excess protein from food, but instead it breaks it down for conversion to body fat or to glycogen for energy storage. The minimum protein requirement (or RDA: recommended daily amount) is 0.8 grams of protein per kilogram of body weight. But be mindful that protein needs may increase for healing, certain health problems, for older adults, athletic performance, among other circumstances. Specific needs vary from person to person. To be on the safe side, it is not contradicted for vegetarian to consume a slightly higher amount of protein than the RDA indicated considering variation in digestibility between animal and plant based proteins, which brings us to:
Other things to keep in mind when considering plant based diet: adequacy of nutrients such as omega 3 fatty acids, Iron, Zinc, Vitamin D, Vitamin B12; digestibility of plant based products vs animal products and how cooking can affect it; the differences in postprandial anabolic effects between plant and animal proteins; and many new emerging questions.
If you have diabetes or kidney disease, recommendation in regards to protein vary and should be taken with caution. Speak to you doctor or Registered Dietitian before taking any dietary supplements or making drastic dietary changes.
References
Gordon B. How much protein should I eat? Eatright.org. https://www.eatright.org/food/nutrition/dietary-guidelines-and-myplate/how-much-protein-should-i-eat. Published May 2019. Accessed February 1, 2020.
Intiquilla A, Jiménez-Aliaga K, Zavaleta AI, Hernández-Ledesma B. Production of Antioxidant Hydrolyzates from a Lupinus mutabilis (Tarwi) Protein Concentrate with Alcalase: Optimization by Response Surface Methodology. Natural Product Communications. 2018;13(6): 751-756. doi:10.1177/1934578x1801300626.
Melina V, Craig W, Levin S. Position of the Academy of Nutrition and Dietetics: Vegetarian Diets. Journal of the Academy of Nutrition and Dietetics. 2016; 116 (12): 1970-1980.doi: 10.1016/j.jand.2016.09.25
POR LA DRA. DANIELA GUTIERREZ MORE
Masters of Science in Human
Nutrition, Winthrop University
Dietetic Intern, Morrison
Healthcaredelgado2@winthropalumni.com