Lately, I've noticed a lot of foods popping up with labels bragging about how much protein they contain. The popularity of protein supplements and protein-rich foods might have some of you questioning; What exactly is protein? Should I be buying more products with protein in them? My short answer is this: protein is very important, but probably not as important as people want you to think, and you probably get enough of it already. So, here it goes.
What is Protein?
Protein is one of the three nutrients that give you energy (macronutrients or macros). The other two macros are carbohydrates (carbs) and fats. While the body stores excess of any macronutrient as fatty tissue, moderate amounts of protein are generally not stored in the body the way that carbs and fats get stored. Instead, the body is continuously breaking down and using proteins for bodily functions. This means that the body needs proteins in a continuous supply from food. Dietary protein is also important because it is the body's only source of essential amino acids (the building blocks of protein), and the only practical source of nitrogen, which the body needs to build nonessential amino acids (Whitney & Rolfes, 2016). Each combination of amino acids has a specific job in the body, such as:
Extreme deficiency of proteins can lead to marasmus and kwashiorkor, which mostly occurs in developing nations with food access challenges. Cases of starvation also come with problems caused by vitamin and mineral deficiencies. However, in the U.S., protein deficiencies are rare and people typically get 40% more protein than their recommended daily allowance (RDA) (Whitney & Roles, 2016). While some people eat too much protein, some people's bodies need more, including:
Also, because protein intake stimulates the excretion of certain nutrients (i.e. calcium), too protein much can lead to micronutrient inefficiencies. To healthy individuals: when planning protein amounts in your diet, you should consider:
For more info, the USDA offers this online calculator to find out your RDA for protein. NOTE: RDA's are meant to be applied to the majority of the healthy population, and only suggest an average intake for individuals. Individual nutrient requirements may vary from the RDA.
What foods have protein?
Protein comes from animal products (i.e. meat, poultry, greek yogurt, eggs), seafood, and vegetables (i.e. beans, lentils, broccoli, nuts, and seeds). Animal products are the most packed with amino acids and have the most bioavailability (meaning they are more absorbable).
So does this mean I should always get my protein from animal sources? Not necessarily. First, vegetarians are still able to get enough protein from their diet (just not as easily as omnivores). Second, animal sources of protein are higher in saturated fat than vegetable protein sources. High amounts of saturated fat can lead to plaque buildup in the arteries, which is a stepping stone toward heart disease. An analysis of data from 10 studies estimates that every 50 gram portion of processed meat eaten daily also increases the risk of colorectal cancer by about 18% (WHO, 2015). To put it in perspective, a 50 gram portion of processed meat roughly equates to the current RDA for protein for most adults. In a study by Lin and colleagues (2015) plant protein intakes may play also role in preventing obesity in teens. Evidence showed that plant protein (soy in particular) can stimulate lipid metabolism. This can result in a better blood lipid profile, by lowering total cholesterol, triglyceride, low-density lipoprotein-cholesterol and reducing insulin resistance (Lin et al., 2015).
The fundamental principle to planning a healthy diet is to have protein in moderation. It's also important to include high quality proteins from a variety of sources. For non-vegetarians, especially, buying and eating protein-fortified foods, protein powders, and supplements is not usually unnecessary.
American College of Sports Medicine [ACSM]. 2015. PROTEIN INTAKE FOR OPTIMAL MUSCLE MAINTENANCE. https://www.acsm.org/docs/default-source/files-for-resource-library/protein-intake-for-optimal-muscle-maintenance.pdf?sfvrsn=688d8896_2
Lin, Y. et al. (2015). Dietary animal and plant protein intakes and their associations with obesity and cardio-metabolic indicators in European adolescents: the HELENA cross-sectional study. Nutrition Journal, 14(10). DOI: 10.1186/1475-2891-14-10
Whitney, E., & Rolfes, S.R., (2016). Understanding Nutrition (15th Ed.). Boston, MA: Cengage.
World Health Organization. (2015). Q&A on the carcinogenicity of the consumption of red meat and processed meat. Retrieved from http://www.who.int/features/qa/cancer-red-meat/en/
I'm Sierra, a nutrition educator and health coach. Here you can read my take on various nutrition and wellness topics, with the help of peer-reviewed research and sources you can trust. Thanks for stopping by!