Protein Basics


There are many misconceptions about dietary protein.  This video is intended to provide the basics of what protein is, what essential amino acids and complete proteins are, and the primary differences (and similarities) between plant and animal sources of protein.

In this first chapter, we’ll discuss some basics about protein. We’ll talk later about the relationship between animal protein and our health, but for this first chapter let’s start with some general information.

As Dr. Walter Willett, the chair of Harvard’s Department of Nutrition, explains, “To the metabolic systems engaged in protein production and repair, it is immaterial whether amino acids come from animal or plant protein. However, protein is not consumed in isolation. [I]t is packaged with a host of other nutrients” that vary depending on the source. He therefore recommends to, “Pick the best protein packages by emphasizing plant sources of protein rather than animal sources[.]”

Although meat has long been touted as a “basic food group” and many people assume it’s a necessary part of a healthy diet, there is a broad body of scientific literature and studies that lead physicians like Dr. Willett and myself to recommend plant protein over animal protein

First, it’s important to note that proteins are abundant in both animals sources (like meat, fish, dairy and eggs), as well as plant sources (like vegetables, grains, legumes and nuts). Proteins are chains of organic compounds, called amino acids, which are joined together by peptide bonds. The term “essential amino acids” refers to nine amino acids that our bodies do not synthesize and we therefore need to get from food. With few exceptions such as gelatin, most proteins, from both animal and plant sources, are “complete proteins,” meaning they contain all of the essential amino acids our bodies need.

The fact that plants have protein is for some reason, not always well known. But, just as an example, according to the USDA, broccoli has more protein per calorie than beef. Specifically, beef has 14.63 grams of proteins in 204 calories, whereas broccoli has 17.15 grams of protein in 207 calories. This equates to about fifteen and one-half percent (15.5%) more protein per calorie in broccoli than in beef.

This well cited review in the American Journal of Clinical Nutrition addresses protein in plant foods, noting that most animal and plant foods, not only meet — but exceed the required concentration of essential amino acids. A joint panel of the Food and Agriculture Organization, World Health Organization and United Nations University, estimated our nutritional amino acid requirements. When those requirements are compared with the amino acid patterns of plant and animal sources of protein, the amount of amino acids in all of these foods was found to be “much higher (per unit of protein) than required.” “Thus,” the review concludes, “all usual food proteins would readily meet and even exceed the requirement for indispensable amino acids.”

To be clear, this means we can get more than enough, and even exceed, our protein requirements, including all of the essential amino acids, from either animal foods or a purely plant-based diet. So, if we can get adequate protein from either plants or animals, which one should we use? Well, Harvard’s Healthy Eating Plate states, “Go with plants. Eating a plant-based diet is healthiest.”

And, as mentioned earlier, the chair of Harvard’s Department of Nutrition recommends that you, “Pick the best protein packages by emphasizing plant sources of protein rather than animal sources.” Also physicians from Kaiser Permanente have recently suggested the same thing, noting in their medical journal that, “Further research is needed to find ways to make plant-based diets the new normal for our patients and employees.” And, as I mentioned earlier, that’s what I recommend to my patients.

So, let’s talk more about animal protein and health, which we’ll do in the next video chapters.

This transcript is an approximation of the audio in above video. To hear the audio and see the accompanying visuals, please play the video.

This presentation was written and narrated by Sofia Pineda Ochoa, MD, and edited by Bob Rapfogel.

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The illustration diagrams of the essential amino acids were provided by Wikimedia Commons free media repository.