The Plant Rx

Your resource for a plant-based diet

The Protein Conundrum: the REAL truth about Protein

Posted by Jenn on February 7, 2011

Out of all the conflicting information that is bestowed upon the American public in regards to nutrition, the one seemingly straight forward and universally agreed upon tenet is the importance of protein.  The general consensus is that in order to maintain a healthy weight and be healthy in general, it is vital to consume enough lean protein (which in America typically equates to white meat and fish) and limit intake of carbohydrates. It is commonplace to hear people say,”I really need to eat more protein”.  Whereas it would be almost shocking to hear someone say,”I really need to eat more carbs”. One might go so far as to say American’s are obsessed with protein.

It is for this reason that protein is frequently at the top of the list of concerned family members and skeptical friends and why those who eat a plant-based diet are bombarded by questions about where they get their protein.  In fact, people not familiar with plant-based nutrition often assume that it is terribly hard to get enough protein by consuming a diet free of meat and dairy products. In the same vein, most carnivores are not aware of how much protein they are consuming on a daily basis and that they are likely consuming far too much which can be detrimental over time.

So, what is the real truth? Below, I will address and answer the common questions I am asked regarding protein consumption and a plant-based diet.

  • Where do people who consume a plant-based diet get their protein? Do plant-based protein sources provide enough protein to be healthy?

Almost every food contains protein, so it’s nearly impossible not to get enough if you’re consuming an adequate amount of calories.  Protein is found in ALL plant foods including vegetables (yes, vegetables!), grains, legumes (such as beans and lentils), soy foods, seeds and nuts. As long as your diet contains a variety of grains, legumes and vegetables protein needs are easily met.

Protein Comparison Chart

  • Is there a difference between Plant-based protein sources and Animal-based ones? I heard animal sources provide better (quality) protein, is this true?

Protein is an essential nutrient which when ingested is broken down into it’s building blocks which are called amino acids. There are 20 amino acids used by our bodies to build the various proteins our body needs.  Of these 20 our body is capable of making 11 of them on its on.  Nine of them cannot be made by the body and therefore must be obtained through our diet. Because our bodies cannot make these 9 amino acids they are termed “essential” amino acids meaning it is essential to get these through our diets.

In the past, food sources that contained all of the essential amino acids were called “high quality” or “complete” proteins.  Animal proteins contain this complete complement of essential amino acids and therefore are termed “high quality”. This is where the notion of protein from animal sources having better quality protein over that of plant sources originated. This is not true, however.  The truth is all plant proteins have some of every essential amino acid.  The difference is that some plant protein sources have this full complement of amino acids in abundance (soybeans, quinoa, spinach) like animal sources do whereas as some have all of these essential amino acids but the amounts of one or two of these amino acids may be low. For example, grains are lower in lysine and legumes are lower in methionine than those protein sources designated as “high quality”.  This is where the idea of combining or complementing of proteins came from for vegetarians and vegans.

  • Do I need to combine proteins or monitor my consumption?

In an effort to make sure that all vegetarians and vegans were getting enough of all the amino acids, in the early 1970’s in her book Diet for a Small PlanetFrances Moore Lappe popularized this idea of combining plant proteins at each meal in order to get a “complete” protein.  For example, mixing beans and grains to get enough Lysine and Methionine at each meal. This practice has since been refuted as unnecessary since it is now well-known that our livers store the various amino acids and it’s not critical to combine different protein sources at each meal.

The findings of a 59-day investigation with six male subjects who consumed diets in which virtually the sole source of protein was rice is an excellent example.  In 3 of the subjects the diets remained composed of rice as the sole source of protein and in the other three 15-30% of the rice protein was replaced by chicken.  In this study, even the “low” protein (and low “quality” of that protein source) diet of rice as the sole source provided between 2 and 4.5 times the WHO-recommended amounts of all amino acids except lysine of which it supplied 1.5 times the suggested level.  On the higher protein diet, between two and six times essential amino acid levels suggested by WHO.

This and other similar much larger scale experiments clearly illustrate that diets based solely on plant sources of protein are adequate and supply the recommended amounts of all essential amino acids for adults, even when a single plant food, such as rice, is virtually the sole source of protein. The 2009 American Dietetic Association’s position paper on vegetarian and vegan diets states that:

“Plant proteins can meet requirements when a variety of plant foods are consumed and energy needs are met.  Research indicates that an assortment of plant foods eaten over the course of a day can provide all essential amino acids and ensure adequate nitrogen retention and use in healthy adults, thus complementary proteins do not need to be consumed at each meal”.

  • What about fish and getting the essential Omega-3 amino acids I hear about?

Omega- 3 fatty acids are essential for heart, brain, skin and joint health.  Fortunately, you can get them without all the toxins,cholesterol (in salmon types there is 23 – 485 mg per 3 oz serving) and fat (10.5 g per 3 oz serving) found in fish.  Flaxseeds, walnuts, avocados, nut butters, almonds and canola oil are all good examples of good sources of the Omega-3 ALA.  It is a good idea to take vegan DHA capsules which contain Omega-3’s derived from algae (where the fish get it from!). It is also interesting to note here that the highest cholesterol levels in seafood are found in salmon products, followed by shrimp products – the so-called “good” fish.

  • But, isn’t it better to get more protein than less?

Protein RequirementsWhat do we really need?

With the  Standard American Diet (SAD) the average American consumes more than double the protein that their bodies need.  Further, the main sources of this protein tend to be from animals which means that they are also high in saturated fat.  The national and international organizations which advise on nutrient requirements suggest standards which are calculated to meet or exceed the requirements of practically everyone, therefore they have a very generous safety margin built-in.  The Recommended Dietary Allowance (RDA) for protein for an average adult who is sedentary is .08 grams per kilogram of body weight (.36 grams of protein per pound that we weigh) which translates into approximately less than 10% of calories coming from protein sources.

To find out your average individual protein needs simply perform the calculation:

Body Weight (in lbs) x .36 = RDA for protein intake

*For example: a 125 lb female needs approximately 45g of protein per day (with a large margin of safety already included); another way to look at it would be that on a 2,000 calorie diet, less than 200 calories should come from protein.

Thus, we do NOT need huge quantities of protein, rather in reality we need only very small amounts of it.

  • I heard there are detrimental effects of eating too much protein over time.  Is this true?

Yes, according to research, there do not appear to be any health advantages  to consuming a high-protein diet. In fact, diets high in animal protein can actually contribute and promote diseases and health problems such as: Osteoporosis, Cancer, Impaired Kidney Function and Heart Disease. Excess amounts of plant proteins do not appear to cause these same problems.  Here’s why:

  • Osteoporosis– high protein intake causes urinary calcium loss therefore increasing fracture risk.
  • Cancer– dietary fat increases overall cancer risk. Further, high amounts of protein from animal sources (not the case with plant sources) liberates substances called heterocyclic amines when cooked at high temperatures especially from grilling and frying and we typically do not eat animal proteins raw. High protein diets from animal sources also lack fiber and antioxidants.  Both fiber and antioxidants appear to be protective against cancer.
  • Impaired Kidney Function– high protein diets are associated with reduced kidney function due to the excess nitrogen that is liberated during protein digestion and metabolization which must be excreted via the urine as waste. High amounts of protein consumption risk permanent loss of kidney function according to the nurses Health Study conducted by Harvard researchers. The good news is that this kidney-damaging effect was only seen with animal protein consumption.  Plant protein consumption had NO harmful effect.  Additionally, the American Academy of Family Physicians (AAFP) has stated that animal protein consumption is responsible for the high prevalence of kidney stones in the U.S. and recommends animal protein restriction for the prevention of recurrent kidney stones.
  • Heart Disease– because animal protein sources are also extremely high in cholesterol and saturated fat (neither are the case with plant protein sources) which is a known contributor to plaque build-up in arteries due to endothelial cell damage.

In summary, it is extremely easy for someone consuming a plant-based diet to get more than adequate protein from a variety of plant sources.  In fact, odds are, they will be getting more than necessary without the need for copious combining or monitoring of protein intake.  Further, unlike animal sources of protein, this over-consumption will not lead to nor put one at increased risk for osteoporosis, stroke, heart disease, cancer or impaired kidney function. This is because plant protein sources do NOT have any cholesterol content, they HAVE fiber and antioxidants(animal protein lacks these) which are protective and they are very low in fat (most importantly saturated fat) which is a known risk factor to the aforementioned disease states.


2 Responses to “The Protein Conundrum: the REAL truth about Protein”

  1. Anastasia "The Veganbetic" Brown said

    Jenn, thanks for posting this utterly important information. I can’t tell you how many times I have been asked “You’re a VEGAN?! HOW do you get your protein?!” LOL!

  2. Absolutely, this is the most common concern I hear from people switching to a plant-based diet. Thanks for providing such a useful and informative tutorial Jenna!

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