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Myth: You cannot eat enough plants to provide for the protein needs of a human

May 2, 2013

When looking at the serving of broccoli compared to the serving of cow this seems to be the case.  But upon further investigation of human protein needs the truth is you can meet all of your protein needs through plant foods alone and easily without having to consume 15 or 20 servings of broccoli per day.  A lesson in adequate protein intake for human health taken from the Sports and Exercise Nutrition book:

  • The average adult male needs 60 grams of protein per day, average female 48 grams
  • Despite the beliefs of many coaches, trainers, and athletes, no benefit accrues from eating excessive protein.
  • With adequate protein intake, consuming animal sources of protein does not facilitate muscle strength or size gains with resistance training any more than protein intake from plant sources
  • Adequate intake of complex carbohydrates is what ensures protein from muscle tissue will not be used as an energy source thus contributing to muscle loss.  Excess protein is not stored and therefore not used to maintain or build muscle later on.
  • Complex carbohydrates should make up 60% to 70% of the average person’s diet.
  • During intense training an athlete should consume 70% of their diet as complex carbohydrates.  Therefore it is the carbohydrate, not the protein intake, that should increase for an athlete.  Only during muscle mass building should a person increase their protein to about an extra 10 grams per day.
  • It is recommended that calories from protein represent between 10% and not more than 30% of daily caloric consumption

The healthiest diet for a human being, one that maintains muscle and bone and provides fuel for energy is one that is balanced.  Research shows this balance is 10 to 30% protein and 60% to 70% carbohydrate.

It just so happens that many plants provide this balance while animal flesh does not.  Animal flesh contains only the protein and zero carbohydrate.  It is not balanced.

Let’s revisit our peanut butter sandwich.  The bread is at perfect balance with approximately 70% of its calories from complex carbohydrates and 23% of its calories from protein.  Two slices provide 8 grams of protein.  Two tablespoons of peanut butter provide another 8 grams of protein.  In the case of peanut butter 21% of its calories come from protein and 18% from carbohydrate.  The rest come from fat.  However a fruit spread which is commonly part of a peanut butter sandwich rounds this out to a nice ratio of carbs versus protein.

One peanut butter sandwich at 340 calories provides 16 grams of protein.  For women this is equal to 33% of their daily requirement and 26% for men.

As you can see if a simple common sandwich eaten by millions of people every day can provide this much protein, there is no need for for those on a plant based diet to eat an excessive amount of plant based foods.  Anyone can down a PB and J!

One cup of cheerios with 3/4 cup soy milk provides 10 grams of protein for 130 calories.  Cereal for breakfast and a peanut butter sandwich for lunch equals 26 grams of protein: more than half and nearly half of the protein requirement met for men and women in a simple bowl of cereal and a small sandwich.

Getting enough protein is not a problem for someone who eats a plant based diet.  Actually it is not a problem for anyone in a developed country.

The average person who is free of disease in a developed country will never have a protein deficiency.  This is because protein is in every single food we eat except for oils and a few fruits and the human body only needs approximately 50 to 60 grams per day.  Any extra is not stored as protein for future use as protein to meet any physiological needs which require protein.


Six foot tall boy and cow both made from the same protein source: Plants!

A plant based diet is balanced perfectly for human health.  The protein is not inferior.  And there is no need to consume massive amounts of vegetables to get enough protein.  There is no need to consume servings that are any larger than is normal.  The difference is that all of our servings come from plants.  But our plates and meal sizes are the same.  Where others eat a piece of animal flesh, a salad, and a baked potato we don’t just skip the animal and only eat the salad and potato.  We fill that spot with pasta and veggies and sauce or some other plant based entree.

People forget that it is the carbohydrate that fuels our bodies.  Protein does not make muscles more massive – only strength resistance training can do that.  Protein maintains the muscle we already have along with regular physical use of those muscles.  Without adequate carbohydrate intake the body will use protein for fuel and this may reduce your muscle mass.  There are many negative effects of a higher than necessary protein intake as well as lower than needed carbohydrate intake but I will save that for another post since most people are not even aware of physiological and metabolic processes anymore than they are aware of how their car engine works.  Therefore I rarely get asked questions about catabolism.

(My information comes from nutrition courses taken at Rochester Institute of Technology and the textbooks shown in my first post “Where do you get your protein?”  These classes and books are not based on veganism.  They are objective courses based on research and science intended for students seeking a degree in nutrition.  I highly encourage anyone who has an interest in their own health to purchase these textbooks.)

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