Nutrition 101. Proteins

Why read about Proteins? Because food molecules such as Proteins, Lipids/Fats and Carbohydrates sustain life.

They maintain structure and vital functions for our bodies, and provide us with energy to live. Therefore, Proteins are known as essential nutrients. We must consume them in order to live and live well.

Before I explain the kinds of Protein and how much we need in our food, let’s first look at some fundamental facts about Proteins:

  • They provide building blocks for our bodies to grow and repair all organs and tissues;
  • They are critical for function of Immune System, that protects us against bacteria, viruses, fungi, parasites, etc.;
  • They participate in the production of enzymes and hormones, which, in turn, govern a multitude of daily processes in our bodies;
  • They control water balance by holding  fluids;
  • They keep blood from becoming too acidic or basic/alkaline;
  • They supply energy at 4 kcals for each gram of Protein we eat.

Considering all these critical functions, Proteins must be replenished daily and make up 10% to 20% of the daily diet.

What exactly is a Protein? It is a complex molecule that is made of smaller units (building blocks) called amino acids, which are grouped together to offer endless variations of Proteins. There are 20 different kinds of amino acids. Eleven of these 20 amino acids are non-essential, meaning they can be made by our body and do not have to be consumed by eating the right food. Nine of the 20 amino acids, on the other hand, are essential because they cannot be manufactured by the body and must come from food.

It is crucial to understand that if one or more essential amino acids are not consumed, the body’s need to produce a Protein requiring  that essential amino acid  will not just slow down and wait for you to eat the right Protein. Instead, assembly of the Protein will STOP, and the body’s need for a certain kind of Protein will not be met.  That is not a good thing. In other words, any of the critical functions mentioned above can be compromised.

So, the question becomes: How can you know if you are getting all the essential amino acids that you need?

First, it is important to understand that the food that is the source of Proteins can be divided into two categories:

  • A source of Complete Proteins will contain all the essential amino acids. Animal-derived Proteins are always complete,  such as in fish, eggs, milk, cheese and the like;
  • A source of Incomplete Proteins does not contain all the essential amino acids. Plant sources of Proteins are mostly incomplete. Soy and quinoa are notable plant exceptions, and those provide all essential amino acids.

With this said, if you prefer plants as a source of Proteins (and it is definitely advisable that you eat large amounts of plant-based food) certain combinations will provide you with complete Proteins. Examples are rice and beans or peanut butter and toast. While separately those foods do not contain all the essential amino acids, together, they do. If you have ever wondered why these particular “food duos” are so popular, now you know!

So, to follow the Academy of Nutrition and Dietetics’ direction that we must eat complete Proteins every day to function well, you probably want to know how much we need.

The current recommendation for adults is to consume approximately 0.4 g per pound of your ideal weight per day. Endurance and power athletes, persons recovering from injury, or growing children need around 1 g/pound or more. Here are couple examples:

A 250 lb. adult needs approximately 100 g of Protein/day
A 150 lb. adult needs approximately 60 g of Protein/day

Now let’s look at some examples of Protein rich foods to see how much Protein they can provide to us (numbers are approximate):

1 serving (100 g) of salmon or chicken, 1 can of tuna or sardines = 22 g

1 cup of soybeans = 22 g

1 15 oz. can of red kidney beans = 28 g

1 cup of cooked brown rice = 5 g

1 cup of quinoa = 10 g

1 slice of bread = 3-5 g

1 cup of 0% fat Greek yogurt  or 1 glass of 1% milk = 10-15 g

1 egg = 7 g

14 halves of walnuts = 4 g

22 whole almonds = 7 g

1 cup of cooked spinach or broccoli = 4-5 g

Of course, Protein amounts are printed on nutrition labels. Whole foods often do not come with nutrition facts, so please check this great link http://ndb.nal.usda.gov/ndb/search/list  and make a note of nutrient quantities in your favorite food.

In conclusion, if I can impress one thing upon you that reflects current nutritional guidance about Proteins, it is this: 

Everyone must consume a sufficient amount of complete Proteins every day!

Enjoy great food!

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Upcoming post: Fats. Now that’s exciting.