Phys.(iology) Ed. : Protein

As most of you know, protein is one of three macronutrients (protein, fat, carbohydrate) that your body requires to function. Refresher from last week: according to US Department of Agriculture (USDA) the RDA for men is around 56 grams of protein per day and 46 grams per day for women. It’s also important to note that this recommended amount is not a MINIMUM but rather an OPTIMUM. As a country, we eat the most protein and we are one of, if not the THE, sickest first world country. This is especially unsettling when we think about how fixated we remain on protein!

Before we dive in further, I’m generally not a big fan of ‘reductionist nutrition science.’ This means reducing foods down to the nutrients they contain. We don’t eat nutrients, we eat FOOD. However, most nutrition research is just that: reductionist. And in order to discuss some of the ideas out there on protein, we have to become reductionist for a little while. Stick with me!

When you eat food that contains protein, from either animal or plant sources, your body proceeds to denature it, or break it down. The resulting products of this protein breakdown are amino acids. Amino acids are transported into the blood stream and synthesized into new proteins that meet your needs. The functions of synthesized protein include:

  • structurally (skin and bones)
  • motor proteins (muscular)
  • enzymes (help with chemical reactions everywhere in the body)
  • hormones (chemical messengers)
  • immune function (antibodies that fight disease)
  • maintain fluid balance (the fluid in and outside our cells and blood vessels)
  • maintain acid-base balance (remember pH? This balance is vital for our health)
  • transport channels (move substances across cell membranes)

There are nine essential and eleven non-essential amino acids involved in protein synthesis. Your body cannot make essential amino acids and must get these from food. Both animal and plant protein sources can provide all nine essential amino acids to meet your needs. Your body is also crazy efficient at recycling amino acids. It's not completely up to your diet to meet these needs.

There is a good deal of controversy when it comes how much protein your body can absorb and synthesize per meal. Let’s say you take in 40 grams of protein in the form of a shake. Is all of that protein really utilized? If you search on google, you will find countless bodybuilding blogs that assure you all that protein is going straight to your muscles. The real answer seems to be: the research is slim and it seems depend on the person.

If you look back at those protein uses in your body, you'll see that protein isn’t just used for building muscle. In fact, that’s a relatively low priority in your hierarchy of metabolic needs. We don’t know for sure what the amino acid distribution looks like in each and every individual (In the average person, it’s likely that excess amounts of protein taken in gets stored as fat. It’s actually more efficient for our body to convert protein to fat when compared with carbohydrates. Not surprisingly, excess fat from calories is easily stored as fat.)

We do know that research shows no benefit in long term health and longevity when it comes to consuming large amounts of protein regularly. On the contrary, high protein diets tend to be associated with disease. Specifically, diets high in animal protein are linked to higher rates of diabetes, heart disease, hypertension, and cancer.

Stay tuned for next week - I'll be talking about our protein obsessed culture, the role marketing plays, and how it all started. 

Additional References:

Proteinaholic - Garth Davis, M.D.

Nutrition, fifth edition

Keep up with this protein-packed series! 

Week 1 - Plant Protein Sources

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