Saturday, June 27, 2015

Macronutrients: proteins


There is a myth that is dangerously spreading in some circles today, that “anyway we eat too many proteins”. Some invoke health issues, others environmental concerns (which in any case are being proven wrong).

I noticed a curious thing: the sentence is always reported exactly this way, with a leading “anyway” which supposedly validates the statement by giving the impression that this is the deeply pondered outcome of a longer analysis.

In reality the sentence is just repeated as-is and nobody ever cares to check how much of this is true. Just look around at other people’s plates or even yours: unless you happen to be attending a BBQ party or a post-workout dinner with a group of crossfitters in a brazilian churrascaria, the reality is that "people eat too many carbs". Anyway.

Good sources of proteins are fundamental

I mentioned that carbohydrates are an important macronutrient and that low-carb or zero-carb diets, although interesting under certain aspects, are not meant to replace a well-balanced diet, especially on the long term. I will however come back on this topic with more detailed explanations.

Fats are even more important than carbohydrates, with some being essential or conditionally essential.

What about proteins? Proteins are long chains of amino acids. There are 20 amino acids in nature. Of these 20 building blocks, 9 are essential and 6 more are conditionally essential. Just like it happens for the fats, the requirements of the conditionally essential ones vary from individual to individual and depend on special pathophysiological conditions and sometimes genetics.

Not all protein sources are made equal, some have a well balanced composition of aminoacids, some others are unbalanced or even missing some of the essentials. In short, just like with fats, quality matters.

Unlike fats, amino acids cannot be stored efficiently by the body and must therefore be introduced regularly through one’s diet on a daily basis. In reality, for optimal health, there should be a source of proteins at every meal (more on this).

Excellent sources of complete proteins include animal sources, this shouldn't come as a surprise: eggs, meat (both muscle tissue and internal organs), fish and dairy products. Good sources of proteins also exist in the vegetal kingdom, they include:
  • pulses (beans, chickpeas, lentils, peas, fenugreek, ...)
  • nuts (almonds, pecams, wallnuts, hezelnuts, brazilnuts, ...)
  • seeds (pumpkin seeds, pineseeds, chiaseeds, flaxseeds, ...)
  • cereals (wheat, oat, rye, ...)
  • pseudo-grains (millet, quinoa, amaranth, buckwheat...)
Soy, a favourite amongst vegetarians and vegans, is a problematic source of proteins with several drawbacks. I will dedicate a number of articles on this because I want to empower people with good information and the current information about soy is not good at all.

Requirements, not an easy answer

Failure to introduce and to properly digest and absorb enough high quality amino acids to satisfy the requirements, forces the organism to satisfy the needs for proteins through the downregulation of some processes, or via catabolism. Catabolism is the destruction of your own muscular tissues to obtain aminoacids, which are then used either as energy (gluconeogenesis) or in metabolic processes. In short, your body will eventually eat meat: yourself. I guess you never saw it in this way, I know what you are thinking right now and I agree: it’s creepy.

On the other side, eating too many proteins puts a lot of stress on the kidneys which are in charge of eliminating the nitrogenous waste products (carbamide) of the metabolism of proteins. These extra proteins, those not used in physiological processes or in building/repairing processes, will be either converted into glycogen and burnt as an overly expensive source of energy or converted to fat and stored.
Which means in other words: too many proteins won’t make you more muscular, just fatter. In case you were wondering why your protein shake isn’t delivering that six-pack.

How many to eat, then?

I shouldn't repeat it, but this is another example of biochemical individuality. We all agree that adolescents and athletes need more than adults and couch potatoes. The requirements of the elderlies is less, but that’s just the theory: in reality, considering that they may have an impaired absorption, the intake would reasonably be the same as a healthy adult.

It gets confusing so I prefer to close here: the role of this post is just to introduce the macronutrient proteins and to raise awareness on the importance of good quality sources of them same. I will spend a lot of time presenting the details of this interesting and once again controversial subject.

For the time being I prefer to list the...

Roles of proteins in the body

Similarly to carbohydrates and fats, proteins have multiple roles. Examples are:
  • Proteins are the building blocks for tissues (muscles, bones, nervous system, blood, etc)
  • Antibodies (immune system) are made of proteins
  • Enzymes are made of proteins
  • Some hormones are made of proteins
  • Proteins, like other essential nutrients, satiate: you will keep craving food as long as you haven't had your requirements
  • As already mentioned, proteins are also a source of energy

Starting from the next post I will start discussing some general guidelines to healthy eating, proper ratios and common errors. There will be place for myth busting, too. Things get practical, always keeping an eye on the theory, so... stay tuned!

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