Thursday, February 15, 2018

Liz's Nutrition Notes: Amino Acids and Protein

Happy Valentine's [yester]Day!

Last week my sister asked me about amino acids, so I did a bit of reading/writing to give a quick briefing in today's post.

Amino acids are the building blocks of proteins. They are linked together by peptide bonds and the sequence determines their function in the body. Amino acids are important, because they build proteins and proteins perform various jobs in our body:

  • Structural Proteins: proteins are found in many parts of our bodies and are important for maintenance, growth, and repair (i.e. keratin in our hair)
  • Immunoproteins: help rid the body of foreign molecules that pose a threat to our health
  • Transport Proteins: help transport molecules throughout the body (i.e. hemoglobin is a protein that transports oxygen throughout our body)
  • Enzymes: proteins that assist with the biochemical reactions in ours bodies
  • Hormones: some proteins are hormones in the body that play a part in everyday living (i.e insulin is a protein that helps regulate our blood sugars)
  • Energy: proteins are a source of energy

There are 20 amino acids, 9 of which our bodies cannot produce on their own. These are called essential amino acids, because they must be obtained through our diet. In order to memorize the 9 essential amino acids, most dietitians use the mnemonic device TV TILL PMH

TV: Threonine, Valine
TILL: Tryptophan, Isoleucine, Leucine, Lysine
PMH: Phenylalanine, Methionine, Histidine

(Side Note: During catabolic stress, there is an increase in muscle breakdown and thus protein loss. During this time, the amino acids cysteine, glycine, proline, tyrosine, arginine and glutamine are also considered “essential” amino acids.)

Since we need to supply our bodies with the above essential amino acids, it is good to know what foods are good sources. The best sources of essential amino acids are found in animal byproducts: meat, poultry, eggs, fish, and dairy. Animal byproducts have a high HBV (high biological value), meaning they contain all the essential amino acids in the right proportions for your body to use.

While plant proteins are also a good source of protein, they are considered incomplete proteins since they usually are missing one or two essential amino acids. Soy protein constitutes a vast majority of the protein consumed by most people on a plant based diet. However, it is lacking in methionine, and thus an incomplete protein. You can still get all your essential amino acids on a plant based diet, but you will need to eat a vast variety of plants or eat combinations (i.e. beans and rice together) as opposed to just a serving of animal protein with all the essential amino acids in it.

If you are someone who exercises regularly and partakes in strength training/HIIT gym sessions, I actually would recommend supplementing with amino acids to help repair muscles. Although I personally believe in supplementation, I will never force this belief on anyone opposed to it. There is SO MUCH conflicting research about the need to supplement or consume amino acids pre/post exercise. In writing this, I just googled research articles and read two conflicting articles on the National Institute of Health website; one from June 2017 and one from August 2017. What I have learned with research articles is you have to read strategically and understand how the conclusions were reached. I’m always looking for confounders that impacted the outcome as well as other things that I will not go into for the sake of not making this article too long…maybe, in the future, I will discuss strategically reading nutrition research articles. 

So which is better for you - plant-based protein or animal protein? While animal proteins provide the essential amino acids, they also have a higher saturated fat content. On the other hand, plant-based diets often lack a few essential amino acids, yet are better in terms of their lack of saturated fat content. So, my answer to that question is: “we can make an informed decision based on your health background and goals.”

Part of being a dietitian or nutritionist is catering to your patient’s needs/wants/desires. You can preach all you want about what you think is best, but at the end of the day, the patient is going to do what they want, so working with him/her is important in helping construct a proper diet. If you have a patient who hates vegetables, then prescribing a diet rich in vegetables isn't going to work. While it might be a healthy recommendation, it's not feasible if you know the person won’t follow it!

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