Protein and Carbohydrates
In this article, we will continue our discussion with macronutrients, starting with protein and carbohydrates. Macronutrients are much larger molecules when compared to micronutrients, and they contain calories. Above is an x-ray crystallography image (what a protein really looks like at the molecular level) of pyruvate carboxylase, a key regulatory enzyme in the gluconeogenesis pathway (the mechanism our body creates sugar/glucose in the absence of dietary sugar), pretty cool looking.
Proteins are complex molecules that perform multiple important roles. They are made up of long amino acid polymers or polypeptides (many amino acid molecules that are chained together) which constitute the basic structural unit of proteins.
For example, an internal protein network, the cytoskeleton maintains cellular shape and physical integrity.
Actin and myosin filaments form the contractile machinery of muscle.
Hemoglobin transports oxygen, while circulating antibodies defend against foreign invaders.
Enzymes catalyze reactions (make chemical reactions happen much much faster) that generate energy, synthesize and degrade biomolecules, replicate and transcribe genes, process mRNAs, etc.
Now what do you notice on the enzyme diagram below? There is a cofactor (probably a mineral) and a co-enzyme (which is probably a vitamin). See how this all starts to fit together?
Now what do you notice on the enzyme diagram below? There is a cofactor (probably a mineral) and a co-enzyme (which is probably a vitamin). See how this all starts to fit together?
This is a picture of a holo-enzyme or an enzyme that is complete with all its parts, without certain components it becomes an apo-enzyme or an incomplete enzyme and they usually do not work or don't work very well.
The non-biochemicical example would be a car. Now if the car doesnt have tires (a co-factor) it still runs but doesn't maneuver well. If that same car is without clean fuel injectors, the fuel doesn't get into the engine and it just kinda sputters along. So without the tires (minerals/co-factors) and clean injectors (vitamins/co-enzymes) the car still runs (apo-enzyme). Can we now see how supplement companies make claims that B-vitamins give you energy? Not yet? Well what if I told you many B-vitamins are co-enzymes for the body's energy pathways? While they aren't the fuel (carbohydrates/fats) and they aren't the car (apo-enzyme) they are the fuel injectors and all the system to work optimally. Make sense?
Protein contains 4 calories (kcal)/gram. So lets pretend in a serving of food, you have 20 grams of protein, that serving would contain 80 calories (kcal) from the protein portion of that food.
One of the most respected and well known Professors of Nutritional Biochemistry, Dr. T. Colin Campbell at Cornell University, has repeatedly stated the scientific evidence shows that the best intake of protein is between 5-10% of daily calories. He takes the statement further by saying that if you are getting enough calories from plant sources, you are getting sufficient protein in your diet since plant foods average 3-20% protein. For example dates have about 3% protein, but in contrast quinoa has nearly 15% protein and kale is upwards of 35% protein!
One of the most respected and well known Professors of Nutritional Biochemistry, Dr. T. Colin Campbell at Cornell University, has repeatedly stated the scientific evidence shows that the best intake of protein is between 5-10% of daily calories. He takes the statement further by saying that if you are getting enough calories from plant sources, you are getting sufficient protein in your diet since plant foods average 3-20% protein. For example dates have about 3% protein, but in contrast quinoa has nearly 15% protein and kale is upwards of 35% protein!
What doc? You say veggies have protein!? Yes, they do. I would say for whatever reason, when I talk about a plant based diet to anyone, one of the first questions people ask is are you getting enough protein, and I can say that, as long as we have a good variety and sufficient quantity of plant foods, we are without a doubt getting plenty of protein.
On to carbohydrates! Carbohydrates are categorized into 4 major categories monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Monosaccharides are those sugars that cannot be cannot into simpler carbohydrates. Disaccharides are two monosaccharide units connected by a chemical bond, for example, lactose, maltose, sucrose, etc. The mono and disaccharides are collectively known as simple carbohydrates, simple carbs, simple sugars, or just simply sugar.
In addition to starches and dextrins, foods contain a wide variety of other polysaccharides that are collectively known as nonstarch polysaccharides; they are not digested by human enzymes, and are the major component of dietary fiber. Because they cannot be broken down by enzymes and absorbed into the small intestine, these foods contain no calories.
Carbohydrates are the body's major source of fuel. Dr. T Colin Campbell states the best nutritional research suggests that 80-90% of the daily calories ideally would come from carbohydrates. Carbohydrates, just as protein does, contains 4 calories (kcal)/gram. If we eat a serving of food with 20 grams of carbohydrates, we would take 20 grams x 4 calories/gram and come up with 80 calories (kcal) from the carbohydrate component of that serving of food.
So other than the definitions, terminology, biology of these substances what can we away from this article?
1) Ideal caloric ratio for human beings according to nutritional biochemical research is 80-90% of calories from carbohydrates. 5-10% of calories coming from protein and fat. The so called 80/10/10 diet.
2) A variety of plant foods will give us more than enough protein. I say again more than enough. However, if you decide to eat animal food, wild varieties of fish (not atlantic/farm raised salmon for example), organic/grass fed beef. I do not recommend eating meat, but if you so choose, please keep this to a minimum, as in once per week or less.
3) Whole food carbohydrates (not flour, not processed, etc) are by far the best. Essentially processing turns complex carbohydrates into simple carbohydrates. This would include brown rice, wild rice, quinoa, old fashioned oats, other grains, potatoes of all kinds, squash, all the fruit you can eat. Just make sure that if you decided to eat mostly grains, to drink lots of water because those foods are relatively dehydrated, in comparison to watermelon or mangoes.
We will continue our discussion about the glycemic index/glycemic load phenomenon in future articles, just in case you were wondering. So far we have covered 2 of the 4 macronutrients. Alcohol is considered a macronutrient, but since it isn't a major source of calories for most of us we will probably just skip it. Alcohol does contain 7 calories (kcal)/gram.
In our next article will talk about fat and we will attempt to demystify it...
To your health,
Dr. Peavler
References
"Chapter 3. Amino Acids & Peptides" Harper's Illustrated Biochemistry, 29e
"Chapter 4. Proteins: Determination of Primary Structure" Harper's Illustrated Biochemistry, 29e
"Chapter 14. Carbohydrates of Physiologic Significance" Harper's Illustrated Biochemistry, 29e
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