Protein is an essential part of the human diet. It's found in a variety of foods like eggs
dairy seafood legumes meats nuts and seeds
Regardless of the source the protein that we eat gets broken down and reformed into new proteins in our bodies
These proteins do everything from fighting infections to helping cells divide. You name it
They're doing it at its simplest a protein is a chain of amino acids bound to one another by peptide
Bonds like a string of beads
These strings get twisted and folded into a final protein shape
When we eat protein, it gets broken down into its individual amino acids
Most amino acids have a central carbon atom bonded to one amino or nitrogen-containing group and one
Carboxylic acid group. That's why it's called an amino acid
The carbon also has one hydrogen atom and a sidechain which is unique to each amino acid
The exception to this is prolene, which is a tiny little ring structure instead
Although there are hundreds of amino acids in nature humans only use about 20 of them to make basically every type of protein
they include
alanine arginine asparagine aspartic acid cysteine glutamic acid glutamine glycine
histidine isoleucine leucine lysine
methionine phenylalanine
prolene serine threonine
tryptophan tyrosine and valine
Huh? That's twenty
One way to divide them is by defining which ones our bodies can make and which ones we can't
There are five amino acids alanine asparagine aspartic acid glutamic acid and serine that we can get from foods
But we can also make ourselves
These are called non-essential amino acids
Then there are six that we call conditionally essential because healthy bodies can make them under normal circumstances arginine cysteine
glutamine glycine proline and tyrosine
But we can't make them in cases like starvation or certain inborn errors of metabolism
Finally there are nine of them that we can only get from food
histidine isoleucine
leucine lysine methionine phenylalanine threonine
Tryptophan and valine we call these the essential amino acids
Dietary protein provides the essential amino acids that are needed to make our own proteins
hormones and other important molecules a circle of life of sorts but to do so
We need to break the dietary protein down first through a process called proteolysis
when we first eat a protein containing food proteolysis begins when the food reaches the stomach
First hydrochloric acid denatures the protein unfolding it and making the amino acid chain more accessible to enzymatic action
Then pepsin which is a itself made by gastric chief cells enters the picture
pepsin cludes any available protein into smaller oligopeptide chains
Which move into the duodenum where a second set of digestive enzymes made by the pancreas
further chopped the oligopeptides into tripeptides
dipeptides and
individual amino acids
These can all be taken up to the intestinal cells where died and tripeptides are then converted into amino acids
Some amino acids remain in these cells and are used to synthesize
intestinal enzymes and new cells
But most enter the bloodstream and are transported to other parts of the body in general
animal-based protein foods like eggs
Dairy seafood and meat provide all nine essential amino acids in adequate amounts
Soy foods are unique in that they are plant-based and also provide all nine essential amino acids in adequate amounts
most other plant foods including whole grains legumes nuts and seeds
Have high amounts of some amino acids and low amounts of others
Hearing this it might be easy to assume that animal-based foods provide more protein than plant-based ones
But as it turns out a cup of tofu has the same number of grams of protein as three ounces of steak chicken or fish
and
half a cup of lentils has more grams of protein than an egg and
Not all plant foods are low in the same amino acids
so eating a variety of plant-based foods can provide all nine of the essentials for
Example pairing protein sources like rice and beans or hummus and pita bread or oatmeal topped with almond butter
However, in terms of volume it may be necessary to eat more plant-based foods to get a similar amount of protein and amino acid
profile provided by animal-based proteins
generally speaking daily protein requirements are based on studies that estimate the minimum amount of protein needed to avoid a
progressive nitrogen loss
the World Health Organization guidelines and the u.s
Recommended dietary allowance each estimate that daily protein requirements for healthy adults are about point
eight grams per kilogram of body weight
Protein recommendations per day vary by age as well children one to three years of age are recommended to get 13 grams
for ages 4 to 8 19 grams are recommended and
Between ages 9 and 13 34 grams are recommended whether a person is male or female also impacts protein needs
Females ages 14 and above are recommended to get 46 grams of protein per day
males aged 14 to 18 needs slightly more about 52 grams per day and
Males 19 and older are recommended to get 56 grams per day
some groups like pregnant and breastfeeding women as well as athletes have elevated needs and
Older adults may also benefit from eating more protein
Getting the right amount of protein per day can be achieved in multiple ways
for example
one serving of Greek yogurt with breakfast a salad topped with three ounces of chicken for lunch and
Three to four ounces of fish at dinner provides about 64 grams of protein
getting the same amount of protein could also be achieved by eating a cup of tofu scramble and a slice of peanut butter toast for
Breakfast a cup of shelled edamame with lunch and one cup of lentils and brown rice at dinner
Which also offers about 64 grams of protein in total?
Now the fact is that it's still unclear. What an optimal amount of protein is and the research is ongoing in
Clinical settings. There are certain individuals who may be at risk for a protein deficiency
including patients with malnutrition
Trauma and burn injuries as well as various conditions impacting nutrient absorption like inflammatory bowel disease
These individuals may have increased protein needs compared to the general population
Except for certain circumstances like kidney disease there usually isn't a health risk associated with eating a lot of protein
Because our bodies are able to process it
Alright is a quick recap
Protein is a cornerstone of the human diet and a major component of our bodies
There are five non-essential six conditionally essential and nine essential amino acids
We need to get essential amine acids from our diet
Protein needs vary depending on lifecycle stage level of physical activity and health status
Some health conditions may put people at risk for protein deficiency or increased protein needs
Everyone whether omnivorous vegetarian or vegan can get enough protein by eating a variety of foods