By Amber Charles, MSPH, RDN
November 9, 2020
Protein is an important macronutrient that is often raved about in the world of health and wellness...but how much do we need, and where should we get it from?
In this article:
What Is Protein?
Why Do We Need It?
How Much Do We need?
Food Sources of Protein
Which Protein Is Better?
What Is Protein?
Protein is one of the three macronutrients (the other two being starches and fats) that the body requires in large amounts.
It is made up of amino acids - the 20 building blocks of proteins. Of these, 9 cannot be made by the body and must be obtained from the diet; these are the essential amino acids, and their presence/absence determines the quality of the protein source.
Why Do We Need It?
The 'scab' that forms over your cut...the blood clot that prevents bleeding out...skin, hair and nails...you've got it, all protein!
Not only is protein important for developing muscles and wound healing, it is found in essentially every cell in the body and aids in maintaining water balance, transports fats, vitamins & minerals, hormone production and many other roles.
How Much do We Need?
The 2015-2020 Dietary Guidelines recommend an average intake of 0.8 grams of protein for every kilogram of body weight. For a 70 kg individual, that is 56 g of protein daily - the equivalent of 8 whole eggs!
Of course, individual needs vary based on age, sex, physical activity level, medical conditions, smoking & alcohol intake, calcium & vitamin D levels, and menopause status.
Food Sources of Protein
Some animal sources:
Meat (beef/veal/pork/lamb/goat/wild meat)
Poultry (chicken/duck/turkey)
Fish & seafoods (salmon/shrimp/mussels/oysters)
Dairy & eggs (milk/yogurt/cheese/eggs & egg substitutes)
Some plant sources:
Peas/beans (lentils/black beans/soy beans/split peas)
Nuts, nut butters & seeds (peanuts/walnuts/almonds/pumpkin seeds)
Vegetables (broccoli/spinach)
Grains (quinoa/buckwheat)
Which Protein is Better?
To compare animal and plant protein, several concepts must first be reviewed:
1. Essential Amino Acid Profile
The body requires the essential amino acids in specific proportions, and their concentration in foods determine the quality/completeness of the protein source.
An incomplete protein source lacks one or more of the essential amino acids.
Animal proteins, except gelatin, are complete, unlike most plant sources, of which soy protein is the most complete - hence soy milk is recommended as an equal substitute for cow's milk in children.
2. Digestibility
The protein's digestibility, also called its bioavailability, refers to how well it is absorbed by the body.
About 97% of animal protein is absorbed, while only 87% of plant protein is. The fiber found in plant foods, while beneficial for digestive health, can reduce the amount of nutrients and protein absorbed in the gut.
This is why vegetarians and vegans may be advised to consume a variety of protein-rich plant foods often.
3. Saturated Fat
Another major difference between animal and plant protein is the saturated fat content of the foods.
Consuming too much saturated fat can increase total cholesterol and the risk for heart disease.
Plant sources of protein are typically lower in saturated fat, but those that do contain them, such as coconut oil, also contribute to increasing the "good" cholesterol, HDL, according to Harvard Health. The saturated fat in animal protein does not do this.
4. Scientific Research
Some studies have shown that the source of protein does not matter, but the amount eaten does - eat less protein and you'll have less muscle mass and strength - eat more protein and you'll have more muscle mass/strength.
Other studies suggest that, while animal protein has a better amino acid profile and bioavailability, consumption of plant protein in athletes (rice protein isolate) showed a decrease in fat-mass and an increase in lean body mass, skeletal muscle and power and strength, compared to athletes using animal protein (whey protein).
Takeaways
Protein quality is judged based on the concentration of the essential amino acids in foods and bioavailability in the body.
Animal protein sources have higher concentrations of the essential amino acids and are better absorbed in the gut compared to plant protein sources.
Consuming a variety of plant-based sources can achieve adequate daily protein intake while promoting decreased fat-mass and increased lean body mass.
It is important for vegetarians and vegans to mix their protein sources and ensure that they are getting all of the essential amino acids.
Choosing animal or plant protein foods is a personal choice.