From muscle to skin to bone, protein is found in most parts of the body. But what exactly is it and why is it so important to us?
Protein is used by the body to form structural components of cells, tissues, hormones, and enzymes, all of which are vital components of our bodies and are renewed continuously by a process called protein synthesis.1
During this process, protein is broken down into its component amino acids, which are in turn converted into our body’s proteins and used for various essential applications. Amino acids, the building blocks of protein, are not stored by our bodies, meaning we need to eat them constantly. Although the human body is incredibly resourceful and capable of modifying amino acids to create others or even creating them from scratch, there are certain amino acids (known as essential amino acids) which our bodies simply cannot make, meaning we must get from our diets.2
Protein is not only found in meats. It is also found in high quantities in vegetables, grains, nuts, and seeds - although these are known as incomplete proteins, meaning they’re lacking one or more of the nine essential amino acids. Poultry, meat, fish, dairy foods, and eggs are often complete proteins.
High protein foods
What is good about high protein foods?
High protein food is good for the body in many ways. It is conducive to good health and beneficial for recovery. It can also be used to ward off age-related muscle degeneration and can aid in weight loss.
There’s evidence to show that protein-rich meals can increase alertness and reaction time while improving cerebral function.4, 5 Consuming high protein foods affects the gut microbiota and could potentially have antidepressant effects on the brain.6 The gut also seems to respond well to a protein-rich diet, eliciting a dopamine response in the brain and creating a reward-based relationship with particular food types.7
Protein helps throughout the body. It has been proven to have a role in preventing liver disease, for example.8,9 There is also some evidence to show that plant-based proteins may reduce blood pressure.12 It is commonly known that it plays a huge part in muscle growth and cell regeneration, too. One review study suggests that eating the right protein and optimising intake enhanced the process of repairing muscle tissue and synthesising new muscle protein, thereby stimulating the maintenance and growth of muscles.13
There has recently been an association with a high-protein diet and weight loss in athletes. This comes from the notion that by eating the right types of protein around exercise, the body will burn excess fat and expend excess energy from protein whilst building muscle mass and undergoing recovery.14
These results are most pronounced in resistance exercise, such as weight lifting, where diet-based protein have been shown to preserve lean mass over fat mass.14 Protein’s effects on metabolism are the cause of the fat burning, but there is also a psychological factor whereby the gut-brain reward relationship makes us feel more full after eating protein-rich foods.15,16
What is bad about high protein foods?
All things should be consumed in moderation. As stated above, there are many merits to the consumption of protein, but as with anything that is good for us in regulated quantities, too much can be bad, and in some cases, make us seriously ill.
For example, after the onset of kidney disease, it is advised to cut down on protein. This is because an excess of protein can cause waste to build up in your blood which the kidneys can no longer get rid of.20 A tell-tale sign of excess protein in the diet is a build up of albumin and its detection in the urine. Albium, the protein made in the liver from protein-rich foods, should be filtered by healthy kidneys. Simple urine tests can detect traces of this protein, letting us know if we’re consuming too much.21
Some high-protein diets can limit intake of carbohydrates and fats to such a degree that the body might not get enough fibre or nutrients. Known as protein poisoning, this is an acute form of malnutrition brought about by consuming only lean meats and depriving the body of other nutrients.
This study covers many of the potential pitfalls of protein overconsumption.22 The paper lists several harmful effects of overconsumption: bone disorders due to the buildup of acid in the body; increased risk of cancer; precipitation of coronary artery disease; and damage to liver function.
The increased risk of cancer is always associated with meat-based proteins, and is usually attributed to red meats. There is a strong correlation between red meat intake and colon cancer, in addition to a correlation between general meat consumption and breast cancer.23
Tips for choosing the right high protein foods for you
Although individuals advocate different proteins to supplement different lifestyles, it is important to have a balanced diet and not consume too much of any one thing.
Proteins are classified by two metrics which inform on various properties:
- Biological value: This provides a measurement of how efficiently the body utilises protein from food. This is usually higher for animal proteins because of their complete amino acid content
- Protein efficiency ratio: This value provides a measure of animal growth which corresponds to human weight gain. Quite literally, this metric involves feeding rats a certain food type and measuring how much weight they put on24
According to the Cleveland Clinic, the best way to encourage muscle growth are proteins or protein powder with high biological value, such as whey protein and most other complete proteins from animal sources. Examples are whey protein, eggs, red meat, and poultry. This has historically been recommended for most athletic lifestyles. Cottage cheese and peanut butter are other examples.25
Foods with a high protein efficiency ratio are thought to encourage weight loss and body weight maintenance. Foods within this category are beef, poultry, and oily fish.
Vegetarian diets also provide enough proteins to encourage healthy muscle growth and longevity. Variety is key to meeting protein requirements with vegetables alone. High protein sources for vegans can be found in nut butter, such as peanut butter, pea protein, soy protein, and beans, and many also double as slow-releasing carbs, providing long-lasting energy.26
How much high-protein foods should I take for a healthy diet?
The recommended daily allowance for adults with a sedentary lifestyle is 0.8 grams per kilogram of body weight. In later life, it is recommended to increase this intake to between 1.2 and 1.7 grams per kg of body weight per day. It is also recommended to consume as much as 1.7 grams whilst undergoing athletic training.27 Any more than 2 grams per kilogram of body weight is considered to be excessive protein consumption.28
Why is protein important?
Protein is important because it is a macronutrient, meaning that we need it in large quantities to produce energy to live. It is made up of chains of amino acids which our bodies break down to make their own proteins. Those proteins are then used for cell growth, repair and maintenance.
It is important to consume protein everyday but also good to have more when undertaking exercise, when we are young, and in old age as a preventative measure against natural muscle degeneration.
What happens if I lack protein?
If you don’t have enough protein, you will begin to suffer from weakness and fatigue as your body won’t have enough energy to function properly. Another sign of a lack of protein is hunger between meals.29 Frequent bouts of sickness are a signal that our bodies lack the resources to maintain strong immune systems.
Which food has the highest protein?
Nut butters such as peanut butter are great high protein foods. Other meats that are low in saturated fat, such as lean meat, are very high in protein and great for building muscle mass. Eggs are generally recommended because they are extremely low carb for the amount of protein that they contain.
Protein is extremely important. We must attempt to meet the RDA whenever possible, and at certain times it is important to have a high-protein diet, not just as a lifestyle choice but for health.
Remember that protein comes in a variety of forms. Balance and variety are important, especially in a vegan or vegetarian diet where those forms of protein are incomplete, and eating a broad variety is essential in ensuring the body gets all of the amino acids it requires to function.