How much protein do we really need? What are signs of protein deficiency?

How much protein do we really need?

A short while ago, we received an urgent message from Jarrow Formulas with an apology on how they erroneously had created a faulty label their bone broths. Upon questioning what was wrong, it was stated how the % of Recommended Daily Intake (RDI) for the protein content was not correct. 
For the moment, there will be only information stating how many grams of protein a portion contains, but not what % of the RDI this amounts to.
 
To be honest, this entire communication almost made me burst out laughing if it hadn't been such a serious subject. 
If anything, most people who are serious about their health, consider the RDI to be woefully inadequate for most micro- and macronutrients and don't lead their lives following these to a T. 
If you have spent time reading articles related to fitness, you will know how recommendations for protein intake are generally at least twice as high as what 'normal' people eat as well as how it is not recommended to go by percentages for protein intake. 
Yet at the same time, we notice how the importance of protein intake is being downplayed, even more so when it involves animal protein. 
 
Which is why I've set myself to the task of finding out what serious implications a shortage of protein intake may have on our health and how much protein we actually need for optimal health and muscle growth. 

What are signs of protein deficiency? 

Few nutrients are as important as protein.
Protein is the building block of your muscles, skin, enzymes and hormones, and it plays an essential role in all body tissues.
Most foods contain some protein. As a result, true protein deficiency is rare in developed countries. However, some people may still be at risk such as those suffering from anorexia, cancer and malabsorption. 
 
Deficiency leads to various health problems, while low protein intake may also be a concern, as it can cause subtle changes in your body over time.
 
Protein deficiency is when your intake is unable to meet your body’s requirements.
An estimated one billion people worldwide suffer from inadequate protein intake.
The problem is especially severe in Central Africa and South Asia, where up to 30% of children get too little protein from their diet.
Certain people in developed countries are also at risk. This includes people who follow an imbalanced diet, as well as institutionalized older people and hospitalized patients.
While true protein deficiency is uncommon in the Western world, some people get very low amounts from their diet.
Too little protein may cause changes in body composition that develop over a long period of time, such as muscle wasting.
The most severe form of protein deficiency is known as kwashiorkor. It most often occurs in children in developing countries where famine and imbalanced diets are common.
Protein deficiency can affect almost all aspects of body function. As a result, it is associated with many symptoms.
Some of these symptoms may start to occur even when protein deficiency is marginal. They are listed below, along with some typical symptoms of kwashiorkor.

Edema

Edema, which is characterized by swollen and puffy skin, is a classic symptom of kwashiorkor.
Scientists believe it is caused by low amounts of human serum albumin, which is the most abundant protein in the liquid part of blood, or blood plasma.
One of albumin’s main functions is to maintain oncotic pressure — a force that draws fluid into the blood circulation. In this way, albumin prevents excessive amounts of fluid from accumulating in tissues or other body compartments.
Because of reduced human serum albumin levels, severe protein deficiency leads to lower oncotic pressure. As a result, fluid accumulates in tissues, causing swelling.
For the same reason, protein deficiency may lead to fluid build-up inside the abdominal cavity. A bloated belly is a characteristic sign of kwashiorkor.
Keep in mind that edema is a symptom of severe protein deficiency, which is unlikely to happen in developed countries.

Fatty liver

Another common symptom of kwashiorkor is a fatty liver, or fat accumulation in liver cells.
Left untreated, the condition may develop into fatty liver disease, causing inflammation, liver scarring and potentially liver failure.
Fatty liver is a common condition in obese people, as well as those who consume a lot of alcohol.
Why it occurs in cases of protein deficiency is unclear, but studies suggest that an impaired synthesis of fat-transporting proteins, known as lipoproteins, may contribute to the condition.

Skin, hair and nail problems

Protein deficiency often leaves its mark on the skin, hair and nails, which are largely made of protein.
For instance, kwashiorkor in children is distinguished by flaky or splitting skin, redness and patches of depigmented skin.
Hair thinning, faded hair colour, hair loss (alopecia) and brittle nails are also common symptoms.
However, these symptoms are unlikely to appear unless you have a severe protein deficiency.

Loss of muscle mass

Your muscles are your body’s largest reservoir of protein.
 When dietary protein is in short supply, the body tends to take protein from skeletal muscles to preserve more important tissues and body functions. As a result, lack of protein leads to muscle wasting over time.
Even moderate protein insufficiency may cause muscle wasting, especially in elderly people.
One study in elderly men and women found that muscle loss was greater among those who consumed the lowest amounts of protein.
This has been confirmed by other studies that show that an increased protein intake may slow the muscle degeneration that comes with old age.

Greater risk of bone fractures

Muscles are not the only tissues affected by low protein intake.
Your bones are also at risk. Not consuming enough protein may weaken your bones and increase the risk of fractures.
One study in postmenopausal women found that a higher protein intake was associated with a lower risk of hip fractures. The highest intake was linked to a 69% reduced risk, and animal-source protein appeared to have the greatest benefits.
Another study in postmenopausal women with recent hip fractures showed that taking 20 grams of protein supplements per day for half a year slowed bone loss by 2.3%.

Stunted growth in children

Protein not only helps maintain muscle and bone mass, but it’s also essential for body growth.
Thus, deficiency or insufficiency is especially harmful to children whose growing bodies require a steady supply.
In fact, stunting is the most common sign of childhood malnutrition. 
Observational studies show a strong association between low protein intake and impaired growth.
Stunted growth is also one of the main characteristics of kwashiorkor in children.

Increased severity of infections

A protein deficit can also take its toll on the immune system.
Impaired immune function may increase the risk or severity of infections, a common symptom of severe protein deficiency.
For instance, one study in mice showed that following a diet consisting of only 2% protein was associated with a more severe influenza infection, compared to a diet providing 18% protein.
Even marginally low protein intake may impair immune function. One small study in older women showed following a low-protein diet for nine weeks significantly reduced their immune response.

Greater appetite and calorie intake

Although poor appetite is one of the symptoms of severe protein deficiency, the opposite seems to be true for milder forms of deficiency.
When your protein intake is inadequate, your body attempts to restore your protein status by increasing your appetite, encouraging you to find something to eat.
But a protein deficit doesn’t aimlessly drive the urge to eat, at least not for everyone. It may selectively increase people’s appetite for savoury foods, which tend to be high in protein.
While this may certainly help in times of food shortage, the problem is that modern society offers unlimited access to savoury, high-calorie foods.
Many of these convenience foods contain some protein. However, the amount of protein in these foods is often considerably low compared to the number of calories they provide.
As a result, poor protein intake may lead to weight gain and obesity, an idea known as the protein leverage hypothesis.
Not all studies support the hypothesis, but protein is clearly more satiating than carbs and fat.
This is part of the reason why increased protein intake can reduce overall calorie intake and promote weight loss.
If you are feeling hungry all the time and have difficulties keeping your calorie intake in check, try adding some lean protein to every meal.

How much protein do you need?

Not everyone has the same protein requirement. It depends on many factors, including body weight, muscle mass, physical activity and age.
Arguably, body weight is the most important determinant of protein requirements. As a result, recommendations are usually presented as grams for each kilogram of body weight.
 
The recommended daily allowance in the USA is 0.8 grams of protein for each per kg of body weight. Scientist estimate this should be enough for most people.
For athletes, the American College of Sports Medicine recommends a daily protein intake ranging from 1.2–1.4 grams per kg body weight, which should be enough for muscle maintenance and training recovery.
However, scientists don’t agree how much is enough. The International Society of Sports Nutrition’s daily recommendation is 2 grams of protein per kg of body weight for athletes.
Just like athletes, older adults also seem to have higher protein requirements.
 
While the RDA is currently the same for old and young adults, studies indicate it is underestimated and should be raised to 1.2–1.5 grams per kg of body weight for older people.
Simply put, if you are older or physically active, your daily protein requirements are probably higher than the current RDA of 0.8 grams per kg of body weight. The richest sources of protein include fish, meat, eggs, dairy products and legumes. 

What's the optimal amount of protein to eat at each meal for athletes?

It used to be that one of the oldest and most persistent "myths" on protein intake was that you couldn't absorb more than 20 to 25 grams of protein in a single sitting. This belief, more than anything, probably gave rise to the seemingly universal habit among bodybuilders of eating six or more meals a day.
How and why this belief came about is a mystery. Luckily, we now have research that allows us to ignore this mythical protein barrier for once and for all.
After conducting a meta-study on the topic, it was concluded that athletes interested in maximizing muscle protein synthesis should consume protein at a minimum rate of 0.4 g/kg per meal (spread across a minimum of four meals) in order to reach a minimum daily goal of 1.6 grams of protein per kilogram.
In the past, many researchers, in accordance with the old 20-25 gram per meal barrier, believed that any amount of protein beyond this amount was oxidized for energy or used to form different compounds.
In reality, following the digestion of a meal, the constituent amino acids are transported through specialized cells into the liver and those that aren't sucked up by the liver enter the bloodstream where they are picked up by any body tissues that want them.
While consumption of higher protein doses does indeed result in greater oxidation for energy, it's certainly not the fate of all additional ingested protein.

How much protein do you need per day while dieting or fasting to prevent muscle loss?

Dieting reduces fat storage, of course, but it also robs you muscle unless you keep protein intake high. 
The end fate of most dieters is an unacceptable amount of muscle loss. Rather than looking better, dieters often end up looking like slightly smaller versions with equal amounts of muscle and fat being lost.
 
The truth is you need to eat even more protein during dieting than you do to build muscle. 
After a study done on a group of British bodybuilders it was concluded an intake of 2.3g protein/kg of bodyweight allowed them to preserve all of their muscle mass, while they remained as strong as before (some even gained strength) and only had minimal reduction of free testosterone levels.  

Bottom line

Protein is found everywhere in your body. Your muscles, skin, hair, bones and blood are largely made of protein.
For this reason, protein deficiency has a wide range of symptoms.
Serious protein deficiency can cause swelling, fatty liver, skin degeneration, increase the severity of infections and stunt growth in children.
While true deficiency is rare in developed countries, low intake may cause muscle wasting and increase the risk of bone fractures.
Some evidence even suggests that getting too little protein may increase appetite and promote overeating and obesity.
For optimal health, make sure to include protein-rich foods in every meal. 
To ensure optimal muscle building and more so to to prevent muscle loss while dieting, adequate protein intake becomes even more important. 
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