Protein deficiency occurs when your intake does not meet your body’s needs. Protein deficiency affects about one billion people globally (1).
Certain people in developed countries are likewise vulnerable.
This includes people with an unbalanced diet, as well as the older and hospitalized patients (2, 3).
While true protein deficiency is uncommon in the Western world, some people consume far too little.
Insufficient protein intake may cause long-term changes in body composition, such as muscle loss.
Kwashiorkor is the most severe form of protein deficiency. It is more common in children in developing countries, where starvation and unbalanced nutrition are common.
Protein deficiency can affect every aspect of physiological function. As a result, it is linked to a variety of symptoms.
Some of these symptoms may appear even when protein deficiency is mild.
Here are 7 risks and symptoms of protein deficiency.
Table of Contents
1. Loss of Lean Muscle Mass
Your muscles are the greatest protein reservoir in your body. The body takes the protein from skeletal muscles to maintain more important tissue functions.
As a result, the lack of protein over time leads to muscle loss. Even mild protein deficiencies can cause muscle loss in older people.
One study in older individuals showed that muscle loss among those who ate low-protein diets was higher (4).
Other studies show that an increased intake of protein can delay the muscle degeneration that comes with old age (5).
2. Risk of Bone Fractures
Muscle tissues are not the only thing affected by protein deficiency. The bones are also at risk.
Not eating enough protein can weaken your bones and increase bone fracture risks (6, 7, 8).
One study found a higher intake of the protein could lower the risk of hip fractures (9).
The study associated a high protein diet with a reduced risk of fracture by 69%, and the highest outcomes were linked to animal-protein sources.
Another study of hip fractures in postmenopausal women found that taking 20 grams of protein supplements per day for half a year reduced bone loss by 2.3% (10).
3. Stunted Growth
Protein not only helps build muscle and bone mass, but it is also important to the overall growth of the body.
Protein deficiency is detrimental to children, whose growing bodies need a steady supply. Stunting is the most common sign of malnutrition in children.
Stunted growth affected about 161 million children only in 2013 (11).
Studies show a strong correlation between low protein intake and stunted growth (12, 13).
Kwashiorkor is also the major culprit behind the stunted growth of children, which is usually caused by malnutrition (14).
4. Skin, Hair, and Nail Problems
Protein deficiency also affects the skin, hair, and nails. In children, for example, flaky, split skin and depigmented skin patches or redness are the symptoms of kwashiorkor (15, 16).
Also, hair thinning, fading hair color, hair loss, and brittle nails are signs of protein deficiency (17, 18).
However, unless you have a serious protein deficiency, such signs would not occur.
5. Edema
Edema, or swollen and puffy skin, is usually a symptom of kwashiorkor. Scientists believe low levels of human serum albumin, the most abundant protein in the blood’s fluid portion, or blood plasma, cause it (19).
One of the major functions of albumin is to maintain oncotic pressure that brings fluid into the blood flow.
Albumin thus avoids the accumulation of excessive amounts of fluid in tissues or other body areas.
Severe protein deficiency leads to lower oncotic stress because of reduced levels of human serum albumin. As a result, water accumulates and induces swelling of the tissues.
6. Greater Calorie Intake
If your intake of protein is insufficient, your body will try to restore your protein stores by increasing your appetite and motivating you to find something to eat (20, 21).
But a protein deficiency does not trigger the appetite to eat, at least not for everyone.
It can increase the appetite for sweet foods that appear to be high in protein in some people (22).
A low intake of protein can cause weight gain and obesity, a concept known as the protein leverage hypothesis (23).
Not all studies support the hypothesis, but protein satiates more than fat and carbs (24, 25).
This is part of why increased consumption of protein can reduce the overall intake of calories and encourage weight loss (26, 27).
When you feel hungry all the time and have trouble monitoring your calorie intake, try to add some lean protein to each meal.
7. Fatty Liver
A fatty liver or fat accumulation in liver cells is another common symptom of kwashiorkor (28).
This condition will lead to fatty liver disease if left untreated, causing inflammation, hepatic scarring, and possibly liver failure.
Among heavy people, fatty liver is a common condition, especially for those who drink a lot of alcohol (29, 30).
Yet, studies suggest that impaired synthesis of fat-transporting proteins, known as lipoproteins, may lead to the condition (31).
Does Protein Deficiency Affect Immunity?
Protein deficiency can impair the immune system. Impaired immune function can increase the risk of infection (32, 33).
For example, one study in mice found that a more serious influenza infection followed a diet containing only 2% protein, compared to an 18% protein diet (34).
A low intake of protein can actually increase the risk of infection.
Another nine-week study of older women found that their immune response was reduced after a low-protein diet (35).
How Much Protein Do I Need?
The recommended daily allowance for each pound of body weight is 0.4 grams (0.8 grams per kg). Scientists estimate that for most people, this should be enough.
A person weighing 165 pounds (75 kg) should take 66 grams of protein per day.
For athletes, the American College of Sports Medicine advises a daily protein consumption of 0.5 to 0.6 grams per pound of body weight (1.2–1.4 grams per kg), which should be enough for muscle maintenance and training recovery (36).
However, scientists disagree on how much is sufficient. Athletes should consume 0.9 grams of protein per pound of body weight (2 grams per kg) daily (37).
Just like athletes, older people appear to have higher protein requirements.
While the RDA for older and young adults is currently the same, research shows that it is underestimated and should be increased to 0.5 to 0.7 grams per pound of body weight (1.2–1.5 grams per kg) for older people (38, 39).
What Foods are High in Protein?
High-protein foods include meats, poultry, and fish, dairy products, tofu, grains, other vegetables and fruits, eggs, legumes, nuts, and seeds.
Eating a variety of protein-rich foods will increase the intake of nutrients. Some healthy sources of protein are lean and low-fat poultry and foods.
For vegetarians, there are choices such as lentils, peas, beans, nuts, grains, and refined soy products.
Conclusion
Most of the muscles, skin, hair, bones, and blood are protein.
Protein deficiency, therefore, has a wide range of symptoms.
Serious protein deficiency in children can cause swelling, fatty liver, skin degeneration, increase infection severity, and stunt growth.