6 Signs & Symptoms of Deficient Protein Intake

What Is Protein and Why Is it Important for the Skin and Hair?

Protein, made up of long chains of amino acids, is important for almost every structure in the body.  Our body is made of protein, and we consume protein in our diets to replenish and build healthy tissues and cells. We obtain protein by eating foods that contain different types of amino acids. Amino acids are present in a huge variety of foods, including both animal and plant-based foods.

Amino acids derived from protein in the food we eat contribute to collagen and elastin, which are essential to the structure and fullness of our skin. In fact, some amino acids have been identified (ex – proline and glutamate) in cell studies and shown to possibly slow signs of skin aging by enhancing collagen production in the skin.^[1] In a study conducted in the UK, people were given weekly injections and daily oral supplements containing the amino acids proline, glycine, leucine, and lysine for six weeks.^[3] The participants were reported to have significant improvement in the appearance of aging and wrinkles with improved collagen synthesis. Other amino acids consumed in our diets, such as arginine and ornithine, can enhance the rate of wound healing.^[4,5] Protein is also an essential component of healthy hair since hair is mostly made of a protein called keratin.^[6] Consuming adequate amounts of nutrient-dense foods containing protein can help keep hair strong and healthy. 

Signs and Symptoms of Protein Deficiency

Most people in the United States get enough protein most of the time, and it is uncommon in the US and other developed countries for people to have full-blown protein deficiency. The following signs are common clues to not eating enough protein.

1) Slow wound healing 

Each stage of wound healing requires protein, making it an extremely important part of a diet. Collagen is a protein that makes up a whopping one-third of the protein in the body and is responsible for the skin’s strength and structure.^[7] In people who are protein deficient, wound healing is impeded because proteins are shunted to other processes in the body.^[8] Adequate dietary protein intake, along with other key nutrients, is important in wound healing; however, people who are experiencing a slow or non-healing wound should first see a physician for assessment. 

2) Fingernail grooves

Several different proteins make up the nail unit, giving it strength and hardness. Protein deficiency has been associated with a horizontal groove across the nail, called Beau lines. Other factors such as metabolic disorders or certain medications can contribute to Beau lines, and protein deficiency is one of the causes.^[9] 

3) Get sick often

The immune system requires protein in order to perform its full-time job of protecting us from illness caused by viruses, bacteria, and parasites. Protein energy malnutrition is associated with significantly increased susceptibility to infections, even to common viruses that most people are able to naturally fight off.^[10]

4) Poor concentration

Amino acids are important to form the neurotransmitters in the brain, and protein deficiency can result in poor mood, trouble focusing, and difficulty in learning.^[11]

5) Fluid retention

Some people with severe protein deficiency can retain excess fluid, where the body may feel and appear puffier than usual.^[12]

6) Hair thinning 

Protein deficiency, also referred to as protein energy malnutrition, has been associated with hair loss and hair thinning, finer hairs with smaller diameters, less curly hairs, easy breakage, and even loss of color.^[13] There are many intrinsic and environmental causes of hair thinning and hair breakage, and protein deficiency is just one of many contributors to thinning hair.

How Much Protein Should Someone Be Eating Each Day?

Daily protein needs ultimately depend on age, sex, and activity level. The daily recommended intake of protein is approximately 10-35% of the total daily calories. This simply means that if someone usually eats 2,000 calories per day, eating 400 calories worth of protein would make up 20% of the total calories. Remember, there are 4 calories per gram of protein, so 400 calories would be 100 grams of protein.

How Much Is Too Much?

There are a few potential consequences of eating too much protein. The exact amount that is considered “too much” depends on many factors, including a person’s age and weight, activity level, underlying medical conditions, and more. The most likely consequence of eating too much protein is weight gain. Many bodybuilders eat a very high amount of protein because they are constantly tearing down and rebuilding their muscles in order to put on muscle. In this case, the weight gain is intentional; however, for the general population, the excess protein that is eaten and not used will be stored as fat.^[14] It is also important to carefully select protein-containing food sources for optimal health. Eating high-fat animal products, such as red meat and full-fat dairy, can elevate cholesterol and lead to other health conditions. Instead, opt for whole, lean protein-containing foods such as legumes, soybeans, or fish. A serious concern of eating too much protein is kidney damage. Dietary protein results in nitrogen by-products, which must be filtered by the kidney. Consuming excessive protein can be dangerous in people with pre-existing kidney disease.^[15]