Protein Deficiency: Risks, Consequences and Solutions
Daniel-J. CRISAFI, ND.A., PhD
I recently consulted a dietician who suggested I have a protein deficiency and need to increase my protein intake. But my doctor tells me I don’t have any of the symptoms associated with protein deficiency. Whom should I believe?
Thank you for this question. It highlights an important dilemma when it comes to nutritional deficiencies, namely, the difference between the classic clinical symptoms associated with severe deficiency disease and the subclinical symptoms associated with a lack of optimal function. Indeed, in most cases, the symptoms associated with a nutritional deficiency are major symptoms that develop rapidly following a significant deficiency.
The protein deficiency disease is called kwashiorkor. It is manifested by important symptoms such as stunted growth, muscle atrophy, swelling of the feet and stomach, alteration or loss of hair, skin changes, diarrhea and anemia. It usually leads to death in the short or medium term. Kwashiorkor is generally present in malnourished children or in adults who have undergone bariatric interventions. By this definition, your doctor is probably right - you do not have a protein deficiency.
However, there is another form of deficiency - one that is more insidious and often goes undiagnosed. This is the subclinical deficiency. The term subclinical is used for situations where symptoms are not the classic symptoms associated with these diseases or when standard analyses turn out to be normal. Or both.
The subclinical protein deficiency can cause a variety of disorders that are not usually associated with protein deficiencies. To name but a few: slowing metabolism, and difficulty losing weight; difficulty in increasing muscle mass; reduced energy and fatigue; poor concentration, learning difficulties; mood changes; muscle, bone and joint pain; hypoglycemia, followed by hyperglycemia (type II diabetes); slow wound healing; decreased immunity. This is probably the type of protein deficiency referred to by your dietician.
Therefore, it is likely that both your dietician and your doctor are right. You probably do not have the classic symptoms of a protein deficiency disease, but you may have a subclinical deficiency disease, which your dietician has spotted.
The Role of Proteins
As I have already written elsewhere, proteins are not just for bulging biceps and bodybuilders. The word protein comes from the Greek, "πρωτεῖον" "proteion" which means "what comes first" or "which ranks first". And it is a fact that proteins are the most important of the macromolecules in living beings. Indeed, the difference between the living (animal, microbial or plant) and the non-living - the mineral - is the presence of proteins.
Proteins, therefore, are important to the development and maintenance of life. But there is more. Proteins play a vital and sometimes neglected role in obtaining and maintaining optimal health. Let's take a closer look at this role of proteins.
First, proteins are composed of amino acids. When we digest and absorb dietary proteins, we use these amino acids to produce our own proteins known as native proteins. When we talk about proteins and their effects on the body, we are referring to native proteins produced from the amino acids we obtain from the proteins we consume.
Our native proteins have a "plastic" or structural function. We all know that they play a role in the development of muscle tissue, but what is often not known is that all body tissues are made up of proteins. Take the bone structure, for example. The dry mass of bone is made up of about 60% minerals and about 40% protein, especially collagen. Indeed, protein makes up almost half the bone mass.
Enzymes are molecules that catalyze or accelerate chemical reactions. This accelerating effect ensures that chemical reactions take place at a speed that allows biological life to be maintained. How fast do they act? Thanks to the enzyme orotate decarboxylase, a reaction that would normally take millions of years takes only 18 milliseconds! In humans, these enzymes are involved in at least 4,000 chemical reactions. Enzymes are proteins.
Proteins also have a caloric role. Indeed, they are an important source of energy, providing 4 calories per gram, just like carbohydrates do. When needed, the body can use its own proteins as a source of energy - a form of auto-cannibalism. The body can also, if necessary, convert proteins into glucose (a sugar), a phenomenon called gluconeogenesis. Proteins are, therefore, a dual source of energy, both directly as a protein and indirectly as a source of glucose.
Some proteins act to "inform" or signal cells. Their role is a bit like a key that triggers or stops a biochemical reaction. An example of this type of molecule is insulin. Some hormones are proteins while others are steroids. Protein-based hormones or protein hormones include, among others, insulin and glucagon, growth hormones and certain reproductive hormones. Antibodies and neurotransmitters are also protein-based molecules.
As a source of energy, proteins have other important effects: maintaining bone health and providing building blocks for enzymes, antibodies, neurotransmitters as well as several hormones. As you can see, proteins play a vital role in maintaining health.
Consequences of a Deficiency
This very brief description of the role proteins play in the body allows us to understand how a protein deficiency can have effects as varied and important as those mentioned at the beginning of this article. In fact, a protein deficiency can have effects on blood sugar, our hormones and our cognitive ability as well as our immunity or bone density.
- Dietary proteins provide the body with calories or energy. Each gram of protein provides 4 calories.
- The body's cells are made up of proteins. These are needed for normal cell growth and development during childhood, adolescence and pregnancy.
- Proteins help build and repair the cells and tissues of the body in both children and adults
- The skin, hair, nails, bones and internal organs are largely composed of proteins.
- Protein is found in almost all body fluids.
- Proteins play an important role in several physiological processes such as coagulation, fluid balance, immune response, vision, hormone and enzyme production, and cognition.
Risks of a Deficiency
A protein deficiency may be due to 4 major factors. Either inadequate intake, poor digestion, inadequate absorption, overuse or a sluggish metabolism.
Obviously, we cannot use what we do not consume! Protein intake is therefore the first factor to evaluate to make sure we don’t develop a deficiency. Although there is some disagreement among health professionals as to how much protein should be consumed, I offer two suggestions to help you make sure you get enough.
According to Health Canada, the minimum amount of protein consumed daily is 0.8 grams per kilogram of weight for an adult. So, an adult weighing 72.6 kilos (160 lbs) should consume at least 58 grams of protein a day. However, new studies suggest that the level should be much higher, 1.2 grams per kilogram of weight. These protein levels are obviously for a relatively sedentary adult. Those who are more physically active and / or who want to increase their muscle mass should consume much more.
Another way to get enough protein is to make sure you eat high-protein foods at every meal. These can include foods from animal sources (seafood, eggs, fish, dairy products, meat or poultry) or from plant sources (mushrooms, seeds, legumes, yeast and nuts).
No, we are not what we eat! What we consume must be well digested. However, the proper digestion of proteins requires three factors. First, proteins - like any food - should be well chewed. Proper mastication allows a larger surface of the protein to come into contact with enzymes, thus accelerating digestion. It is also necessary that the stomach environment be sufficiently acidic. The acidic environment of the stomach, provided by hydrochloric acid, activates the proteolytic enzymes - the enzymes which digest the proteins. One of the effects of taking drugs that reduce stomach acid - known as proton pump inhibitors - is to reduce the absorbability of proteins. People who take this type of medication should increase their protein intake to compensate for the reduction in protein absorption. As we age, digestive enzyme production is reduced thus increasing the loss of native proteins. Protein intake should, therefore, be higher among older people compared to when these same individuals were younger. In their 2015 study, Nowson and O'Connell recommend 1.3 grams per kilogram of weight, which is 62% higher than the 0.8 grams proposed by Health Canada.
We are not what we eat or what we digest - we are what we absorb. Indeed, once digested, the components of the protein must pass through the gastrointestinal mucosa so they can end up in the blood where they can be transported wherever they are needed. However, several factors can affect intestinal absorption. The most important is, without a doubt, intestinal inflammation.
According to a study published in July 2017 in the journal American Journal of Gastroenterology, Canada wins the prize when it comes to inflammatory bowel disease - especially among children. Individuals who suffer from Crohn's disease or ulcerative colitis, therefore, have a reduced absorption of amino acids – the building blocks for proteins. It is also likely that people with nonspecific bowel disorders such as Irritable Bowel Syndrome (IBS) also have problems absorbing proteins.
Some groups of people need a lot more protein than most due to increased use, overuse or increased loss. Indeed, some people have an increased need for protein because of increased demand. This is the case, for example, in people engaged in intense physical exercise. Physical exercise increases the need for protein. For example, a person who is following a moderately intense bodybuilding program will benefit from consuming up to 2 grams of protein per kilogram. A person doing competitive weight training, weightlifting or powerlifting may need 3 grams of protein or more per kilogram of body weight. Protein needs, therefore, increase according to the type and intensity of physical activity.
Seniors may also need more protein because they lose more as they get older. This degradation of proteins is both a cause and an effect of aging. But here too, studies suggest that older people should compensate for this loss by increasing their protein intake. Unfortunately, the food trend is generally the opposite of this recommendation. In fact, older people generally tend to consume less protein as they get older.
Stress is also a factor that causes protein overuse. Studies have also shown that stress has a double impact on our protein levels. The main stress hormone, cortisol, causes a reduction in protein storage in all cells of the body except the liver. This effect is due to a decrease in protein synthesis as well as degradation of cellular proteins during stress. We lose more native proteins and we produce less thanks to stress!
Metabolism is the set of chemical reactions by which certain substances are produced or broken down. Even if we consume, digest and absorb the protein components as needed, we must also metabolize them properly. This metabolism is multifactorial. Nevertheless, I would like to mention one of the most important elements associated with protein metabolism - the micronutrient factor.
Several micronutrients (minerals, trace elements and vitamins) are involved in protein metabolism. These include B-complex vitamins, magnesium and zinc. A deficiency in one or more of these nutrients can, therefore, have a negative effect on the body's ability to use protein. Another important fact is that when we increase our protein intake, we should also increase our consumption of these vitamins and minerals proportionately. This is usually the case when our dietary proteins come from unrefined natural foods. However, if the increased protein intake is from supplements there should be a proportional increase in B-complex vitamins, magnesium and zinc, to name only the most important nutrients.
Everything that has been alive contains protein whether it is an animal or a plant. Nevertheless, some foods contain more than others. These are the ones we call "proteins" whether they are animal or plant-based foods. Without repeating myself, protein-rich foods from animal sources are seafood, eggs, fish, dairy products, meat and poultry while those from vegetable sources are mushrooms, seeds, legumes, yeast and nuts. Below, you will find two tables with examples of high-protein foods and their protein content. For reasons of space, I will not elaborate on the quantitative difference of animal proteins versus vegetable proteins.
|Food source||Percentage of protein|
|Food Source||Percentage of protein|
Can we eat too much protein?
Most North Americans do not consume enough quality protein in their daily diet. On the other hand - and this is an important point - it is also possible to eat too much protein. This overconsumption, as well as protein deficiency, is associated with an increased risk of osteoporosis. Overconsumption of proteins can affect the body in two ways: it can disrupt the acid-base balance of the body and it can place a significant load on the kidneys.
Proteins are acidifying for the body while vegetables and most fruits are alkalizing. Although we do not usually consume enough protein, we must not forget that we can over consume. So, to avoid issues related to too much protein, make sure you eat more alkalizing foods such as vegetables and fruits. But beware of excess fruit!
Generally, I recommend that about 25% lunch and dinner meals should consist of protein foods and at least 50-60% in vegetables. I also advise them to eat their fruits in the morning along with a protein. Here, as elsewhere, dietary health is a matter of balance.
As we have seen, proteins are not just for big muscles. A healthy diet the goal of which is to maintain or restore optimal health does not only require a diet high in vitamins, minerals or fatty acids - it also needs a sufficient amount of quality protein. In some individuals, the lack of protein may be the missing link in an approach to optimal health. It's up to you to make the call.
- Radzicka A, Wolfenden R (1995). A proficient enzyme. Science. 267 (5194): 90–93
- Bairoch A (2000). The ENZYME database in 2000. Nucleic Acids Research. 28 (1): 304–305.
- Expert Consultation on Protein and Amino Acid Requirements in Human Nutrition Protein and amino acid requirements in human nutrition, World Health Organization (2007)
- Santé Canada, Apports nutritionnels de référence, https://www.canada.ca/fr/sante-canada/services/aliments-nutrition/saine-alimentation/apports-nutritionnels-reference/tableaux/valeurs-reference-relatives-macronutriments-tableaux-apports-nutritionnels-reference-2005.html
- Humayun MA et al. Reevaluation of the protein requirement in young men with the indicator amino acid oxidation technique. Am J Clin Nutr 2007;86:995-1002.
- Nowson, Carly and Stella O’Connell Protein Requirements and Recommendations for Older People: A Review Nutrients 2015, 7, 6874-6899
- Benchimol EI, Bernstein CN, Bitton A, et al. Trends in Epidemiology of Pediatric Inflammatory Bowel Disease in Canada: Distributed Network Analysis of Multiple Population-Based Provincial Health Administrative Databases. The American Journal of Gastroenterology. 2017;112(7):1120-1134.
- Kung, Marnie Can IBS Cause Malabsorption of Nutrients? LiveStrong, Aug 14, 2017
- Martinez-Vicente, Marta, GuySovak, Ana Maria Cuervo, Protein degradation and aging. Experimental Gerontology Volume 40, Issues 8–9, Pages 621-758 (2005)
- Bonjour, J-P Protein intake and bone health. Int J Vitam Nutr Res. 2011 Mar;81(2-3):134-42.
- Service des politiques et de la science alimentaires, Division de la nutrition, FAO Teneur des aliments en acides aminés et données biologiques sur les protéines FAO: Alimentation et nutrition, No. 21 (1981)