The Effects of Protein Deficiency
The Importance of Amino Acids
Protein deficiency, or hypoproteinemia, happens when you have low levels of protein in your blood, which can occur if you don't have enough protein in your diet to meet your body's needs, such as when following a diet that severely restricts protein consumption. The most severe form of protein deficiency is called kwashiorkor, and is most common in children who live in developing countries.
You may also become deficient if your body isn't able to effectively digest and absorb the proteins within the foods you eat due to another medical condition.
Most Americans consume enough protein to meet generalized nutrition guidelines.
What Does Protein Do?
When digested, protein breaks down into amino acids. These amino acids help the body's tissues function and grow. That makes this macronutrient important to having healthy and strong muscles and bones, as well as impacting your hair and nails.
There are nine essential amino acids and 11 non-essential amino acids. Essential amino acids are "essential" in that they must be consumed through the diet because our bodies cannot make them.
Unlike with carbohydrates and fats, there is no mechanism to store excess amino acids that are consumed in the diet. So a continuous supply is needed. Put simply, you need to consume protein daily to meet your body's needs.
Protein Deficiency Symptoms
When your body doesn't get the required protein amounts or isn't able to use protein efficiently, research has shown that it can lead to a number of symptoms including increased infections and illnesses and reduced muscle mass, often referred to as sarcopenia in older patients. Lack of protein also may lead to swelling in the legs, slower wound healing times, and high blood pressure during the second trimester of pregnancy, also called preeclampsia
Protein deficiency may show up differently in infants and children. For example, one study found that a child had developed silvery hair and lighter patches of skin as a result of disease-induced protein deficiency. Preterm infants born with hypoproteinemia also have a higher risk of severe neurological injury and death.
These studies reinforce why adequate protein intake is essential for maintaining proper body function at every stage in life. Going a step further, understanding the role of protein and ensuring adequate intake in your diet is critical too.
If you believe that you may have a protein deficiency, contact your doctor. While this deficiency is more common in developing countries, your doctor can test your blood to find out whether your protein levels are too low, as well as provide advice as to how to bring those levels back up.
What Causes Protein Deficiency?
Current dietary guidelines recommend that adults consume between 10% and 35% of daily calories from protein. However, some researchers believe that this may be too low and should be reconsidered.
Some studies suggest that most Americans consume about 14% to 16% of their daily calories from protein.
Another theory is that eating a vegetarian diet contributes protein deficiency. The thought is that eliminating all meat-based foods severely restricts protein intake, sometimes to unhealthy levels. While this may happen in some cases, research reveals that most vegetarian diets supply enough protein via legumes, nuts, and seeds.
Protein deficiency can also be caused by certain medical conditions, some of which include:
- Acquired immune deficiency syndrome (AIDS)
- Anorexia nervosa
- Cancer
- Chronic obstructive pulmonary disease (COPD)
- Gastrointestinal conditions, such as amyloidosis
- Renal failure
How Common Is Protein Deficiency?
According to a study published in the Annals of the New York Academy of Sciences, approximately one billion people worldwide have inadequate protein intake. This is largely due to limited access to food in general.
Because protein sources are so widely available in the United States, the Physician's Committee for Responsible Medicine reports that eating enough protein is hardly an issue stateside. This infers that deficiency due to medical conditions may be more common in this area of the world.
Yet, some pieces of research have found that approximately one-third of adults over age 50 are failing to meet the recommended daily allowance (RDA) for protein intake. People following a restrictive diet can also become protein deficient.
How Much Protein Do You Need?
In order to maintain a steady flow of amino acids, adequate protein intake is essential. Therefore, it is recommended that you eat enough protein to support your cell's structure and function. This requirement will be different for each person based on factors like age, sex, and physical activity levels.
The 2020-2025 U.S. Department of Agriculture (USDA) guidelines recommend that most adults consume 5.5 ounces of protein each day, or 38.5 ounces per week. Roughly 26 of these weekly ounces should be meat, poultry, or eggs. Eight ounces should be seafood and five ounces of nuts, seeds, and soy products.
For those following a vegetarian diet, the USDA recommends 3.5 to 5.5 ounces of protein daily depending on total caloric intake. This is split fairly evenly between beans, peas, and lentils; soy products; and nuts and seeds, with approximately 3 to 4 ounces per week of eggs.
For comparison purposes, 3 ounces of protein is roughly the size of the palm of your hand. Another way to visualize this amount is that it is about the same size as a deck of cards.
How to Increase Protein Intake
Protein is available in a wide variety of animal and plant foods. Choosing nutritious protein sources is recommended for optimal health and fitness. This includes foods such as:
- Beans and legumes
- Cheese
- Eggs
- Greek yogurt
- Lean beef, chicken, turkey, and pork
- Nuts and nut butters
- Oats
- Quinoa
- Seafood
- Seeds
- Tofu
6 Tips for Getting More Protein in Your Diet
A Word From Verywell
Protein is essential for all cells and body tissue and when in short supply can impair body function. While diet-related protein deficiency is rare in the United States, it exists for some at marginal levels. Certain medical conditions can also increase this risk.
Regardless, some people will benefit from increasing their protein intake. Thankfully, adding protein to your diet is simple and can be achieved by incorporating a wide variety of foods from either plant or animal sources.
Moriyama K, Watanabe M, Yamada Y, Shiihara T. Protein-losing enteropathy as a rare complication of the ketogenic diet. Pediatric Neurology. 2015;52(5):P526-8. doi:10.1016/j.pediatrneurol.2015.01.009
U.S. National Library of Medicine. Dietary Proteins.
Rose AJ. Amino acid nutrition and metabolism in health and disease. Nutrients. 2019;11(11):2623. doi:10.3390/nu11112623
Karacabey K, Ozdemir N. The effect of nutritional elements on the immune system. J Obes Wt Loss Ther. 2012;2:152. doi:10.4172/2165-7904.1000152
Ha YC, Choi C, Kim KH, et al. Malnutrition and chronic inflammation as risk factors for sarcopenia in elderly patients with hip fracture. Asia Pac J Clin Nutr. 2018;27(3):527-32. doi:10.6133/apjcn.082017.02
Schellong SM, Wollina U, Unger L, Machetanz J, Stelzner C. The swollen leg. Internist. 2013;54:1294-1303. doi:10.1007/s00108-013-3339-z
Barchitta M, Maugeri A, Favara G, et al. Nutrition and wound healing: An overview focusing on the beneficial effects of curcumin. Int J Mol Sci. 2019;20(5):1119. doi:10.3390/ijms20051119
Takahashi H, Hisano M, Sago H, Murashima A, Yamaguchi K. Hypoproteinemia in the second trimester among patients with preeclampsia prior to the onset of clinical symptoms. Hypertension in Pregn. 2014;33(1):55-60. doi:10.3109/10641955.2013.837172
Galve J, Martin-Santiago A, Clavero C, et al. Spontaneous repigmentation of silvery hair in an infant with congenital hydrops fetalis and hypoproteinemia. Cutis. 2016;97(6):E1-5.
Iacobelli S, Bonsante F, Lacoutiere C, et al. Hypoproteinemia on the first day of life and adverse outcome in very preterm infants admitted to the neonatal intensive care unit. J Perinatol. 2012:520-4. doi:10.1038/jp.2011.137
Semba R. The rise and fall of protein malnutrition in global health. Ann Nutr Metab. 2016;69(2):79-88. doi:10.1159/000449175
U.S. Department of Health and Human Services and U.S. Department of Agriculture. 2020–2025 Dietary Guidelines for Americans. Ninth Edition. December 2020
Carbone JW, Pasiakos SM. Dietary protein and muscle mass: Translating science to application and health benefit. Nutrients. 2019;11(5):1136. doi:10.3390/nu11051136
Mariotti F, Gardner C. Dietary protein and amino acids in vegetarian diets—a review. Nutrients. 2019;11(11):2661. doi:10.3390/nu11112661
Yuan Z, Zhou B, Meng S, et al. Development and external-validation of a nomogram for predicting the survival of hospitalized HIV/AIDS patients based on a large study cohort in western China. Epidemiol and Infect. 2020;148:E84. doi:10.1017/S0950268820000758
Ozenoglu A. Nutritional and metabolic alterations in a patient with anorexia nervosa and the importance of experienced dietician in the treatment team: Case report. J Diseas Global Health. 2015;5(1):41-8. doi:
Ohki S, Shibata M, Gonda K, et al. Circulating myeloid-derived suppressor cells are increased and correlate to immune suppression, inflammation and hypoproteinemia in patients with cancer. Oncology Rep. 2012;28(2). doi:10.3892/or.2012.1812
Yamaya M, Usami O, Nakayama S, et al. Malnutrition, airflow limitation and severe emphysema are risks for exacerbation of chronic obstructive pulmonary disease in Japanese subjects: A retrospective single-center study. Int J Chron Obstruct Pulmon Dis. 2020;15:857-68. doi:10.2147/COPD.S238457
Dainaka K, Isozaki Y, Kunieda K, et al. A case of gastrointestinal amyloidosis and hypoproteinemia improved by tocilizumab. J Japan Soc Gastroenterol. 2016;113(2):245-53. doi:10.11405/nisshoshi.113.245
Le W, Liang S, Hu Y, et al. Long-term renal survival and related risk factors in patients with IgA nephropathy: Results from a cohort of 1155 cases in a Chinese adult population. Nephr Dialys Transplant. 2012;27(4):1479-85. doi:10.1093/ndt/gfr527
Wu G, Fanzo J, Miller DD, et al. Production and supply of high-quality food protein for human consumption: Sustainability, challenges, and innovations. Ann N Y Acad Sci. 2014;1321:1-19.
Physicians Committee for Responsible Medicine. Protein.
Paddon-Jones D, Campbell WW, Jacques PF, Kritchevsky SB, Moore LL, Rodriguez NR, van Loon L. Protein and healthy aging. The American Journal of Clinical Nutrition. 2015;101(6):1339S-1345S. doi:10.3945/ajcn.114.084061
Geisler C, Prado CM, Müller MJ. Inadequacy of body weight-based recommendations for individual protein intake—Lessons from body composition analysis. Journal of Nutrients. 2017;9(1):23. doi:10.3390/nu9010023
Guoyao W. Dietary protein intake and human health. Journal of Food and Function. 2016;3. doi:10.1039/C5FO01530H
Henley EC, Taylor JRN, Obukosia SD. The importance of dietary protein in human health: Combating protein deficiency in sub-Saharan Africa through transgenic biofortified sorghum. Advances in Food and Nutrition Research. 2010;60:21-52. doi:10.1016/S1043-4526(10)60002-2