Health Consequences of Too Little and Too Much Dietary Protein

A salubrious diet incorporates all nutrients in moderation, meaning that in that location's neither as well little nor too much. As with all nutrients, having too little or too much protein can have health consequences.

The AMDR for protein for adults is between 10 and 35 percent of kilocalories. That's a fairly wide range, and it encompasses typical protein intakes of many traditional human cultures.

Two photos depicts dietary differences in human cultures. The photo on the left shows Inuit families sharing frozen, aged walrus meat. Their traditional diet is very dependent on meat and high in both protein and fat. On the right is a traditional vegetarian meal in India, representing dietary patterns dependent on grains, legumes, and vegetables that provide adequate, but not excess, levels of protein.

Fig. 5.1 - Various human being cultures take survived on different levels of dietary poly peptide. The photograph on the left shows Inuit families sharing frozen, aged walrus meat. Their traditional diet is very dependent on meat and high in both protein and fat. On the right is a traditional vegetarian meal in Bharat, high in carbohydrates merely even so providing adequate levels of protein.

Protein intake below the RDA is inadequate to support the body's needs for synthesis of structural and functional proteins. On the other mitt, in that location are some concerns that high poly peptide intake is associated with chronic disease. However, equally we'll discuss, it's non just the quantity of protein that matters, but also the nutritional parcel that it comes in.

According to a 2018 study published in the American Journal of Clinical Nutrition, well-nigh Americans get enough protein, averaging most 88 grams per day and xiv to 16 percent of caloric intake. The study also found that diets with protein above 35 percent of caloric intake, the upper end of the AMDR, were extremely rare.

Health Consequences of Protein Deficiency

Although severe poly peptide deficiency is rare in the adult world, it is a leading cause of death in children in many poor, underdeveloped countries. There are two main syndromes associated with poly peptide deficiencies: Kwashiorkor and Marasmus.

Kwashiorkor affects millions of children worldwide. When it was first described in 1935, more than ninety percent of children with Kwashiorkor died. Although the associated mortality is slightly lower now, almost children still dice after the initiation of handling.

The name Kwashiorkor comes from a language in Ghana and means, "rejected 1." The syndrome was named because information technology occurs most commonly in children recently weaned from breastfeeding, usually because the mother had a new baby, and the older kid is switched to a diet of watery porridge fabricated from low-poly peptide grains. The kid may be consuming enough calories, but non plenty poly peptide.

Kwashiorkor is characterized past swelling (edema) of the feet and belly, poor skin health, poor growth, low musculus mass, and liver malfunction. Recall that ane of the roles of protein in the torso is fluid rest. Diets extremely depression in protein do not provide enough amino acids for the synthesis of the protein albumin. One of the functions of albumin is to hold water in the blood vessels, and so having lower concentrations of claret albumin results in water moving out of the blood vessels and into tissues, causing swelling. The primary symptoms of Kwashiorkor include not only swelling, merely also diarrhea, fatigue, peeling skin, and irritability. Severe poly peptide deficiency in addition to other micronutrient deficiencies, such as folate, iodine, iron, and vitamin C all contribute to the many health manifestations of this syndrome.

Children and adults with marasmus are poly peptide deficient, but at the same fourth dimension, they're also not taking in enough calories. Body weights of children with Marasmus may be up to 80 percentage less than that of a healthy child of the same historic period. Marasmus is a Greek word significant "starvation." The syndrome affects more than than fifty million children under age five worldwide. Information technology is characterized by an farthermost emaciated appearance, poor peel health, poor growth, and increased hazard of infection. The symptoms are astute fatigue, hunger, and diarrhea.

Two photos show children suffering from protein energy malnutrition. On the left is a child with kwashiorkor, showing the hallmark swollen belly. On the right is a child with marasmus, showing very thin limbs and visible ribs, no swollen belly.

Figure five.2. The photo on the left shows a kid suffering from kwashiorkor (note the swollen belly) in the late 1960s in a Nigerian relief camp during the Nigerian-Biafran War. The photograph on the right shows an Indian child suffering from marasmus.

Kwashiorkor and marasmus frequently coexist as a combined syndrome termed marasmic kwashiorkor. Children with the combined syndrome have variable amounts of edema and the characterizations and symptoms of marasmus. Although organ system office is compromised past undernutrition, the ultimate crusade of death is usually infection. Undernutrition is intricately linked with suppression of the allowed arrangement at multiple levels, then undernourished children commonly dice from severe diarrhea and/or pneumonia resulting from bacterial or viral infection. According to the United nations Children'south Fund (UNICEF), almost half of all deaths of children under historic period five are related to malnutrition. That translates to virtually iii million kid deaths each year.

While severe protein deficiency is rare in the U.S., in that location are several groups at adventure of depression protein intake. A 2018 report found that 23 percent of U.S. adolescent girls (aged 14 to 18 years former) and 11 percentage of adolescent boys were consuming beneath the RDA for protein, which may compromise their growth and development. This is thought to exist related to the growing independence in food choices and the high prevalence of dieting in this group.

Depression poly peptide intake is also a concern for the elderly in the U.Due south. The same 2018 study found that among those 71 years and older, 19 percentage of women and 13 percent of men consume less protein than the RDA. This is a particular concern in this historic period group, every bit loss of musculus is accelerated with crumbling, and that can lead to greater frailty, loss of balance, and greater risk of falls. Some researchers argue that older adults actually demand more than protein than recommended by the RDA in order to maintain musculus mass and function.

Wellness Consequences of Also Much Protein in the Diet

When the Nutrient and Nutrition Board of the Establish of Medicine wrote the DRI for macronutrients, published in 2005, they concluded that in that location wasn't plenty prove to establish an Upper Limit for protein. The high terminate of the AMDR, 35 percent of kilocalories for protein, was set in club to allow the full nutrition to be well-balanced with saccharide and fat. Higher levels of protein intake haven't been well-studied, just over the years, there have been many concerns with high protein diets. Nonetheless, current evidence indicates it's large amounts of animal protein (particularly from red meat or processed meats) that tin can be problematic, non high amounts of protein per se.

For case, a nutrition containing lots of steak, bacon, and sausage would be high in protein, only information technology as well might exist loftier in saturated fat, cholesterol, common salt, and nitrates. Eating more crimson meat and processed red meat is linked to an increased gamble of heart disease, stroke, and cancer (particularly colorectal, tummy, pancreatic, prostate, and breast cancers). This link doesn't seem to be caused by the protein merely rather the nutritional packet that it comes in. In addition, the link to cancer may exist related to the carcinogens that can form when meat is cooked at high temperatures, particularly when information technology'due south charred by grilling.

On the other hand, studies show that when protein comes from lean meat and plant sources, risk of chronic diseases may exist reduced. For case, a 2015 study found that frequent consumption of red meat in adolescence was associated with a higher risk of chest cancer afterwards in life, whereas consuming poultry, fish, legumes, and nuts instead lowered risk. Other studies accept shown that higher protein diets can reduce the chance of eye disease, provided the protein comes from healthier sources.

The image shows 4 different foods providing different protein packages, with nutritional information given below.

Fig. 5.3. Compare several different "protein packages." The steak and bacon provide protein but also large amounts of saturated fat and sodium. Salmon provides as much protein equally the steak but with less saturated fat and more polyunsaturated fats. Lentils are a good source of protein, are low in fat, and are a great source of fiber.

Several other concerns about loftier protein diets haven't turned out to be problematic later on all:

  • Osteoporosis - Loftier poly peptide diets were once thought to increase risk of osteoporosis, because researchers noticed that urinary calcium excretion increases when people consume high amounts of protein. All the same, a 2017 systematic review and meta-assay from the National Osteoporosis Foundation institute that this is not a business, and some studies fifty-fifty bear witness that higher protein intake is associated with greater bone mineral density.

  • Kidney function -  Some other business organization was that loftier protein diets would strain the kidneys because of the increased need to filter and excrete nitrogen. A 2018 meta-analysis ended that this is not a concern. However, people who already have chronic kidney disease should avoid high protein diets and maintain protein intake around the RDA of 0.8 yard/kg, a lower intake than many Americans are consuming. A 2009 study tested a very depression protein nutrition of 0.6 m/kg protein per day in people with chronic kidney disease and found that it did not prevent the development of kidney failure but did increase the take a chance of death, underscoring the importance of acceptable poly peptide fifty-fifty in people with kidney disease.

From all of this research, there'south footling evidence that a high protein nutrition is inherently harmful, and then long as the poly peptide doesn't come up packaged with a lot of saturated fat and ruby meat consumption is limited. Nonetheless, there's picayune research direct testing the health effects of very loftier protein diets, including those achieved using protein supplements of purified poly peptide, so it'due south probably wise to keep protein balanced with the other macronutrients, focusing on whole foods from all the nutrient groups.


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References:

  1. Lindshield, B. L. Kansas State University Human Nutrition (FNDH 400) Flexbook. goo.gl/vOAnR

  2. "Diseases Involving Proteins," department half-dozen.five from An Introduction to Nutrition (v. i.0), CC by-nc-sa iii.0

  3. Nutrient and Nutrition Lath & Constitute of Medicine. Dietary Reference Intakes for Free energy, Carbohydrate, Fiber, Fatty, Fatty Acids, Cholesterol, Poly peptide, and Amino Acids. 1359 pp. (The National Academies Press, 2005).

  4. Berryman, C. E., Lieberman, H. R., Fulgoni, V. L. & Pasiakos, South. M. Protein intake trends and conformity with the Dietary Reference Intakes in the United States: analysis of the National Health and Nutrition Test Survey, 2001-2014. Am. J. Clin. Nutr. 108, 405–413 (2018).

  5. UNICEF, "Malnutrition in Children - UNICEF Data," May 2018, https://data.unicef.org/topic/nutrition/malnutrition/, last accessed November 29, 2018.

  6. Traylor, D. A., Gorissen, Southward. H. M. & Phillips, Due south. M. Perspective: Protein Requirements and Optimal Intakes in Aging: Are We Ready to Recommend More the Recommended Daily Assart? Adv Nutr ix, 171–182 (2018).

  7. Harvard T.H. Chan Schoolhouse of Public Wellness. Poly peptide. https://www.hsph.harvard.edu/nutritionsource/what-should-you-swallow/poly peptide/#protein-inquiry, final accessed November xxx, 2018.

  8. Farvid, M. S., Cho, Eastward., Chen, Westward. Y., Eliassen, A. H. & Willett, W. C. Adolescent meat intake and breast cancer take chances. Int. J. Cancer 136, 1909–1920 (2015).

  9. Shams-White, M. M. et al. Dietary protein and os health: a systematic review and meta-analysis from the National Osteoporosis Foundation. Am. J. Clin. Nutr. 105, 1528–1543 (2017).

  10. Devries, K. C. et al. Changes in Kidney Function Do Non Differ betwixt Healthy Adults Consuming Higher- Compared with Lower- or Normal-Protein Diets: A Systematic Review and Meta-Analysis. J Nutr 148, 1760–1775 (2018).

  11. Menon, V. et al. Effect of a very low-protein diet on outcomes: long-term follow-up of the Modification of Nutrition in Renal Illness (MDRD) Study. Am. J. Kidney Dis. 53, 208–217 (2009).

Image Credits:

  1. Photo of Inuit families sharing walrus meat, past Ansgar Walk, https://eatables.wikimedia.org/wiki/File:Walrus_meat_1_1999-04-01.jpg, CC Past-2.0

  2. Photo of traditional Indian vegetarian meal, by GracinhaMarco Abundo, https://en.wikipedia.org/wiki/Indian_cuisine#/media/File:Vegetarian_Curry.jpeg, CC Past-2.0

  3. Photo of kid with kwashiorkor, Centers for Disease Control and Prevention, public domain, https://phil.cdc.gov/details.aspx?pid=6901

  4. Photo of child with marasmus, Centers for Illness Control and Prevention, public domain, https://phil.cdc.gov/Details.aspx?pid=1702

  5. Photo of sirloin steak by Steven Depolo, CC BY-2.0, https://flic.kr/p/9rc1i2

  6. Photo of bacon by Bradley Gordon, CC By-2.0, https://flic.kr/p/676bHJ

  7. Photo of salmon past Ketzirah Lesser and Art Drau, CC Past-SA 2.0, https://flic.kr/p/5UQ3B6

  8. Photo of lentils past Lucas Falcao, CC Past-NC-ND ii.0, https://flic.kr/p/G4yt11

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