Macronutrients Series- Proteins. A Detailed Guide to Functions, Benefits and Effects on Aging.

What does research say about proteins intake and what happens with aging?

[dropcap]I[/dropcap]f you’ve ever read a health article or seen a fitness advertisement on television, you’ve undoubtedly heard protein mentioned in relation to a healthy diet. Protein is important to our bodily functions and wellness. To what end, though, do we use it? Read on to find out how and why you should include protein in your diet.

Proteins are huge, complex molecules that serve several essential functions throughout the body. They are very important for the development, maintenance, and control of all bodily tissues and organs and account for the vast majority of cellular activity.

Each protein organic molecule is composed of 300 or more of the 20 distinct amino acids found in plants and animals, with the exact amount and order being specific to each protein. Substantial quantities of amino acids are bonded end to end to form proteins. The strands fold up to create three-dimensional molecules with intricate structures; you might compare it to folding origami with a very long and thin sheet of paper. The particular structure of each protein and the amino acids it contains define its function. The final structure and hence its function, such as its ability to serve as a muscle or an enzyme, is determined by the particular amount and sequence of these acids.

Therefore, the two forms of protein in the body are amino acids that are not required and amino acids that are essential.

  • Non-Essential Amino Acids: The human body produces these naturally.
  • Essential Amino Acids: Since the human body cannot synthesize them, they must be ingested through diet or supplements.
Essential amino acids Conditionally essential amino acids Nonessential amino acids
  • Histidine
  • Isoleucine
  • Leucine
  • Lysine
  • Methionine
  • Phenylalanine
  • Threonine
  • Tryptophan
  • Valine
  • Arginine
  • Cysteine
  • Glutamine
  • Tyrosine
  • Alanine
  • Asparagine
  • Aspartic acid
  • Glutamic acid
  • Proline

When a protein has taken its proper form, it can bind to certain molecules to perform its intended function.  It’s probable that this function is related to signaling, storing, transporting, providing structure, repelling invaders, catalyzing reactions, or something else entirely.

Functions Of Proteins.


Each of the hundreds of proteins that make up our body has a unique purpose. They constitute the structural components of our cells and tissues as well as numerous enzymes, hormones, and immune cell-secreted active proteins. Following are the functions of proteins that are described and studied in various researches,

  1. Structural component: Proteins having a fibrous structure provide cells and tissues with their structure and rigidity. Cells rely on these proteins for structure and support. They also facilitate movement on a wider scale within the body. These proteins include keratin, collagen, and elastin, which contribute to the formation of the connective framework of many bodily structures. Such as,
  • Keratin is found in your nails, hair, and skin providing strength.
  • Collagen is the most abundant protein in your body, providing benefits in bones, tendons, and ligaments.
  • Elastin, the most flexible protein, makes many of your body’s tissues, including the uterus, lungs, and arteries, spring back to their normal size and form after being stretched or contracted.

2. Transporters. These proteins function as molecular messengers such as hormones, transporting molecules and atoms within cells and between tissues. Most hormones are proteins and peptides category, with the following types in the body. 

  • Insulin: Signals glucose or sugar absorption into the cell.
  • Glucagon is a hormone that signals the breakdown of glucose in the liver. hGH (human growth hormone) stimulates the development of several tissues, including bone.
  • ADH (antidiuretic hormone) instructs the kidneys to reabsorb water
  • ACTH (adrenocorticotropic hormone) Stimulates the secretion of cortisol, an important metabolic component.

3. They Are Enzymes. The hundreds of biological events that occur within and outside of your cells rely on proteins called enzymes. They play a huge role as researched in digestion, blood clotting, muscle contraction, and energy production. In addition to reading the DNA, they help build new molecules based on its instructions. Insufficiency or dysfunction of enzymes can lead to illness.

4. Streamlines Growth. Throughout our lifetimes, they are continuously replaced and maintained. In order to do so, we require a constant supply of amino acids, which we obtain from dietary protein. As a routine, your body will utilize the same amount of protein to break down as it will use in tissue repair and growth. At times of illness and other medical conditions (pregnancy, breastfeeding, etc.), though, it degrades more protein than it can produce, raising the bar for what your body requires.

5. Fluid Balancing. Proteins in the blood, such as albumin and globulin, aid in the regulation of bodily fluids by collecting and conserving water. Lack of these proteins in the diet leads to a decline in albumin and globulin which consequently causes loss of water in the body. Edema, or swelling, happens as fluid continues to accumulate in the gaps between your cells, most noticeably in the abdominal area. This condition is known as kwashiorkor (an insufficient protein intake despite an adequate caloric intake).

6. Act as Antibodies. Antibodies play an important role in the immune system by recognizing and binding to harmful invaders like viruses and bacteria and fighting to eradicate the disease. The information is stored in cells whenever such pathogens again attack the body. Because of this, your immune system strengthens and you become resistant to the diseases to which you are exposed.

7. Maintains pH Levels. Any fluctuation in pH, however little, can cause serious problems or even death. That is why the levels of acids and bases in your blood and other body fluids are closely regulated by proteins. Hemoglobin, a protein found in red blood cells, serves as an example. The normal pH of your blood is maintained in part by the hemoglobin in your red blood cells, which binds very minute amounts of acid. Other examples include bicarbonate and phosphate.
proteins function in body

Proteins are vital to the body’s correct functioning and play important roles in a wide variety of biological activities.

Maintains Weight loss: Many people who increase their protein consumption tend to lose weight very immediately because a high-protein diet increases metabolism and causes an automatic reduction in calorie intake and cravings. (1) Researchers showed that overweight women who consumed 30% of their daily calories from protein were able to shed 11 pounds (5 kg) in only 12 weeks without making any other dietary changes.

Research conducted on 130 overweight individuals found that those assigned to the high-protein diet shed 53% more fat than those assigned to the normal-protein diet, despite both groups ingesting the same number of calories over the course of 12 months. Studies have indicated that keeping the same weight while eating more protein can benefit. One research found that a rise in protein intake from 15% to 18% of calories resulted in a 50% decrease in weight regain.

Maintains MusclesMuscle weakness is a natural part of becoming aging.  Age-related sarcopenia, the most severe form, is a leading cause of weakness, bone fractures, and poor quality of life in the elderly. One of the greatest approaches to delay sarcopenia (muscle loss associated with aging) as per research is to increase your protein intake.

It’s a Filler: It is recommended that those who wish to reduce their weight and abdominal fat increase their protein intake and reduce their carbohydrate and fat intake respectively. Protein, according to the research, is the most satiating macronutrient. You might feel fuller after eating less. The hormone ghrelin is responsible for part of this effect by reducing your hunger. Peptide YY, a hormone that helps you feel full, also has increased its levels.  Those are some potent appetite suppressants. Overweight women in the research were able to reduce their daily calorie consumption by 441 calories simply by increasing their protein intake from 15% to 30%.

Controlling Cravings: Controlling your food cravings isn’t always easy. But it is possible with the help of increasing protein intake. One research found that boosting protein to 25% of calories decreased cravings by 60% and the tendency to eat at night by 50% among overweight men. Similarly, research with overweight adolescent females found that consuming a high-protein breakfast decreased appetite and late-night snacking. This happens due to dopamine, one of the main brain chemicals linked to cravings and addiction, influencing it.

Reduces Blood Pressure: Increasing one’s protein consumption offers a surprising benefit: reduced blood pressure. A high-protein diet has been shown to decrease LDL (bad) cholesterol and triglycerides in addition to decreasing blood pressure. Another meta-analysis of 40 randomized controlled studies found that eating more protein reduced both systolic (the top number) and diastolic (the bottom number) blood pressure by an average of 1.76- and 1.15-mm Hg, respectively.

Boost Metabolism: Researchers have shown that eating a lot of protein dramatically increases metabolic rate and calorie burning up to 80-100 more calories burned each day. (1) (2) It can be due to the high thermic effect of proteins. One research found that people who consumed more protein burned an extra 260 calories daily. That’s the same as doing 60 minutes of light exercise every day.

Good For Bones: There is a widespread misunderstanding that protein, especially animal protein, is harmful to bone health. However, the vast majority of long-term research shows that protein, especially animal protein, offers significant advantages for bone health. (1) (2) High-protein diets have been linked to reduced risk of osteoporosis and fractures in older adults.

Builds Muscles: If you’re trying to gain muscles, lift weights, or engage in other physically demanding activities, you need to increase your protein intake. Eating a high-protein diet has been shown in a wide variety of studies to promote muscle growth and strength gains. (1) Maintaining a high protein intake can also assist in avoiding the atrophy of muscle tissue during weight loss.

How Much Protein Is Required?

For both women and men, the DRI (Dietary Reference Intake) for protein is 46 and 56 grams, respectively. The recommended dietary allowance (RDA) for protein, as determined by the Institute of Medicine is as follows,

Life stage and gender RDA in grams (g) per day
Infants and children
0–6 months 9.1
6–12 months 11.0
1–3 years 13.0
4–8 years 19.0
9–13 years 34.0
14–18 years 52.0
19–70 years and older 56.0
9–13 years 34.0
14–70 years and older 46.0
Pregnant or breastfeeding women
All ages 71.0


A protein intake of 180–630 calories per day is recommended for someone consuming 1,800 calories daily.

Consuming more than 2g of g / kg body weight on a regular basis has been linked to an increased risk of kidney stones, heart disease, and gastrointestinal issues.  According to a study published in Public Health Nutrition, Americans often consume more protein than is recommended for their daily needs.

Eating a wide variety of foods makes it simple to consume enough protein. Food protein sources include both plant and animal products, such as (1) (2):

Food Sources  Protein Content in serving/g/ounces
  1. Chicken Breast 
31.4g/ 100g
2. Turkey Breast 30.1g/ 100g
3.  Cottage Cheese  28g/ cup
4. Salmon Fish 25.3/ 100g fillet
5. Lean Beef 24.6/100g
6. Shellfish/Shrimps 21.8 and 20.4/ 3 ounces
7. Chia Seeds 16g/ 100g
8. Greek Yogurt 19g/ 200g serving
9. Lentils  11.4g/ cup
10. Oats 10.9g/ 100g
11. Milk 8.32g/ cup
12. Tofu 8g/100g
13. Quinoa 8 g/ cup
14. Peanuts 7.3g/ ounce
15. Egg 6.3g / 50 g egg

sources of proteins

These are the true sources of protein, and how to incorporate them into your diet is discussed here. If you find it difficult to get enough protein, perhaps taking a protein supplement may be helpful. How can you utilize it in your diet? Let’s have a look at our article here.

Proteins & Aging.

With aging, the amount of protein present in the body also decreases at age 70, this rate has decreased to 20% or less as compared to the normal composition of 30%.

Changes that are associated with protein synthesis are.

Muscle loss: According to studies, beyond the age of 30, adults experience a gradual loss of lean muscle mass at a rate of 3%-8% every decade. Sarcopenia is the gradual decrease of muscle mass that comes with advancing age. It has been linked to weakening, movement problems, and even falling. It has also been studied that a lack of protein can lead to an increase in mortality, overall frailty, weariness, and a decline in muscular strength among the elderly.

Researchers estimate that adults between the ages of 60 and 70 have lost 12% of their muscle mass, while those older than 80 have lost 30%.

Fat Accumulation: According to a study showed that age-related muscle loss is commonly accompanied by an increase in fat storage up to 13.8% to 27.6%

Loss of Elasticity: Researchers have discovered that a certain type of collagen protein, COL17A1, is essential for the preservation of youthful skin, as reported in a publication published in Nature. This study states that, as we age, our skin produces less of this protein, which leads to wrinkles, sagging, and a loss of elasticity.

Alzheimer’s: Proteins gradually lose their function; thus, they must be regenerated frequently. Our ability to recycle worn-out proteins declines with aging. Abnormal proteins can accumulate and become hazardous if our bodies are unable to dispose of them. Among the hallmarks of Alzheimer’s disease is the buildup of proteins, specifically beta-amyloid proteins, which clump together in the brain and cause the death of neurons.

Since a lot of the weight that the elderly lose is a muscle, many of them find that taking protein smoothies and other protein supplements helps.

Signs of Low and High Proteins level. 

Proteins play a crucial role in maintaining and fostering cellular and tissue growth. Too much or too little protein might result in unexpected weight loss, exhaustion, or inflammation. The quantity of protein in your blood can be determined by taking a total protein test, which can be prescribed during a typical physical exam, a physician as part of a comprehensive metabolic panel (CMP).  The total protein test can assist in the diagnosis of liver and renal disorders as well as other ailments.

The normal range for protein concentrations ranges between 6 – 8 grams per deciliter. This is comprised of 3.5 to 5.0 g/dl of albumin and the remainder of total globulins.

Protein Insufficiency. 

When a person does not consume enough protein, they are said to be suffering from protein insufficiency. Muscle loss and other slow-moving changes in body composition have been linked to inadequate protein intake. True protein insufficiency is rare in the Western world, but some people get very little of it through their diet. The worst case of protein deprivation is kwashiorkor. Famine and poor diet play a major role in its prevalence among youngsters in poor countries.

Signs & symptoms of Hypoproteinemia, include,

  • The skin may become red, flaking, and hypopigmented if your protein intake is extremely low. Nail breakage and hair loss are other possible side signs.  According to a study published in the Indian Dermatology Online Journal in 2019, hair loss, acne, melasma, and accelerated ageing are among the skin and hair problems associated with a protein consumption of less than half the RDI.
  • In an effort to compensate for insufficient protein, the body stimulates hunger, making it more likely that you will seek out food.
  • Swelling originates from plasma protein levels being too low, namely human serum albumin.
  • Protein deficiency, even minimal, can lead to muscle loss, especially in the elderly.
  • One of the most noticeable effects of a disease due to protein deficiency is a decrease in immune function, which can lead to an increase in the frequency or severity of illnesses. Keeping to a low-protein diet for nine weeks greatly lowered the immunological response in one research of elderly women. For this reason, protein deficiency may have a negative impact on wound healing, delaying the process by which damaged cells are restored and the body is returned to a healthy state.
  • Fatty Liver develops, A deficiency in the creation of fat-transporting proteins, known as lipoproteins, may contribute to the illness, according to research.
  • The risk of bone fractures is increased if protein intake is inadequate.
  • Observational research suggests a substantial relationship between inadequate protein consumption and stunted development.
Over Intake of Protein.

Daily intake of 0.8 g of protein per kilogram of body weight, or 0.36 g per pound, is suggested by the Dietary Reference Intake report for micronutrients. Because eating too much protein is bad for your health, this can lead to hyperproteinemia,

  • In most cases, eating too much protein won’t cause any issues, but if you keep it up for a while, you may end up dehydrated as your kidneys work harder to excrete it and nitrogen waste through urine. This increases toilet visits and dehydration risk.
  • Particularly if you’re cutting back on carbs, eating a lot of protein might make your breath smell unpleasant.
  • Overloading your liver with protein over a lengthy period of time might impair its function.
  • Consuming a high-protein diet was shown to raise one’s chance of having heart failure by 33%, according to a study conducted by scientists at the University of Eastern Finland.
  • Weight gain is associated with an over intake of proteins,
  • Low-carbohydrate, high-protein diets may accelerate bone mineral loss. This is a condition that is occasionally linked to brittle bones and osteoporosis.

The recommended daily intake of protein varies with age, gender, level of physical activity, overall health, and other factors. A high-protein diet may have positive effects on health in otherwise healthy people, what are the benefits of it? Learn here.

However, if you follow a very high-protein diet for a lengthy period of time, it is essential that you be aware of the health issues associated with excess proteins in the body.

You wouldn’t be you without the work of at least 10,000 distinct proteins working together to keep you in perfect shape. Muscle, bone, skin, hair, and pretty much everywhere else in the body all contain protein.








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Dr Aimen

Being a Doctor by profession, Aimen is passionate about helping people get better health in their lives. Aimen enjoys her research on Prime With Time subjects and strives to create better awareness of the problems and changes related to women's health.
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