Importance of Protein and Calcium in Bone Health

Protein Digestion in the Mouth: 

The first step in protein digestion is chewing, which mechanically breaks down large protein pieces into smaller pieces. Saliva aids in swallowing and the passage of partially mashed protein through the esophagus. Protein digestion primarily occurs in the stomach due to its acidic environment, which denatures proteins. Insulin is given through injections because it is a protein and would be denatured in the stomach if taken orally. 

Pepsin, an enzyme in the stomach, begins breaking peptide bonds, creating shorter polypeptides. Protein digestion takes longer than carbohydrate digestion. When we consume high-protein foods, they can feel heavy in the stomach due to the presence of hydrochloric acid (HCl). Proteins are converted into peptones and proteoses, and their digestion continues in the intestine with the enzyme trypsinogen, activated by enterokinase, converting it into trypsin. 

Proteins that aren’t fully digested in the small intestine pass into the large intestine and are excreted in the feces. Plant-based proteins are less digestible than animal proteins due to some proteins being bound in plant cell walls. Once amino acids are in the blood, they are transported to the liver, where they become part of the body’s amino acid pool. 

In critical conditions, supplements may be necessary, but direct interference with the body’s metabolism can sometimes cause harm rather than benefit. Therefore, it is advisable to use supplements only when needed. To use amino acids for energy production, glucose, or fat, nitrogen must first be removed in a process called deamination, which occurs in the liver and kidneys. The nitrogen is converted into urea and excreted in the urine, as excess ammonia is toxic to the body. 

Sources of Protein: 

According to the Dietary Guidelines for Americans 2015-2020, a healthy eating pattern includes a variety of foods containing protein. Both animal and plant foods can be excellent sources of protein. The guidelines classify the following foods as protein foods: 

• Seafood 
• Lean meats and poultry 
• Eggs 
• Legumes, which include beans and peas 
• Nuts and seeds 
• Soy products 
• Dairy products, such as milk, cheese, and yogurt 

Whole grains and vegetables also contain some protein, but generally less than other sources. Animal products tend to contain higher amounts of protein than plant foods. Therefore, individuals following a vegetarian or vegan diet may need to plan their meals carefully to ensure they meet their protein needs. 

Protein Deficiency: 

Protein-energy undernutrition (PEU), previously known as protein-energy malnutrition, is an energy deficit due to a deficiency of all macronutrients. It commonly includes deficiencies of many micronutrients. PEU can occur suddenly and completely (starvation) or gradually. 

When malnutrition occurs due to protein deficiency, it can affect a child’s height, weight, and overall growth. The child may either be in a wasted form, with a long height but low weight, or they may be underweight. Proper protein intake is crucial for supporting healthy growth and development in children. 

Symptoms and Treatment of Protein Deficiency: 

Protein deficiency can lead to various symptoms, including underweight, impaired brain development, decreased appetite, and low blood levels. To treat protein deficiency, it is important to provide adequate protein. A dosage of 1 gram of protein per body weight can be given, and in severe cases, up to 2 grams can be provided. Groundnuts, peas, milk, and leafy vegetables are excellent sources of protein. Meat and fish are also good sources for non-vegetarians. In severe cases such as kwashiorkor, where the entire body appears skeletal, protein supplementation is crucial. 

Hypercholesterolemia: 

Hypercholesterolemia is a condition that occurs in adults, characterized by high cholesterol levels. One of the reasons for this condition is a high intake of unsaturated fats and low protein intake. It is important to avoid excessive intake of oils and fats in such cases, as it can hinder protein absorption. Obesity can also be caused by inadequate protein intake, as excessive carbohydrate consumption can lead to weight gain. Inadequate protein intake can also lead to vitamin D deficiency, which can manifest as white spots on the skin. 

Recommended Dietary Allowances (RDA): 

The Recommended Dietary Allowances (RDA) represent the quantities of nutrients needed daily for maintaining good health and physical efficiency. The protein requirement varies with age, with growing children requiring about 2 grams per kilogram of body weight per day, compared to 1 gram per kilogram for adults. For adults, 0.8-1.0 grams of protein per kilogram of body weight per day is adequate. Pregnant and lactating women also have higher protein requirements. 

Prevention: 

Prevention strategies include educating people about the nutritional quality of common foods, the importance of breastfeeding, and the need for a balanced diet. It is also important to promote the consumption of milk, eggs, meat, or pulses to enhance dietary protein value. Additionally, early detection of malnutrition and intervention are crucial. Naturopathy also emphasizes reducing food intake during illness. 

Nutritional Supplementation: 

Nutritional deficiencies can often be attributed to a lack of knowledge rather than the cost of food. While some foods like peanut butter may be costly, peanuts themselves are affordable and nutritious. A simple calculation for nutritional supplementation includes 40 grams of whole wheat, 16 grams of chickpeas, 10 grams of groundnuts, and 20 grams of jaggery, totaling 86 grams. This amount may not be sufficient to fill your stomach, so it should be consumed three times a day. If your weight is over 60 kilograms, this amount can provide a satisfying meal. Consuming this mixture would provide approximately 11.3 grams of protein, showing that good protein can be obtained from raw sources. 

When we eat food, the body’s digestive system breaks down dietary protein into individual amino acids, which are then absorbed and used by cells to build other proteins and other macromolecules, such as DNA. 

Classification of Amino Acids: 

Essential amino acids are those that must be obtained from food, as the body cannot produce them. Non-essential amino acids are those that the body can synthesize on its own. While there is a large market for essential amino acids in supplements, 20% of amino acids in natural foods are essential amino acids. 

Recommended Dietary Allowances (RDA) in Indians: 

For a man performing sedentary work, moderate work, or heavy work weighing 60 kilograms, protein intake may vary. However, aiming for 60 grams of protein per day is generally sufficient. Calcium intake should be around 600 mg per day, and iron also plays a crucial role in metabolism. Consuming 60 grams of protein should ensure normal bodily functions, reducing the need for supplements. 

Functions of Structural Proteins: 

Structural proteins form components of connective tissue, bone, tendons, cartilage, skin, feathers, nails, hairs, and horns. They are mostly fibrous and insoluble in water. Examples include collagen, keratin, and elastin. 

Functions of Enzymes: 

Enzymes are biological catalysts that reduce the activation energy of reactions and speed up metabolic reactions in cells. Most enzymes are globular and conjugated proteins. Examples include DNA polymerase, nitrogenase, and lipase. 

Functions of Hormones: 

Hormones are proteinaceous and regulate various cellular functions. 

Functions of Respiratory Pigments: 

Respiratory pigments are colored proteins that contain pigments as their prosthetic group. Examples include hemoglobin and myoglobin. 

Functions of Transport Proteins: 

Transport proteins form channels in the plasma membrane and transport materials in cells. They are also components of blood and lymph. An example is serum albumin. 

Functions of Contractile Proteins: 

Contractile proteins are responsible for muscle contractions and work with ATP molecules. Examples include actin and myosin. 

Functions of Storage Proteins: 

Storage proteins store metal ions and amino acids in cells. They are found in seeds, eggs, and milk. Examples include ferritin, casein, ovalbumin, and gluten. 

Functions of Toxins: 

Toxins are toxic proteins, such as those found in snake venom. 

Introduction to Calcium: 

Calcium (Ca) is an essential mineral required for various bodily functions, including muscle contraction, nerve conduction, hormone release, and blood clotting. It is also crucial for several metabolic processes that require specific calcium concentrations. 

Sources of Calcium: 

Calcium is an important nutrient, with a daily intake requirement of approximately 1000 mg per day, roughly equivalent to the amount found in one liter of milk. It is widely distributed in food sources such as milk, cheese, egg yolks, fish, beans, lentils, nuts, and cabbage. A balanced diet can provide an adequate amount of calcium.