Protein is the building block of life. During infancy, protein comes mostly from milk and dairy products. As people grow older, their diets become more varied, with protein obtained from both animal and plant sources. Non-vegetarian sources include eggs, fish and meat. Vegetarians obtain protein from legumes, lentils, nuts, seeds and dairy products.
Digestion of protein begins in the stomach and continues in the intestines. The protein is broken down into amino acids, absorbed into the bloodstream and transported to the liver. From there they are distributed throughout the body, where they are used to produce enzymes, hormones and other important molecules, and to repair and build muscles and tissues.
Consuming very large amounts of protein is not necessarily beneficial. The body cannot store excess protein. It is either converted into fat or excreted through the kidneys.
Too little protein may lead to muscle weakness, fatigue and slower recovery from illness. It can also produce brittle hair and nails.
Excessive protein intake, however, may be harmful for people with kidney disease, because the kidneys must work harder to remove the by-products of protein metabolism.
Protein requirements vary depending on age and activity level. Adults who lead largely sedentary lives need about 0.8gram of protein per kilogram of body weight per day. Active individuals and athletes may require between 1.2 and 2gram per kilogram daily. Older adults, particularly those aged 65 and older, may benefit from a slightly higher intake of 1 to 1.2gram per kilogram per day to maintain muscle mass and strength. Bodybuilders require about 1.6 to 2.2gram per kilogram per day. Ideally, protein intake should be distributed across three to six meals.
Athletes and bodybuilders sometimes consume a lot of eggs. While eggs are an excellent source of high-quality protein, the yolk also contains cholesterol (186mg/egg) and fat. Eating about three whole eggs a day is generally considered reasonable, while additional eggs can be consumed as egg whites, which provide protein without cholesterol.
Proteins make people feel full for longer. This has led to the popularity of high-protein diets that drastically reduce carbohydrates. However, carbohydrates are important for maintaining gut health because they support the growth of beneficial intestinal bacteria. A balanced diet consisting of roughly 30 per cent protein, 40 per cent carbohydrates and 30 per cent fat is probably best.
Gyms and sports shops are filled with protein powders, shakes and bars marketed for muscle building. Many contain whey protein derived from milk. While supplements may be useful in specific situations, it is generally healthier to obtain protein from natural foods.
Taking a supplement may seem like an easy route to fitness, but there is no shortcut to health. Building strength, endurance and muscle requires regular exercise and sensible nutrition. Supplements, if used, should be taken cautiously and can never replace the benefits of a balanced diet and physical activity.
The writer has a family practice at Vellore and is the author of Staying Healthy in Modern India. If you have any questions on health issues please write to yourhealthgm@yahoo.co.in