Whey protein is a liquid constituent of cow's milk. Dairy whey is a by-product of cheese made from cow's milk which is filtered to remove the fat and lactose. This liquid whey is then dried and converted into a powdered form. The powder has a pleasant taste and is easily absorbed by the body. There are three different types of whey protein; whey protein concentrate (WPC), whey protein isolate (WPI), and hydrolyzed whey protein. It is the ultimate and the richest source of protein available. A complex protein, whey consists of many smaller protein subfractions like immunoglobulins (IgGs), glycomacropeptides, alpha-lactalbumin, beta-lactoglobulin, bovine serum albumin (BSA) and minor peptides such as lactoperoxidase, lysozyme and lactoferrin. Each of these protein fractions have their own unique health benefits. This protein has a high biological value rating and is a priority for many modern-day athletes. There has been a strong debate over the side effects of whey protein. Although there is no scientific evidence to prove its negative effects, experts insist that there can be some risk factors involved in its consumption. Some of its side effects are listed below. Diarrhea and vomiting in infants Fatigue Loss of appetite Headache Swelling and cramps Increased stool frequency Bloating Thirst A few allergic reactions seen in people who are allergic to lactose (as whey is manufactured from cow's milk) are rashes, itching, wheezing and difficulty in breathing, and swelling of mouth, throat or lips. Such people should always consult a doctor before incorporating whey into their diet. According to some experts, long-term and excessive intake of this protein can cause kidney deterioration. Excessive protein in the blood reduces the kidney's metabolism rate and makes the blood acidic. Though there isn't any research that supports this idea, many experts believe that there is a risk of kidney damage. Calcium is used to reverse the effects of blood acidity, but due to excessive intake of whey protein, calcium may get deposited on the kidney which leads to the formation of kidney stones. Experts also believe that excessive intake of whey can cause liver damage, as the ketone level in the blood increases and causes stress on the liver. They have also warned that too much intake of this protein can cause osteoporosis, which can lead to joint problems in the long run. Depending upon your body weight, protein intake varies from person to person. Generally, it is recommended to have one gram of whey protein per pound of body weight. However, a bodybuilder can consume 150 grams of whey protein per day. Some of its health benefits are given below. Increases lean muscle mass Helps in weight loss or fat loss Strengthens immunity by increasing the glutathione levels in the body Beneficial in treating high cholesterol Helps HIV/AIDS-infected people to gain weight Helps in treating asthma Helps in preventing cancer, especially breast cancer It is used in infant formulas and acts as a source of nutrition for people with lactose intolerance. For individuals suffering from any kind of chronic or medical problems and allergies, it is advisable to consult a health care provider before consuming whey protein. Due to its high nutritional benefits and taste, whey protein can be consumed by people of all ages. But one shouldn't forget that excess of anything is bad.