The main protein found in milk and other dairy products

Celiac disease
A disorder resulting from an immune reaction to gluten, a protein found in wheat and related grains, and present in many foods. Celiac disease causes impaired absorption and digestion of nutrients through the small intestine. Symptoms include frequent diarrhea and weight loss. A skin condition dermatitis herpetiformis can be associated with celiac disease. The most accurate test for celiac disease is a biopsy of the involved small bowel. Treatment is to avoid gluten in the diet.

Chemotherapy is the use of special medicines to treat cancer. They can be given alone, but often several chemotherapy drugs are combined to attack the cancer cells in different ways. The exact combination depends on the type of cancer and whether the cancer has spread to other parts of the body. These medicines are very powerful and sometimes get the normal cells, too. That's why people with cancer often lose their hair.

Cholesterol is a fatty substance (a lipid) that is an important part of the outer lining (membrane) of cells in the body of animals. Cholesterol is also found in the blood circulation of humans. The cholesterol in a person's blood originates from two major sources; dietary intake and liver production. Dietary cholesterol comes mainly from meat, poultry, fish, and dairy products. Organ meats, such as liver, are especially high in cholesterol content, while foods of plant origin contain no cholesterol. After a meal, cholesterol is absorbed by the intestines into the blood circulation and is then packaged inside a protein coat. LDL cholesterol is called "bad" cholesterol, because elevated levels of LDL cholesterol are associated with an increased risk of coronary heart disease. LDL lipoprotein deposits cholesterol on the artery walls, causing the formation of a hard, thick substance called cholesterol plaque. Over time, cholesterol plaque causes thickening of the artery walls and narrowing of the arteries, a process called atherosclerosis. HDL cholesterol is called the "good cholesterol" because HDL cholesterol particles prevent atherosclerosis by extracting cholesterol from the artery walls and disposing of them through the liver.

The microscopically visible carriers of the genetic material. They are composed of deoxyribonucleic acid (DNA) and proteins and, under a microscope, look like little rods. Humans normally have 46 chromosomes: 44 autosomes (nonsex chromosomes) plus XX sex chromosomes in the case of the female and XY sex chromosomes in the case of the male.

The part of the large intestine that runs from the cecum to the rectum as a long hollow tube that serves to remove water from digested food and let the remaining material, solid waste called stool, move through it to the rectum and leave the body through the anus. The colon measures about 5 ft (1.5 m) in length.

Colonoscopy is a procedure that enables an examiner (usually a gastroenterologist) to evaluate the appearance of the inside of the colon (large bowel). This is accomplished by inserting a flexible tube that is about the thickness of a finger into the anus, and then advancing it slowly, under visual control, into the rectum and through the colon. It is performed with the visual control of either looking through the instrument or with viewing a TV monitor.

Constipation means different things to different people. For many people, it simply means infrequent stools. For others, however, constipation means hard stools, difficulty passing stools (straining), or a sense of incomplete emptying after a bowel movement. Constipation can also alternate with diarrhea. This pattern is more commonly considered as part of the irritable bowel syndrome (IBS). At the extreme end of the constipation spectrum is fecal impaction, a condition in which stool hardens in the rectum and prevents the passage of any stool. The number of bowel movements generally decreases with age. The most common pattern is one bowel movement a day, but this pattern is seen in less than 50% of people. Medically speaking, constipation usually is defined as fewer than three bowel movements per week. Severe constipation is defined as less than one bowel movement per week. There is no medical reason to have a bowel movement every day. Going without a bowel movement for two or three days does not cause physical discomfort, only mental distress for some people. It is important to distinguish acute (recent onset) constipation from chronic (long duration) constipation. Acute constipation requires urgent assessment because a serious medical illness may be the underlying cause (e.g., tumors of the colon). Constipation also requires an immediate assessment if it is accompanied by worrisome symptoms such as rectal bleeding, abdominal pain and cramps, nausea and vomiting, and involuntary weight loss