The human digestive tract, while living, measures approximately 20 feet long. Your mouth is the entrance, and your anus is the main exit. When you swallow foods or beverages, you also swallow air, which contains oxygen and nitrogen.

Iodine is a trace mineral that's usually found in the form of iodide. It's needed for your thyroid gland to make thyroid hormones called thyroxine and triiodothyronine. Iodine is also needed for your immune system and might help treat fibrocystic breast disease.

Digestion is the body’s process for breaking down foods that you eat. Some elements of these foods are used to produce energy and the remaining waste is prepared for excretion. Slow digestion can make you feel sluggish and may cause constipation. However, you can take a number of steps to naturally speed up digestion.

Spinach is a leafy green flowering plant that can be consumed in both raw and cooked forms. While consuming spinach in its raw state can often make it difficult to digest, the nutrients and vitamins that are preserved in this raw vegetable can actually help improve digestion in the long run.

Your digestive system is essentially one long tube that starts at your mouth and ends at your anus. Organs such as the stomach and large and small intestines digest and process the food you eat. Organs outside the digestive tract also play a part in digestion.

An estimated 30 to 50 million children and adults in the United States have a food intolerance condition called lactose intolerance, according to the University of Maryland Medical Center. People who are lactose intolerant are unable to digest milk and dairy foods properly due to the lack of an enzyme called lactase.

Everyone's bowel habits, including the frequency, shape and color of movements, are different. When your bowel movements suddenly change to a very dark color, you might become alarmed. Color changes can indicate health problems, but think first about your diet. A number of foods can turn bowel movements dark.

A bowel obstruction is the partial or complete blockage of areas of the small intestines, preventing food and digestive liquid from moving through. A bowel obstruction is caused by either something being in the way or because the intestinal muscles are not functioning properly, according to MedlinePlus.com.

Digestive upset, constipation, acid reflux and other gastrointestinal complaints are common during pregnancy. If you're pregnant and experience any of these symptoms, you might find yourself wondering if supplemental digestive enzymes could help alleviate your discomfort.

According to the University of Michigan Health System, digestive enzymes are complex proteins that work to maintain pH balance and digestion in the human body. According to the University of Maryland Medical Center, a lack of digestive enzymes is caused by injuries to the small intestine or digestive diseases.

Grapes are a a common type of berry fruit that have been included in cooking and wine for centuries.

Some fruits are good for digestion because they provide fiber that keeps the gastrointestinal tract in good working order. They also contain enzymes that break down hard-to-digest proteins.