Digestion

Digestion – Breakin’ It Down

Ok.  This is where it all begins, I guess.  If you can’t properly digest what you ingest then what you eat doesn’t really have much nutritional value for your body.  Digestion begins in the mouth and ends in the small intestines and then absorption occurs.  Sounds simple, right?  Let’s break it down.

The Mouth

Digestion starts in the mouth.  Saliva contains chemicals which start the process, but first you must masticate (sounds like it would be embarrassing if you were caught doing it, but it actually means “chew your food”).  Chewing your food flattens it out, tears it apart into smaller pieces and allows the enzymes in your saliva to start the process of  breaking down the carbohydrates.  This is a very important step in the digestive process, so masticate as much as you can before swallowing!

The Stomach

The next step is in the stomach.  Here, gastric acid (hydrochloric acid + potassium chloride + sodium chloride) is released to kill most contaminating bacteria and start breaking down some food.  Gastric acid, being acidic, has a low pH of about 1 or 2, which allows digestive enzymes to do their job (remember they break down food to ready it for absorption?).  After 1 or 2 hours, the food becomes a thick liquid called chyme.  Then the great stuff you need from your food moves on to the small intestine for absorption; all in good chyme. 🙂

The Small Intestine

Approximately 95% of absorption of nutrients in food happens in the small intestine.  The small intestine measures about 6 metres (19 feet).  The pancreas and liver release digestive juices into the small intestine (juices from the liver are actually stored in the gallbladder before they are released).  These juices degrade the chyme even further and then carbohydrates, proteins, fats, vitamins, water and salt are absorbed through the walls of the small intestine.

So What Happens to the Good Stuff?

Carbohydrates = Energy (either used up or stored as fat)

Carbohydrates are found in almost all the foods we eat. Carbohydrate rich foods include bread, potatoes, dried peas and beans, rice, pasta, fruits, and vegetables.  There are two types of carbohydrates, digestible and undigestible.  The digestible carbohydrates are starches and sugars.  The undigestible carbohydrates are fibre.

Starches are broken down in a two step process.  First an enzyme in the saliva and digestive juices from the pancreas break it down into maltose.  Then another enzyme degrades it even further into glucose that is absorbed into the blood.  The blood takes it to the liver and it is either used as energy for body functions or stored for use later.

Degrading of sugar happens in one step. An enzyme in small intestine breaks down sucrose (you may know it as table sugar) into glucose and fructose.  Again, this goes directly into the blood. In milk the process is slightly different as there is another kind of sugar called lactose.  It gets transformed into absorbable molecules by a different enzyme in the lining of the small intestine.

As mentioned above, fibre cannot be digested.  There are two kinds of fibre, soluble and insoluble. and moves through the digestive tract without being broken down by enzymes. Soluble fibre dissolves in water into a soft jelly in the intestines and insoluble fibre just passes through the intestines unchanged for the most part.

Protein = Work Horse of the Body

Proteins are crazy little things!  They perform so many tasks in the body, even though we associate them most commonly with building muscle.  Here is a list of some of their functions:

• Contributing to enzyme activity that promotes chemical reactions in the body
• Signaling cells what to do and when to do it
• Transporting substances around the body
• Keeping fluids and pH balanced in the body
• Serving as building blocks for hormone production
• Helping blood clot
• Promoting antibody activity that controls immune and allergy functions
• Serving as structural components that give our body parts their shapes

So, where do we get protein? From foods such as meat, eggs, and beans.  These foods are made up of huge molecules of protein and must be torn apart by enzymes into peptides and then into amino acids.  Once absorbed, they can then be used to for the functions listed above.

Fats = Energy & Nutrient Storage

Fat stores energy & nutrients for the body to use in times when you don’t have food.  It also protects organs in the body and acts as an insulator against cooler temperatures.  The body uses fats for making steroids and hormones that regulate growth and maintenance of tissue.

Fat is dissolved into the watery content of the intestine by the bile acids produced by the liver.  The fat breaks down into tiny droplets and then the pancreatic and intestinal enzymes degrade the large fat molecules into smaller ones. Some of these small molecules are fatty acids and cholesterol which combine with the bile acids and help these molecules move into the cells of the mucosa (mucous membrane). The small molecules are then formed back into larger ones, most of which pass into vessels called lymphatics. Lymphatics carry the fat to the veins of the chest, and blood carries the fat to storage deposits in different parts of the body.

Vitamins

Another vital part of food that is absorbed through the small intestine are vitamins.

Vitamins promote normal growth, provide proper metabolism, ensure good health and protect against certain diseases. Vitamins are required by the body in small amounts for metabolism, to protect health, and for proper growth in children. They assist in the formation of hormones, blood cells, nervous-system chemicals, and genetic material. Vitamins mainly serve as catalysts for certain reactions in the body. They combine with proteins to create metabolically active enzymes that in turn produce hundreds of important chemical reactions throughout the body. The fundamentals of cells depend greatly upon vitamins. Vitamins are responsible for keeping cells strong, binding tissues, fighting infections, etc. Without vitamins our cells would not function properly and thus our organs would suffer and eventually we would no longer be able to survive. Vitamins help regulate metabolism, help convert fat and carbohydrates into energy, and assist in forming bone and tissue.

There are two types of vitamins: water-soluble vitamins (all the B vitamins and vitamin C) and fat-soluble vitamins (vitamins A, D, E, and K). Fat-soluble vitamins are stored in the liver and fatty tissue of the body and may become toxic in the body if one takes too much.  Water-soluble vitamins are not easily stored and excess amounts are flushed out in the urine, so do not pose any danger.

Water and Salt

Most of the material absorbed through the small intestine is water in which salt is dissolved. The salt and water comes from the food and liquid you swallow and the juices secreted by the many digestive glands.

The Least You Need to Know

1) Masticate a lot and eat slowly.

• Take smaller bites and chew thoroughly.  You will actually feel the saliva increase in your mouth and mix with the food.
• Take at least a half hour to finish your meal; chat it up at the table with family and friends to enjoy your meal even more.
• Pay attention to the taste and smells of the food as you put it in your mouth and while you chew.

2) Drink plenty of water.

• Drinking a glass of water before a meal aids digestion, as the small intestine uses the water in its processes.
• Keep drinking water throughout the day; 8-10 glasses (3 litres) a day should be enough for the average Joe.
• Lack of water can cause constipation.

3) Eat more fibre!!

• It helps clean out the intestines.
• It reduces sugar uptake into the blood stream, thereby reducing insulin spikes, thereby reducing the risk of diabetes
• It reduces the risk of heart disease, the incidences of infectious and respirator illnesses, and some cancers
• It will extend your life!  It has been reported by Archives of Internal Medicine in February 2011 that consuming enough fibre can extend your lifespan by up to 9 years!  Wowzers!

4) Increase the amount of good bacteria in your gut.

• Eat more good quality, organic yogurt with active cultures that are added after pasteurization.  Pasteurization kills off both helpful and harmful bacteria.
• Eat fermented foods such as kefir (I’ll be expanding on kefir in another post), sauerkraut, kimchee, etc.
• Take a probiotic supplement that you can buy at health food stores and many supermarkets, such as Bio-K.

5) Make sure you attend to any food allergies you may have.

• Food allergies can interfere with the digestive process and can result in bloating, gas and abdominal pain.
• If lactose intolerant, kefir and raw milk (if it is available in your area) are often tolerable and are a great source of calcium and extra protein and vitamins.