Your body uses inflammation to protect you from invading germs and to heal injuries. When a germ gets into your body, your immune system makes cells and proteins to kill that germ. As soon as the germ is gone, your immune system is supposed to dampen down and stop making large amounts of these cells and antibodies. If your immune system does not stop making excessive amounts of cells and proteins to kill germs, these same cells and proteins can attack you to cause "auto-immune" diseases such as rheumatoid arthritis and increase your risk for heart attacks, cancers, strokes, diabetes and many other diseases.
How Your Immune System Protects You
Your immune system protects you by:
• preventing invading germs (infections) from harming you
• healing damaged tissue when you are injured
• destroying cancer cells
• combating high blood sugar levels
Preventing Infections by Killing Invading Germs
You have no germs in your body before you are born, but soon after birth, bacteria start to grow everywhere on your skin surface, in your respiratory tract and in your entire digestive tract. Most of these germs are good for you and help in many different ways. They help you to digest and absorb nutrients from the food that you eat, and to eliminate waste products. They colonize the linings of your respiratory tract and intestines to help keep harmful germs from growing there.
Germs are not supposed to get into your bloodstream. When germs invade your bloodstream through breaks in your skin, intestinal tract or respiratory tract, your immune system recognizes that the germs' sugar-proteins are different from the sugar-proteins on your own cells. Your immune system produces proteins called antibodies that attach to and try to kill the invading bacteria or virus, cells that literally eat the invading germs, and cytokines that marshal your entire immune system to destroy harmful germs that are trying to invade your body. The visible signs of inflammation — redness, swelling, tenderness or soreness, fever — tell you that your immune system is working to combat an infection.
Helping to Heal Damaged Tissue
When you cut your skin, pull a muscle, break a bone or damage any part of your body, your immune system produces large amounts of the same cells and proteins that you use to kill germs to start the healing process. Anything that slows down your immune system also delays healing. While your injury is healing, you will notice the symptoms of your immune system in action — swelling, heat and pain — called inflammation, the same signs you see and feel when your body is fighting an infection.
Helping to Prevent Cancer
Every day, your body makes new cells to replace worn out and damaged cells. Normal cells live a certain number of days and then die. For example, normal red blood cells live 120 days and die. Normal skin cells live 28 days and die. Normal cells lining your inner lips live 24 to 48 hours and then die. Cancer means that a cell does not die and tries to live forever. For example, breast cancer does not kill when it stays in the breast, but breast cancer cells can become so numerous that they leave the breast and can kill you by traveling to and destroying your brain, your liver, your bones or any other vital organ. Each day your body make millions of cancer cells, but your immune system recognizes that the cancer cells are different from your normal cells and kills them the same way it kills germs. You develop cancer only when your immune system fails to kill the the cancer cells and they are allowed to multiply in your body. Cancer spreads when your immune system can no longer recognize that the spreading cancer cells are different from your normal cells.
Helping to Combat High Blood Sugar
When your blood sugar rises too high, sugar can stick to the outside membranes of cells throughout your body. Once there, it can never get off. The sugar is converted by a series of chemical reactions eventually to sorbitol that destroys that cell. Your immune system responds to these damaged cells by producing immune cells and proteins to rid your body of the damaged cells and chemicals that accumulate. Damaged cells in the liver can lead to diabetes, and removing the damaged cells helps the liver to heal and continue its function of controlling blood sugar levels.
Chronic Inflammation: When an Overactive Immune System Attacks Healthy Tissue
While you are fighting a cold or the flu or healing from an injury, you can expect to see the signs of your immune system in action, such as a fever, swelling and pain. When the job is done, those symptoms are supposed to go away. Chronic inflammation means that your immune system does not stop working, even though there are no germs that need fighting or injuries that need to be healed. Your immune system stays active and uses the same cells and proteins that kill germs to attack and damage your own healthy cells. Chronic inflammation can lead to:
• Heart attacks: The same immune chemicals that dissolve the outer membranes of bacteria can dissolve the inner linings of your arteries to punch holes in them and start the formation of plaques. A heart attack occurs when a plaque breaks off from the inner lining of an artery leading to your heart and clots form, which can prevent blood from reaching parts of your heart muscle. If you do not die during a heart attack, the part of your heart muscle that was deprived of oxygen dies and is replaced by scar tissue.
• Strokes: A stroke can occur when plaque breaks off from an artery leading to your brain, causing bleeding and then clotting that can eventually extend to block blood flow to the brain.
• Diabetes: One type of diabetes can occur when your immune system attacks and kills the beta cells of the pancreas that produce insulin. You develop diabetes because you lack insulin. Another type of diabetes can occur when your overactive immune system prevents your cells from responding to insulin, causing very high rises in blood sugar and insulin levels.
• Cancers: An overactive immune system can attack cells to damage the genetic material called DNA. The abnormal DNA allows cells that normally live for a limited time to try to live forever. If your immune system does not recognize and kill these cancer cells, they can spread to and damage other parts of your body.
• Auto-Immune Diseases: Specific diseases that appear to be caused by your own immune system attacking your own healthy tissues, and not just germs, are grouped together and called auto-immune diseases. Your overactive immune system can cause rheumatoid arthritis to destroy your joints and tendons, lupus to destroy your kidneys and other parts of your body, or many other auto-immune diseases such as dermatomyositis and scleroderma.
What Increases Risk for Chronic Inflammation?
Scientists have not worked out all the mechanisms, but anything that damages cells in your body can cause inflammation. That is why many unhealthful lifestyle habits appear to promote chronic inflammation:
• drinking too much alcohol
• being overweight
• lack of exercise
• exposure to excess sunlight
• vitamin D deficiency
• dietary factors: red meat, fried foods and sugar-added drinks and foods increase inflammation, while fruits and vegetables decrease it. See Anti-Inflammatory and Pro-Inflammatory Foods
Other sources of chronic inflammation include:
• exposure to X rays and other radiation
• exposure to harmful chemicals such as certain insecticides, herbicides or industrial chemicals
• a chronic infection anywhere in the body
How Exercise Reduces Inflammation
To make a muscle stronger, you have to exercise that muscle vigorously enough to feel burning in your muscle and damage muscle fibers. Then, when the muscle heals, it is bigger and stronger. Theoretically, damage to any cells in your body turns on your immune system and therefore can cause inflammation, but most studies show that exercise helps to prevent or reduce inflammation.
A major cause of inflammation is a high rise in blood sugar that causes sugar to stick to the membranes of cells and damage them. Exercise helps to control rises in blood sugar after meals and therefore helps to prevent inflammation. Your blood sugar rises after eating, and to prevent blood sugar from rising too high, your pancreas releases insulin which lowers blood sugar by driving sugar into your muscles and liver, the only places that store significant amounts of sugar in your body. When your muscles and liver are full of sugar, all extra sugar is converted to triglycerides that, in high levels, can damage every cell in your body and cause inflammation. Exercising prevents and treats inflammation by rapidly emptying sugar from your muscles and liver to prevent high rises in blood sugar and triglycerides.
More Reasons to Live Healthfully
I believe that everyone should try to develop healthful habits. A healthful lifestyle can reduce chronic inflammation and help you to avoid many diseases, and if you already have a disease, a healthful lifestyle can help you fight that disease and prolong your life. You may correct a faulty habit and still develop a related disease years later. For example, if you stop smoking, you are still at risk for smoking-related cancers for the rest of your life, but one year after you stop smoking, your risk for a heart attack is no greater than that of a non-smoker. The same lifestyle factors that increase your risk for heart attacks also increase risk for strokes, dementia, diabetes and many other diseases. Any scientific breakthrough that helps to prevent one disease will probably help to prevent other diseases also.