The immune system – which is made up of special cells, proteins, tissues, and organs – defends people against germs and microorganisms every day. In most cases, the immune system does a great job of keeping people healthy and preventing infections. But sometimes problems with the immune system can lead to illness and infection.
Components of the Immune System
The most obvious part of the immune system is what you can see. For example, skin is an important part of the immune system, since it acts as the primary boundary between germs and your body. Skin is tough and generally impermeable to bacteria and viruses.
Your nose, mouth and eyes are also obvious entry points for germs. Tears and mucus contain an enzyme (lysozyme) that breaks down the cell wall of many bacteria. Saliva is also anti-bacterial. Since the nasal passage and lungs are coated in mucus, many germs not killed immediately are trapped in the mucus and soon swallowed. Any bacteria or virus that wants to gain entry to your body must first make it past these defenses.
Once inside the body, a germ deals with the immune system at a different level. The major components of the immune system are:
- Lymph system
- Bone marrow
- White blood cells
- Complement system
Types of Immunity
Humans have three types of immunity — innate, adaptive, and passive:
- Innate Immunity: Innate (or natural) immunity is the basic protection our bodies provide. This includes the body’s external barriers to germs and disease (the skin and mucous membranes), which are the first line of defense. If this outer defensive wall is broken (as through a cut), the skin attempts to heal the break quickly and special immune cells on the skin attack invading germs.
- Adaptive Immunity: Adaptive (or active) immunity develops throughout our lives. Adaptive immunity involves the lymphocytes and develops as people are exposed to diseases or immunized against diseases through vaccination.
- Passive Immunity: Passive immunity is “borrowed” from another source and it lasts for a short time. For example, antibodies in breast milk provide babies with temporary immunity to diseases the mother has been exposed to.
Everyone’s immune system is different. Some people never seem to get infections, whereas others seem to be sick all the time. As people get older, they usually become immune to more germs as the immune system comes into contact with more and more of them. That’s why adults and teens tend to get fewer colds than kids — their bodies have learned to recognize and immediately attack many of the viruses that cause colds.
Problems of the Immune System
Disorders of the immune system fall into four main categories:
- immunodeficiency disorders (primary or acquired)
- autoimmune disorders (in which the body’s own immune system attacks its own tissue as foreign matter)
- allergic disorders (in which the immune system overreacts in response to an antigen)
- cancers of the immune system
For more information about vaccines and antibiotics and how they play a role in your immune system, click here.
What Affects Immunity
Much like soldiers who grow weary in battle, your immune cells can also lose some of their protective effects when your body is constantly battling poor health habits. As such, it’s not surprising that doctors frequently recommend certain lifestyle changes as a way to optimize the function of your immune system. One of the most important steps someone can take to help the immune system is to achieve balance and adopt the fundamentals of healthy living. This includes reducing stress, as there is ample evidence that stress negatively impacts one’s health. Lowering stress can help the body maintain both physical and emotional health.
Nutrition and diet
The functioning of the immune system, like most systems in the body, is dependent on proper nutrition. It has been long known that severe malnutrition leads to immunodeficiency, while receiving too many nutrients can lead to diseases such as diabetes and obesity.
Specific foods may also affect the immune system; for example, fresh fruits, vegetables, and foods rich in certain fatty acids may foster a healthy immune system.
Antioxidants and immune health
One of the best ways to keep your immune system strong and prevent colds and flu might surprise you: Shop your supermarket’s produce aisle. Experts say a diet rich in fruits and vegetables can help you ward off infections like colds and flu. That’s because these super foods contain immune-boosting antioxidants.
What are antioxidants? They are vitamins, minerals, and other nutrients that protect and repair cells from damage caused by free radicals. Many experts believe this damage plays a part in a number of chronic diseases, including hardening of the arteries (atherosclerosis), cancer, and arthritis. Free radicals can also interfere with your immune system. So fighting off damage with antioxidants helps keep your immune system strong, making you better able to ward off colds, flu, and other infections.
A diet rich in antioxidant vitamins and nutrients can boost immunity to help fight infection. Researchers believe that when the balance between free radicals and antioxidants is upset, it can contribute to developing cancer and heart disease, as well as age-related diseases.
For additional information about antioxidants and free radicals, click here.
Things that can zap your Immune System
Lack of exercise: Studies show that regular, moderate exercise – like a daily 30 minute walk – can help your immune system fight infection. When you’re a non-exerciser, your risk of infections – such as colds — increases. Also, a sedentary lifestyle can interfere with sleep quality at night and can lead to obesity and other problems that increase your risk of illness. Getting your heart rate up for just 20 minutes just three times a week is associated with increased immune function, and a brisk walk five days a week can help reduce your risk of catching a cold.
Being overweight: Studies show that being overweight or obese can impair the immune system. For example, studies have shown that obese and overweight mice make fewer antibodies after receiving common vaccinations. Antibodies are a measured immune response to vaccination.
Eating foods high in sugar and fat: Consuming too much sugar suppresses immune system cells responsible for attacking bacteria. Even consuming just two 12-ounce sodas reduces the ability of white blood cells to overpower and destroy bacteria. This effect is seen for at least a few hours after consuming a sugary drink. A diet high in saturated fat has a similar effect.
Experiencing constant stress: While short-term stress may actually boost the immune system – the body produces more cortisol to make “fight or flight” possible – chronic stress has the opposite effect. It makes you more vulnerable to illness, from colds to serious diseases. Chronic stress exposes your body to a steady cascade of the stress hormones cortisol and adrenaline, which suppress the immune system.
Fatigue increases your susceptibility to illness: You’re more likely to catch a cold or other infection when you’re not getting enough sleep. Like stress, insomnia can cause a rise in inflammation in the body – possibly because lack of sleep also leads to an increase in the stress hormone cortisol. Although researchers aren’t exactly sure how sleep boosts the immune system, it’s clear that getting adequate amounts – usually 7 to 9 hours for an adult – is essential to good health.
Being socially isolated: Having strong relationships and a good social network is important to your physical health as well as your mental health – and specifically your immune system. Several studies support the idea that people who feel connected to friends – whether it’s a few close friends or a large group – have stronger immunity than those who feel alone. Another recent study found that isolation changed the immune system on a cellular level: Being lonely affected the way some genes that controlled the immune system were expressed.