Read an Excerpt
CHAPTER 1
Immunity 101: Getting to Know Your Immune Network
You've had a few stressful weeks. There's a deadline looming for a big project you're working on, so you've been eating on the run, grabbing whatever's quick and easy. No time for sitting down to enjoy a meal with your family, and even less time to relax.
Then, from out of the blue, the thing you need the least: You wake up with a hint of a sore throat. By the end of the day, your nose is dripping and you begin coughing. Why now? Maybe your immune system is as stressed out as you are, and you just can't cope with one more assault.
Here's what's probably going on: Worn out with worry and work, you stopped taking good care of yourself and didn't pay attention to what you really needed. So the cells* that protect you from germs took time out, too, allowing viruses to set up house in your body and ultimately sending you to bed.
But before your head even hits the pillow, you're bombarded with advice. Everybody and their cousin has a favorite home remedy, and ads for cold medicine seem to pop up everywhere. Some of those medicines might weaken the viruses that are knocking you out. But more likely, those little bugs will grab hold and make you feel lousy for a few days.
Are you helpless against everything from the common cold to a bout of pneumonia? Well, not exactly.
What happens when you're exposed to all those microbes that can make you sick is partly up to you. One of our goals for this book is to guide you in knowing how to care for and feed your all-powerful immune healing system. With the right approach, you're less likely to get sick, and if you do become ill, you're more likely to bounce back a bit quicker.
A speedy recovery is thanks to the hard work of your immune system. Your body is constantly exposed to microbes—it's actually home to trillions of bacteria. In fact, there are more microbes in your body than your own cells, and yet you avoid getting any kind of infectious illness from these microbes inside you. An amazing collaboration between your cells and the "magic molecules" they produce keeps you protected from both what's inside you as well as what can invade from the outside world. How come you don't catch everything that's going around? The short answer: your amazing immune system, the focus of this book.
Sometimes, a vast army of microbes sneaks past your immune defenses and threatens to make you ill with an infection—from a simple cold to herpes or measles; from food poisoning to a life-threatening bout of hepatitis. Generally, these infections are self-limited as your body rallies to fight off the invaders; at other times, you need stronger support.
This book provides a treasure trove of information about how the vast immune network works to protect you and how you can nurture it so that potentially harmful microbes—known as pathogens—don't make you sick. You'll learn what the consequences are if and when our immune system is thrown out of balance and becomes misguided. Then you'll need strategies to strengthen it or calm it down. By getting to know and care for your immune system, you can help it deliver better care to you.
MEET YOUR IMMUNE SYSTEM
If it's been a long time since you had high school or college biology, these first two chapters may seem pretty technical and heady. After all, we're providing you with a basic scientific overview of how this very complicated system functions. Don't worry—the rest of the book veers away from hard science. You can read ahead and come back here when you need to understand a specific point.
What exactly is the immune system, and where is it located? Turns out, it's not just parked in one place. It has outposts all over your body. It's really a protection or guardian network, since the immune cells connect with every other system and part of your body. This network encompasses your skin, bone marrow, organs like the thymus and spleen, hormones and molecular messengers, as well as your brain, muscles, and even your mind. This network is a master of communications, and it consists of four main parts:
• Physical barriers, such as your skin, saliva, tears, and stomach acid
• White blood cells, including phagocytes and lymphocytes
• Organs where immune cells are produced (thymus and bone marrow) and where they do most of their work (lymph nodes and spleen)
• Molecules, including antibodies and cytokines
Although the immune system is spread throughout your entire body and has lots of different functions, it features two kinds of immune cells with specific jobs to provide both short-term "inborn" protection and lifelong protection.
PHAGOCYTES are white blood cells that engulf and destroy anything they consider to be "foreign." They act fast, yet they'll never remember the foe. They're part of your short-term natural instinctive immunity.
LYMPHOCYTES, though, are in the battle for the long haul. They're called in to manufacture specific weapons against their "favorite" microbe. They're smart, trainable cells with additional skills as warriors and managers. In general, their responses take longer to develop than those of the phagocytes, since lymphocytes have to hone their abilities whereas phagocytes are born with their know-how. (One exception: the natural killer lymphocyte, or NK cell, which responds quickly after a virus has made its way inside you. The NK cell is part of your innate immune response, just like the phagocytes.)
Your immune cells don't operate alone, though; they're influenced by what you think, what you do, and the choices you make every day. Chronic stress, depression, poor sleep, or a steady diet of junk food can keep them from working at their best.1 But there's good news: You can improve and rebalance your immune functions with stress-reduction strategies; healthy, nutritious food; the right supplements; a good night's sleep; and healthy, supportive relationships. And here's a bonus: Laughter and love also strengthen immunity and boost your mood.2
Even your attitudes and beliefs contribute to your immune functions. After all, attitudes don't simply stay inside your head. They direct your emotions and your behaviors. Your behaviors and daily choices—whether or not to exercise, smoke, take long walks, or talk to a friend—all affect the health of your immune system and, ultimately, your overall health and well-being.
Although the immune system is viewed as one system, its cells, organs, and chemicals are distributed throughout your body and are in constant communication. Sometimes called a roving sensory network, your immune cells patrol your whole body. When they're working well, you don't even know they're there. But when they're overwhelmed by an invading army of germs or get confused about what's safe and what's not, you may find yourself with infections, allergies, or an autoimmune disease.
Let's zero in on how this complex network functions and how it protects you from a host of problems. Later, in Chapter 2, you'll learn what happens when the network becomes misguided and immune cells destroy your own cells or react to a food or a plant. We call these inappropriate behaviors hyperactive immune states.
Q HOW HEALTHY IS YOUR IMMUNE NETWORK?
To see how the immune network is involved in your health, take a few minutes to reflect on these questions.
1. Do you get frequent colds, more than three a year? Y N
2. Do you often experience itchy, red skin? Y N
3. Do you seem to have a runny nose most of the time? Y N
4. Do you get an upset stomach when you eat certain foods? Y N
5. Do you put on weight no matter how hard you try to lose it? Y N
6. Do you often have trouble getting a good night's sleep? Y N
Score! Tally up your yes and no responses. If you've answered yes to two or more questions, your immune system could use a recharge. The problems you're experiencing could result from a misguided immunity.
YOUR BODY'S DEFENSIVE BARRIERS
Every second of every day, you're protected from dangerous microscopic invaders by a powerful, all-encompassing immune network of cells and chemicals that work together to keep the bad guys out, create barriers against physical threats, handle damage control, and even build new tissues.
First of all, there are the physical and chemical barriers. Think of the immune system as a couple of defense teams. The first line of defense, or layer of protection, consists of the physical and chemical barriers at your body's boundaries and entryways. Naturally, your skin and mucous membranes are the first to prevent dangerous microbes from entering your body at its most vulnerable places—those directly exposed to the external environment. Protein molecules in your tears and saliva dissolve microbes that reach these sensitive areas. Other proteins in your saliva prevent microbes from getting beyond your mouth. Your stomach's hydrochloric acid eliminates microbes that make it into your digestive tract.
If potential pathogens get past that first line of defense, there's another lineup waiting for them—the fast-acting phagocyte white blood cells, the first immune cellular team aimed at eliminating bacteria and fungi. These quick-acting scavenger phagocytes are called neutrophils. They're first on the scene to kill and eliminate microbes. The neutrophils are short lived, lasting only a few hours. When these first cell responders are done—or even while still in action—the second team of responders, the lymphocytes, enters into protective mode.
All these defense cells—phagocytes and lymphocytes—know to eliminate a bacteria or fungus because they recognize patterns or designs on the microbe's surface, like a scanner recognizes a bar code. These molecular patterns aren't found on your body's own cells or on viruses.
Because viruses don't have molecular designs that neutrophils recognize, another immune cell must step in to detect and eliminate them—and that's the natural killer (NK) lymphocyte. The NK cell is the first responder to a viral invasion, usually within 4 hours. Then, within 24 hours, other cells come on the scene to broadcast the initial alarm of invasion so that all the immune cells can do their part in protecting you from a viral infection.
First Immune Responders in Action
If an invader penetrates the body's physical boundaries, the phagocytes scan the microbe or particle. Once the invader is recognized as "not self," it's engulfed by the phagocytes, which release a cocktail of chemicals to kill it and break it down. There are two kinds of phagocytes—the quick- acting neutrophils (discussed above) that work in your blood and the more complex, long-lasting monocytes that work in your tissues. When monocytes wander out of your bloodstream into your tissues, they get a new name: macrophages. Monocytes have more responsibilities than simply acting as a phagocyte: They can also regulate immune responses, not just defend against microbes.
The phagocyte's killing weapons include hydrogen peroxide, free radicals, and a variety of proteins. In addition, the macrophages send out signals to the second team of cellular responders, the lymphocytes, to prompt them into action. And this first cellular defense team also initiates the powerful inflammatory response. It's a complex and amazing dance, and some of its most important steps are triggered by the free radicals.
Free Radicals, a Defense and Communication Strategy
Chances are, you've heard of free radicals as bad things that damage your cells and accelerate aging. But they have a good side, too—they help eliminate and destroy microbes. Free radicals (also known as oxidants) are highly reactive molecules that are electrically out of balance. That means they carry around just one electron that's always looking for a partner— you may remember from high school biology that electrons like to travel in pairs. To find a mate, those electrons will grab another electron from other molecules or tissues, bringing itself into balance. But that starts a chain reaction, as more and more molecules have their electrons raided and begin stealing from other molecules in turn.
Although free radicals sound like dangerous troublemakers—and sometimes they are—they are also essential for life. Besides helping to kill microbes, they can signal blood vessels to relax and activate other important chemical processes in your body. Where do free radicals come from? Turns out, lots of places. Your phagocytes make them; your body produces them as it breaks down the food you eat; you even manufacture them after an intense workout or when you've been out in the sun for a while. Toxins, like cigarette smoking and air pollution, also create free radicals. Although most of these environmental free radicals aren't so good for you, the ones that your body makes can support your health.
Free radicals can cause trouble through a process called oxidative stress. Starved for electrons and pilfering them at will, free radicals can damage your tissues or molecules, and the effects can be serious: gene mutations, altered proteins, macular degeneration (an eye disease resulting in loss of vision), skin wrinkles, and many conditions associated with unhealthy aging.
Yet your body can protect you by producing antioxidants, molecules that balance the free radicals. And your foods and supplements can supply antioxidants to maintain oxidative balance. Too many free radicals can lead to more inflammation, but an antioxidant-rich diet supports your body to stay more in balance. Think carrots, oranges, and lots of green vegetables.
Inflammation Creation
Inflammation is another basic innate immune response. It's initiated by the phagocytes— blood neutrophils and monocytes—and by tissue mast cells. What triggers the inflammatory response? One switch that turns on inflammation is when tissues are damaged by burns, cuts, sprains, and other physical traumas. Damaged cells send out the call for inflammation to get into action. Free radicals and chemical signals from the phagocytes also contribute to inflammation. Acute inflammation is a good thing. It protects you from further damage. Chronic inflammation? Not so good. It can cause many illnesses, like heart disease, as well as allergy symptoms and chronic pain.
What actually happens during inflammation? Injured tissue cells or a foreign object like a splinter stimulates the damaged cells to release "inflammatory" chemicals. The first chemical released on the scene is histamine, which summons blood cells to the area and initiates the entire inflammatory process. Then your brave phagocyte warriors join the battle, engulfing and destroying any toxic agents or microbes that came through the damaged tissues. The serum—that's the fluid in your blood—seeps in, flooding the area to dilute any toxins, while platelets, cells in your blood, wall off the area to prevent dangerous microbes from moving beyond this region and creating further damage.
THAT'S INFLAMMATION!
• You sprained an ankle and it becomes swollen and painful.
• You burn your wrist taking baked lasagna out of the oven. It hurts for a few hours, then forms a blister, becomes red, and takes several weeks to heal.
• You're allergic to pollens: Your nose gets runny, your eyes itch, and you have a little tickle in your throat.
• After a bug bite, your skin becomes itchy and swollen, and big red bumps appear.
