The Immune Miracle – Chapter 2 – Immune System Overview

The Immune Miracle

The all-natural approach for better health, increased energy, & improved mood.

Shawn M. Talbott, PhD, CNS, LDN, FACSM, FAIS, FACN

 

Chapter 2

Immune System Overview

We typically think of the immune system in two parts – the “innate” and the “acquired” (adaptive) immune systems. After the “barriers” to pathogens, such as our skin and the mucous membranes surrounding our airways and intestinal linings, the innate immune system is our primary, fast-acting line of defense against invading bacteria and viruses, environmental toxins, and even against damaged cells, including cancer cells. The adaptive immune system is what most people think of when they consider the immune system, because it’s the part of our immune system that “learns” to protect us from specific diseases such as measles and chicken pox. Our adaptive immune system enables us to develop these diseases just once (or be vaccinated against them), because the adaptive system has learned to recognize and destroy that particular virus if we ever encounter it again. The specificity of the adaptive immune system is amazing and is crucial for our survival; yet, it suffers from being a delayed response (several days or weeks for optimal development) and requires action from the innate immune system to be initiated.

As mentioned in the Introduction, our immune systems are comprised of a complex network of multiple parts communicating and interacting with each other. In addition to the skin and mucous membranes that “block” infections, we also have acidic and enzymatic secretions in the stomach and in our the tear ducts of our eyes that can destroy viruses and bacteria before they gain entry into the body. The innate immune system also encompasses a group of serum proteins called the “complement” system that can directly kill or dissolve pathogens or “tag” them for destruction by certain immune cells (called macrophages, they can engulf and destroy pathogens by a process called phagocytosis).

Cells of the innate immune system include Macrophages, Neutrophils, and Natural Killer (NK) cells. Macrophages perform day-to-day functions as “garbage collectors” and “handy men,” cleaning up damaged cells and cellular debris; its not glamorous work, but it’s vital to our well-being and optimal function. However, as soon as we encounter a bacteria, our macrophages quickly turn from garbage-men to Superman and leap into action to fight the invaders.

As they fight bacteria, macrophages send out hormone-like messengers called cytokines that alert other immune system cells such as neutrophils to join the fight. Within a very short period of time, cytokine signaling induces a full-blown “inflammatory” reaction that “walls off” or “quarantines” the infectious invaders and sends out the alert to the rest of the immune system – and it’s the innate immune system that’s responsible for the initial reaction and the ultimate coordination of the different immune system cells.

Primed Versus Stimulated

You can see how important it is to keep your innate immune system properly “primed” for rapid action, but we also want that activity to be “smart” – so we attack only the “bad guys” (infectious pathogens) and not the “good guys” (our own healthy tissues). One way research has shown effective to actively prime our innate immune system for rapid and intelligent activity is through exposure to yeast.

The health benefits of yeast have been known for many years, but it was only in the 1960’s that scientists were able to identify the natural compounds in the cell walls of yeast, called “whole-gluco-polysaccharides” (WGP) as the components responsible for improved immune system function. When we eat yeast (as in bread or beer), the WGP particles are actively absorbed and transported from the small intestine to the immune system by macrophage cells. WGPs are absorbed through a particular region of the small intestine known as Peyer’s patches, an area which immunologists have shown to be comprised of a specialized concentration of epithelial cells that act to alert the body when a pathogen is present in the system.

After transport and signaling via the Peyer’s patches, the WGPs are engulfed (phagocytized) by macrophages and broken down into active fragments that interact with specialized receptors (called “CR3” receptors) on neutrophils and NK cells – causing these cells to become “primed” and ready for action. This priming effect is very different from typical approaches to “stimulating” immune system activity, because while a “stimulated” cell is immediately turned on and starts looking for something to attack, a “primed” cell is only in “standby” mode: it does not turn on its “attack” mode until it encounters a true pathogen. The priming effect is possible because the CR3 receptor has two binding sites – so when WGP occupies one site, the neutrophil “gets ready” – and when a virus occupies the other site, the neutrophil is immediately stimulated to destroy it.

The main source of WGPs in the human diet is from brewer’s or baker’s yeast (Saccharomyces cerevisiae), but purified yeast extracts containing specialized WGP particles are also available as dietary supplements. In supplements, WGP particles may be generically referred to as “beta-glucan” (see Chapter 6). However, there can be important molecular differences between different types of WGP particles – and even the slightest structural difference can affect bioactivity at a cellular level. For example, one form of WGP (a type with a 1-3/1-6 branching structure) has been shown to increase levels of two cytokines in the blood (INF-y and TNF-a), both of which play an important role in regulating the body’s immune response. But, an equally important finding was that this type of WGP does not cause any increase in another cytokine (IL-1), which can cause the symptoms of fever, chills, and muscle aches that are associated with active infections and often with other immune “stimulating” supplements. Using WGPs as daily dietary supplements (250-500mg/day) can be an effective and safe approach to actively nourishing and priming your immune system for optimal health and well-being. In fact, results from a 1999 study published in the American Journal of Clinical Nutrition showed that even consuming huge doses of WGP (15 grams per day or 30-60 times the recommended daily dosage) resulted in no adverse effects.

Obesity Infection?

It turns out that comparing the “spread” of obesity to an “epidemic” like the flu may not be very far off the mark. There is a growing body of scientific evidence that obesity might actually be caused by an infectious virus known as Adenovirus 36 (AD36). Researchers at several universities have shown that AD36 infection is related to a higher rate of fat storage in adipocytes (fat cells) – an effect thought to be due to the ability of the AD36 virus to “turn on” certain genes involved in fat production and storage. In laboratory studies of isolated fat cells, the AD36 virus has been shown to infect immature fat cells (called pre-adipocytes) and stimulate them to develop faster than normal as well as grow in both number and size.

It’s interesting that rates of AD36 infection in obese individuals are more than double those of the non-obese. In a recent study of AD36 infection among obese children (ages 8-18), researchers from the San Diego School of Medicine and the University of California found that the majority (78%) of children who tested positive for AD36 infection were obese – weighing an average of 35-50 pounds more than non-infected children.

AD36 is currently the only virus linked directly to human obesity; and, it raises the tantalizing idea that improving our immune system function may help protect us from the fat-storage effects of AD36 – and possibly, even help those who are already infected.

Inflammation and Immunity

The word “inflammation” is derived from the Latin “inflammare”—meaning to “set on fire”—because an injury or infection is typically red, warm, and painful. Think of pain and inflammation as different sides of the same coin: they coincide with each other, but are driven by different—yet related—biochemical factors.

Pain and inflammation are normal body processes. Without them, you would literally not be able to survive for very long. Pain is a signal to your body that damage is occurring, and you need to stop doing whatever is causing that damage. Inflammation is a process controlled by the immune system that protects your body from invading bacteria and viruses, but this process also serves to regulate heart function, blood flow, and many vital functions. Maintaining a normal balance of pain signals and inflammation is critical to good health and vigor; it is the link between having a properly primed immune system (high vigor, abundant energy, and a good mood) or a poorly functioning immune system (a daily struggle with pain, fatigue, and depression).

When this balance becomes disrupted, you experience more inflammation and increased pain along with less flexibility and reduced mobility. When you have too much inflammation, this process—which is supposed to be protecting you—actually causes more and more damage. For example, an overactive inflammatory response is known to stimulate bone breakdown (leading to osteoporosis), interfere with cartilage repair (leading to a worsening of arthritis), and accelerate muscle breakdown (leading to flare-ups of fibromyalgia). Inflammation is also involved in emotional balance and brain function. So, when your body experiences too much inflammation, you simply don’t feel happy. Instead you feel mentally exhausted and burned out—obviously, the opposite of vigor.

Your doctor may also give your unbalanced inflammation another kind of label—one that ends in “-itis.” In medical terminology, “-itis” is used to denote inflammation. Therefore, you may have arthritis (inflammation of the joint—“arthros” is Latin for joint), tendonitis (inflammation of the tendon), or fasciitis (inflammation of the fascia—the tough layer of connective tissue over muscles, tendons, and ligaments that can become inflamed following excessive exercise or with lower-back pain and fibromyalgia).

Normal Inflammation vs. Chronic Inflammation

As mentioned earlier, the normal process of inflammation helps dismantle and recycle older tissues that have become damaged or worn out or that simply need repair (remember those macrophage garbage-men). This process of normal and balanced inflammation is called “turnover,” and it occurs when older tissue is replaced with newer tissue. Before the age of thirty or so, this normal turnover process is perfectly balanced—for every bit of tissue that is damaged and removed, another similar (or greater) bit is put in its place. This means that, under ordinary circumstances, you’re always making your tissue stronger and more resilient. After about age thirty, however, the immune system can lose some of its precision, and the turnover process becomes somewhat less efficient year after year. This causes a very slight loss of healthy tissue—you continue to break down and to remove some tissue, but the amount of healthy tissue added back to replace it is just a bit less than it should be. As you age, the turnover process becomes less and less efficient, and your body’s ability to heal itself from injury and protect itself from infection is reduced. This imbalance in tissue turnover and the “normal inflammation” process is the primary cause of the loss of flexibility, vigor, and the various “-itis” diseases that people tend to encounter as they get older.

With aging, these normal repair mechanisms start to dwindle; and, ironically, the very inflammatory process that has been helping “turn over” older tissue into healthy new tissue can completely turn on you. That leads to problems with pain, mobility, and flexibility. The same process of inflammation that naturally governs your body’s repair and protection starts to accelerate tissue breakdown and impede that repair. The end result, as you may have already started to experience, is that your tissues literally begin to fall apart. Cartilage degrades; muscles lose tone; ligaments and tendons creak; bones become brittle; energy and mood falter, and vigor is sapped.

Let’s keep in mind that not all inflammation is bad. As you’ve just learned, inflammation is part of the normal healing and turnover process for any tissue. But, when you experience too much inflammation or “chronic” inflammation, things go awry. With chronic inflammation, healing is suppressed, and tissue destruction is accelerated. Your body simply cannot heal itself or stop the damage when inflammation gets out of control. To illustrate this point, think about the ocean crashing against a protective seawall. The seawall represents your tissues, and the ocean is your inflammatory process. Over time, that wall will become weakened and broken by the crashing waves; it will need to be repaired to return to optimal functioning. If the pace of repair fails to keep up with the pace of destruction, then the seawall fails, and the ocean comes rushing in (leading to tissue destruction and dysfunction). You need to maintain the integrity of the seawall (your tissue) by keeping up with repair and maintenance—but, you can’t do that if the ocean is continually crashing down on you.

A plethora of scientific and medical evidence demonstrates how to use diet, exercise, and supplementation to “calm” the ocean (reduce damage caused by excessive inflammation) and to accelerate tissue repair (keep that seawall intact). It is all a question of balance. You want to maintain a normal level of inflammation so you can then maintain a normal pace of tissue turnover and, thus, retain healthy tissue, flexibility, and mobility. As soon as you get too much inflammation—that is, chronic inflammation—even by a small amount, you see a bit more tissue deterioration, leading to a little more inflammation and still more tissue breakdown. Once this vicious cycle of inflammation/damage has begun, it can be very difficult to stop—unless you have a comprehensive plan to control inflammation via multiple health practices.

Chronic Inflammation—The World on Fire

Like the seawall metaphor above, it may help you to think of chronic inflammation as you would a fire in an apartment building. Let’s say you live in a twenty-story apartment building, which represents your body. Then, a fire (inflammation) breaks out on the fifteenth floor, causing destruction (tissue damage) to that entire floor. But your penthouse apartment on the twentieth floor is fine. To put out the fire, you call in the firefighters (immune cells), which may cause a bit more damage by tearing down some walls and spraying water (cytokines, the signaling substance secreted by immune system cells)—all in an effort to solve the bigger problem of putting out the fire. Let’s now say that the fifteenth floor is a complete loss, while other floors suffer some repairable damage (water damage on the fourteenth floor, smoke damage on the sixteenth floor). The repair process begins on all three floors, with carpenters, painters, and other “builders” brought in to repair the damage. On floors fourteen and sixteen, where the damage is less severe, the repair process might be complete within a few weeks; but on the fifteenth floor, where the fire was concentrated and the damage was most severe, the repair process may take a year.

Your body also has an entire team of “builder” cells in each and every tissue. In cartilage, these “builders” are called chondrocytes; in bone, they are called osteoblasts; in muscles, they are myocytes; in skin and some other tissues, they are fibroblasts—the list goes on and on. In your own tissues, you can have the equivalent of a raging fire and firefighting (tissue damage and inflammation). But if you’re not able to shut off this process—that is, if your level of inflammation is thrown off by something—your body is then in a continual state of destruction and pain. You’ll never be able to get to the rebuilding and repair stages unless you can shut off this process of chronic inflammation.

How Normal Inflammation Becomes Chronic

When a tissue is damaged—whether from infection, trauma, or unbalanced turnover—it releases signaling chemicals called “cytokines.” These cytokines are like flare guns, sending up a call for help that signals surrounding cells to jump into action to stop (wall off) and repair the damage. The cytokines also call immune-system cells (white blood cells) into the area to help clean up the damaged tissue. You have no doubt experienced the blood rush that leads to the recognizable redness, warmth, and swelling common to many injuries. As the white blood cells rush in to the damaged area, they release more and more of their own inflammatory chemicals. This blast of inflammation is intended to cause even more tissue destruction as a way to either kill bacteria and viruses or to take away damaged tissue and set the stage for repair efforts to begin. As you can imagine, this part of the inflammatory process is supposed to be short-term. If it were to continue without shutting down, you’d simply destroy your own tissue without ever rebuilding healthy tissue in its place. Unfortunately, this “never-shut-down” scenario precisely describes the chronic inflammation and constant state of tissue destruction with which millions of Americans live their lives every day.

A number of mechanisms are in place to shut down the process of inflammation, including the naturally short half-life of cytokines and other inflammatory molecules, and the production of anti-inflammatory cytokines (with such names as TGF-beta and IL-10). Unfortunately, immune-system cells can remain in a state of chronic inflammation if the “cell-damage” signals keep coming from free-radical damage (which can be controlled via antioxidant nutrients found in brightly colored fruits & vegetables), from cortisol-induced tissue breakdown (resulting from chronic stress), or if signals to “shut down” the inflammatory process are not “heard” by target cells (as in the case of cells damaged by problems with blood-sugar levels).

Unfortunately, chronic inflammation is not confined to the tissue in which it starts. Cytokines—such as IL-6, IL-8, and TNF-alpha—are able to leave the original site of inflammation. They can then travel in the blood to spread inflammatory signals through the blood vessels and into every tissue in the body (leading to metabolic diseases, such as obesity, diabetes, and depression, and to structural/damage diseases, such as Alzheimer’s, Parkinson’s, and arthritis). Because most cytokine molecules are produced by immune-system cells (specifically by macrophages, neutrophils, and NK cells of the innate immune system), numerous drug companies attempt to control chronic inflammation by suppressing immune function. The problem, of course, is that wholesale suppression of immune function also limits your body’s ability to protect you from actual pathogens—so you’re “protected” from chronic inflammation, but become more susceptible to infections and certain cancers. Not a great trade-off!

Chronic Inflammation and Chronic Diseases

Chronic inflammation is not just a problem that affects the way you feel on a daily basis or the level of vigor you experience. It also contributes to the development of serious health conditions, including four that we will briefly discuss in this section: heart disease, cancer, obesity, and diabetes.

Heart Disease

Researchers may know the most about the adverse effects of chronic inflammation when it comes to heart disease. Until about ten years ago, most cardiologists and other health experts believed that heart disease was a simple “plumbing” problem, with too much cholesterol being the culprit that clogged up blood vessels and led to heart attacks. Unfortunately, the cause of heart attacks was found to be a little more complicated: population studies showed that at least half of all heart attacks occurred in people with perfectly normal cholesterol levels. What scientists know now is that oxidative damage (by free radicals) is what allows cholesterol to become “sticky” in the first place and start plugging blood-vessel linings with plaque deposits. Chronic inflammation, therefore, seems to be the “trigger” what causes those deposits to rupture and create a blockage in the heart, leading to a heart attack. The degree of chronic inflammation throughout the body can be measured by blood levels of a protein called “C-Reactive Protein” (CRP). CRP is produced in the liver, with levels rising in direct proportion to inflammatory signals in the body. During times of active infection (acute inflammation), CRP levels may rise by a factor of one thousand to fifty thousand in response to the increased production of cytokines, such as IL-6, from macrophages. A CRP value of 3.0 mg/L is associated with a tripling of heart-attack risk, while people with very low CRP levels (below 0.5 mg/L) rarely have any sign of inflammatory heart disease. You may have to push for it, but you can have your CRP levels tested the next time you’re at the doctor’s office.

Cancer

For more than one hundred years, researchers have known that cancerous tumors tend to arise from and cluster at sites of chronic inflammation. Stated another way, sites of chronic inflammation seem to attract and promote the growth of cancer. Part of this effect might have to do with the fact that sites with more inflammation will also have more oxidative free-radical damage; so, DNA damage and subsequent “mistakes” during repair may result in more mutations and a higher chance for cancer development. Another factor may be that a higher concentration of inflammatory cytokines attracts a greater number of immune cells, which “think” they’re being called to the site of an infection and, thus, create even more damage as they try to “kill” a nonexistent pathogen. So here is evidence of the ultimate conundrum: your immune cells, which normally protect you against cancer, may actually be co-opted by excessive inflammatory signals into actually stimulating further cancer growth. If there were ever a reason to be interested in maintaining a properly primed immune system, it is for the reduced risk of cancer it may confer.

Obesity and Diabetes

Earlier in this chapter, I wrote about the growing body of research suggesting that a viral infection (AD36) may be linked to increased rates of obesity. But, some researchers are not convinced whether the infection comes first (causing increased fat storage and obesity) or the obesity comes first (leading to an inflammatory state that interferes with normal immune function and allows AD36 infection).

Obesity is defined as an excess of adipose (fat) tissue, with adipose tissue producing a range of inflammatory cytokines (adipokines, adiponectin, leptin, resistin, TNF-alpha, IL-6, IL-1, and many others). Adiponectin and leptin are the most abundant adipokines and are considered key signaling compounds in regulating inflammation within fat cells and throughout the body. Adiponectin levels are markedly decreased in obesity, diabetes, and heart disease and are thought to contribute direct anti-inflammatory effects. Leptin, on the other hand, is considered a highly pro-inflammatory and pro-atherogenic cytokine that is associated with elevated body fat levels and reduced insulin sensitivity. The ratio between adiponectin and leptin has been proposed by some researchers as a useful index of heart-disease risk in patients with obesity and diabetes. Leptin acts directly on the hypothalamus region of the brain to regulate food intake and energy expenditure. Leptin is a general “satiety” signal that tells the brain that “enough” fat is stored. The amount of leptin produced is proportional to the amount of body fat stored; so, when you lose body fat, your leptin levels fall and your hunger increases to drive you to eat in order to “replace” the lost fat. On the other hand, adiponectin increases fat oxidation and improves the activity of insulin to regulate blood-sugar levels.

Through the action of cytokines/adipokines, fat tissue can be directly influenced by the overall inflammatory state of the body; but, through the action of cytokines/adipokines on the brain, fat tissue can also influence inflammation throughout the entire body. Aside from the adipokine signaling mentioned above, another important source of chronic inflammation associated with abdominal obesity is the constant activation of the innate immune system. As they grow, changes in cell-surface proteins on adipose tissue can allow swollen abdominal fat cells to resemble bacterial cells or tumor cells in certain ways. This effect attracts cells from the innate immune system (macrophages, neutrophils, and NK cells), which attempt to destroy the “tumor” (your own fat cells) with their normal bursts of free radicals and cytokines. Unfortunately, rather than killing off your fat (if only it were that simple!), this immune system attack merely damages your fat cells; this, in turn, sets off the expected normal cycle of injury/inflammation/repair that any of your body cells would undergo. The really bad news is that the end result is yet a higher level of inflammation and oxidation—and a growth of fat stores through a variety of metabolic signals.

Control Inflammation—Naturally—For Superior Immune Function and More Vigor

The immune system responds to and creates oxidative “free radicals” and responds to and creates inflammatory cytokines. “Normal” inflammation exists to protect us from invading pathogens (viruses, bacteria, and even uncontrolled cell growth that could lead to cancerous tumors). Sometimes, however, the walling-off and destroying process of the immune system’s inflammatory response doesn’t shut off the way it is supposed to: immune-system cells, such as macrophages (which fight bacteria), neutrophils (which fight viruses), and natural killer cells (which fight tumors), respond to free radicals as if they were toxins. A small amount of free radical signaling is a “good thing” for immune cells, keeping them vigilant to defend us against “real” pathogens. But when free radical exposure becomes excessive, immune cells release a wide array of pro-inflammatory cytokines, such as interleukins (IL-1, IL-6, TNF-alpha), to “wall off” tissues from further free radical damage. And that can lead to chronic inflammation as well as a cascade of diseases, including heart disease, obesity, diabetes, Alzheimer’s, and certain cancers.

Unfortunately, the Western lifestyle is a perfect recipe for increasing chronic inflammation, with its high intake of sugar, refined carbohydrates, and saturated fats. Such a diet, combined with low levels of fiber, infrequent exercise, and sleep deprivation, make it more likely that inflammation becomes too high—and stays that way.

Thousands of years ago, ancient herbal practitioners were prescribing all-natural foods and herbal extracts for controlling pain and inflammation. What these traditional healers did not realize at the time, but what we now know thanks to advances in nutritional biochemistry, is that these natural anti-inflammatory nutrients were effective at controlling inflammation and improving immune system function in many ways simultaneously. This balanced approach is associated not only with a greater degree of overall effectiveness, but also with a restoration of normal tissue function and fewer side effects. As is so often the case, however, the drug industry has tried to synthetically copy the extraordinary healing properties and powers of natural medicine—only to create more suffering, injury, and even death. Fortunately, those herbs and natural products cannot be “owned” by the drug companies, thus keeping them widely available to anyone who wants to enjoy the safe and effective benefits of controlling pain and inflammation naturally.

The obvious dilemma when it comes to selecting a natural option for inflammatory balance and pain relief is that you want something that is safe, natural, fast-acting, and long-lasting. It is a tall order to get all four “wants” in a single item—but a growing number of products offer a suitable range of options (mostly by combining the most effective ingredients into a single multi-faceted product solution).

Now that I’ve presented the idea that herbs and natural products can combat inflammation, pain, and immune dysfunction, you may be wondering what, exactly, you need to ingest in order to address these health issues. Let me stop you right there for a moment. To get the real benefits from natural products and traditional healing wisdom, you have to break out of the mind-set that tells you taking one pill or that one drug will cure your ills with a “quick fix.” This mind-set is pervasive in modern society, and countless ads and commercials constantly reinforce it. So, before considering specific natural strategies for controlling inflammation, the first thing you need to do is to be willing to change the mind-set that says you can take a pill and forget the problem. You may also need to change your lifestyle and recognize the importance of being an active participant in developing your health and wellness, instead of a passive recipient of a prescription from a physician. Many of you reading this are undoubtedly aware of the benefits of changing your mind-set and lifestyle in order to embrace a view of health that’s more comprehensive and multi-faceted than the typical Western medical approach. Nevertheless, it bears repeating, because even people who appreciate traditional medicine can fall back into thinking that one “superfood” or one “special” herb will solve a health problem as quickly and efficiently as a pill from the pharmacist.

Having said that, here are a few specific, natural options that you can pursue to control inflammation and get your immune system function back on an even keel:

Exercise—Numerous studies confirm that moderate exercise reduces inflammation as well as the production of C-reactive protein, which plays a role in heart disease. A study from researchers at the Emory University School of Medicine in Atlanta that was published in the Archives of Internal Medicine (2002) found that the more frequently you exercise, the lower your overall level of inflammation, and the more robust your immune response. The study looked at nearly four thousand U.S. adults ages forty and older and found that exercising approximately five times per week was associated with almost a 40% reduction in overall inflammation.

Sleep—Sleep is crucial to your health and vigor in countless ways, including helping to corral chronic inflammation. In a study published in the Archives of Internal Medicine (2006), researchers from the UCLA School of Medicine found that even a single night of disrupted sleep increases levels of inflammation throughout the body by two to three times compared to a normal night’s sleep.

Herbs and Supplements—As you’ll read in greater detail in Chapter 5, there are a great many safe and effective dietary supplements for reducing inflammation and bolstering immune function naturally. For instance, ginger, turmeric, boswellia, papain, and bromelain are all derived from nature and have long been used in traditional Indian medicine to treat arthritis and other inflammatory conditions, as well as to ward off infections and heal injuries.

To sum up: The human immune system is an exquisite network of active cells, cytokines, and multiple interacting defenses. The walling-off aspect of the inflammatory process is an ideal response for keeping viruses or bacteria from moving into other parts of your body. However, free radical–generated inflammation encourages immune cells to fight “yourself” in a vicious cycle of oxidation/inflammation, which ends up creating more problems and eventually leads to a lower state of vigor. Coming chapters discuss a variety of natural options for priming optimal immune system activity, controlling inflammation, and improving vigor and overall well-being.

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