It’s around this time of year that I start to get questions from parents about “boosting” their child’s immune system. School in most districts is in session for the year and parents dread the eventual onslaught of coughs, colds and other illnesses that their kids will pick up from their classmates on the playground. I love my role as a board certified allergist/immunologist as I can often help answer complicated questions about allergies and the immune system that cause a lot of confusion.

Every week, I see referrals from concerned primary care pediatricians or parents for children with frequent infections. Often the parents believe, or have been told, that their child has a “low immune system”. The immune system is complicated and even family doctors or general practice pediatricians can find themselves a little in over their heads when dealing with specific immune system issues. Pediatric allergists and immunologists receive additional training and education in the area of the immune system. Fortunately, very few of these children have any problems at all with their immune system.

The average child experiences between 6-10 viral upper respiratory infections a year. The average duration of each cold is 7-14 days. That means, on average, infants and toddlers can be sick for 4-6 months each year. With a normal bell curve distribution, 50% of children will be sick more than this. Parents, you’re not imagining things when you think your kids are sick all the time. Sometimes they are, and that’s not abnormal. Ugh.

It’s actually counterintuitive, but if your child falls within the realm of the average number of illnesses, for the average duration, this is a sign that they actually have a healthy and strong immune system. Many people mistake frequent colds for a sign of a “low immune system,” but it’s actually the opposite: it means your child’s immune system is working.

So why do so many people, including some doctors, misunderstand the immune system? How does the immune system even work? Herein, I will attempt to deconstruct this complicated topic.

At it’s most basic the immune system is the way your body defends itself from foreign invaders (also called antigens). A foreign invader could be, a virus, bacteria, a foreign body (like a splinter) or a parasite. Our immune system is able to recognize an invader and depending on what it is, has more than one way to vanquish it. In a healthy immune system, the components are able to tell the difference between normal and healthy parts of the body and a foreign invader, and only attack the invader. The immune system isn’t a specific organ like the liver or heart, but includes multiple organs and has multiple components. The cells that carry out our body’s defenses circulate and patrol our bloodstream all the time.

Something I hear frequently is the claim that “[organ] composes [xx%] of our immune system, so we should take special supplements to boost the health of [organ] to promote a strong immune system.” Claims like this aren’t based in any real science. It’s really hard to accurately quantify the immune system, even with advanced tests (which I will get into later) and a healthy immune system requires that the component organs are all healthy most of the time. The major components of the immune system include:

immune systemSkin and Mucous Membranes: These are the largest part of our immune system and serve as our first line of defense. These tissues line all parts of our body and encounter bacteria, viruses, and other causes of illness on a constant basis. When invaders elude our first line of defense, other immune cells in our tissues and bloodstream take over.

Lymph Nodes: These are small structures, sometimes called glands, that produce and store immune system cells. You’ve likely felt swollen lymph nodes before if you or your child has been sick. The lymph nodes most of us are familiar with are located on the neck, between the ear and the jaw, as well as under the arms, and near the groin.

Bone Marrow: Our bone marrow produces major parts of our immune system called T and B cells. T cells fight intracellular infections such as viruses and also serve to regulate for cancer producing cells and other internal badness. T cells are also tasked with educating B cells, which are charged with production of antibodies, also known as immunoglobulins.

Spleen: If you’ve ever wondered what your spleen does, you’re about to find out. The spleen is actually part of the lymphatic system (of which lymph nodes are also member) and it contains white blood cells, which are important for fighting off infections. It also acts as a sort of quality control for our blood cells, destroying old or damaged blood cells.

When your immune system senses a foreign invader immunoglobulins are the main source of defense. There are several types of immunoglobulins, but we’re only going to address two here, but they all have a long-lasting memory: IgM and IgG.

IgM is the first responder and notifies the immune system to produce IgG, the memory antibody. The IgGs examine the invader and tries to remember if it’s ever encountered it before, and if so how it fought the invader off. If the IgGs recognize the virus, it may be able to destroy it without you or your child ever knowing you’d been infected (this happens most of the time). If it hasn’t seen the invader before, or doesn’t remember it, that’s when you get sick, as your immune system throws the kitchen sink at the invader to destroy it.

IgM is the first responder and notifies the immune system to produce IgG, the memory antibody. This is how vaccines work – a small amount of protein from a virus or bacteria is introduced to our immune system, which then responds by making IgG that remembers that infection (without actually causing us to get sick in the process). Then, if we ever encounter that infection in real life, our body calls in the IgG memory soldiers to mount a swift and thorough response, thus preventing an infection from occurring. IgA is an antibody that lives on the lining of our mucous membranes and serves to defend from ear infections, sinus infections, and pneumonia. Lastly, IgE originally evolved to protect against parasites, but as society evolved and these infections became less common, IgE started to react against benign things in our environment, such as ragweed and peanut. IgE is the antibody involved in allergic reactions. In addition to the memory function of our immune system, we all have innate immunity from cells called neutrophils, macrophages and other types of white blood cells that recognize and gobble up any foreign invaders such as viruses and bacteria.

Remember those checks and balances I mentioned before? If an IgM misses an invader or we don’t have enough of them, also have innate immunity from cells called neutrophils, macrophages and other types of white blood cells that recognize and gobble up any foreign invaders such as viruses and bacteria. When one part is missing, another part picks up the slack.

Now that you’re a budding immunologist, let’s discuss a normal pattern of infections. There are literally hundreds of families of viruses and bacteria that can cause us to get sick? Most of these cause illnesses like the common cold, but some can cause more severe infections such as diarrhea, meningitis, or pneumonia. Just like our kids in the classroom, our immune system needs to practice against specific types of infection before getting really good at fighting it off.

Infants and toddlers are expected to have frequent colds and infections. They have never encountered these infections, and thus, aren’t very good at fighting them off yet. The number of apparent illnesses can be very concerning for parents. It also causes chaos at home (trust me, I know) as parents often have to take time off work, their children may not be eating or sleeping well when ill, and it just plain sucks when our kids are sick all the time.

There are a few common factors that contribute to young children experiencing a higher number or longer duration of upper respiratory infections than average. Things like, attendance at daycare and preschool or having older siblings at home means exposure to a larger number and diversity of infections. These kids are often sick more frequently simply because they are exposed more often to viruses and bacteria. Another factor is exposure to cigarette smoke. The smoke irritates and inflames the mucous membranes of the ears, nose, and throat and can result in more frequent infections.

These factors don’t mean that your child has a “low immune system” or needs a “boost.” It simply means that their immune system is healthy and normal, but has been exposed to more invaders through the environment.

Children also may have anatomic abnormalities when younger that impedes normal drainage from the nose and sinuses. This includes enlarged tonsils and adenoids, crooked ear canals, and naturally smaller airways. There are also a host of medical conditions that can predispose a child to more frequent infections as well. Children with allergic rhinitis often have inflamed mucous membranes, which make a cold seem 10 times worse. Children with cystic fibrosis, diabetes, or kidney problems often suffer from recurrent infections. Malnutrition, extreme physical or emotional stress, sleep deprivation, and drug/alcohol use also contribute to increased infections.

Again, children with anatomic abnormalities or certain underlying medical conditions still have healthy immune systems, but their bodies make them more vulnerable to exposure. Additional exposure means their immune system is still running at full-tilt, but the exposure means more illnesses.

Let’s take a deep breath and circle back to your child’s “low immune system”. Without actually checking levels of some of these immune cells through blood work, there is no way to determine if this is actually the case. Even with blood work, immunology lab values are often misinterpreted as abnormal when the reference laboratory compares results to improper age groups as the normal values for a 3 year old are not the same as for a 23 year old. Many other factors including acute infection, improper specimen handling, and improper selection of laboratory tests can also impact results. If your child is otherwise healthy, but has a lot of coughs and colds, chances are their immune system is working just fine.

Primary immune deficiencies are thankfully rare in the general population but certainly result in increased frequency and severity of infections. All other factors that may impact a child’s infection history must be evaluated prior to becoming concerned about an underlying immune deficiency. However, when the clinical history is suggestive for severe or recurrent infections, then proper immunologic testing can help guide evaluation. There are dozens of tests that can be ordered, but the location and type of infections can guide which tests should be ordered.

But what about products that claim they can boost your child’s immune system?

Lots of people swear that a certain product, juice, probiotic or high doses of a specific vitamin will boost your immune system. The claims on these products don’t stand up to the test of science, and several of these companies have found themselves at the center of consumer-driven lawsuits. There are also many products that claim they can shorten the duration of an illness, but they have also found themselves in a similar position.

If your child has a mild illness like a cold or flu, there is really nothing you can do to shorten the duration of the illness, that includes using antibiotics. Antibiotics are significantly overprescribed for children experiencing viral infections and antibiotics won’t cure a cold or fever. Current guidelines suggest watchful waiting with supportive care for at least 7 days to determine if symptoms are gradually improving or getting worse before discussing the use of antibiotics. Antibiotics should only be used to treat an infection like pneumonia, which requires a chest x-ray as many cases of presumed pneumonia aren’t actually that. These points are important to understand as frequent use of antibiotics often leads parents to feel their children are much sicker than they truly are.

If you have concerns about your child’s immune system I encourage you to speak with your child’s pediatrician regarding your concerns. Consultation with a board certified pediatric allergist/immunologist can often help sort out what factors may be contributing to your child’s infections, or even determine that they fall within the ‘normal’ range for their age. Cold and flu season is almost here, and we’re all in this together.

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Categories: Infectious Disease + Vaccines, Science 101 + Mythbusting