How Age Influences Your Immune System

author avatar Dr. Eric Berg 08/31/2023

Let’s talk about the effects of aging on the immune system. As you age, the reality is that your risk factor goes up dramatically for viral and bacterial infections.

There are a few reasons behind this.

In this article, I will cover those reasons. As you age:

Here are more details about each of these age and immune system concerns and what you can do to resolve them.


1. The Microbiome Degenerates

What Is the Microbiome

The microbiome is a term to describe, collectively, all the microbes - bacteria, fungi, protozoa, and viruses - living in your body. These microbes are there to make up a great majority of your immune system, and they play a key role in the day-to-day functions of the human body. Specifically, the microbiome helps with:

  • Stimulating the immune system
  • Breaking down potentially toxic food compounds
  • Synthesizing vitamins and amino acids
  • Providing protection against pathogenic organisms

That said, I want to focus specifically on the immune factor.

The Microbiome and Your Immune System

Your microbiome degenerates as you age

As you age, the microbes in your body age as well. You get less diversity and you have more pathogenic bacteria. In other words, you have a higher ratio of pathogenic bacteria and less friendly bacteria in the gut. This imbalance makes you more susceptible to getting infections.

Also, because you lose the diversity of microbes, you’re not going to make the correct quantity of butyrate.

Butyrate is a short-chain fatty acid that’s involved in helping someone with Fat Storing Hormone resistance and their blood sugars. Also, it has a connection to supporting a healthy immune system, reducing inflammation, and helping support healthy digestion.

So, if this goes down as you age, then many immune and bodily functions are going to get worse, as well.

On the flip side, a baby who’s getting breast milk is getting a tremendous amount of good bacteria in that breast milk - not to mention immune factors, antimicrobials, and colostrum, which is building his or her immune system.

It’s very important as you age, then, to do your best to maintain your gut flora and even take a very high-quality probiotic so you don’t have to deal with these deficiencies and concerns.


2. The Thymus Shrinks

Now, the second thing to know is that babies and children have a huge thymus gland. The thymus gland is not the thyroid; the thyroid is in the front part of the neck, while the thymus is a little bit lower - right underneath your sternum and right on top of the heart.

The thymus is a key lymph gland that essentially acts as a training camp for your white blood cells. It’s also a reservoir for a lot of your immune cells. If a major infection happens, your body will recruit a lot of its T-cells (T standing for thymus) from the thymus and pull those cells into the battle to fight off the invading microbe. That’s a huge part of how you successfully fight off an infection. Similarly, B cells make antibodies. The fewer antibodies you have for different things, the less defense you’re going to have against certain microbes.

Now, the problem is that, when you get older, your thymus shrinks down to nothing as part of an aging immune system. You really lose the ability to make the T-cells and B-cells that are vital to immune functions.

The solution: make sure you take enough zinc to support healthy thymus function (8-11 mg a day). Why zinc? If you’re zinc deficient - which a lot of people are, especially as they age - you will also have atrophy of the thymus gland. So addressing zinc deficiency can be a really effective way to treat any age-related thymus concerns.

It could also be very beneficial to take a thymus extract, which you can purchase as a supplement. I don’t have any brand names - you’re going to have to do your own research - but I think that would be a really good thing to support if you’re getting older and you want to boost your immune system.


3. You Take More Medications

As a person ages, he or she usually takes more medications. The one that really destroys the microbiome is the antibiotic.

You probably already know that, but antibiotics aren’t the only concern here. Many other common medications can seriously and negatively impact the microbiome These include:

  • PPIs
  • Antacids
  • Any medications that have to do with acid reflux, GERD, indigestion, or heartburn,
  • Metformin (a medication used for diabetes type 2)
  • SSRIs, which are used for anxiety or depression
  • Laxatives
  • Corticosteroids

Again, the fewer microbiome good bacteria you have, the less of an immune system you have. If you take any of these medications, then, this is something that you should discuss with your doctor.


4. Your Body Is Less Able to Absorb Vitamin D

Vitamin D is a vital immune modulator

Lastly, as you age, you have a much more difficult time absorbing vitamin D.

Vitamin D is one of the most important immune modulators, helping to control an overactive immune system.

It helps specifically with the inflammatory response, hypersensitivities, asthma, allergies, and autoimmune problems - as well as with a condition called the cytokine storm, which is a flurry of immune overreactions that can occur in your lung and that can actually kill you.

Vitamin D can help against all of these issues by providing a really good calming effect on a hyperreactive immune system.

This is especially important to supplement if you get an infection - from a virus, for example - because that the virus has a sneaky little strategy of blocking the vitamin D receptors inside the cell and knocking out your ability to use it.

That’s why you’re going to have to take a lot more vitamin D to counter that effect and help your body effectively fight any viral or bacterial attacks.


Overall, there are really two main things you want to support as you get older: the microbiome (your friendly bacteria) and the thymus gland. If you take care of these two things, you’re more likely to avoid the most prevalent age-related immune concerns.

If you want more information about how to boost the immune system, check out these videos. I recommend that you start with the first one:

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Disclaimer: Our educational content is not meant or intended for medical advice or treatment.

Editor’s Note: This post has been updated for quality and relevancy.

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