Published 26th September 2022

Inflammaging: Welcome the worms?

Before we get started, we need to make something clear: ZOE does not recommend for anyone to purposefully infect themselves with a parasite.

OK, let’s continue.

In this article, we’ll talk about inflammaging and ask whether parasites — parasitic worms in particular — might help fend it off.

It sounds unusual, gross, and unlikely. But, as we’ll find out, there is some supporting evidence. 

Although this topic is theoretical, at ZOE, we’re always fascinated by the edges of science, however unsavory.

So today, we’re asking a question you never thought you’d ask. As one review puts it, “Could maintaining half a dozen hookworms in your bowel help slow aging?”

You’ve met “good” gut bacteria; now get ready for “good” parasites (maybe). 

What is inflammaging?

Inflammation is a healthy response. It’s one of your body’s weapons against injury or infection.

But if inflammation continues for long periods, it can damage organs and tissues. So, your immune system tightly regulates inflammation to ensure it’s only “switched on” when needed.

As you age, though, your immune system regulates inflammation less tightly. Because of this, inflammation can become chronic, meaning it continues at a low level even when there’s no infection to fight or injury to heal.

This persistent state of inflammation with age is called inflammaging. 

Scientists have linked inflammation to many diseases that are more likely in older age, such as type 2 diabetes, cancer, and heart disease.

Where do worms come into it?

Before we drill down into the specifics of parasites versus inflammaging, it’s worth looking at some studies into how parasites can influence your immune system in general. 

Although it might sound far-fetched that a worm could influence your immune system, when you think about it, it kind of makes sense.

Parasites have been living in human guts since we evolved. But to make a home, they’ve had to reckon with our immune system.

For a worm to survive in us, it needs to avoid destruction. As a result, some have developed the ability to influence our immune system and affect how it operates.

So, the worms have evolved to manipulate our immune system, and our immune system has evolved over countless generations alongside the worms’ manipulation. 

In many industrialized regions today, parasites are much less common than they used to be. But this is a very recent thing as far as evolution is concerned. The worms and us have been together since the start.  

So, feel free to bring your skepticism, but get ready for a roller coaster ride from doubting to dazzled. First stop, 1976. 

Self-infection

In 1976, the Lancet journal published a letter from J. A. Turton. He outlines how he purposefully and repeatedly infected himself with hookworm larvae. 

Hookworms are a very common form of parasitic worm, or helminth. They infect an estimated 576–740 million people worldwide — mostly in low- and middle-income countries.

According to his letter, this self-infection cured his long-standing problems with hay fever, much to his surprise.

Of course, one man’s experience doesn’t prove anything. But it’s a little glimpse into how a parasite might influence the immune system positively.

Next, we’ll provide a rundown of some larger, real-world studies. They look at links between helminth infection and medical conditions that involve inflammation or the immune system in general.

Asthma in Ecuador

Asthma is a common respiratory condition, and it’s driven by inflammation in the airways. 

One group of researchers working in a rural region of tropical Ecuador looked at helminth exposure in more than 2,000 children.

They found that during the study, around one-third of the children had exposure to these parasites. 

Those who experienced an infection were 40% less likely to develop asthma.

Eczema in Uganda

Eczema is another common condition, and it’s characterized by skin inflammation. Scientists in Uganda investigated whether early life worm exposure might be linked to the condition.

They recruited more than 2,000 children. This time, they found that children whose mothers had experienced a worm infection were 30% less likely to develop eczema.

Skin sensitivity in Gabon

Another African study, this time in Gabon, looked at atopy — when your immune system is oversensitive and you're more likely to develop allergies.

The researchers recruited more than 300 children, all infected with significant numbers of intestinal worms.

After treating the children and removing the parasites, they found that their skin became more sensitive to dust mites. 

Multiple sclerosis

As a final bit of evidence before we move on to inflammaging, we’ll cover a couple of studies on people with multiple sclerosis (MS). 

MS is an autoimmune condition: The immune system wrongly attacks healthy nerves.

Although the following studies are small, the results are eye-opening.

The first recruited 24 people with MS. Half had an intestinal parasite and the remaining 12 did not. The scientists followed them for an average of 4.6 years.

All participants had a form of MS called relapsing-remitting MS. This form is characterized by relapses, where symptoms get worse, followed by remissions, where symptoms improve.

The scientists found that individuals with a parasite infection had significantly fewer relapses.

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The second study followed up the 12 individuals from the first study who had both MS and a parasite infection. Four of the participants received treatment to clear the parasites.

Three months after the treatment, the scientists assessed their symptoms. 

They found that, compared with the participants who kept their parasites, those who were treated had significantly worse symptoms.

Again, these are small studies, so we can’t put too much weight on them. But, taken together, it seems that — at least in some cases — parasites might positively influence our immune system.

Finally, inflammaging

According to some studies, parasitic worms can dial down inflammation. So, in theory at least, it might help reduce inflammaging. Let’s look at some of the research.

One study recruited 118 people with type 2 diabetes. Of these, 60 had a roundworm infection. The authors found that individuals with an infection had reduced levels of inflammatory proteins called cytokines and chemokines.

Conversely, when the scientists treated the parasite infection, levels of these pro-inflammatory compounds increased.

Similarly, a study in which scientists infected people with hookworm measured a reduction in pro-inflammatory compounds following infection.

Following infection, they also spotted an increase in compounds that prevent inflammation and promote wound healing in the gut.

If gut parasites can reduce inflammation, perhaps they might reduce inflammaging. But do we have any evidence that this would work in the real world? In humans, no. But an intriguing mouse study provides hints.

The study focused on ES-62, a compound secreted by a particular parasitic worm. And the scientists used a mouse model designed to mimic accelerated aging due to a high-calorie diet.

The researchers found that ES-62 injections extended the lifespan of these mice by around 12% compared with mice that didn’t receive the injections. 

Interestingly, only male mice enjoyed this extended life. Strangely, the compound reduced inflammation in both males and females, but the females’ lives were still cut short.

As ever, findings from mouse studies must be taken with a pinch of salt. There’s a great deal of difference between you and a rodent.  

Is there any evidence in humans?

There’s no direct evidence that parasites reduce inflammaging in humans. But there are some tantalizing glimpses. To be super clear, these associations don’t prove causation, but they’re pretty interesting.

In a review called “Gross ways to live long: Parasitic worms as an anti-inflammaging therapy?” the authors explain that if parasites do reduce inflammaging, there should be fewer diseases related to inflammaging in parts of the world with more parasites. 

And there’s some evidence that this is the case.

For instance, a group of researchers in India focused on rheumatoid arthritis (RA), a condition linked to inflammaging. 

The scientists looked for filariasis — an infection by parasitic roundworms — in 207 people with RA and 222 people without RA.

While 40% of the controls had an infection, not a single participant with RA had filariasis.

A similar study, also in India, looked for links between type 2 diabetes and filariasis in 1,416 people.

They found that people without diabetes were around twice as likely to have filariasis than those with type 2 diabetes. 

Our final bit of evidence comes from an analysis of more than 300 cadavers. The individuals lived in an area of Russia where a particular parasitic flatworm is common.

The scientists focused on atherosclerosis — an age-related inflammatory disease where fatty plaques build up on the walls of blood vessels.

They found that individuals with the highest number of worms had lower blood cholesterol levels and fewer plaques in their blood vessels than those with fewer worms.

None of the above proves that parasites protect against diabetes, atherosclerosis, or RA, but the theory seems worth pursuing.

Should I…?

Before we close, we should re-iterate: ZOE does not recommend that people self-infect themselves with parasites. 

Current research into helminth therapy isn’t conclusive, and although it has a lot of fans, it’s not backed by enough evidence.

Plus, there is a range of potential dangers, so it’s not something to dabble in randomly. 

These potential dangers include:

  • malnutrition

  • anemia

  • vision loss

  • blocked intestines

  • bleeding in the gut 

  • neurological problems, like seizures 

  • infertility 

  • ectopic pregnancy 

  • inflammation of the pancreas

With that said, evidence is mounting that these tiny worms might someday be useful for treating certain conditions. 

It will take some time to tease out the details, but understanding how they modify our immune system could lead to new drugs for difficult-to-treat conditions and, who knows, perhaps slow inflammaging.

If you’d like to reverse or slow inflammaging without introducing worms to your intestines, we have some safer tips here.

Sources

Association between parasite infection and immune responses in multiple sclerosis. Annals of Neurology. (2007). https://onlinelibrary.wiley.com/doi/abs/10.1002/ana.21067 

Characterising the mucosal and systemic immune responses to experimental human hookworm infection. PLOS Pathogens. (2021). https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1002520 

Chronic Opisthorchis felineus infection attenuates atherosclerosis – an autopsy study. International Journal for Parasitology. (2013). https://www.sciencedirect.com/science/article/abs/pii/S0020751913001537 

Decreased prevalence of lymphatic filariasis among diabetic subjects associated with a diminished pro-inflammatory cytokine response (CURES 83). PLOS Neglected Tropical Diseases. (2010). https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0000707 

Effect of early-life geohelminth infections on the development of wheezing at 5 years of age. American Journal of Respiratory and Critical Care Medicine. (2017). https://www.atsjournals.org/doi/full/10.1164/rccm.201706-1222OC 

Gross ways to live long: Parasitic worms as an anti-inflammaging therapy? eLife. (2021). https://elifesciences.org/articles/65180 

Helminth infection modulates systemic pro-inflammatory cytokines and chemokines implicated in type 2 diabetes mellitus pathogenesis. PLOS Neglected Tropical Diseases. (2020). https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0008101 

Helminthiasis. (2022). https://www.ncbi.nlm.nih.gov/books/NBK560525/ 

IgE, parasites, and allergy. Lancet. (1976). https://helminthictherapywiki.org/wiki/images/f/fd/Letter_-_IgE%2C_parasites%2C_and_allergy_%28Turton%29.pdf 

Long-term treatment of intestinal helminths increases mite skin-test reactivity in Gabonese schoolchildren. The Journal of Infectious Diseases. (2004). https://academic.oup.com/jid/article/189/5/892/2085835 

Maternal hookworm modifies risk factors for childhood eczema: Results from a birth cohort in Uganda. Pediatric Allergy & Immunology. (2014). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4312885/ 

Overcoming evolutionary mismatch by self-treatment with helminths: Current practices and experience. Journal of Evolutionary Medicine. (2015). https://www.ashdin.com/abstract/overcoming-evolutionary-mismatch-by-selftreatment-with-helminths-current-practices-and-experience-3226.html 

Parasites - hookworm. (2022). https://www.cdc.gov/parasites/hookworm/index.html 

Rheumatoid arthritis patients are free of filarial infection in an area where filariasis is endemic: Comment on the article by Pineda et al. Arthritis & Rheumatology. (2013). https://onlinelibrary.wiley.com/doi/abs/10.1002/art.37883 

The global economic and health burden of human hookworm infection. PLOS Neglected Tropical Diseases. (2016). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5015833/ 

The impact of parasite infections on the course of multiple sclerosis. Journal of Neuroimmunology. (2011). https://www.sciencedirect.com/science/article/abs/pii/S0165572811000051 

The parasitic worm product ES-62 promotes health- and life-span in a high-calorie diet-accelerated mouse model of aging. PLOS Pathogens. (2020). https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1008391

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