Illustration created with AI. It does not depict a real person.
The eight forces quietly wearing down your body’s defenses
By Pam Killeen
You know people like this. Maybe you’re one of them.
They eat well. They exercise. They take the supplements, they’ve cut out the seed oils, and they’ve done a cleanse or two. They still wake up tired, they still bloat after dinner, and there’s still the rash that comes and goes, the aching that moves around, and the sleep that never quite finishes the job.
They’ve done everything right and it isn’t working.
I was one of them once. Chronic fatigue, fibromyalgia, multiple chemical sensitivities. The advice I got was the advice everybody gets, which is to try harder or try something else. A stricter diet, a different protocol, one more supplement.
There’s another possibility, and it’s what this article is about. The problem might not be what you’re doing. It might be the ground you’re doing it on, meaning the body itself and what condition it’s in.
What Terrain Actually Means
Terrain is everything that shapes your internal environment. Your light exposure and your sleep and wake cycles. Your mineral status. Your stomach acid and your bile (the fluid your liver makes to break down fats and carry waste out). The tone of your nervous system, your circulation, your lymph, and the ordinary daily signals you live inside without noticing.
That’s a long list, so here’s the short version. Terrain is what a microbe finds when it arrives.
In a well-timed, mineral-rich body, microbes behave like neighbors. In a tired, inflamed, off-schedule body, they organize, they overstay, and they slowly push the whole system out of balance. Same organisms. Different ground.
It’s also why the symptom list of a worn-down terrain reads like a pile of unrelated complaints: bloating, brain fog, a rash, aches that migrate, poor sleep, and food reactions that keep expanding. Microbes rarely arrive one at a time. Bacteria and fungi settle in together, share resources, and build biofilms that shelter whatever is inside them from the immune system, which is part of why the resulting mess is so hard to pin on any single cause.1 Parasites live in that same crowded neighborhood. No individual symptom points anywhere. Together they describe a pattern: timing disrupted, flow stagnant, minerals depleted.
Florence Nightingale Worked This Out in 1860
Terrain isn’t a new idea and it isn’t a fringe one. It came out of the 1800s, and collecting on it is most of what public health accomplished in the 1900s.
Start with Florence Nightingale, the British nurse and statistician who founded modern nursing. She watched soldiers recover, or fail to recover, under conditions that looked identical, and she concluded that infection was only part of the story. What decided the outcome was air, sunlight, nutrition, cleanliness, and rest.2
She was wrong about why. She thought disease rose out of foul air, and she resisted germ theory for most of her life. But she was right that the conditions around a patient decided the outcome, and she proved it with statistics before anyone could explain the mechanism. That’s the argument this article is making, and it predates penicillin by eighty years.
The pattern repeats across the history of public health. In 1850s London, cholera moved through contaminated wells until the physician John Snow traced the deaths back to a single pump on Broad Street, and the handle came off.3 That was the entire intervention. No examinations, no prescriptions, no treatment of any kind. People walked to a different well, and cholera stopped moving through that neighborhood.
Water filtration spread through North American and European cities over the decades that followed, and continuous chlorination of municipal supplies began in 1908. Deaths from typhoid and the other waterborne diseases dropped hard. Two economists later estimated that filtration alone accounted for something close to 40 percent of the entire decline in urban death rates over the first third of the twentieth century.4 That number was challenged, and the original authors revised it down a little when they rechecked their data.5,6 Nobody in the argument disputes the direction.
Again, no one was treated. The conditions changed, and the outcomes changed with them.
That’s terrain thinking, and it built the world you live in, though almost none of it looks like medicine. Sewers replaced open drains and backyard privies. Housing got less crowded. Refrigeration slowed the spoiling of food between the farm and the table. Streets got paved and swept, garbage got collected, and window screens kept flies off what people were about to eat. When the car replaced the horse, it took with it the tons of manure sitting in every city street and the flies that bred in it. Water still gets filtered and restaurants still get inspected. Nobody calls any of that terrain work, but that’s what it is.
What we stopped doing is asking the same question about one person. We’ll spend billions chlorinating a city’s water and nobody calls it alternative medicine. Sit in an exam room and say your sleep has been broken for two years, you eat at midnight, and your job has been grinding you down for a decade. Those become background details. The bloodwork gets ordered, and whatever it says is the answer.
Conditions decide the outcome in a reservoir. They decide it in a body too. We only ever act on the reservoir. And the conditions themselves have moved since then, because the century that filtered the water introduced a great deal that Nightingale never had to account for.
Eight Forces Tilting the Terrain
Eight stand out. None of them acts alone, which is why no single one of them looks like much on its own.
1. Food that’s lighter than it looks
Modern food manages to be calorie-dense and nutrient-poor at the same time. In 2004, researchers compared USDA nutrient data for 43 garden crops between 1950 and 1999. They found statistically reliable declines in six of the thirteen nutrients they examined: protein, calcium, phosphorus, iron, riboflavin, and vitamin C. The drops ranged from roughly 6 to 38 percent.7
Half a century of records, and the only reliable changes ran downward. What’s on the plate isn’t what it used to be, and a lifetime of meals is a long time to be running a little behind.
The obvious response is to reach for supplements, and that’s where plenty of people make things worse. Minerals work against each other as much as with each other, so pushing one up in isolation can pull another down. In food and water they arrive in company. In a capsule they arrive alone. The work is in getting them back into balance, not in topping up whichever one looks low.
2. Iron you didn’t ask for
In the United States, flour labeled “enriched” has to carry added iron under the FDA standard of identity, which sets an amount but not a form.8 One of the cheapest options is elemental iron powder. When researchers compared three forms of added iron in Thai women, all three improved iron status, but the powder did it at about half the efficiency of the best of the three.9 What’s on the label and what a body takes up are different numbers.
The rest doesn’t quietly disappear. Unabsorbed iron carries on into the colon, where it acts as a pro-oxidant (a substance that drives the kind of chemical damage antioxidants exist to prevent) and meets organisms happy to use it as fuel.
In two double-blind randomized trials, Kenyan infants given iron-fortified porridge for four months ended up with more disease-causing E. coli and a higher marker of intestinal inflammation than infants given the same porridge without it.10 Those infants already carried a heavy pathogen load, and the iron in that porridge wasn’t the same compound as the powder in bread, so it doesn’t transfer straight to a North American adult. What it shows is that iron passing through a gut changes what grows there.
For anyone eating red meat, intake is rarely the problem. Meat carries iron in the form the body absorbs well, while plant iron binds up with fiber and other plant compounds and largely passes through. Real deficiency usually comes from losing iron or failing to absorb it. Heavy periods, chronic blood loss and a hookworm all drain it. Low stomach acid and a damaged gut lining block it on the way in. Those cases need medical supervision, and fortified flour fixes none of them.
3. What happens before you can talk
Terrain starts forming long before anyone thinks to worry about it. Many infant formulas and baby cereals carry added iron, and it’s in there because iron matters enormously in the first year. In some babies it can pass through without any obvious symptoms. In others it shows up as colic, gas, constipation, or eczema that nobody connects back to the formula. That’s clinical observation, not trial data.
Carrageenan is the other thing worth knowing about. It’s a thickener made from red seaweed, it goes into formula to stop it separating on the shelf, and it is permitted in infant formula across North America.11 The FDA says ready-to-feed and liquid formulas often contain it.12 The European Union does not allow it in infant formula.13
One regulator took it out of baby food. Another left it in. That gap is the story.
In a 2024 randomized trial, 20 healthy young men took 250 milligrams of carrageenan twice a day for two weeks, and their intestinal permeability rose.14 Small study, grown men, and one of very few times anyone has measured carrageenan doing anything inside a living person. Nobody has run it in babies.
European reviewers looked at the whole evidence base in 2018 and could not confirm a safe daily intake, while the WHO’s committee judged it not of concern at the concentrations formula uses.15,16 Parents have reported for years that colic and reflux settle when they switch to a formula without it. Those reports aren’t proof. Nobody has tested them either, and that is the actual problem.
So a mother is being asked to accept an additive that is there for shelf life, that one major regulator removed from baby food, that raised gut permeability in the only human trial anyone ran, and that has never been studied in the babies drinking it. That isn’t a settled question. It’s an untested one, and the person carrying the risk can’t talk yet.
Breast milk has no added iron and no carrageenan, which makes it the safest option where it’s possible. Where it isn’t, formulas without carrageenan exist and the ingredient list will tell you which.
Stress, Light, and the Clock
4. Stress that never switches off
The body was built for short bursts of stress, not permanent alertness. Sustained pressure flattens the normal daily rise and fall of cortisol, the hormone that helps you wake up, hold blood sugar steady, and keep inflammation in check.17
Digestion runs on that same daily rhythm and suffers when it goes flat. Stomach acid tends to drop. Motility slows. (Motility is the wave of muscle contraction that carries everything along your gut.) Meals sit longer than they should, and the small intestine loses the strong clearing waves that sweep through between them. In a slower, less acidic gut, things that would ordinarily pass through have more time to settle.
Worth knowing that stress here isn’t only the psychological kind. A long infection, broken sleep, chronic pain and hard training all switch on the same system. That last one catches people out. A hard session at the gym reads as health, and the body still runs it as stress.
5. A body clock with no signal
Indoor days and lit-up nights blur the cues that used to anchor digestion, immunity, and mood. Morning light lines cortisol up with the day, and evening darkness invites melatonin, which deepens sleep and also works as a powerful antioxidant in the gut and brain.18
The clock isn’t a metaphor. Almost every tissue in the body keeps its own daily rhythm, and the gut runs one of the strongest. Digestion, immune activity and overnight repair all work to a schedule. Those rhythms are built in rather than borrowed, but without daily light and dark to set them against, they drift out of step with each other.
Take those cues away and gut motility turns erratic, stomach acid loses its timing, and immune function drifts off schedule. Groggy mornings and wired evenings aren’t always bad luck. Often they’re a timing problem.
Chemicals, Medicine, and a Wider World
6. The chemical background hum
Pesticides, plasticizers, solvents, fragrances, food additives, and heavy metals circulate at doses too low to make anyone obviously sick. What they do instead is raise oxidative stress (the same chemical wear that unabsorbed iron drives, happening in the background everywhere at once) and keep the body’s detoxification systems permanently busy. Some concentrate in fat and cell membranes and change how cells signal. Others work closer to the surface, and the carrageenan trial above is one of the few times anyone has measured a common additive doing exactly that in living people.14
The lining gets more permeable and bile gets sluggish. Nothing has to attack anything, because things simply settle where the defenses have gone soft.
7. Medicine that helps, and also costs
Modern medicine saves lives every day, and some of its most common tools reshape terrain in ways nobody intended. Repeated antibiotics thin microbial diversity. Nonsteroidal anti-inflammatories irritate the gut lining. Acid-suppressing drugs weaken stomach acid, which is one of your first barriers against anything you swallow, and people taking them show higher rates of several gut infections, including Salmonella and Campylobacter.19
Any of these can be the right call in the moment. Over years, the pattern thins the defenses a parasite would otherwise have to get past.
8. A much bigger world
Travel, trade, and daily contact with animals put us in front of organisms our great-grandparents would rarely have met. Food is grown, processed, and shipped through long chains that can carry organisms a long way from the soil they started in. Pets share the couch and sometimes the plate.
None of that is a reason to be afraid. It only means a softened terrain now meets far more opportunities than it used to.
Put the eight together and they push on the same axis. They thin the body’s boundaries and slow its recovery between insults. Tilt that axis far enough and a parasite doesn’t need to be aggressive at all. It can simply occupy the space we prepared for it.
Why the Garden Comparison Holds Up
Think of your body as a garden. Minerals are the soil. Light sets the seasons. Bile is the irrigation system. Motility is what keeps things from going stagnant.
In rich, well-tended ground, plants grow the way they are supposed to and the occasional weed never amounts to much. In thin, compacted soil the weeds take over, not because the weeds got stronger but because nothing is competing with them anymore. The weeds were always there. The soil is what changed.
Here’s the part that matters for anyone who has been through a cleanse. You can pull weeds all summer, and if you never touch the soil you’ll be out there again next year doing exactly the same work. Most people draw the obvious conclusion from that, which is that weeding doesn’t work.
Weeding works fine. It just isn’t gardening.
Tending soil is slower work, and it only holds if you do it in the right order. That order is what Parasites & the Terrain is built around.
What Changes If This Is Right
If the ground decides the outcome, then two questions matter more than anything else. What wears the terrain down, and what builds it back?
The eight forces above are the first half of that answer. They’re also why the second half can’t be a single supplement or a two-week protocol. You can’t out-supplement a body clock that has lost its signal, and you can’t out-cleanse food that’s lighter than it looks.
It’s also why food poisoning symptoms can last for years in some people and not others. When researchers followed people after an episode, the ones who didn’t bounce back shared a set of risk factors: chronic stress, antibiotics taken during the illness, and a first episode that ran longer or harder than average.20 Most of that list describes the person rather than the organism.
Over the coming months I’ll write about these pieces one at a time. Why the popular cleanse protocols give people a promising few weeks before they become impossible to sustain. Why minerals have gotten harder to get from food than they used to be. What ten minutes of morning light does to your body clock.
The order those pieces go in matters more than any single one of them, and that order is the subject of my book, Parasites & the Terrain, out from Skyhorse Publishing on January 19, 2027.
For now, the useful shift is smaller than it sounds. Stop asking what’s wrong with you, and start asking what the ground is like.
Frequently Asked Questions
What does terrain mean in health?
Terrain is what a microbe finds when it arrives: your mineral status, your light exposure and sleep timing, your stomach acid and bile, and the tone of your nervous system. The same organism behaves differently in a well-timed body than it does in a depleted one.
Why do I still feel unwell when I am doing everything right?
Because effort and conditions aren’t the same thing. A clean diet and a careful cleanse still land on whatever ground you happen to have. If your minerals are out of balance, your body clock is off, or your digestion has slowed, the same good habits produce much less than they should.
Can a parasite cleanse fix the underlying problem?
A cleanse aims at the organisms. Even where it works, it doesn’t change the conditions that let them settle in, which is why so many people feel better for a few weeks and then slide back. Removing what’s there and rebuilding what’s missing are two different jobs, and the second takes longer.
Is the iron added to enriched flour a problem?
It can be for some people. Iron the body doesn’t absorb acts as a pro-oxidant in the gut, and much of the iron added to flour is never taken up. Trials in infants found that iron fortification raised gut pathogens and inflammation. True iron deficiency is a different matter and needs medical care.
What is carrageenan and is it safe?
Carrageenan is a seaweed-derived thickener used in dairy products, plant milks, deli meats, and infant formula. A 2024 trial found it raised intestinal permeability in healthy young men. The European Union keeps it out of infant formula, while Canada and the United States permit it there. Regulators disagree, so the question stays open.
Does stress really affect digestion?
Yes. Sustained stress flattens the normal daily cortisol rhythm, and digestion runs on that same rhythm. Stomach acid tends to drop and motility slows. That leaves a slower, less acidic gut where things that would ordinarily pass straight through have more time to settle.
This article is for general information and is not medical advice. Please speak with a qualified healthcare provider about your own symptoms or before making changes to your care.
References
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Pam Killeen is a health coach and nutritional consultant with nearly forty years of experience helping people restore the foundations of their health. Her own recovery from chronic fatigue, fibromyalgia, and multiple chemical sensitivities shaped the approach she teaches today. She co-authored Dr. Joseph Mercola’s New York Times bestseller The Great Bird Flu Hoax, and is the author of Addiction: The Hidden Epidemic and Survival of the Unfittest. She is the creator of the Circadian Reboot and Truth Over Spin podcasts.
Her new book, Parasites & the Terrain: How Circadian Rhythm, Sunlight, and Minerals Build Natural Resistance, with a foreword by Dr. Mercola, will be published by Skyhorse Publishing on January 19, 2027. Read more and preorder here.