Let Them Eat Dirt: Saving Our Children from an Oversanitized World
by B. Brett Finlay and MarieClaire Arrieta (Greystone 2016)
Review by Mark Forsythe
Our kids need dirt and face licks from the family dog.
We live in an obsessively clean world with antibiotic soaps, cleansers, antibiotic drugs and body washes. For some good reasons….
Killer microbes like H1N1 influenza claimed millions more lives at the end of the First World War than the war itself? not to mention the toll from other deadly diseases like cholera, tuberculosis and bacterial meningitis.
Before antibiotics were developed, 90 percent of children died if they contracted meningitis. But about 25 years ago scientists began to realize that lack of exposure to microbes could partially explain an increase in childhood allergies. This research has now expanded to examine the origins of obesity, diabetes, asthma and possibly autism.
In Let Them Eat Dirt (Greystone $19.95), UBC microbiologists Brett Finlay and Marie Claire Arrieta caution parents not to create hermetically sealed cocoons for their young children. Early exposure to a wide variety of microbes is key to firing up the immune system.
“The consequences of missing out… appears to be that, later in life, the immune system may react too fiercely to these harmless microbes, which could trigger inflammatory responses in various organs of the body,” they write. “This contributes to the appearance of “developed country diseases” (like asthma and obesity) that are becoming so prevalent today.”
Let Them Eat Dirt is crammed with fascinating research (babies born on farms have fewer allergies or asthma), historical detours (the Father of Microbiology was a lens maker) and practical Do’s and Don’ts for pregnant women and new parents with questions about breastfeeding, hygiene, antibiotic use, allergies, probiotics, vaccines and diet.
-- Invisible to the naked eye, microbes are the smallest, oldest and most successful forms of life on earth.
-- Microbes weigh more than all plants and animals on the entire planet combined
-- For every single human cell in our bodies there are 10 bacterial cells and for every gene in our cells, there are 150 bacterial genes
-- 500 -1,500 species of bacteria live in the human gut. They look after digesting most of our food and fabricate essential vitamins B and K
-- A single bowel movement is 60 percent bacteria, numbering more than all the people on earth
Antibiotics are important and necessary interventions for life threatening or serious bacterial infections, but applying antibacterial hand sanitizers every time a child plays outside could be eliminating microbes that help keep them healthy later in life.
We can thank the human discovery of fire for a whole new stage of evolutionary development that also created a more diverse forest of healthy microbes in our guts.
“We completely take it for granted now, but cooking food made it safer to eat, as heat kills the disease causing bacteria that thrive in decomposing meat... If humans hadn’t developed a way to cook food we, too, would have to spend six hours chewing five kilos of raw food every day to get enough energy to survive, just like our primate cousins do.”
With fire, human brain size grew by about twenty percent, improving our ability to hunt, communicate and socialize. “In other words, cooking made us smarter and it made us human.”
Microbes play a role starting in the womb. Pregnancy generates changes in the mother’s micro biota makeup, especially during the third trimester, helping create more energy for mother and fetus. That same microbial mix has been found in babies at one month of age.
“From a genetic perspective, having babies is the only way to propagate our genes? from a microbial perspective, a newborn is brand new real estate where microbial genes can also multiply and propagate.”
During vaginal birth babies are exposed to lactic microbes that help the baby digest mother’s milk, develop the immune system and protect against infections. (Some mothers who experience C Section births are now “seeding” these microbes into their newborns.)
Antibiotic use during pregnancy can also have consequences for children. A recent New York study showed children were at an 85 percent higher risk to be obese by age seven (if antiobiotics intervene). This is new research, but if the trend continues, it could mean that, “antibiotic use during pregnancy has significantly more risk than is currently assumed in medical practice.”
The married authors think antibiotics are too readily administered to pregnant women, often for the flu virus, which does not require antibiotics. Mother’s milk also delivers beneficial bacteria that help the baby’s immune system develop, and with the introduction of solid foods and a diverse diet, new microbial species begin to bloom.
As with all ecosystems, the more diversity the better.
And yes, kids should absolutely get outside and roll around in the dirt with the family dog. Slobber included. As Grandma was heard to say, “You have to eat a peck of dirt before you die.” It seems that peck of dirt is mostly good for you.
Former CBC Radio host Mark Forsythe is now a man of free intelligence in Fort Langley.