18.5.1 Organic vs. Non-organic
Organic food production might be one way to mitigate the effects of environmental
pollution by industrial and agrochemicals. A recent meta-analysis of 56 studies and
149 paired comparisons of organic and conventional farming systems based on
global data accumulated over 20 years, demonstrated that organic farming increases
the biomass and activity of the soil microbiota (Lori et al. 2017). This must affect our
exposure to environmental microbiota in air and dust, but what about the organisms
we take in with organically grown food? The answer is unclear.
A recent study compared conventionally grown fruit and vegetables to products
that were labelled organic, and purchased from the same grocery stores in the USA.
The findings were different for different products. Organic spinach, lettuce, and
tomatoes had more diverse microbiota than conventionally grown products, whereas
the opposite was true for peaches and grapes, where the conventionally grown
products had richer microbiota (Leff and Fierer 2013). There were also differences
in the composition of the microbiota, the most consistent being a greater relative
abundance of Enterobacteriaceae on conventional spinach, lettuce, tomatoes, and
peaches when compared to organic produce (Leff and Fierer 2013). This study found
little difference between conventional and organic apples. However, a more detailed
study that looked separately at the microbiota of the stem, peel, fruit pulp, seeds, and
calyx found a different microbiota at each site, and significantly increased diversity
at each site in organic apples (Wassermann et al. 2019). Thus, according to this
study, consuming an apple corresponds to an intake of about 10
8 bacteria, and these
are more diverse, and include more lactobacilli, if the apple is organic.
18.6 Conclusions
It is now generally accepted that populations in developed countries are suffering
from striking increases in disorders that involve faulty regulation of the immune
system, and that this faulty immunoregulation is at least partly attributable to
diminished or distorted exposure to the microorganisms with which we coevolved,
because these play a crucial role in setting up immunoregulatory mechanisms. Much
attention has been focussed on the obvious ways in which the modern Western
lifestyle impedes mother-to-baby transmission of the microbiota, and on the further
distortion of the child’s microbiota caused by unvarying diets and antibiotics. Much
less attention has been applied to the issue of contact with the microbiota of the
natural environment, although contact with this was inevitable during our evolution,
and has therefore become a necessity. The coining of the misleading expression
“hygiene hypothesis” has led to an unproductive obsession with home hygiene
practices, whereas the most careful studies reveal that what matters is not how you
clean your toilet, but whether you are exposed directly to the natural environment,
and whether the microbiota of the home resembles that of the natural environment
18 Darwinian Medicine: We Evolved to Require Continuing Contact with the. . .
353
Organic food production might be one way to mitigate the effects of environmental
pollution by industrial and agrochemicals. A recent meta-analysis of 56 studies and
149 paired comparisons of organic and conventional farming systems based on
global data accumulated over 20 years, demonstrated that organic farming increases
the biomass and activity of the soil microbiota (Lori et al. 2017). This must affect our
exposure to environmental microbiota in air and dust, but what about the organisms
we take in with organically grown food? The answer is unclear.
A recent study compared conventionally grown fruit and vegetables to products
that were labelled organic, and purchased from the same grocery stores in the USA.
The findings were different for different products. Organic spinach, lettuce, and
tomatoes had more diverse microbiota than conventionally grown products, whereas
the opposite was true for peaches and grapes, where the conventionally grown
products had richer microbiota (Leff and Fierer 2013). There were also differences
in the composition of the microbiota, the most consistent being a greater relative
abundance of Enterobacteriaceae on conventional spinach, lettuce, tomatoes, and
peaches when compared to organic produce (Leff and Fierer 2013). This study found
little difference between conventional and organic apples. However, a more detailed
study that looked separately at the microbiota of the stem, peel, fruit pulp, seeds, and
calyx found a different microbiota at each site, and significantly increased diversity
at each site in organic apples (Wassermann et al. 2019). Thus, according to this
study, consuming an apple corresponds to an intake of about 10
8 bacteria, and these
are more diverse, and include more lactobacilli, if the apple is organic.
18.6 Conclusions
It is now generally accepted that populations in developed countries are suffering
from striking increases in disorders that involve faulty regulation of the immune
system, and that this faulty immunoregulation is at least partly attributable to
diminished or distorted exposure to the microorganisms with which we coevolved,
because these play a crucial role in setting up immunoregulatory mechanisms. Much
attention has been focussed on the obvious ways in which the modern Western
lifestyle impedes mother-to-baby transmission of the microbiota, and on the further
distortion of the child’s microbiota caused by unvarying diets and antibiotics. Much
less attention has been applied to the issue of contact with the microbiota of the
natural environment, although contact with this was inevitable during our evolution,
and has therefore become a necessity. The coining of the misleading expression
“hygiene hypothesis” has led to an unproductive obsession with home hygiene
practices, whereas the most careful studies reveal that what matters is not how you
clean your toilet, but whether you are exposed directly to the natural environment,
and whether the microbiota of the home resembles that of the natural environment
18 Darwinian Medicine: We Evolved to Require Continuing Contact with the. . .
353