Take home message
- Children growing up on a dairy farm have different colonisation of their gut than non-farm children (less Escherichia coli and less Clostridium difficile)
- Children who grow up with ‘pets’ (dog, cat) also develop a different composition of their gut flora (former occupation with Bifidobacteria and Bacteriodes)
- There is a clear correlation between developing an allergy (8 years old) and colonisation of the gut. Early, rapid colonisation with so-called ‘obligate anaerobic’ bacteria (read: live only in a completely oxygen-free environment) gives protection in this respect. C.difficile is an important bacterium in this respect, which is there quickly but should not dominate.
- Persistently high numbers of C.difficile are indicative of an undeveloped, immature gut, linked to allergy later in life.
How important are the first 1,000 days of your life, and do you count from conception or from birth? In any case, it is clear, that it is only after birth as a new human that you get the exposition with the world outside. There are food proteins that you must ‘learn to recognise and digest’, where your immune system learns and recognises what is edible and what is potentially pathogenic. If that doesn’t go well, allergies and asthma can develop. The 2nd exposition is with the micro-organisms, the living bacteria that are all around you. You must learn to render these harmless or integrate them into your own gut flora. Bacteria must colonise the young gut, and what settles there depends, among other things, on birth (vaginal/home or caesarean/hospital), it depends on whether and for how long your mother’s own milk is given, early and frequent antibiotic use, on the environment you live in, or whether there are pets.
In the Swedish FARMFLORA birth cohort study, all kinds of children are followed from conception to adolescent age. A previous study by this group (Jonsson et al., 2016) looked at the impact of raw milk consumption in young children living on farms, among other things. A recent study compared children on whether they lived with pets (Ljung et al., 2024). The FARMFLORA study is a so-called prospective study, making the outcomes scientifically strong. Pets such as dog and cat, as well as farm animals, were present in some of the children when they grew up on a farm. Stool samples were taken from the children regularly from 3 days to 1½ years old. The study focused on the colonisation of the young gut with the microorganisms in relation to the development of allergy and asthma later in life (3 and 8 years old).
Growing up on a dairy farm
Numerous studies suggest that children growing up on a dairy farm have an advantage in terms of developing milk allergy, food allergy or asthma (Riedler et al., 2001). Both the barn environment, pets, and the consumption of raw milk provide a balanced and well-functioning immune regulation. That is, these children do not later suffer from the allergic problems.
The Swedish study (Ljung et al., 2024) focuses on the role of the ‘pets’, the dog and the cat, and the colonisation of the gut with microorganisms. Again, it appears, that farm children have an advantage over non-farm children. Numerous measures have been developed for this, such as the ratio between certain groups of bacteria (anaerobic/ facultative ratio), the rate of emergence of Bifidobacteria, keeping unwanted bacteria (C.difficile or E.coli) low. They also wanted to know, whether early colonisation of the gut influences the development of allergy at ages 3 and 8 years. Children with allergy were compared in terms of gut flora with children without allergy. Some interesting differences emerge.
Early intestinal flora of children with and without allergy
Obviously, some things are already known about the intensity and sequence of how a young gut is, or should be, colonised. Bifidobacteria come first, mostly growing on the many oligosaccharides present in breast milk. Then soon come Clostridium spp, followed by Bacteriodes spp towards the end of the first year of life. Lactobacilli also arrive quite early, but never become dominant. Colonisation is shown in the figures below.
In allergic children, the gut is colonised later and slower with, among others, the group of Bacteriodes (under 4 months) or with Bifidobacteria (under 6 months). You also see a higher proportion of the unwanted C.difficile showing up in allergic children (4-12 months), but also less Lactobacilli at certain stages (4-6 months). Allergy is also associated with more Coagulase Negative Staphylococci or more Staphylococcus aureus.
There are differences in outcomes between allergy at ages 3 and 8 years. Especially for late allergy at 8 years, the differences are large in the rate of intestinal colonisation. Other correlations found again here are that of the short-chain fatty acids (C4 and C5 fatty acids) in the colon produced by certain groups of gut bacteria and the reduction of allergy.
Conclusion
The environment in which children grow up co-determines the development of allergy later in life. The early, rapid and right colonisation of the young child’s gut plays a crucial role in this, and is expressed in certain groups of bacteria, as well as the concentration of short-chain fatty acids.
Literature
- Jonsson, K., Green, M., Barman, M., Sjöberg, A., Brekke, H. K., Wold, A. E., & Sandberg, A. S. (2016). Diet in 1-year-old farm and control children and allergy development: results from the FARMFLORA birth cohort. Food & nutrition research, 60(1), 32721.
- Ljung, A., Gio-Batta, M., Hesselmar, B., Imberg, H., Rabe, H., Nowrouzian, F. L., … & Adlerberth, I. (2024). Gut microbiota markers in early childhood are linked to farm living, pets in household and allergy. PloS one, 19(11), e0313078.
- Riedler, J., Braun-Fahrländer, C., Eder, W., Schreuer, M., Waser, M., Maisch, S., … & Von Mutius, E. (2001). Exposure to farming in early life and development of asthma and allergy: a cross-sectional survey. The Lancet, 358(9288), 1129-1133.
