Research conducted by Weizmann Institute of Science suggests that diet & lifestyle dominates gut microbiota, not genetics
Published: 16 APR 2018 09:23AM
Words by Holly McHugh | Staff Writer
A STUDY conducted at the Weizmann Institute of Science
challenges the long standing hypothesis that gut microbiome variation between individuals is due to genetic differences. The presence of certain strains of bacteria and the microbial composition of our microbiomes significantly impacts our mental health, weight, athleticism, immune function, inflammation, allergies, metabolism and appetite – a lengthy list.
Nature vs Nurture?
Scientists believe the genetic makeup of individuals determines the environment in our digestive systems, and what particular strains of bacteria are present. However, according to Weizmann researchers, diet and lifestyle are the most important factors in determining the composition and health of our microbiome. Those excusing their scale reading because it’s “in their genes,” may need to think again.
What is the gut microbiome?
The human gut contains an ecosystem of trillions of microorganisms such as bacteria, fungi, yeasts, viruses and other microscopic living things; the good guys and the bad guys. A healthy microbiome is one that comprises of mostly the good guys – probiotics are good bacteria associated with healthy gut flora – to assist with the breakdown of food and toxins to make vitamins and to train immune systems to be stronger.
To gain a better understanding: imagine growing a garden in your digestive system. You want beautiful flowers and bushy plants, with insects buzzing. In order to achieve this you must kill weeds, water the soil, provide plant food, and whatever else gardeners do to encourage their gardens to flourish.
On the other hand, a neglected garden that isn’t provided with the right nutrients and has unhealthy soil will breed weeds and insects are likely to be absent –the odd diseased rat may even take up residence. The same applies to our guts. Providing the body with the correct nutrients, vitamins and minerals and remaining hydrated, nurtures a healthy gut flora.
PTSD and gut bacteria
Stellenbosch University researchers investigated the relationship between posttraumatic stress disorder (PTSD) and bacteria in the gut. PTSD is a serious psychiatric disorder developed after experiences of life threatening trauma. It is believed that the gut microbiome influences the brain by producing neurotransmitters/hormones, immune-regulating molecules and bacterial toxins. Stress can change composition of gut microbes as stress hormones affect bacterial growth, causing inflammation associated with several psychiatric disorders.
The study found individuals with PTSD had significantly lower levels of three strains of bacteria involved in immune system regulation and had heightened levels of inflammation that may have contributed to their symptoms. Additionally, those who experienced trauma as a child also had lower levels of two of the strains of bacteria, indicating they may be at higher risk of developing PTSD later on in life.
Microbiome influencing factors
It is widely believed that genes play an extremely important part in determining the composition of gut microbiomes and account for the variation between people. Scientists from the Weizmann Institute of Science challenge this theory, suggesting that genetics in fact play a very minor part – accounting for only 2% of variation.
Their findings are based on a study that examined around 1,000 Israelis
who had previously participated in a study of personalised nutrition. Participant’s genetic data, microbiome compositions, dietary habits, lifestyle and medications were recorded and data analysed. It was concluded that diet and lifestyle were the most important factors in influencing microbiome composition, rather than genes. Connections between microbiome and cholesterol, weight and blood glucose were investigated and results show associations with bacterial genomes were stronger than associations with the host’s genome.
These studies highlight the importance of how microbiome composition affects health. An internal garden of weeds increases the likelihood of weight gain and suffering from depression and illness. An understanding of what affects our gut flora could be essential in understanding and treating health problems.
It is known that the composition of our microbiome’s affects our mental health, weight, athleticism, immune function, inflammation, allergies, metabolism and appetite – a lengthy list. The good news is it can be easily altered. Use of probiotics (live beneficial microorganisms), prebiotics (non-digestible food substances), synbiotics (combination of both) and dietary interventions, can all promote healthier guts.
Professor Segal from the Weizmann institute of science says: “we cannot shape our genes, but we now know that we can affect and even reshape the composition of different kinds of bacteria in our bodies. Findings from this research suggest that our microbiome could be a powerful means for improving our health”.
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