The impact of diet on the microbiomes of the teeth

Carbohydrates and their relationship with microbes on the teeth

Human diet has evolved throughout time. This evolution has completely changed human microbes on teeth. Humans have increased in regular diets carbohydrates which in turn increases cariogenicity (Cornejo et al., 2013). The constant supply of carbohydrates aid in the cause of diseases which in turn require the human body to adapt. Additionally, the transition from gathering to agriculture allowed the exponential population expansion of streptococcus mutants (Cornejo et al., 2013). This major shift restructured the microbial ecology of humans. The change went from balanced highly diverse microbes to a low-diversity acid dominant microbe (Adler et al., 2017).

The complexity of human teeth and carbs

Figure 1 provides a good example of how human diet and intervention directly affect the human microbe in teeth. A diet low in carbs can help inhibit production of glucans which prevents the formation of cariogenic films (Baker et al. 2019). Understanding the complexity of a system with native microbes that fight with colonizers is important to observe how the human body can adapt (evolve) to changes in its environment. This main shift led to the increase in S. mutants which in turn led to an increase in caries. This is also supported by Figure 2. In the figure it is observed that on (a) S. mutants grew exponentially, especially in the last 2000 years. At the same time, (c) shoes a likelihood heatmap that also shows an exponential factor in S. mutants.

Exponential growth is one of the main reasons that our body had to adapt to fight against S. mutants. Unfortunately, the dominance of S. mutants led to a less diverse microbe in our teeth. Main reason is that our evolution wanted to focus on fighting the most dominant “enemy”. Allocating resources for a more diverse microbiome was a waste.

An Astronaut walking on a terrain
Figure 1 Shows how a healthy tooth can develop caries. Main reason is due to poor oral hygiene but “fuel” to the fire can be attributed to high-sugar diets. The Figure also demonstrates why it is more common to develop caries in contrast to the poor-hygiene from the past.
An Astronaut walking on a terrain
Figure 2 a) shows how as human history reaches “modern” times, the population of S. mutants exponentially evolved. b) shows how it was observed in the S. mutants evolution the behavior of an exponential growth. The lower the allele, the more “rare,” the higher the number of segregating sites, means the more diverse the evolution is. Essentially showing how the S. mutant had an observation of an exponential population. C) shows the areas where there was a likelihood for the exponential growth of S. mutants. The x axis is the normalization of the current population to the ancestral population while the y axis denotes the time since expansion. These figures show that after modernization (which included change in diet), the S. mutants evolved fast which in turn forced the microbials in the human teeth to evolve as well.