Yvain also found a curious link a while ago http://slatestarcodex.com/2014/02/10/links-for-february-2014/ :

One of my interests is weird ways the face interacts with the brain, so I enjoyed this study: "Masticatory deficiency as a risk factor for cognitive dysfunction". People (and lab rats) without their teeth or with otherwise impaired chewing ability become demented much more quickly than controls, apparently because the mechanics of chewing help stimulate or oxygenate certain parts of the brain. No word yet as to whether you can become a super-genius by chewing everything all the time.

The abstract of the paper:

Several studies have demonstrated that chewing helps to maintain cognitive functions in brain regions including the hippocampus, a central nervous system (CNS) region vital for memory and learning. Epidemiological studies suggest that masticatory deficiency is associated with development of dementia, which is related to spatial memory deficits especially in older animals. The purpose of this paper is to review recent work on the effects of masticatory impairment on cognitive functions both in experimental animals and humans. We show that several mechanisms may be involved in the cognitive deficits associated with masticatory deficiency. The epidemiological data suggest a positive correlation between masticatory deficit and Alzheimer's disease. It may be concluded that chewing has important implications for the mechanisms underlying certain cognitive abilities.