Sweetener or Sugar?
The Science Behind Preference for Sucrose over Sucralose
Background
Most people tend to prefer real sugars to various artificial sweeteners, and while you may simply chalk this up to personal preference, it may actually be due to how various cells and nerves in the gut interact with sugars and artificial sweeteners. This link between the sensory cells of the gut and the nervous system is the way that preferences are developed. To see if this preference was linked to those gut-located sensory cells, a group of scientists performed experiments to determine sugar preferences in mice. They wanted to understand how this favoritism towards natural sugars over artificial sweeteners develops.
Summary
Sugars like sucrose and artificial sweeteners like sucralose both create a sweet taste, but sugar is clearly preferred in both animals and humans. This preference, though, is not linked to taste buds as the team of scientists stated that: “Even mice lacking taste receptors can distinguish sugar from sweetener or water,” meaning that this preference is ingrained deeper than just the sensory receptors of the taste buds. The preference for sucrose over sucralose comes from the disaccharide D-glucose that makes up sucrose. D-glucose has a strong preference in the cells of the duodenum of the small intestine. The team noted that all preference for D-glucose went away when the duodenum is bypassed, meaning that the cause of preference for sugar lies in the small intestine.
The gut cells that distinguish between tastes are known as neuropod cells. These cells form synapses with the vagal nerve — the main nerve of the parasympathetic nervous system that controls digestion. To test whether vagal nerve activation was directly tied to the neuropod cells of the duodenum the scientists bred a set of mice where the chloride pump in neuropod cells could be inactivated by light with a frequency of 532nm. When introduced, this light would hyperpolarize a cell’s membrane and prevent nerve signals from being sent to the vagal nerve. The results of the experiment showed that in the presence of the light, the neural response to sucrose was reduced, but the response to sucralose was unchanged. This shows that the neuropod cells of the small intestine play a role in the nervous system’s response to sugar. It still did not answer how that preference develops, though.
To answer that question, the scientists performed another experiment where a group of control and recombinant mice were implanted with a fiber optic cable that would send 532nm light to the neuropod cells. They could then track the differences in vagal nerve impulses in the presence and absence of the light. The results of this experiment showed no significant change in nerve firings in the control group, but in the recombinant group of mice whose neuropod cells could be hyperpolarized, sucrose preference dropped from 98% to 58.9%. This showed that these small intestine cells play a significant role in the preference for natural sugars over artificial sweeteners. Also, the recombinant mice saw an increase in sucralose intake and a decrease in sucrose intake adding further evidence to the fact that the neuropod cells play a larger role in preference for sugars over artificial sweeteners.
