Nicotine and Digestion: It's Complicated

Many people who regularly use nicotine say that it can wake the gut up, but nicotine’s effects on digestion are not as simple as “it speeds things up.” Nicotine can affect how the gut moves and how signals travel between the brain and digestive tract. This is not an article about products, but about what the research says about nicotine and digestion, including why the effects are not always straightforward. 

Everyone knows about the brain in their skull, but not many know about the one in their gut. The digestive tract contains a large network of nerve cells called the enteric nervous system (sometimes called the “second brain”) that controls how the gut functions. It runs largely on autopilot, mostly independent of the brain upstairs.

One thing common to all levels of this gut-brain system is the presence of nicotinic acetylcholine receptors. These receptors are found throughout the gastrointestinal tract: in enteric neurons, in the autonomic nervous system that connects the gut and brain, and in the immune cells lining the bowel wall. In the gut, nicotine can influence neurotransmission (signaling) and motility (how things move through the digestive system). 

The colon is the final stretch of the large intestine and the section where nicotine’s effects on digestion are some of the most consistent and best documented. Research with transdermal nicotine patches has helped show what nicotine alone does to colon function.

In one study of healthy participants, high-dose nicotine given intravenously triggered wave-like muscle contractions in the colon that push contents toward the exit. These are the same general type of contractions that can follow a meal or, for many people, a cup of coffee.

What about the stomach? The picture is more mixed. A study done in smokers found that smoking delayed gastric emptying of solids, but using nicotine gum did not. Another group reported that short-term nicotine patch use did not significantly affect the rate at which solids or liquids exited the stomach in healthy subjects who did not regularly use nicotine. What does this mean? The effects in the stomach appear to be more dose- and route-dependent than what happens further down the line. 

Nicotine doesn’t only act on the gut directly; it also works on the brainstem. Downstream effects are channeled through the vagus nerve, which is the main communication highway between the brain and the digestive tract. So when nicotine activates receptors in the brainstem, it can trigger gut responses.  

Nicotine can influence digestion through two interacting pathways:

• Indirect “fight-or-flight” effects through the sympathetic nervous system, which generally inhibits gut function and reduces gut blood flow   
• Direct effects in the gastrointestinal (GI) tract itself via nicotinic acetylcholine receptors in the enteric nervous system and other local tissues

Because these pathways can push in different directions, people can experience very different (and sometimes opposite-feeling) GI effects. 

Important: The products sold on this site contain nicotine. Nicotine is an addictive chemical that may increase heart rate and blood pressure and pose risks for individuals with certain medical conditions, particularly cardiovascular disease. These products are intended only for adult (21+) current nicotine users and are not for non-users. Sales to persons under 21 are prohibited.