Vitamin C is often talked about in broad terms, from immune support to antioxidant benefits. A new study takes a much narrower look at what it may do in one specific setting: when nitrates and nitrites move through the digestive system.
The study, published in the Journal of Theoretical Biology, used mathematical modeling to examine how vitamin C may influence nitrosation, a chemical reaction that can happen in the stomach and may lead to compounds linked to cancer risk. The findings do not show that vitamin C prevents cancer. Instead, they offer a possible explanation for how the mix of compounds in a meal may affect what happens during digestion.
Nitrates and nitrites are found in a wide range of foods and environmental sources. They are often discussed in connection with cured meats such as bacon and salami, but they also occur naturally in vegetables, including leafy greens. That makes the issue more complicated than simply labeling nitrates or nitrites as harmful.
In the body, nitrates can be converted to nitrites. Under certain conditions in the stomach, nitrites can take part in reactions that form N-nitroso compounds, some of which have raised concern because of their potential connection to cancer risk. Vitamin C, the researchers said, may help block some of those reactions.
“Since at least the ‘90s, researchers have been studying the link between cancer and these compounds, with conflicting results,” said Dr. Gordon McNicol, a post-doctoral researcher in applied mathematics and the study’s first author. “Our work suggests that the presence of dietary vitamin C may help explain these inconsistencies.”
To explore that possibility, the researchers built a model of the salivary glands, stomach, small intestine and plasma. They then simulated how nitrates and nitrites move through the body and change over time under different dietary patterns and water-quality conditions.
In the model, vitamin C appeared to reduce the formation of nitrosation products associated with cancer risk. That may help explain why nitrates from vegetables are often viewed differently than nitrates and nitrites from cured meats. A food like spinach, for example, may contain nitrate, but it can also provide vitamin C and other compounds that may affect the chemistry of digestion.
The study also modeled vitamin C supplements taken after meals and found a possible moderate benefit in reducing nitrosation products. That does not mean people should start taking vitamin C after every meal to lower cancer risk. The study was not a clinical trial, did not test cancer outcomes and cannot show what would happen in real people over time.
Instead, the findings point to questions that future studies could test more directly, including whether vitamin C intake, meal timing, stomach conditions, oral bacteria and nitrate or nitrite exposure may work together in ways that change risk.
“This work provides a mechanistic roadmap for future clinical and laboratory studies by identifying the key interacting drivers of these potentially harmful chemical reactions, including nitrite exposure, antioxidant intake, meal timing, gastric conditions and oral microbiome activity,” said Dr. Anita Layton, professor of applied mathematics and Canada 150 research chair.
The study was supported by an NSERC Discovery Grant awarded to Anita T. Layton. Additional support came from Environment and Climate Change Canada’s Solutionscapes program, the NSERC Alliance program and Canada Research Chair funding related to global water sustainability and ecohydrology. Gordon R. McNicol was supported through these supervisory grants.