Plant compounds work better together 

A new study suggests that combinations of plant-derived compounds – commonly found in foods like mint, eucalyptus, and chilli peppers – may work together to reduce inflammation more effectively than when used alone.

Chronic inflammation, which can sometimes develop without obvious symptoms, is linked to a range of conditions, including type 2 diabetes, heart disease, autoimmune conditions, and even cancer. While some plant-based foods such as herbs and spices have long been associated with anti-inflammatory effects, scientists have struggled to explain how these benefits occur at the levels typically consumed in the diet.

In recent research published in the journal Nutrients, a team led by Professor Gen-ichiro Arimura at Tokyo University of Science investigated how different plant compounds interact inside immune cells. The researchers focused on macrophages – cells that drive inflammation by releasing signalling proteins called cytokines.

To stimulate an inflammatory response, the cells were exposed to a bacterial component and then treated with several plant compounds, including menthol (from mint), 1,8-cineole (from eucalyptus), capsaicin (from chilli peppers), and β-eudesmol (from hops and ginger). Each compound was tested individually and in combination.

While capsaicin showed the strongest anti-inflammatory effect on its own, the most notable findings came from combining compounds.

Professor Arimura and his team found that when capsaicin and menthol or 1,8-cineole were used together, “their anti-inflammatory effect increased several hundred-fold compared to when each compound was used alone”.

Further analysis suggested that this enhanced effect occurs because the compounds act through different biological pathways. Menthol and 1,8-cineole influence inflammation via TRP channels and calcium signalling, while capsaicin appears to act independently of these mechanisms.

‘We demonstrated that this synergistic effect is not a coincidence, but is based on a novel mode of action resulting from the simultaneous activation of different intracellular signalling pathways,” says Professor Arimura. “This provides clear molecular-level evidence for the empirically known effects of combining food ingredients.”

The findings show that plant compounds can interact within cells to amplify their effects. This may help explain how diets rich in herbs, spices, and other plant foods contribute to lower levels of inflammation.  

Although further research is needed, the study sheds light on how plant compounds may work together to help regulate chronic inflammation, with potential implications for supporting long-term health.