The potential health benefits of bioactive compounds in herbs and spices are supported by “moderately strong” science to date, but “it would undoubtedly also be helpful to see more randomized controlled trials”, according to an Oxford University researcher.
In a review published in Current Food Science and Technology Reports, Prof. Charles Spence from Oxford’s Department of Experimental Psychology explained that there are few studies that have the necessary funding to conduct randomized controlled trials (RCT) to decide efficacy.
“To date, much of the research on the health benefits of bioactive compounds tends to focus on a relatively small number of well-known compounds, such as capsaicin, while neglecting the 100 or so other compounds that are also present in chilli peppers,” wrote Prof. Spence.
“At the same time, however, the fact that various compounds in herbs, spices and other ingredients with which they happen to be combined interact to potentially enhance the bioavailability of various bioactive compounds also makes research in this area all the more challenging.”
Economic significance
Spices are the fragrance carriers from many parts of the plant including seeds, arils, bark, flower-buds, stigmas, roots and resins. Herbs are defined as the leafy part of the plant.
Though hundreds of herbs and spices are identified, people often use a small number of them. They are typically sourced locally, though some parts of the world are thought of as particularly robust herb and spice growing regions, including Iran, Spain, Morocco and Greece.
“Nutmeg, mace and cloves, meanwhile, were originally found only in The Spice Islands, The Moluccas, of Indonesia,” explained Prof. Spence. “However, Grenada is now a major exporter, even including a nutmeg on its national flag, thus hinting at the spice’s economic significance for the country.”
Between 2024 and 2034, the compound annual growth rate for herbs and spices is expected to grow from $172 million to $244 million.
Bioactive compounds
Bioactive compounds are certain chemicals found in small amounts in plants and foods that likely promote good health, including being studied in the prevention of some medical conditions.
As examples, bioactive compounds include lycopene, resveratrol, lignan, tannins and indoles (which have antioxidant and anti-inflammatory activities) and are essential and nonessential compounds. Prof. Spence noted that “the most antioxidant-rich products in the human diet are spices and herbs, some of them being exceptionally high.”
In a study of 488,000 Chinese from ten regions followed for seven years, the participants who ate more chilies saw a 14% reduction in their risk of an early death (British Medical Journal, 2015). However, a meta-analysis of 39 studies showed that eating spicy food had no clear protective, nor adverse effects, for some major medical conditions (Chinese Medical Journal, 2017).
For people who consume turmeric (or curcumin), they may experience its anti-carcinogenic properties as well as pain-relief. Research also implicates turmeric in alleviating clinical depression and may be useful in diabetes treatment.
Meanwhile, cloves have been demonstrated to be effective as a topical anesthetic, while cumin has been suggested as an effective aid to weight control in overweight and obese women. Ginger appears to help with the symptoms of certain kinds of nausea.
Prof. Charles Spence, University of Oxford
Prof. Spence also explain that the benefits of bioactive compounds are often dose-dependent, and that excessive consumption of some bioactive compounds could lead to carcinogenic effects. For example, one of the components used to make pesto, methyl eugenol, is carcinogenic at higher concentrations in the animal model, he wrote.
Chefs who work regularly with certain herbs have sometimes experienced the skin condition contact dermatitis but that in most cases the concentration of the bioactive compounds falls below the conditions needed for an adverse health and/or well-being result.
One other problem is in proving the defined health effects of herbs and spices, effects that must show prevention and distinguish them from drugs. The effects of these compounds on the body may be small over months and years but could be significant over a lifetime if incorporated into a daily diet.
“Nevertheless, the antioxidant, anti-inflammatory and anti-carcinogenic properties of many herbs and spices does mean that, on balance, they make an excellent addition to our diets,” wrote Prof. Spence.
“However, given the evidence that is currently available, it would appear that the most appropriate recommendation is probably to consume a broad range of herbs and spices in order to maximize any beneficial effects on human health.”
Source: Current Food Science and Technology Reports
2025, 3, 2, doi: 10.1007/s43555-024-00046-4
“Unveiling the Health-Promoting Power of Bioactive Compounds in Herbs and Spices”
Authors: C. Spence
