The effect of herbs and spices on risk factors for cardiometabolic diseases: a review of human clinical trials

Abstract Herbs and spices are recommended to increase flavor and displace salt in the diet. Accumulating evidence suggests herbs and spices may improve risk factors for cardiometabolic diseases. In this narrative review, an overview of evidence from human clinical trials examining the effect of herbs and spices on risk factors for cardiometabolic diseases is provided. Human clinical trials examining supplemental doses of individual spices and herbs, or the active compounds, have yielded some evidence showing improvements to lipid and lipoprotein levels, glycemic control, blood pressure, adiposity, inflammation, and oxidative stress. However, cautious interpretation is warranted because of methodological limitations and substantial between-trial heterogeneity in the findings. Evidence from acute studies suggests intake of mixed herbs and spices as part of a high-saturated fat, high-carbohydrate meal reduces postprandial metabolic impairments, including lipemia, oxidative stress, and endothelial dysfunction. Limited studies have examined the postprandial metabolic effects of incorporating mixed herbs and spices into healthy meals, and, to our knowledge, no trials have assessed the effect of longer-term intake of mixed herbs and spices on risk factors for cardiometabolic diseases. To inform evidence-based guidelines for intake of herbs and spices for general health and cardiometabolic disease risk reduction, rigorously conducted randomized controlled trials are needed, particularly trials examining herb and spice doses that can be incorporated into healthy dietary patterns.