Herbs, spices improve ambulatory BP of adults at risk of cardiometabolic diseases

Mixed herbs and spices, when added into a US-style dietary pattern at relatively high culinary doses, may help improve 24-h blood pressure in adults at elevated risk of cardiometabolic diseases, suggests a study. Such effects are more pronounced in women.

“Intake of these dosages of herbs/spices did not change lipids and lipoproteins, clinic-measured central or peripheral blood pressure, markers of glycaemic control, vascular function, or oxidative stress,” the researchers said.

This three-period, randomized, crossover, controlled-feeding study was conducted at the Pennsylvania State University, US, and included 71 participants. The researchers examined the effect of an average American diet containing herbs and spices at 0.5 (low-spice diet; LSD), 3.3 (moderate-spice diet; MSD), and 6.6 (high-spice diet; HSD) g · d⁻¹ · 2,100 kcal⁻¹ on lipids and lipoproteins as well as other risk factors for cardiometabolic diseases in at-risk adults. Participants consumed each diet for 4 weeks with a minimum 2-week washout period. Outcomes were assessed at baseline and end of each diet period.

No effects were noted for low-density lipoprotein cholesterol between diets, but differences were observed for mean 24-h systolic (p=0.02) and diastolic (p=0.005) ambulatory blood pressure. [Am J Clin Nutr 2021;114:1936-1948]

The HSD reduced mean 24-h systolic blood pressure relative to the MSD (–1.9 mm Hg, 95 percent confidence interval [CI], –3.6 to –0.2; p=0.02), but the difference between HSD and LSD was not statistically significant (–1.6 mm Hg, 95 percent CI, –3.3 to 0.04; p=0.058). The HSD also reduced mean 24-h diastolic blood pressure compared with the LSD (–1.5 mm Hg, 95 percent CI, –2.5 to –0.4; p=0.003). No significant differences were found between LSD and MSD. In addition, no between-diet effects were noted for clinic-measured blood pressure, markers of glycaemia, or vascular function.

“This study provides evidence that mixed herb/spice intake may benefit 24-h ambulatory blood pressure, a stronger predictor of all-cause and CVD mortality than clinic blood pressure measurement,” the researchers said. [N Engl J Med 2018;378:1509-1520; JAMA 2019;322:409-420]

Despite improvements in blood pressure, the spice-containing diets did not have an impact on markers of vascular function including pulse wave velocity (PWV), augmentation index, or flow-mediated dilation (FMD). The HSD was associated with a trend toward improvement in FMD compared with baseline, but this finding should be interpreted with caution. For instance, the study might have been too short for vascular remodeling to happen; this could potentially explain the lack of effect on arterial stiffness, measured by PWV.

“Previously, improvements in endothelial function, measured by FMD or reactive hyperaemia peripheral artery tonometry, have been observed in the postprandial phase with consumption of meals containing 6, 11.25, and 14.5 g herbs/spices,” the researchers said. [Diabet Med 2013;30:590-595; Nutr J 2014;13:67; Food Funct 2020;11:3191-3200]

“Further research is needed to determine whether inclusion of herbs and spices in a healthy dietary pattern augments diet-induced health benefits,” they noted.