Written by Debbie Lambert – Fact checked by Anna Guildford, Ph.D.
Dietary guidance on reducing blood pressure includes reducing salt intake. The Dietary Guidelines for Americans recommend using herbs and spices instead of salt to flavor food.
Experts know less about the health effects of herbs and spices than they do about those of salt. However, some studies have shown that herbs and spices can reduce lipemia — the excess of lipids in the blood — hyperglycemia, and oxidative stress.
To dig a little deeper, researchers at Pennsylvania State University recently conducted a randomized controlled trial investigating the effect of longer-term consumption of herbs and spices on risk factors for cardiovascular disease.
They found that a higher level of herbs and spices in food reduced 24-hour blood pressure readings.
The findings appear in the American Journal of Clinical Nutrition.
Prof. Penny Kris-Etherton, one of the lead authors of the study, told Medical News Today, “Indeed, the blood pressure-lowering effects of herbs and spices in an average Western diet were surprising to me.”
“We [already know] about the effects of many lifestyle factors, especially dietary factors, that can increase blood pressure — such as sodium, alcohol, and caffeine — and others that can decrease blood pressure, such as potassium, magnesium, and calcium, […] weight loss, physical activity, and some vitamins, including folate and vitamin D when intake is low, but the blood pressure-lowering effects of herbs and spices are new!”
“In terms of herbs and spices,” she continued, “there hasn’t been a clinical trial showing benefits on blood pressure lowering until our study.”
Three test diets
After the participants fasted for 12 hours, the researchers made baseline assessments. These included height, weight, waist circumference, a fasting blood sample, and vascular testing.
Vascular testing included central and peripheral blood pressure and arterial stiffness measurements. The participants also wore a blood pressure monitor for 24 hours.
The researchers then randomly assigned the participants to one of three groups. Each group would eat one of three diets: a low spice diet, a moderately spiced diet, or a high spice diet. These diets included a daily intake of 0.5 grams (g), 3.3 g, and 6.6 g of herbs and spices, respectively.
The participants followed their respective diets for 4 weeks, with a 2-week break in between. At the end of each diet period, the participants returned for follow-up assessments. A total of 63 individuals completed the study.
The study showed that the high spice diet tended to improve 24-hour blood pressure readings, compared with the medium and low spice diets.
The researchers did not observe any effect of the diets on low-density lipoprotein cholesterol, clinic-measured blood pressure, markers of glycemia, vascular function, or oxidative stress.
However, they say that 24-hour blood pressure readings are a stronger predictor of cardiovascular death than clinic blood pressure measurement.
The authors believe that the study might have been too short for vascular remodeling to occur, which might explain why they did not see any effect on arterial stiffness.
They also note that the dosages of herbs and spices might not be adequate to overturn the metabolic effects of an unhealthy background diet. Therefore, they cannot recommend increasing intake of herbs and spices alone in the context of a poor quality diet to lower the risk of cardiovascular disease.
Moreover, because each day of the menu included different amounts of the 24 herbs and spices, exposure was not consistent. As herbs and spices do not stay in the system for very long, the food consumed during the days closest to testing may have influenced the results more strongly.
Dr. Simon Steenson, a nutrition scientist at the British Nutrition Foundation, told MNT, “This study suggests there could be potential benefit in terms of blood pressure reduction for including more herbs and spices within our diet.”
“However,” he continued, “the effects seen were small and not significant between all levels of intake. While the authors suggest there may be some benefit to including herbs and spices in a suboptimal diet, clearly, the aim from a public health point of view must be to improve dietary patterns in line with evidence-based guidance on diet and health.”
Prof. Kris-Etherton said to MNT, “It will be important to evaluate the effects of individual spices on blood pressure and to understand the mechanism[s] by which each lowers blood pressure.”
“It would also be interesting to assess the effects of herbs and spices on the microbiome and evaluate whether the effects of herbs and spices on [blood pressure] are modulated by any changes in the gut microbiome.”
“Beyond clinical trial research, studies are needed to evaluate effective education programs that teach use of herbs and spices in a healthy dietary pattern that is lower in sodium, saturated fat, and added sugar on diet quality and clinical endpoints, such as risk factors for chronic diseases.”
Dr. Steenson concluded:
“It is important to note that while the aim of this study was to look at the average American diet, we need major shifts in average dietary patterns to make our eating habits healthier and more sustainable. While certain foods or ingredients may have a small benefit alone, we need to encourage a shift to healthier eating across the board.”