Eating more herbs and spices may lead to lower blood pressure over the course of 24 hours, according to the results of a study presented at the Nutrition 2021 Live Online conference, the annual conference of the American Society for Nutrition.
Researchers at Penn State University and Texas Tech University sought to look at the effects of including more mixed herbs and spices in the diets of adults at an elevated risk for cardiometabolic disease — such as people with elevated blood glucose or blood lipids (cholesterol and triglycerides). While previous studies have shown that eating herbs and spices can have immediate beneficial effects — such as lower after-meal blood glucose and lipid levels, and better blood vessel function — this study represents the first randomized controlled trial to look at the effects of eating herbs and spices over a longer period of time. Randomized controlled trials are considered the “gold standard” for study design because participants’ preferences don’t play a role in the behavior or intervention that’s being evaluated — instead, participants are randomly assigned to different behaviors as part of the study.
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For this study, 71 participants with an average age of 44 and an average body-mass index (BMI, a measure of body weight that takes height into account) of 29.7 — right on the boundary between overweight and obese — took part in three different arms of the study, in a randomly assigned order. Each arm involved following a different diet, which was provided for four weeks as part of the study. There was a minimum of two weeks between each diet period, during which participants ate whatever they wanted. Each diet contained 2,100 calories and different amounts of herbs and spices — 0.5 grams, 3.3 grams, or 6.6 grams — each day.
Herbs and spices linked to lower blood pressure
Participants had several measurements taken at the beginning of the study, and after each diet period — including blood glucose and lipids, insulin, and blood pressure. Participants also wore a blood pressure monitor for a 24-hour period, in addition to having a standard blood pressure reading taken at a lab visit that also included a blood draw for the other tests.
Between the three diets, there was no difference in the effect on LDL (low-density lipoprotein, or “bad”) cholesterol, the main outcome the researchers were interested in. There were also no differences in glucose levels, markers of blood vessel function, or clinic-measured blood pressure. But eating more herbs and spices had a significant effect on 24-hour blood pressure readings.
The high-spice diet resulted in an average systolic blood pressure (the “top number” measured during heartbeats) 2.2 mmHg lower than the medium-spice diet and 2.1 mmHg lower than the low-spice diet, and an average diastolic blood pressure (the “bottom number” measured between heartbeats) 1.6 mmHg lower than the medium-spice diet and 1.7 mmHg lower than the low-spice diet.
While these benefits may be small in an absolute sense, they were seen even though the overall diet being provided was a “suboptimal U.S. style diet,” according to the researchers. More research is needed to look at the effects of herbs and spices in different types of diets, including whether they may have greater health benefits when they’re included in a healthy dietary pattern such as a Mediterranean-style diet.