Hemp seed protein shows promise in lowering blood pressure

In a recent study published in The American Journal of Clinical Nutrition, researchers investigate the efficacy of hemp seed protein and its bioactive peptide in managing blood pressure in mildly hypertensive individuals.  

Study: Hemp seed protein and its hydrolysate vs. casein protein consumption in adults with hypertension: a double-blind crossover study. Image Credit: BartTa / Shutterstock.com

Managing hypertension

Hypertension is a chronic health condition characterized by systolic and diastolic blood pressure levels above 130 and 80 mmHg, respectively. The global prevalence of hypertension exceeds 30%, and the condition is associated with 8.5 million deaths due to vascular and renal causes.

Blood pressure in humans is primarily regulated by the renin-angiotensin-aldosterone system (RAS). Within RAS, the angiotensin-converting enzyme (ACE) catalyzes the conversion of angiotensin I to angiotensin II, a vasoconstrictor responsible for reducing blood flow. Comparatively, nitric oxide (NO) produced in the vascular endothelium by endothelial NO synthase acts as a vasodilator, leading to reduced vascular tone and induction of blood flow.   

ACE inhibitors that block RAS are often used in the management of hypertension. However, the long-term use of these medications can increase an individual’s risk of various health complications, including cough, hyperkalemia, and angioedema.

Non-pharmacological interventions, including dietary interventions, have recently gained significant attention in the context of hypertension management. Plant- and animal-derived proteins both have vital roles in hypertension management; however, the effects of these proteins on blood pressure primarily depend on their amino acid composition.

Hemp seed is a plant-based protein source rich in amino acids with blood pressure-lowering properties. Bioactive peptides derived from hemp seed protein hydrolysates have been found to reduce systolic blood pressure and inhibit ACE activity in animals.

In the current study, scientists determine the blood pressure regulatory effects of hemp seed protein and its hydrolysate-derived bioactive peptide in adults with mild hypertension. The researchers also compare the impact of these compounds with those of milk protein casein.  

Study design

The study cohort comprised 31 mildly hypertensive adults between 18 and 75 years of age. Dietary interventions included 50 grams of casein, 50 grams of hemp seed protein, 45 grams of hemp seed protein, and five grams of bioactive peptide daily.

The dietary interventions were followed for six weeks, along with a two-week washout period. Fasting blood samples were collected from the study participants at six time points to measure blood pressure biomarkers, including ACE, renin, and NO.

Important observations

The adult participants in the study had mild hypertension, with systolic blood pressure between 130 and 160 mmHg and diastolic blood pressure of 110 mmHg or less. About 35% of participants reported taking anti-hypertensive medications.

Regarding gastrointestinal problems caused by intervention protein consumption, 29 participants reported no problems, whereas six individuals reported transient mild-intensity flatulence and abdominal discomfort.

Effect of dietary interventions on blood pressure

The analysis of 24-hour blood pressure levels revealed that the hemp seed protein-derived bioactive peptide and casein had the highest and lowest blood-pressure-lowering effects, respectively. More specifically, the hydrolysate-derived bioactive peptide reduced systolic and diastolic blood pressure by 8.9 mmHg and 5.8 mmHg, respectively. A reduction of 3.5 and 2.98 mmHg in systolic and diastolic pressure, respectively, was caused by hemp seed protein compared to casein.

A significant difference in blood pressure-lowering effects was also observed between hemp seed protein and its bioactive peptide. Compared to hemp seed protein, its bioactive peptide caused a 5.4 mmHg reduction in systolic pressure and a 2.9 mmHg reduction in diastolic pressure.

A subgroup analysis conducted on participants who were and were not prescribed anti-hypertensive medications revealed similar patterns of blood pressure-lowering effects caused by the three different study interventions.

Effect of dietary interventions on blood pressure biomarkers

Both hemp seed protein and its bioactive peptide significantly reduced plasma renin concentration and ACE activity, in addition to increasing plasma NO concentrations, compared to casein. However, no significant difference in biomarker regulation was observed between hemp seed protein and its bioactive peptide.

Study significance

Hemp seed protein and its bioactive peptide appear to be more efficient in reducing systolic and diastolic blood pressure levels in mildly hypertensive individuals as compared to casein protein. Notably, the blood pressure-lowering effect of the bioactive peptide is higher than that of hemp seed protein.

Based on these findings, the dietary consumption of hemp protein may benefit mildly hypertensive patients by maintaining their systolic and diastolic blood pressure levels within the normal range.