A four-amino-acid peptide (TQVY) isolated from rice protein significantly lowered blood pressure in hypertensive rats by inhibiting ACE, the same enzyme targeted by prescription blood pressure drugs.
IC50: 18.2 μMThe rice-derived peptide TQVY inhibited ACE at a potency level comparable to some food-derived bioactive peptides in the literature
What the researchers found
Rice protein hydrolysate (broken down rice protein) showed strong ACE-inhibiting activity in the lab (IC50 of 0.14 mg/ml) and significantly lowered systolic blood pressure in hypertensive rats after a single oral dose of 600 mg/kg.
Researchers isolated the specific peptide responsible: a four-amino-acid sequence Thr-Gln-Val-Tyr (TQVY). This purified peptide inhibited ACE with an IC50 of 18.2 μM and significantly lowered blood pressure in hypertensive rats at just 30 mg/kg — a 20-fold lower dose than the crude hydrolysate.
Why it matters
ACE inhibitors are among the most prescribed blood pressure medications in the world, but they come with side effects like persistent cough. This study shows that rice — one of the world's most consumed foods — contains peptide fragments that naturally inhibit ACE and lower blood pressure in animals. If validated in humans, rice-derived peptides could become a food-based approach to blood pressure management, either as functional foods or as natural supplements with potentially fewer side effects than pharmaceutical ACE inhibitors.
The numbers in context
IC50 hydrolysate: 0.14 mg/ml · IC50 TQVY peptide: 18.2 μM · hydrolysate dose: 600 mg/kg · peptide dose: 30 mg/kg · significant SBP reduction · Alcalase 2h digestion
How the study worked
Lab and animal study. Rice protein was enzymatically digested with Alcalase for 2 hours. The hydrolysate was tested for ACE inhibitory activity in vitro. The specific ACE-inhibiting peptide (TQVY) was isolated and identified by amino acid sequencing. Both the crude hydrolysate and purified peptide were orally administered to spontaneously hypertensive rats (SHR) to measure blood pressure effects.
Who was studied
Spontaneously hypertensive rats (SHR), a standard model of high blood pressure
What this study cannot tell us
Single-dose study in rats — no chronic dosing data. Spontaneously hypertensive rats may not reflect human hypertension physiology. Oral bioavailability and peptide survival through human digestion was not assessed. No human data. Blood pressure was measured at limited timepoints. No safety or dose-response studies reported.
How to read the evidence
Preliminary evidence from a single-dose animal study. The in vitro ACE inhibition is well-demonstrated, and the in vivo blood pressure reduction in rats is promising. However, this is a single rat study with no chronic dosing, no human data, and no assessment of whether the peptide survives human digestion.
When this study was published
Published in 2007. This is an early study in the food-derived antihypertensive peptide field. Since then, numerous similar peptides have been identified from various food proteins, and some (like milk-derived lactotripeptides) have progressed to human clinical trials.
The bigger picture
Bioactive peptides from food proteins are a growing field bridging nutrition and pharmacology. This study is part of a larger effort to find natural ACE inhibitors in everyday foods — similar peptides have been found in milk (lactotripeptides), fish, and soybeans. The advantage of food-derived peptides is their potential safety profile and accessibility. Rice-based peptides could be particularly impactful in Asian populations where rice is a dietary staple and hypertension is highly prevalent.
Questions still open
- Does the TQVY peptide survive human digestion intact enough to reach the bloodstream and inhibit ACE?
- Could eating rice protein in normal dietary amounts provide meaningful blood pressure reduction?
- How does the antihypertensive potency of rice-derived TQVY compare to milk-derived lactotripeptides (IPP, VPP) that have human clinical data?
Common questions
Could eating rice lower my blood pressure?
How do rice peptides compare to prescription ACE inhibitors?
Read the original research
Antihypertensive effect of rice protein hydrolysate with in vitro angiotensin I-converting enzyme inhibitory activity in spontaneously hypertensive rats.
Asia Pacific journal of clinical nutrition, 16 Suppl 1, 275-80
Citation
Li, Guan-Hong; Qu, Ming-Ren; Wan, Ju-Zhen; You, Jin-Ming. (2007). Antihypertensive effect of rice protein hydrolysate with in vitro angiotensin I-converting enzyme inhibitory activity in spontaneously hypertensive rats.. Asia Pacific journal of clinical nutrition, 16 Suppl 1, 275-80.