Peer Review
Cardiovascular diseases (CVDs) remain the leading cause of mortality worldwide, with hypertension and hyperlipidemia often termed “silent killers” being major modifiable risk factors. This review evaluates the antihypertensive and antihyperlipidemic potential of three dietary secondary metabolites: epigallocatechin-3-gallate (EGCG) from green tea, quercetin from onions, and anthocyanins from berries. Quercetin, incorporated in salads through onion consumption, shows dose-dependent blood pressure (BP) reductions (2.9–8.8 mmHg) and modest low-density lipoprotein cholesterol (LDL-C) lowering (3–8%), primarily via angiotensin-converting enzyme inhibition and modulating the SCAP–SREBP2–LDLr pathway. EGCG, commonly consumed as a breakfast beverage, demonstrates modest but consistent reductions in systolic, diastolic BP (2.8–7 mmHg and 1.2–4 mmHg, respectively) and LDL-C (3–10%), mediated through endothelial nitric oxide synthase activation, endothelin-1 suppression, and improvement in lipid metabolism. Anthocyanins, delivered through berry-based juices, yield substantial systolic and diastolic reductions (6–12 mmHg and 2.5–6 mmHg, respectively) and significant improvements in LDL-C and high-density lipoprotein cholesterol via enhancing nitric oxide production, inhibition of cholesteryl ester transfer protein, and promoting cholesterol efflux. Beyond their physiological benefits, these nutraceuticals represent economically viable interventions, as they can be sourced from affordable, widely available foods, potentially reducing healthcare costs associated with CVD management. Collectively, evidence from clinical trials suggests that integrating these compounds into daily diets may offer a synergistic, safe, cost-effective strategy for managing hypertension and hyperlipidemia. However, heterogeneity in study designs, dosages, and populations underscores the need for standardized long-term trials to validate efficacy and optimize dietary recommendations.
CVD: Cardiovascular diseases
EGCG: Epigallocatechin-3-gallate
LDL-C: Low-density lipoprotein cholesterol
HDL-C: High-density lipoprotein cholesterol
ACE: Angiotensin-converting enzyme
CETP: Cholesteryl ester transfer protein
HTN: Hypertension
SBP: Systolic blood pressure
DBP: Diastolic blood pressure
TC: Total cholesterol
SCAP–SREBP2–LDLr: SCAP (SREBP cleavage-activating protein)-SREBP2 (sterol regulatory element-binding protein 2)-LDLr (low-density lipoprotein receptor)
TNF-α: Tumor necrosis factor alpha
CRP: C-reactive protein
TAG: Triacylglycerols
VCAM-1: Vascular cell adhesion molecule 1
Cardiovascular diseases (CVDs) account for nearly 31% of global mortality,
Bioactive secondary metabolites are found to demonstrate cardioprotective potential by improving lipid metabolism, endothelial function, and oxidative stress.
The articles were retrieved from the electronic databases such as PubMed, Scopus, Web of Science, and Google Scholar. The investigation employed specific search strings with Boolean operators: “quercetin” AND (“blood pressure” OR “hypertension” OR “lipid profile”); (“epigallocatechin gallate” OR “EGCG”) AND (“cholesterol” OR “hyperlipidemia” OR “blood pressure”); and “anthocyanins” AND (“hypertension” OR “dyslipidemia” OR “clinical trial”). The search was limited to publications from the year 2000 through April 2024.
The criteria for inclusion in the narrative review were: peer-reviewed clinical trials or randomized controlled trials (RCTs) that specifically investigated antihypertensive or lipid-lowering effects in mmHg or lipid concentrations (mmol/L or mg/dL). Excluded works were non-English publications, studies conducted solely on animals or in vitro, case reports, and conference abstracts for which a full text was unavailable. The selection process involved a sequential screening of titles and abstracts, followed by a thorough examination of the full-text articles. Studies were excluded at the full-text stage if they lacked a control group or failed to provide measurable cardiovascular outcomes.
The strength of evidence varied across compounds, wherein overall certainty for quercetin in hypertension and hyperlipidemia is moderate, for EGCG is moderate-to-high, and for anthocyanins is low-to-moderate.
The BP- and LDL-C-lowering impact of quercetin, EGCG, and anthocyanins can be seen in
| Citation | Subjects | Dose and Duration | Results |
|---|---|---|---|
| Egert et al. |
150 mg/day for 6 weeks vs baseline | 93 overweight or obese individuals | ↓ SBP: 2.9 mmHg in hypertensive subjects; |
| Lee et al. |
100 mg/day for 10 weeks vs baseline | ↓ SBP: 3 mmHg; |
|
| Zahedi et al. |
500 mg/day for 10 weeks vs baseline | 72 women with type 2 diabetes | ↓ SBP: 8.8 mmHg; |
| Edwards et al. |
730 mg/day for 4 weeks vs baseline | 19 men and women with prehypertension |
↓ SBP: 7 mmHg; |
| Larson et al. |
1095 mg/day for 1 week vs baseline | 12 stage 1 hypertensive |
↓ SBP: 7 mmHg; |
| Bogdanski et al. |
208 mg/day for 3 months vs baseline | 56 obese, hypertensive patients | ↓ SBP: −4 mmHg; ns↓ DBP: −4 mmHg; ns |
| Brown et al. |
400 mg twice daily (800 mg/day) for 8 weeks vs baseline | 40 overweight/obese men (age 40–65) | ↓ SBP: −2.85 mmHg; |
| Chatree et al. |
300 mg/day for 8 weeks vs baseline | 30 obese adults | ↓ SBP: −7 mmHg; |
| Hsu et al. |
302 mg/day for 12 weeks vs baseline | 78 obese women | ↓ SBP: −3.6 mmHg; ns↓ DBP: −1.2 mmHg; ns |
| Chen et al. |
856.8 mg/day for 12 weeks vs baseline | 115 women with central obesity | ↓ SBP: −2 mmHg; ns↓ DBP: −1 mmHg; ns |
| Broncel et al. |
300 mg/day for 2 months vs baseline | 25 patients with metabolic syndrome | ↓ SBP: −12.2 mmHg; |
| Igwe et al. |
369 mg/day for 2 weeks vs baseline | 12 older adults (65+ years) and 12 younger adults (18–45 years) | ↓ SBP in older adults: −12.83 mmHg; |
| Cook et al. |
300 mg/day for 6 days vs baseline | 14 older adults (69 ± 4 years) | ↓ SBP: −6 mmHg; |
| Okamoto et al. |
300 mg/day for 7 days vs baseline | 14 older adults (73.3 ± 1.7 years) | ↓ SBP: −9 mmHg; |
| Johnson et al. |
469 mg/day for 8 weeks vs baseline | 48 postmenopausal women with pre-/stage 1 hypertension | ↓ SBP: −7 mmHg; |
| Basu et al. |
742 mg/day for 8 weeks vs baseline | 48 obese adults with metabolic syndrome | ↓ SBP: −7.8 mmHg (prehypertensive); |
SBP = Systolic blood pressure; DBP = Diastolic blood pressure.
| Citation | Population | Dosage and Duration | Total Cholesterol | Triacylglycerol | LDL-C | HDL-C | Adverse Effects |
|---|---|---|---|---|---|---|---|
| Mielgo-Ayuso et al. |
Obese women ( |
300 mg/day (12 weeks) vs baseline | ↓ (4.81 → 4.42 mmol/L) |
↓ (2.52 → 2.21 mmol/L) |
↓ (2.78 → 2.68 mmol/L) |
↓ (1.42 → 1.29 mmol/L) |
No adverse effects |
| Wu et al. |
Postmenopausal women ( |
400 mg/day (2 months) vs baseline | ↓ (218 → 207 mg/dL) |
↓ (107 → 106 mg/dL) |
↓ (129 → 119 mg/dL) |
No change | |
| Samavat et al. |
Postmenopausal women ( |
843 mg/day (6–12 months) vs baseline | ↓ (206 → 199.4 mg/dL) |
↑ (93 → 94.6 mg/dL) |
↓ (118 → 112.3 mg/dL) |
↓ (70 → 68.7 mg/dL) |
Not reported |
| Chen et al. (2015) | Obese women ( |
856.8 mg/day (12 weeks) vs baseline | ↓ (198.8 → 183.9 mg/dL) |
↑ (129.9 → 132.0 mg/dL) |
↓ (124.7 → 112.1 mg/dL) |
↓ (49.2 → 47.0 mg/dL) |
No adverse events reported |
| Hsu et al. |
Obese women ( |
400 mg/day (12 weeks) vs baseline | ↓ (211.3 → 202.7 mg/dL) |
↓ (141.4 → 135.7 mg/dL) |
↓ (150.6 → 134.5 mg/dL) |
↑ (42.5 → 44.1 mg/dL) |
3 had mild constipation and 2 had abdominal discomfort |
| Lu and Hsu |
Women with acne ( |
856 mg/day (4 weeks) vs baseline | ↓ (174.5 → 163.8 mg/dL) |
↓ (88.7 → 80.2 mg/dL) |
↓ (93.9 → 90.3 mg/dL) |
No change | 1 had mild constipation and 3 had abdominal discomfort |
| De Morais Junior et al. |
Healthy women ( |
800 mg (acute, postprandial) vs baseline | ↓ (151 → 139.9 mg/dL at 120 min) |
↑ (89.9 → 126.0 mg/dL) |
↓ (73 → 61.1 mg/dL) |
↓ (60 → 53.5 mg/dL) |
No adverse effects reported |
| Kajimoto et al. |
Hypercholesterolemic patients ( |
197.4 mg ×2/day (12 weeks) vs baseline | ↓ (228 → 220 mg/dL) |
↓ (133.3 → 125.0 mg/dL) |
↓ (145.9 → 137.0 mg/dL) |
↑ (55.3 → 58.2 mg/dL) |
No adverse effects reported |
| Egert et al. |
Overweight ApoE3 ( |
150 mg/day (6 weeks) vs baseline | ↓ (5.66 → 5.53 mmol/L) |
↑ (1.70 → 1.68 mmol/L) |
↓ (3.56 → 3.40 mmol/L) |
↓ (1.35 → 1.28 mmol/L) |
No adverse effects |
| Lee et al. |
Male smokers ( |
100 mg/day (10 weeks) vs baseline | ↓ (193.5 → 185.2 mg/dL) |
↓ (163.5 → 156.9 mg/dL) |
↓ (113.2 → 106.5 mg/dL) |
↑ (44.3 → 51.4 mg/dL) |
No adverse effects |
| Burak et al. |
Healthy ( |
190 mg/day + ALA (8 weeks) vs baseline | ↓ (4.68 → 4.35 mmol/L) | ↓ (1.24 → 1.02 mmol/L) | ↓ (2.62 → 2.39 mmol/L) | ↑ (1.59 → 1.60 mmol/L) | No adverse effects |
| Nishimura et al. |
Elderly ( |
60 mg/day (12 weeks) vs baseline | ↑ (219.6 → 222.7 mg/dL) |
↑ (110.7 → 119.3 mg/dL) |
No change | ↓ (68.8 → 67.4 mg/dL) |
No adverse effects |
| Brüll et al. |
Overweight ( |
162 mg/day (6 weeks) vs baseline | ↓ (5.44 → 5.38 mmol/L) |
↑ (1.81 → 1.83 mmol/L) |
↓ (3.45 → 3.41 mmol/L) |
↓ (1.39 → 1.36 mmol/L) |
No adverse effects |
| Egert et al. |
Overweight/obese ( |
150 mg/day (6 weeks) vs baseline | ↓ (5.72 → 5.63 mmol/L) |
↑ (1.82 → 1.94 mmol/L) |
↓ (3.59 → 3.46 mmol/L) |
↓ (1.35 → 1.28 mmol/L) |
No adverse effects |
| Conquer et al. |
Healthy ( |
1000 mg/day (4 weeks) vs baseline | ↓ (5.08 → 4.90 mmol/L) |
↓ (1.27 → 1.15 mmol/L) |
↓ (2.84 → 2.82 mmol/L) |
↑ (1.50 → 1.57 mmol/L) |
Not reported |
| Zahedi et al. |
T2DM women ( |
500 mg/day (10 weeks) |
↓ (189.2 → 188.6 mg/dL) |
↓ (198.4 → 186.1 mg/dL) |
↓ (106.1 → 105.9 mg/dL) |
↓ (45.2 → 41.8 mg/dL) |
No adverse effects |
| Nishihira et al. |
Elderly ( |
50 mg/day (24 weeks) |
↑ (233 → 235 mg/dL) |
↑ (106 → 112 mg/dL) |
↑ (139 → 140 mg/dL) |
↓ (76 → 75 mg/dL) |
No adverse effects |
| Chopra et al. |
Healthy ( |
30 mg/day (2 weeks) |
↑ (5.56 → 5.70 mmol/L) |
↓ (1.19 → 1.18 mmol/L) |
↑ (3.66 → 3.88 mmol/L) |
↓ (1.36 → 1.29 mmol/L) |
No adverse effects |
| Qin et al. |
Dyslipidemic ( |
320 mg/day (12 weeks) |
↓ (226.2 → 220.5 mg/dL) |
↓ (197.9 → 189.5 mg/dL) |
↓ (159.2 → 139.9 mg/dL) |
↑ (45.9 → 51.2 mg/dL) |
No adverse effects |
| Zhu et al. |
Hypercholesterolemic ( |
320 mg/day (24 weeks) |
- | - | - | ↑ (5.26 → 5.40 mmol/L) |
No adverse effects |
| Okamoto et al. |
Older adults ( |
210 mg/day (7 days) |
- | ↓ (88 → 85 mg/dL) |
↓ (124 → 120 mg/dL) |
↑ (73 → 76 mg/dL) |
Not reported |
| Zhu et al. |
Hypercholesterolemic ( |
320 mg/day (24 weeks) |
↓ (6.45 → 6.18 mmol/L) |
↓ (2.45 → 2.35 mmol/L) |
↓ (3.36 → 3.01 mmol/L) |
↑ (1.22 → 1.37 mmol/L) |
No adverse effects |
| Xu et al. |
Dyslipidemic ( |
320 mg/day (6 weeks) |
↓ (6.33 → 6.21 mmol/L) |
↑ (2.02 → 2.13 mmol/L) |
↓ (4.33 → 4.16 mmol/L) |
↑ (1.47 → 1.55 mmol/L) |
No adverse effects |
| Li et al. |
T2DM ( |
320 mg/day (24 weeks) |
↓ (5.07 → 4.88 mmol/L) |
↓ (2.04 → 1.57 mmol/L) |
↓ (3.17 → 2.92 mmol/L) |
↑ (1.03 → 1.23 mmol/L) |
No adverse effects |
| Lee et al. |
Obese ( |
31.45 mg/day (8 weeks) |
↓ (227.6 → 178.6 mg/dL) |
↓ (182.4 → 130.5 mg/dL) |
↓ (122.5 → 98.5 mg/dL) |
↓ (56.0 → 49.8 mg/dL) |
No adverse effects |
| Aboufarrag et al. |
Hyperlipidemic ( |
320 mg/day (28 days) |
No change | No change | No change | No change | No adverse effects |
EGCG = Epigallocatechin-3-gallate; LDL-C = Low-density lipoprotein cholesterol; HDL-C = High-density lipoprotein cholesterol; ns = Nonsignificant.
Quercetin, a dietary flavonol abundant in onions, apples, and leafy vegetables, has been extensively studied for its vascular health benefits.
Across RCTs, quercetin supplementation has demonstrated dose-dependent BP reductions, particularly in individuals with established hypertension.
Overall, clinical evidence on quercetin’s effects on lipid profiles shows mixed but generally modest benefits, with outcomes influenced by dose, duration, population, and source. Moderate doses of 100–200 mg/day for 6–10 weeks in at-risk groups such as overweight individuals or smokers consistently reduced total cholesterol, LDL-C, and triglycerides, with occasional high-density lipoprotein cholesterol (HDL-C) increases.
For lipid modulation, the most promising approach appears to be purified quercetin at 100–200 mg/day for at least 8 weeks in individuals with elevated cardiovascular risk, ideally alongside dietary and lifestyle interventions, while monitoring HDL-C responses. Quercetin exhibits antihyperlipidemic effects by modulating the SCAP–SREBP2–LDLr pathway, upregulating LDL-C receptor expression to enhance cholesterol clearance.
The reviewed studies collectively demonstrate that EGCG, the primary bioactive polyphenol in green tea, exerts modest but consistent BP-lowering effects in individuals with obesity, hypertension, or metabolic syndrome. The mechanisms underlying EGCG’s antihypertensive effects are multifaceted. Primarily, EGCG enhances endothelial function by upregulating nitric oxide (NO) synthase activity, thereby promoting vasodilation.
The observed reductions in SBP (ranging from −2.85 to −7 mmHg) and DBP (−1.2 to −4 mmHg) across multiple RCTs suggest that EGCG supplementation may serve as a supportive intervention for improving cardiovascular health.
EGCG demonstrates modest but consistent benefits in improving lipid profiles, particularly in reducing total cholesterol and LDL-C. Several RCTs support this effect, with reductions in LDL-C ranging from 3 to 10%.
Anthocyanins, a class of bioactive flavonoids found in deeply pigmented fruits including
A range of clinical trials outlined that anthocyanin intake at doses of 300–742 mg/day for periods ranging from 6 days to 8 weeks shows consistent benefits, particularly in high-risk populations. In metabolic syndrome patients, studies by Broncel et al.
Current evidence, while promising, has limitations including short durations (typically ≤8 weeks), small sample sizes (often <50 participants), and variability in anthocyanin sources and doses.
Anthocyanins demonstrate moderate but meaningful improvements in lipid metabolism, particularly in reducing LDL-C and increasing HDL-C. Clinical trials indicate that anthocyanin supplementation (typically at 320 mg/day) leads to 5–20% reductions in LDL-C
In the present review, across trials, the nutraceuticals were generally well tolerated. For example, no adverse events were reported for quercetin even at a high dose of 1000 mg/day for short durations. EGCG doses up to 856 mg/day for 12 months were observed to have no negative impacts and to be well tolerated, other than mild constipation (4 subjects) and abdominal discomfort (5 subjects). Anthocyanin intake was also reported to be safe across randomized trials.
Green tea, mainly EGCG, may increase the systemic circulation of several statins and calcium channel blockers and may cause drug toxicity, while reducing the bioavailability of beta-blockers may decrease the drug efficacy.
These nutraceuticals are inexpensive and widely available through daily diets (e.g., green tea, onions, berries), suggesting potential for cost-effective integration into public health strategies. While preliminary cost comparisons with pharmacological interventions are encouraging, robust economic modeling is required before firm conclusions can be drawn (
| Nutraceutical | Effective Daily Dose | Primary Mechanisms | Target Populations | Key Dietary Sources |
|---|---|---|---|---|
| Quercetin | 100–200 mg (up to 500 mg for hypertension) | ACE inhibition- SCAP-SREBP2-LDLr pathway modulation- Endothelial NO enhancement- Gut microbiota modulation |
Stage 1 hypertension- Overweight/obese individuals- Smokers |
Onions and apples |
| EGCG | 200–300 mg (up to 856 mg in trials) | eNOS activation- Endothelin-1 suppression- LDL receptor upregulation- Antioxidant effects |
Obesity/metabolic syndrome- Postmenopausal women- Central obesity |
Green tea (2–3 cups/day) |
| Anthocyanins | 300–500 mg | CETP inhibition- NO production enhancement- Cholesterol efflux promotion- Antiinflammatory effects |
Elderly adults- Metabolic syndrome- Postmenopausal hypertension |
Berries (blueberries, chokeberries), purple grapes, plums |
Regular dietary incorporation of EGCG from green tea, quercetin from onions, and anthocyanins from berries provides a promising, natural, and accessible approach to mitigating hypertension and dyslipidemia. These compounds exert complementary mechanisms, i.e., spanning vasodilation, oxidative stress reduction, ACE inhibition, improved lipid clearance, and modulation of inflammatory markers, offering comprehensive cardiovascular protection. Clinical evidence supports meaningful reductions in BP and LDL-C, with anthocyanins showing the most pronounced BP-lowering effect, quercetin delivering consistent benefits in stage 1 hypertensive individuals, and EGCG offering broad metabolic improvements in obese or metabolically compromised populations. Clinical evidence suggests optimal daily doses of 100–200 mg for quercetin, 200–300 mg for EGCG, and 300–500 mg for anthocyanins, with longer durations (≥8 weeks) yielding more consistent benefits. Importantly, their integration into common dietary items such as breakfast drinks, salads, and juices leverages culturally acceptable eating patterns, potentially enhancing adherence. Economically, these nutraceuticals can be obtained from low-cost, locally available foods, representing a sustainable alternative or adjunct to pharmacotherapy, with the potential to alleviate the economic burden of CVD treatment. Current evidence on these nutraceuticals faces challenges due to inconsistent study designs, including small participant groups and short trial durations (typically under 12 weeks). Additionally, results vary depending on whether compounds were tested as purified supplements or whole-food sources. To establish clear guidelines, rigorous long-term studies with standardized protocols and larger, diverse populations are urgently needed.
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Muhammad Qamar: Conceptualization; Muhammad Qamar, Muhammad Zulqarnain Khan, Eisha Ismail, Bushra Irum Fatim, Maryam Jalal Ud Din and Malik Waseem Abbas: Investigation and resources; Muhammad Qamar, Muhammad Zulqarnain Khan: Writing — original draft preparation; Muhammad Qamar: Project administration. All authors have read and agreed to the published version of the manuscript
Muhammad Qamar
Unsolicited and externally peer-reviewed
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