Blueberries for High Blood Pressure

Overseen By Sarah A Johnson, PhD, RDN

Age: 18+

Sex: Male

Trial Phase: Phase 1 & 2

Sponsor: Colorado State University

Must not be taking: Lipid-lowering, Glucose-lowering

Disqualifiers: Cancer, Cardiovascular, Diabetes, others

Compensation: Varies

Number of Visits: Unknown

Duration: 12 weeks

58 Participants Needed

Trial Summary

What is the purpose of this trial?

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide. Aging is the primary risk factor for CVD, in large part due to adverse modifications to the arteries. These modifications include vascular endothelial dysfunction and arterial stiffness. Vascular endothelial dysfunction is an initiating step in atherosclerosis, and is primarily caused by reduced nitric oxide (NO) bioavailability secondary to excessive superoxide-driven oxidative stress and inflammation. Endothelial dysfunction leads to arterial stiffness and the development of hypertension (HTN) which further increases CVD. Greater than 2/3 of the US population has elevated blood pressure or stage 1-HTN. As such, interventions that improve vascular endothelial dysfunction by increasing NO bioavailability and mitigating excessive oxidative stress and inflammation are needed. Blueberries are rich in bioactive compounds including flavonoids, phenolic acids, and pterostilbene. These compounds and their metabolites have been shown to attenuate oxidative stress and inflammation. The primary goal of this study is to assess the efficacy of blueberries to improve reduce blood pressure and improve vascular endothelial dysfunction and arterial stiffness in middle-aged/older men with elevated blood pressure or stage 1-HTN.

Will I have to stop taking my current medications?

The trial does not specify if you need to stop taking your current medications, but you cannot participate if you are taking more than one blood pressure medication, taking it more than once a day, or have been on it for less than three months. Also, you cannot be on any lipid-lowering or glucose-lowering medications.

What data supports the effectiveness of the treatment Blueberry Powder, Wild Blueberry Powder, Freeze-Dried Wild Blueberry Powder, Placebo Powder, Control Powder, Inactive Ingredient for high blood pressure?

Some studies suggest that blueberries, which are rich in natural compounds, may help lower blood pressure. For example, one study found that daily blueberry consumption reduced certain blood pressure measures in people with prehypertensive pressures. ^{1 2 3 4 5}

Is blueberry powder safe for humans?

Research shows that consuming blueberries or blueberry powder is generally safe for humans, with no significant adverse effects reported in studies involving healthy adults and those with cardiovascular conditions. ^{1 2 3 4 5}

How does blueberry powder treatment for high blood pressure differ from other treatments?

Blueberry powder is unique because it is a natural treatment rich in polyphenols, which may help improve blood pressure by inhibiting angiotensin-converting enzyme (ACE) activity, similar to some medications, but without the use of synthetic drugs. ^{1 2 3 5 6}

Eligibility Criteria

This trial is for men aged 45-70 and postmenopausal women with elevated blood pressure or stage 1 hypertension. Participants must be able to consent, not have had cancer, cardiovascular disease, diabetes, or certain other health conditions. They shouldn't be on multiple antihypertensive drugs or recent smokers.

Inclusion Criteria

I am a man or a postmenopausal woman aged between 45 and 70.

Your blood pressure is too high.

Ability to provide informed consent

Exclusion Criteria

I have been diagnosed with cancer or a major organ disease.

I have been on hormone replacement therapy for the last 6 months.

I am a current smoker or have smoked in the last year.

Timeline

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants receive 22 g of blueberry or placebo powder daily to assess the efficacy of blueberries in reducing blood pressure and improving vascular endothelial dysfunction and arterial stiffness

12 weeks

Follow-up

Participants are monitored for safety and effectiveness after treatment

4 weeks

Treatment Details

Interventions

• Blueberry Powder
• Placebo Powder

Trial Overview The study tests if blueberry powder can lower blood pressure and improve vascular health compared to a placebo in middle-aged/older individuals with high blood pressure. It aims to see if the antioxidants in blueberries help reduce oxidative stress and inflammation.

Participant Groups

Group I: Blueberry Experimental Treatment 1 Intervention

22 g blueberry powder per day

Group II: Control Placebo Group 1 Intervention

22 g placebo control powder per day

Who Is Running the Clinical Trial?

Colorado State University

Lead Sponsor

Trials

138

Recruited

38,200+

Wild Blueberry Association of North America

Collaborator

Trials

7

Recruited

340+

Wild Blueberry Association of North America

Collaborator

Trials

3

Recruited

100+

Findings from Research

In a study involving 37 young adults, both whole blueberries and freeze-dried blueberry powder did not show significant differences in improving cardiovascular health compared to a control group, indicating that the form of blueberry may not matter for cardiovascular benefits.

However, both blueberry treatments improved plasma nitrite levels significantly compared to baseline, suggesting a potential positive effect on vascular function, even though other cardiovascular risk factors like blood pressure and cholesterol levels did not show significant changes.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effects of Blueberry Consumption on Cardiovascular Health in Healthy Adults: A Cross-Over Randomised Controlled Trial. Wang, Y., Gallegos, JL., Haskell-Ramsay, C., et al.[2022]

Feeding flavonoid-rich blueberries to spontaneously hypertensive stroke-prone rats significantly lowered their blood pressure by inhibiting angiotensin-converting enzyme (ACE) activity, which was elevated in these rats compared to normotensive rats.

After 2 weeks on a blueberry diet, ACE activity in the hypertensive rats decreased, and this effect persisted for up to 6 weeks, suggesting that blueberries could be a beneficial dietary intervention for managing early hypertension.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Feeding blueberry diets inhibits angiotensin II-converting enzyme (ACE) activity in spontaneously hypertensive stroke-prone rats. Wiseman, W., Egan, JM., Slemmer, JE., et al.[2022]

Daily consumption of blueberries for 6 weeks significantly increased natural killer (NK) cell counts in participants, suggesting an enhancement of immune function.

Blueberry intake also led to reductions in augmentation index (AIx) and aortic systolic pressures (ASPs), indicating potential cardiovascular benefits, particularly in individuals with prehypertensive blood pressure levels.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Six weeks daily ingestion of whole blueberry powder increases natural killer cell counts and reduces arterial stiffness in sedentary males and females. McAnulty, LS., Collier, SR., Landram, MJ., et al.[2022]

Wild blueberry powder retains a significant amount of its health-promoting anthocyanins in ice pops and refrigerated juice, with both products maintaining over 90% of their initial anthocyanin content after 8 weeks of storage.

The stability of polyphenolic compounds varies by product, with gummies showing much lower retention of anthocyanins (43-51%) compared to other formulations, likely due to gel hardening affecting extraction efficiency at lower temperatures.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Changes in Polyphenolics during Storage of Products Prepared with Freeze-Dried Wild Blueberry Powder. Lavefve, L., Brownmiller, C., Howard, L., et al.[2020]

A systematic review of 17 randomized clinical trials found that blueberry and cranberry supplementation had neutral effects on blood pressure (BP) in patients with cardiometabolic diseases, showing no significant reductions in systolic BP (SBP) or diastolic BP (DBP).

Despite some studies indicating potential benefits, the pooled results revealed only minor, statistically non-significant reductions in BP, highlighting the need for further high-quality research to confirm any clinical efficacy.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The effects of blueberry and cranberry supplementation on blood pressure in patients with cardiovascular diseases: A systematic review and meta-analysis of randomized clinical trials. Delpino, FM., Dos Santos, FS., Flores, TR., et al.[2023]

Current clinical evidence suggests that while there is no direct blood pressure lowering effect from dietary berry consumption, certain berries may help normalize blood pressure in individuals who are already hypertensive.

The review highlights the potential role of specific berry polyphenols, such as anthocyanins and ellagic acid, in influencing blood pressure regulation, although results are mixed and complicated by confounding factors.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The Role of Berry Consumption on Blood Pressure Regulation and Hypertension: An Overview of the Clinical Evidence. Vendrame, S., Adekeye, TE., Klimis-Zacas, D.[2022]

References

1. Switzerland pubmed.ncbi.nlm.nih.gov

Effects of Blueberry Consumption on Cardiovascular Health in Healthy Adults: A Cross-Over Randomised Controlled Trial. [2022]

2. Canada pubmed.ncbi.nlm.nih.gov

Feeding blueberry diets inhibits angiotensin II-converting enzyme (ACE) activity in spontaneously hypertensive stroke-prone rats. [2022]

3. United States pubmed.ncbi.nlm.nih.gov

Six weeks daily ingestion of whole blueberry powder increases natural killer cell counts and reduces arterial stiffness in sedentary males and females. [2022]

4. Switzerland pubmed.ncbi.nlm.nih.gov

Changes in Polyphenolics during Storage of Products Prepared with Freeze-Dried Wild Blueberry Powder. [2020]

5. England pubmed.ncbi.nlm.nih.gov

The effects of blueberry and cranberry supplementation on blood pressure in patients with cardiovascular diseases: A systematic review and meta-analysis of randomized clinical trials. [2023]

6. Switzerland pubmed.ncbi.nlm.nih.gov

The Role of Berry Consumption on Blood Pressure Regulation and Hypertension: An Overview of the Clinical Evidence. [2022]