Algae Effects in Markers of Cardiovascular Risk and Gut Microbiome

Not Applicable

Recruiting

• Conditions: Stroke; Myocardial Infarction (MI); Peripheral Artery Disease (PAD); Chronic Kidney Disease(CKD); Coronary Arterial Disease (CAD); Diabetes Mellitus; Albuminuria

• Registration Number: NCT07173062
• Lead Sponsor: Universidade do Porto

Brief Summary

The Western diet, rich in fat and sugar, contributes to cardiovascular risk and alters the body metabolism, specifically through the modulation of the microbiome. Microbiome is considered the "second genome", functioning as an endocrine-like organ. Gut microbiota-derived metabolites, namely trimethylamine- N-oxide and short-chain fatty acids have been associated with atherosclerosis, vascular and cardiac diseases. Regarding trimethylamine- N-oxide, its association with cardiovascular disease is positive and dose-dependent. In contrast, short-chain fatty acids have been positively associated with the improvement of cardiovascular health.

Algae probiotics can modulate gut microbiome, stimulating the growth of commensal micro-organisms with health benefits. Previous studies suggested that Spirulina Arthrospira platensis supplementation could improve blood lipid levels and lower blood pressure, revealing anti-inflammatory and antioxidant roles. Other probiotics that could be beneficial to gut microbiota are macroalgae or seaweed. Macroalgae are a rich source of components which may prompt bacterial diversity and abundance.

The present prospective, randomized, three-armed parallel trial aims to generate good-quality evidence about the potential health effects and impact of Spirulina Arthrospira platensis (microalgae) and Gelidium corneum (macroalgae) supplements in humans. These participants will undergo 3 clinical evaluations: 2 before the beginning of micro- and macro-algae supplementation and the last one after 20 weeks of supplementation. The evaluation includes a vascular, nutritional and physical activity assessment, as well as blood, urine, saliva and stool collection for quantification of plasma biomarkers, oral and gut microbiota analysis, respectively.

Detailed Description

Not available

Study Timeline

• Study Start: 2025-03-11
• Study First Submitted: 2025-08-12
• Status Verified: 2025-09
• Study First Submitted QC: 2025-09-12
• Last Update Submitted: 2025-09-12
• Study First Posted: 2025-09-15
• Last Update Posted: 2025-09-15
• Primary Completion: 2026-08
• Study Completion: 2026-08-01

Recruitment & Eligibility

• Status: RECRUITING
• Sex: All
• Target Recruitment: 150

Inclusion Criteria

• ≥50 years

• BMI ≥20 kg/m2

• History of stroke, coronary artery disease, myocardial infarction, peripheral artery disease, chronic kidney disease (eGFR <75 ml/min at least for 3 months), albuminuria >300 mg/g, or diabetes mellitus

• No antibiotics in the previous 30 days

• If a woman, she must be a woman of non-childbearing potential. That is, she must be:

  • Surgically sterilized (e.g. underwent hysterectomy, bilateral salpingectomy or bilateral oophorectomy);
  • Clinically diagnosed infertile;
  • In a post-menopausal state, defined as no menses for 12 months without an alternative medical cause.

• A woman patient of childbearing potential must have a negative serum pregnancy test at Visit 0 (Day 0) and must agree to use consistently and correctly (from 28 days prior to first study treatment administration until at least 7 days after last study treatment administration) one of the following highly effective methods of contraception:

  • Abstinence of heterosexual intercourse (when this is in line with preferred and usual lifestyle of the subject);
  • Progestogen-only hormonal contraception associated with inhibition of ovulation (oral, injectable, implantable);
  • Combined (oestrogen and progestogen containing) hormonal contraception associated with inhibition of ovulation (oral, intravaginal, transdermal);
  • Intrauterine device;
  • Intrauterine hormone-releasing system;
  • Bilateral tubal occlusion;
  • Vasectomized partner, who has received medical assessment of the surgical success, or clinically diagnosed infertile partner.

Exclusion Criteria

• Unwilling to sign the informed consent form (if the patient wants to participate but cannot sign for any reason, then a third-person testimony may sign/complete the informed consent form on the patient's behalf).
• Involvement in the planning and/or conduct of the study (applies to both Investigator staff and/or staff at the study site).
• Participation in another clinical study with an investigational product during the last month.
• In participants recruited at Unidade Local de Saúde de São João, the exclusion criteria applied is estimated Glomerular Filtration Rate (eGFR) <30 ml/min/1.73m2 estimated with the CKD-EPI (2021) formula or dialysis. For participants recruited at community, this exclusion criteria is adapted for diagnosis of end-stage renal disease or dialysis (no need to quantify the eGFR).

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Primary Outcome Measures

Name	Time	Method
Plasma trimethylamine-N-oxide levels	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the between-group ratio of geometric means difference of the Log transformed plasma trimethylamine- N-oxide levels change from baseline to 20 weeks.; The co-primary comparison will be Spirulina Arthrospira platensis versus Placebo and Gelidium corneum versus Placebo with a 2.5% alfa for each comparison.

Secondary Outcome Measures

Name	Time	Method
Lipoprotein A	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
Plasma short-chain fatty acids levels	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
Gut microbiota	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
Systolic blood pressure	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
Diastolic blood pressure	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
Body weight	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
Total cholesterol	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
Low-density lipoprotein cholesterol	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
High-density lipoprotein cholesterol	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
Interleukin-6	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
Glucose	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
Insulin	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
Haemoglobin A1c	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
Estimated Glomerular Filtration Rate	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
High-sensitivity C-reactive protein	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
Cerebral blood flow velocities	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on cerebral blood flow.; Measured by transcranial color-coded duplex Doppler in middle cerebral arteries and posterior cerebral arteries. Expressed in cm/s. Higher values = greater blood flow velocity.
Neurovascular coupling (visual stimulation)	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on neurovascular coupling.; Measured by transcranial color-coded duplex Doppler during visual stimulation with a flickering checkerboard (10 Hz). Expressed as blood velocity change in middle cerebral arteries and posterior cerebral arteries recorded across cycles of 20 seconds stimulation (eyes open) and 20 seconds rest (eyes closed). Greater change = better neurovascular coupling.
Triglycerides	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
Potassium	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
Sodium	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the following measures relative to the baseline measures.
Oral microbiota	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change of the oral microbiota relative to the baseline.
Pulse wave velocity	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on arterial stiffness.; Measured by carotid-femoral pulse wave velocity using pulse wave analysis to assess arterial stiffness. Expressed in m/s. Higher values = greater arterial stiffness.
Intima-media thickness	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on vascular structure, measured by carotid intima-media thickness using cervical echo-Doppler ultrasound.; Measured by cervical echo-Doppler ultrasound in the common carotid artery (automatic recording of 5 cycles). Expressed in mm. Lower values = better vascular structure.
Cerebral blood flow resistance indexes	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on cerebral vascular resistance.; Measured by transcranial color-coded duplex Doppler in middle cerebral arteries and posterior cerebral arteries. Expressed as resistance index (RI), calculated from Doppler waveforms. Higher RI = greater vascular resistance.
Cerebral vascular reactivity	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on cerebral vascular reactivity.; Measured by transcranial color-coded duplex Doppler during a breathing manoeuvre. Expressed as % change in blood flow velocity in middle cerebral arteries and posterior cerebral arteries, in response to hypercapnia. Greater reactivity = better cerebrovascular function.
Breath-holding index	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of the Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on cerebrovascular reserve capacity.; Measured by transcranial color-coded duplex Doppler in middle cerebral arteries and posterior cerebral arteries during a 20-second apnea manoeuvre. Expressed as index value. Higher BHI = better vascular reserve.
Mediterranean diet adherence screener score	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change in adherence to the Mediterranean diet, as measured by the Mediterranean Diet Adherence Screener (MEDAS).; The MEDAS is a 14-item questionnaire that evaluates food intake habits and frequency of consumption of specific foods. Each item receives 1 point for a positive response, resulting in a total score ranging from 0 to 14. Higher scores indicate greater adherence to the Mediterranean diet, with a score of ≥10 considered adherent.
Total score of physical activity	Visit 1 (day 7 to day 30) and Visit 2 (20 weeks ± 15 days from Visit 1)	To assess the effect of Spirulina Arthrospira platensis versus Gelidium corneum versus placebo on the percentage change in total physical activity score, as measured by the International Physical Activity Questionnaire - short version.; This questionnaire includes 7 items assessing frequency and duration of physical activity during the past 7 days across different domains. Activities are weighted by metabolic equivalents (METs) (walking = 3, moderate = 4, vigorous = 8), and a total score is expressed as MET-minutes/week. Scores range from 0 to several thousand, with higher values indicating greater physical activity.

Trial Locations

Locations (1)

Unidade Local de Saúde de São João; 🇵🇹 Porto, Portugal