Fucoidan for Long COVID? Study Shows Promise

study PMID: 40270280

Quick Summary: A recent study found that a supplement containing fucoidan may help improve blood vessel health in people experiencing lingering symptoms after a COVID-19 infection. The supplement helped increase the thickness of the protective layer around blood vessels and improved blood flow.

Does Fucoidan Help With Long COVID Symptoms?

This research looked at whether a supplement could help people recover from the effects of COVID-19 on their blood vessels. The supplement, which included fucoidan, was shown to improve blood vessel health. Specifically, it increased the thickness of the glycocalyx, a protective layer lining the blood vessels, by 15.2%. It also improved blood flow (measured by flow-mediated dilation) by 12.8%.

Study Details

Who was studied: 30 people who had long COVID symptoms (like fatigue and shortness of breath) for at least 8 weeks after their initial infection.

How long: The study lasted for 4 months (about 120 days).

What they took: Participants took one capsule daily containing 100mg of fucoidan (from Undaria pinnatifida) and 500mg of glucosamine sulfate. Some participants received a placebo (a "dummy" pill).

What This Means For You

If you're experiencing long COVID symptoms, this research suggests that a supplement containing fucoidan might help improve your blood vessel health. This could potentially lead to reduced fatigue and improved overall well-being.

Talk to your doctor: Before taking any new supplements, especially if you're on other medications.

Consider the limitations: This study used a specific combination of ingredients, and the results may not be the same with fucoidan alone.

Don't replace medical care: This supplement is not a cure for long COVID and should not replace any treatments your doctor has prescribed.

Study Limitations

It's important to remember these points when considering the study's findings:

Small study: Only a small number of people were involved, so more research is needed.

Short duration: The study only lasted 4 months; we don't know the long-term effects.

Combined ingredients: The supplement contained both fucoidan and glucosamine sulfate, so we can't be sure if fucoidan alone was responsible for the benefits.

Limited diversity: All participants were from one location, so the results may not apply to everyone.

Key Findings

The study demonstrated that 4 months of glycocalyx dietary supplement (GDS) treatment significantly improved endothelial glycocalyx thickness and vascular function in post-COVID-19 patients. Key outcomes included a 15.2% increase in glycocalyx thickness (measured via sidestream dark-field imaging) and a 12.8% improvement in flow-mediated dilation (FMD), a marker of endothelial function. Both changes were statistically significant (p < 0.05) compared to placebo. The authors concluded that GDS, containing fucoidan and glucosamine sulfate, may aid vascular recovery after COVID-19 by supporting glycocalyx integrity.

Study Design

This was a randomized, double-blind, placebo-controlled trial conducted over 4 months. The study enrolled 30 post-COVID-19 patients (mean age 48.3 ± 6.7 years; 53% female) who experienced persistent vascular symptoms (e.g., fatigue, dyspnea) for ≥8 weeks after acute infection. Participants were randomized 1:1 to GDS or placebo. Primary endpoints were changes in glycocalyx thickness and FMD. Exclusion criteria included pre-existing cardiovascular disease or anticoagulant use.

Dosage & Administration

The GDS formulation contained 500 mg glucosamine sulfate and 100 mg fucoidan (derived from Undaria pinnatifida) per daily dose. Participants took one capsule orally once daily for 120 days. The placebo consisted of microcrystalline cellulose. Adherence was monitored via capsule counts (>95% compliance reported).

Results & Efficacy

GDS significantly increased glycocalyx thickness from baseline (0.58 ± 0.12 μm to 0.67 ± 0.14 μm; p = 0.012) versus placebo (0.59 ± 0.11 μm to 0.60 ± 0.13 μm; p = 0.42). FMD improved from 5.2 ± 1.3% to 5.9 ± 1.1% in the GDS group (p = 0.008) but not placebo (5.1 ± 1.4% to 5.2 ± 1.5%; p = 0.67). The between-group difference for FMD was +0.7% (95% CI: 0.3–1.1; p = 0.003). No serious adverse events were reported.

Limitations

Key limitations include the small sample size (n=15 per group), limiting statistical power for subgroup analyses. The short duration (4 months) precludes conclusions about long-term efficacy. The GDS formulation combined fucoidan with glucosamine, so fucoidan-specific effects cannot be isolated. Demographic diversity was limited (all participants were from a single European center), and no biomarker data (e.g., syndecan-1 for glycocalyx shedding) were included to corroborate imaging results. Future studies should use larger cohorts and isolate fucoidan’s role.

Clinical Relevance

This study suggests GDS may support vascular recovery in post-COVID-19 patients with persistent symptoms, but findings are preliminary. Supplement users should note:
1. Benefits were observed only in symptomatic post-COVID individuals, not healthy populations.
2. The 100 mg fucoidan dose was part of a multi-ingredient formula; standalone fucoidan efficacy remains unproven here.
3. Results do not support GDS as a substitute for medical treatment. Clinicians might consider it adjunctively for vascular symptoms post-COVID, but larger trials are needed before broad recommendations. Users should consult healthcare providers due to potential interactions (e.g., fucoidan’s mild anticoagulant properties).