Spirulina dietary supplement beneficial for COVID-19?

Supplementing standard COVID-19 treatment with Spirulina – a nutrient-rich superfood – may improve recovery and reduce mortality in hospitalized COVID-19 patients, a study from Iran suggests.

“[Overall,] a 6-day course of Spirulina platensis plus standard COVID-19 treatment was superior to standard treatment alone for patient recovery,” said the researchers.

By day 7, in non-ICU* patients, four who received standard treatment alone (control arm) died whereas in the Spirulina arm, there were none (hazard ratio [HR], 0.13; p=0.047). Clinical recovery time was shorter in the Spirulina vs control arm, as all but one patient in the former were discharged as opposed to 18 in the latter (HR, 6.52; p<0.001).

Of those admitted to the ICU, mortality rate was higher in the control vs Spirulina arm (21.2 percent vs 0 percent; HR, 0.13; p<0.001), but the discharge rate was lower (5.8 percent vs 12.8 percent; HR, 1.80; p=0.403). [Front Immunol 2024:15:1332425]

Secondary outcomes, safety

The Spirulina arm had lower overall mortality rates than the control arm, both in the non-ICU (0 percent vs 8.7 percent; HR, 0.13; p=0.047) and ICU subgroups (0 percent vs 28.8 percent; HR, 0.16; p=0.001).

Compared with the control arm, the Spirulina arm had higher overall hospital discharge rates (100 percent vs 91.3 percent; HR, 6.56; p<0.001 [non-ICU] and 100 percent vs 71.2 percent; HR, 2.59; p<0.001 [ICU]), lower transfer-to-ICU rate in the non-ICU subgroup (0 percent vs 19.6 percent; HR, 0.12; p=0.002), and higher transfer-to-ward rate in the ICU subset (42.6 percent vs 15.4 percent; HR, 2.69; p=0.017).

While there were no side effects tied to Spirulina supplementation at day 7, some patients expressed dissatisfaction with the 19 capsules that must be taken daily, that 10 withdrew from the study by day 4. Day 6 saw two more patients withdrawing from the trial due to this predicament.

“[P]atients were more willing to take Spirulina supplement tablets or powder than the capsule form [as] it would be easier to consume,” said the researchers.

Laboratory findings, immune mediators

Spirulina effectively reduced inflammatory biomarkers in both non-ICU (absolute risk reduction [ARR], 36.84; p<0.001 [CRP**], ARR, 31.58; p=0.003 [ESR***], and median 233.6 vs 306.4; p<0.001 [ferritin]) and ICU subsets (ARR, 30.36; p=0.008 [ESR] and median 409.7 vs 434.1; p=0.02 [ferritin]).

The levels of the pro-inflammatory cytokine interleukin-6 also dropped significantly in the Spirulina vs control arm in both non-ICU and ICU subgroups (median 75.3 vs 95.9; p<0.001 and 126.2 vs 194.3; p<0.001, respectively).

Conversely, the levels of interferon gamma (IFN-γ) – which has antiviral activity and important immunoregulatory functions – increased in the Spirulina vs control arm (median 64.6 vs 55; p=0.02 [non-ICU] and 93.5 vs 62.8; p<0.001 [ICU]).

“Considering the reduction in hospitalization time and the absence of death in the intervention arm, the … changes in immune mediators in patients receiving Spirulina supplements can be evaluated as beneficial,” the investigators noted.

Supportive therapy remains key

Despite the currently available therapeutic agents against COVID-19, supportive therapy remains the primary management approach due to the absence of a definitive treatment. [Infect Dis Rep 2021;13:259-284; Clin Infect Dis 2020;ciaa478; Front Med (Lausanne) 2020;7:606429]

Spirulina platensis is rich in protein, vitamins, and minerals. It is also particularly high in phycocyanobilin (PCB), a blue pigment protein that is part of the light-harvesting phycobiliprotein family and has anticancer, anti-inflammatory, and antioxidant properties. [Bioengineered 2022;13:14681-14718; Evid Based Complement Alternat Med 2011;2011:531053; J Med Food 2007;10:566-570]

In this open-label trial, 189 COVID-19 patients were randomized 1:1 to receive standard treatment alone or with 15.2 g of Spirulina supplement. Ninety-nine patients were admitted to the ICU while the rest were not. Half of the overall cohort were men, with age ranging between 45 and 51 years. “[We] chose the daily dose of 15.2 g of Spirulina because, on average, each 15 g of Spirulina provides about 100 mg of PCB,” the researchers noted.

Standard COVID-19 treatment includes antivirals (remdesivir), anticoagulants (heparin or enoxaparin), and corticosteroids (dexamethasone). Tocilizumab was administered in patients whose disease progressed and had CRP ≥75 despite receiving standard treatment within 24-72 hours of admission. In keeping with the national protocol at the time of study, methylprednisolone was used for a maximum of 3 days if tocilizumab was contraindicated or unavailable.

“Presently, it is unclear whether this microalga helps recovery of COVID-19 patients due to balancing the immune system and reducing inflammation or via other vital pathways,” said the researchers. “However, these preliminary data will undoubtedly help future studies further investigate this dietary supplement and other drugs in treating COVID-19.”

Given the availability and affordability of Spirulina, the results also underline its potential in reducing hospital burden, especially ICU admissions.

The investigators called for more trials with larger populations and longer follow-up to ascertain the role of Spirulina in the management of COVID-19.