Abstract
- Background
Enhancing immune function is frequently claimed as a primary benefit of various natural health products, though rigorous randomized clinical trials investigating these effects remain scarce. This community-based study evaluated the impact of an oral dietary supplement derived from the edible microalga Chlorella pyrenoidosa on immune responses following seasonal influenza vaccination in older adults.
- Methods
A randomized, double-blind, placebo-controlled clinical trial was conducted with 124 healthy adult participants aged 50 years and older. Subjects were randomly assigned to receive either 200 milligrams or 400 milligrams of the Chlorella-derived dietary supplement, or a matching placebo, taken once daily for 28 days. On day 21 of the intervention, participants received a single dose of a licensed trivalent inactivated influenza vaccine. Serum specimens were collected at baseline, as well as 7 and 21 days post-vaccination, to measure hemagglutination inhibition titers. Primary immunological outcomes included the proportion of participants achieving a fourfold or greater increase in antibodies and geometric mean antibody titers, while safety was monitored through reported adverse events.
- Results
A total of 117 participants (94%) completed the trial. Overall, the Chlorella-derived dietary supplement did not significantly increase the proportion of participants achieving at least a fourfold rise in antibody titers across the entire study population compared to the placebo group ($P > 0.05$). Adverse event rates were generally similar between treatment and placebo arms, except for reports of fatigue, which occurred more frequently in the 200-milligram supplement group compared to the 400-milligram and placebo groups. However, exploratory subgroup analyses revealed that younger participants aged 50 to 55 years receiving 400 milligrams of the supplement exhibited significantly higher geometric mean antibody titers against specific influenza strains post-vaccination.
- Conclusions
While the Chlorella-derived dietary supplement did not globally enhance antibody responses to the influenza vaccine in the overall study population, it demonstrated a favorable safety profile and showed potential immunogenic benefits in a specific younger age subgroup aged 50 to 55 years, warranting further clinical investigation.
https://www.researchgate.net/publication/10651021_Safety_and_immunoenhancing_effect_of_a_Chlorella-derived_dietary_supplement_in_healthy_adults_undergoing_influenza_vaccination_Randomized_double-blind_placebo-controlled_trial