A study to evaluate the efficacy of the continuous intake of food containing flavonoids (quercetin glycoside) on the SARS-CoV-2 vaccine efficacy in a healthy adult with a high body-mass index or elderly.

A randomized, double-blind, placebo-controlled study to evaluate the efficacy of the continuous intake of food containing quercetin glycoside on the SARS-CoV-2 vaccine efficacy in a healthy adult with a high body-mass index or elderly. - A study to evaluate the efficacy of food intake containing quercetin glycoside on the SARS-CoV-2 vaccine efficacy.

Status

Active, not recruiting

Phases

Unknown

Study type

Interventional

Source

JPRN

Registry ID

JPRN-UMIN000046945

Enrollment

Registered

2022-02-21

Start date

2022-03-15

Completion date

Unknown

Last updated

2026-06-29

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Healthy adults

Interventions

Before SARS-CoV-2 booster vaccination, participants will take quercetin glycoside capsules twice a day for 4 weeks. Before SARS-CoV-2 booster vaccination, participants will take placebo capsules twice

Eligibility

Sex/Gender

All

Inclusion criteria

Inclusion criteria: 1. Subjects fully understand the significance, content, and purpose of this study and agree to participate with written informed consent (IC). 2. Japanese healthy males or females who are equal to or over 65 years of age at the time of obtaining IC, or who are equal to or over 20 years old with 23.0 kg/m2 BMI at the time of obtaining IC. 3. No medication for lifestyle disease at the time of obtaining IC. 4. Subjects who have received twice injections of SARS-CoV-2 vaccine, either Pfizer (BNT162b2) or Moderna (mRNA1273), then spent more than 7 months until 4 weeks post food intake. 5. Subjects who would like to have 3rd booster of SARS-CoV-2 vaccine of Moderna (mRNA1273). 6. Subjects who are willing to describe the self-health condition daily and capable of that.

Exclusion criteria

Exclusion criteria: 1. Pacemaker or defibrillator users. 2. Subjects diagnosed as an unappropriated health condition by the corresponding clinician of the study. 3. Subjects who have severe cardiac or vascular disease, including thrombosis, blood, respiratory, hepatic, kidney, digestive, or psychiatric disorders, or have a history of such a condition. 4. Subjects who have an allergy such as systemic rash or a history of such symptoms. 5. Subjects who have seizures including febrile convulsion, Guillain-Barre syndrome, acute disseminated encephalomyelitis, or previous history. 6. Subjects who have been diagnosed with abnormal immunity by clinicians. 7. Subjects who have currently received medications, which potentially affect the evaluation of the immune responses, or who plan to have such drugs during this study. 8. Subjects who have previously anaphylactic reaction by food or drugs. 9. Subjects who have a history of anaphylactic reaction provoked by either the test food, the ingredients of the test food (quercetins or flavonoids), or potentially experience an anaphylactic reaction to them. 10. Subjects who plan to participate in other clinical studies until the end of this study from 4 weeks before the study. 11. Subjects who are pregnant, potentially pregnant, or lactating females.

Design outcomes

Primary

Measure	Time frame
Antibody titers against SARS-CoV-2 RBD at 2, 4, 12 weeks post-vaccination.	—

Secondary

Measure	Time frame
Antibody titers and neutralizing activity against SARS-CoV-2 RBD of variants of concern. Description of the daily health condition by participants.	—

Countries

Japan

Contacts

Public ContactNaoyuki HONMA

Hokkaido Information University Health Information Science Center

clinical-food@do-johodai.ac.jp011-385-4430

Outcome results

None listed

Source: JPRN (via WHO ICTRP) · Data processed: Jul 3, 2026