Funder: National Institutes of Health

Due Dates: May 24, 2025 (Letter of Intent) | June 23, 2025 (New/Renewal/Resubmission/Revision) | July 17, 2025 (AIDS) | Feb 23, 2026 | Mar 17, 2026 (AIDS) | Oct 20, 2026 | Nov 13, 2026 (AIDS)

Funding Amounts: Up to $350,000 direct costs/year (R61 and R33 phases); max 5 years total (up to 3 years per phase)

Summary: Supports early phase, milestone-driven clinical trials of natural products (botanicals, probiotics, dietary supplements, standardized nutritional regimens) to assess pharmacokinetics, target engagement, and links to clinical outcomes.

Key Information: Only U.S.-based organizations may apply; foreign organizations are not eligible, but foreign components are allowed.