Single Herbs For a Healthy Immune & Stress Response Dietary Supplement Ashwagandha Root When the body is stressed, the immune and nervous systems can be affected, leaving a person depleted. Adaptogenic herbs such as Ashwagandha help nourish and restore optimal nervous and immune system healthy by normalizing moods, energy levels and overall immune function. Gaia Herbs uses Ashwagandha root with guaranteed levels of active withanolides.