The perennial herb Valeriana officinalis, commonly known as valerian, has been used in traditional herbalism since ancient Greece and Rome, primarily for its calming properties. The root and rhizomes (underground stems) are the parts most recognized in modern supplements and traditional medicines for their sedative and anxiolytic effects. While the robust, earthy-smelling root is the focus of pharmacological study, the plant also produces fragrant flowers and large, pinnately divided leaves. This raises the question of whether these aerial parts possess the same therapeutic value as the well-established root.
Understanding Chemical Differences in Valerian Plant Parts
The pharmacological profile of valerian root is attributed to specific secondary metabolites, particularly valerenic acids and iridoids (valepotriates). These compounds interact with the brain’s gamma-aminobutyric acid (GABA) system, which regulates nerve activity and promotes relaxation. The root and rhizomes hold the highest concentration of these active components, making them the most potent part for medicinal preparations.
The concentration of these compounds varies significantly across the plant. For instance, valerenic acid derivatives in the root can range up to 1.11% of the dry weight. Conversely, flowers contain much lower levels, sometimes as low as 0.50 milligrams per 100 grams of dry mass. This difference explains why commercial valerian products are standardized based on the root’s valerenic acid content.
The leaves and flowers contain some of the same compounds, but they lack the necessary concentration to elicit the same sedative response as the root. The plant naturally concentrates these chemicals in its underground storage organs. This means preparations made from the aerial parts have substantially reduced biological activity, making them less effective for anxiety or insomnia compared to root extracts.
Traditional and Modern Applications of Valerian Leaves and Flowers
Historically, the leaves and flowers of Valeriana officinalis have been utilized for purposes distinct from the root’s strong sedative action. The flowers, which bloom from June to August, are sweetly scented and appreciated for their aromatic qualities. This pleasant scent contrasts sharply with the root’s musky odor, which is linked to the active sesquiterpenoids.
In modern use, the leaves can be incorporated into mild herbal teas for a lightly flavored, relaxing beverage, not for deep sedation. Some culinary traditions use valerian leaves as a mild condiment. These applications leverage the milder flavor compounds and general herbal properties rather than relying on the high concentrations of valerenic acid found below ground.
The leaves can also be utilized as a nutrient-rich addition to garden compost, stimulating phosphorus and earthworm activity. This highlights the plant’s broader ecological benefits. When grown for its medicinal root, growers often “deadhead” the flowers during the summer to encourage the plant to direct energy toward root growth and greater concentration of active compounds.
Safety Considerations and Preparation Guidelines
The use of valerian’s leaves and flowers carries fewer risks than the highly concentrated root, due to the lower presence of active compounds. However, caution should be exercised when consuming any part of the plant. Root extracts have been linked to potential side effects, including stomach upset or mental dullness.
For preparation, the leaves and flowers are typically harvested when the plant is in full bloom (June to August). The leaves can be picked throughout the growing season. Both parts can be dried and used in an herbal infusion, commonly known as a tea.
To prepare a mild infusion, steep two to three grams of the dried herb in hot water for 10 to 15 minutes. This preparation will not provide the same sedative effect as a root preparation. Pregnant or breastfeeding individuals should avoid consuming valerian, including the leaves and flowers, due to limited safety data.