Rosemary leaf
Also known as: Salvia rosmarinus, Rosemary, Rosmarinus, Rosemary leaf, Rosmarinus officinalis
Overview
Rosemary, scientifically known as *Rosmarinus officinalis* (and recently reclassified as *Salvia rosmarinus*), is a perennial herb native to the Mediterranean region, widely cultivated for its culinary and medicinal properties. It is rich in polyphenols and essential oils, such as rosmarinic acid, carnosic acid, and 1,8-cineole, which contribute to its demonstrated antioxidant and anti-inflammatory effects. Rosemary is primarily used as a herbal supplement for cognitive enhancement, antioxidant support, and skin health. While robust preclinical data exist, the human clinical evidence is growing but still limited by small sample sizes and short study durations. It is generally recognized as safe for most adults at typical doses and is available in various forms, including standardized extracts.
Benefits
Rosemary offers several evidence-based benefits, primarily in cognitive function and skin health. For cognitive enhancement, systematic reviews and meta-analyses, including both animal and limited human studies, indicate that rosemary extract can improve cognitive outcomes such as memory and attention in both healthy individuals and those with mild impairment. The effect sizes are moderate but consistent across studies. For skin health, recent randomized controlled trials (RCTs) have shown significant improvements in skin dullness, roughness, erythema, and pore size after 12 weeks of supplementation with rosemary extract. These studies also provided histological evidence of reduced glycative stress and advanced glycation end products (AGEs), suggesting a clinically meaningful anti-aging effect. While antioxidant and anti-inflammatory effects are well-documented in preclinical models, their direct clinical significance in humans requires further research. Cognitive benefits may be more pronounced in older adults, though this is preliminary.
How it works
Rosemary exerts its effects through multiple biological pathways, primarily due to its rich content of polyphenols and essential oils. Its key mechanisms include potent antioxidant activity, where it scavenges free radicals and inhibits lipid peroxidation, thereby reducing oxidative stress. It also demonstrates anti-inflammatory properties by modulating inflammatory pathways. A significant mechanism for skin health is the inhibition of glycation and the reduction of advanced glycation end products (AGEs), which contribute to skin aging. In the central nervous system, rosemary constituents may modulate neurotransmitter systems, such as inhibiting acetylcholinesterase, which can lead to increased acetylcholine levels and improved cognitive function. These actions collectively interact with the central nervous system for cognitive benefits, the skin for anti-aging effects, and the immune system for anti-inflammatory responses. Polyphenols like rosmarinic acid are absorbed orally, though bioavailability can vary.
Side effects
Rosemary is generally recognized as safe (GRAS) for most adults at typical doses. Common side effects are rare but can include mild gastrointestinal upset. Uncommon side effects (1-5% frequency) may involve allergic reactions or skin irritation, particularly with topical application. Rare side effects (less than 1%) include seizures, which have been reported at very high doses or in susceptible individuals. Rosemary has potential drug interactions; it may interact with anticoagulants due to its vitamin K content, antidiabetic drugs due to a possible hypoglycemic effect, and sedatives due to its essential oil content. Contraindications include pregnancy, as it may have emmenagogue effects, and epilepsy, due to the risk of seizures at high doses. Caution is advised for individuals with bleeding disorders, diabetes, or epilepsy.
Dosage
The minimum effective dose for rosemary extract is not firmly established, but most studies utilize 250–1000 mg/day of a standardized extract. The optimal dosage range for cognitive or skin benefits is generally considered to be 500–1000 mg/day of rosemary leaf extract. A maximum safe dose of up to 1500 mg/day appears safe in short-term studies, though long-term safety data at this higher dose are limited. Rosemary can be taken with or without food, as timing is not considered critical for its efficacy. For consistency and reliable effects, standardized extracts (e.g., containing 5–10% rosmarinic acid) are preferred. While not strictly required, some evidence suggests that absorption may be enhanced when taken with food or specific cofactors like piperine, though more research is needed in this area. No specific cofactors are required for its benefits.
FAQs
Is rosemary safe for everyone?
Rosemary is generally safe for most adults at recommended doses. However, pregnant women, individuals with epilepsy, or those on anticoagulants, antidiabetic drugs, or sedatives should use it with caution or avoid it due to potential interactions and risks.
How long does it take to see benefits from rosemary supplementation?
Benefits for skin health have been observed within 12 weeks in clinical trials. For cognitive benefits, animal studies show effects within weeks, but human data on the exact timing are more limited. Consistent use over several weeks to months is generally recommended.
Can rosemary cure cognitive decline or skin aging?
No, rosemary is not a cure for cognitive decline or skin aging. Its benefits are supportive and preventive, helping to improve cognitive function and skin quality. It should be considered a supplement to a healthy lifestyle, not a replacement for medical treatment.
What is the best form of rosemary to take?
Standardized extracts, typically containing 5–10% rosmarinic acid, are generally recommended for consistency and to ensure a reliable dose of active compounds. These forms are used in most research studies demonstrating benefits.
Research Sources
- https://pubmed.ncbi.nlm.nih.gov/35170682/ – This systematic review and meta-analysis synthesized findings from animal and limited human studies, concluding that rosemary extract improves cognitive outcomes in both normal and impaired subjects. The study highlighted moderate but robust effect sizes across various species and extract types, though it noted limitations due to the scarcity of large-scale human RCTs and heterogeneity in study designs.
- https://www.preprints.org/manuscript/202009.0732/v1 – This preprint provides a comprehensive overview of rosemary's cognitive and antioxidant benefits, summarizing findings from both preclinical and clinical studies. While not a systematic review, it offers valuable insights into the mechanisms and potential applications of rosemary and its active constituents, acknowledging the need for more rigorous human trials.
- https://jcadonline.com/reversing-oxinflammation-gylcative-stress-rosemary/ – This source discusses the role of rosemary in reversing oxinflammation and glycative stress, particularly in the context of skin health. It highlights the herb's potential to combat advanced glycation end products (AGEs) and oxidative damage, which are key contributors to skin aging, providing a mechanistic basis for its dermatological benefits.
- https://jcadonline.com/safety-effiacy-dietary-supplemet-aging-skin/ – This article details the safety and efficacy of a dietary supplement containing rosemary extract for aging skin. It references an RCT demonstrating significant improvements in skin parameters like dullness, roughness, and pore size, along with histological evidence of reduced glycative stress, supporting rosemary's role in improving global skin quality.
