Herb library · Herb · Avena sativa
Oatstraw (green oat)
The green stems and leaves of the oat plant, cut before the grain ripens and sold as tea or extract for stress and sleep. EU regulators accept those uses on long traditional use only; a few small trials of one extract have looked at attention and memory, with mixed results.
Traditional use
Oats have been grown as food since antiquity. The green plant, harvested before flowering, is sold in Europe as a traditional herbal medicine for mild symptoms of mental stress and to aid sleep. In late-1800s American medicine a tincture of the whole green plant was sold as a nerve tonic.
What studies show
- Insufficient
Mild stress and sleep: accepted in the EU on the basis of traditional use only. The European Medicines Agency says there is insufficient evidence from clinical trials; its assessment noted only a study in rats.
- Limited
Attention and memory: small randomized trials of green oat extracts, mostly funded by their makers, give mixed results. A 2020 trial in 132 adults found better scores on two memory and multitasking tests after four weeks, while a 2012 trial in 37 older adults found no effect on any measure of thinking after 12 weeks.
Be careful of
Cautions
- ConditionPeople with celiac disease should be cautious: the EU monograph notes that data on the protein content are not available.
- NoteNo side effects had been reported when the EU assessment was made. The EU monograph says it may impair the ability to drive or use machines, and it is not recommended for children under 12.
- AllergyDo not use it if you are allergic to oats.
- PregnancySafety in pregnancy and breastfeeding has not been established, and use is not recommended.
- Ask a clinicianTalk with a clinician or pharmacist before using this if you take prescription medicines, are pregnant or breastfeeding, or are giving it to a child.
From the old books
What herbals and dispensaries of the past printed. History, in their words.
“A few years ago it was much lauded as a remedy to assist the morphine-consumer to throw off the habit, and to sustain the nervous system while undergoing that ordeal. We have, however, found it to exert but little good in this direction.”
“A strong tincture may be prepared by crushing or pounding to a pulp the entire oat-plant when the grain is “in the milk,” covering with strong alcohol and allowing it to macerate 14 days.”
Sources
- Avenae herba - herbal medicinal product (opens in a new tab) · EMA · read September 25, 2026
- Oat herb: summary for the public (opens in a new tab) · EMA · read September 25, 2026
- Community herbal monograph on Avena sativa L., herba (opens in a new tab) · EMA · read September 25, 2026
- Acute and Chronic Effects of Green Oat (Avena sativa) Extract on Cognitive Function and Mood during a Laboratory Stressor in Healthy Adults (2020) (opens in a new tab) · NIH · read September 25, 2026
- Chronic effects of a wild green oat extract supplementation on cognitive performance in older adults (2012) (opens in a new tab) · NIH · read September 25, 2026
Reviewed September 25, 2026.