🔬 Mechanism of Adaptogens: The Hypothalamic-Pituitary-Adrenal (HPA) Axis
How herbal adaptogens help the body cope with stress
Adaptogens are plants that help the body adapt to stress and normalise physiological processes. Their action is largely linked to the hypothalamic-pituitary-adrenal (HPA) axis — the main stress-response system that regulates cortisol production.
What are adaptogens
The term "adaptogen" was proposed in 1947 by the Soviet scientist Nikolai Lazarev. Adaptogens increase non-specific resistance to stress, helping to maintain homeostasis. They include ashwagandha, rhodiola, ginseng, eleutherococcus and schisandra.
- Increase resistance to stress.
- Normalise physiological processes.
- Act under moderate and chronic stress.
- Studied for their effect on cortisol.
HPA axis and cortisol
The HPA axis is a cascade: hypothalamus → pituitary → adrenal glands. Under stress it triggers the production of cortisol, the main "stress hormone". Chronic stress can disrupt the axis, and adaptogens are studied for their ability to normalise it.
| Step | Organ | Function |
|---|---|---|
| 1 | Hypothalamus | Releases CRH |
| 2 | Pituitary | Releases ACTH |
| 3 | Adrenal glands | Produce cortisol |
Ashwagandha
Ashwagandha (Withania somnifera) is one of the most studied adaptogens. Its active compounds are withanolides. RCTs show a reduction in cortisol and anxiety in people with chronic stress.
- Contains withanolides.
- Lowers cortisol in studies.
- Reduces anxiety.
- Popular as a standardised extract (KSM-66).
Rhodiola rosea
Rhodiola rosea is known as an adaptogen that boosts energy and resistance to fatigue. Its active compounds are rosavins and salidroside. It is studied for its effect on fatigue and stress.
- Contains rosavins and salidroside.
- Boosts energy and endurance.
- Reduces fatigue.
- Studied under stress.
Ginseng
Ginseng (Panax ginseng) is a classic adaptogen whose active compounds are ginsenosides. It is studied for its tonic effect and energy support.
- Contains ginsenosides.
- Tonic and energy support.
- Studied for effect on fatigue.
- Used in traditional medicine.
Norms and dosages
| Adaptogen | Typical dose | Comment |
|---|---|---|
| Ashwagandha | 300–600 mg/day | Standardised |
| Rhodiola | 200–400 mg/day | 3% rosavins |
| Ginseng | 200–400 mg/day | Standardised |
Practice
- Choose standardised extracts with stated active compounds.
- Start with the minimum dose.
- Take in courses, usually 4–8 weeks.
- Adaptogens supplement stress management and sleep.
- Do not combine with medicines without a doctor.
What are adaptogens?
Plants that help the body adapt to stress and normalise physiological processes.
What is the HPA axis?
The hypothalamus → pituitary → adrenal cascade that regulates cortisol production under stress.
How does ashwagandha lower cortisol?
RCTs show a cortisol reduction through the action of withanolides on stress regulation.
What does rhodiola contain?
Rosavins and salidroside — active compounds that support energy and resistance to fatigue.
What does ginseng contain?
Ginsenosides — active compounds with a tonic effect.
How much ashwagandha to take?
Usually 300–600 mg of standardised extract a day, per the label.
How much rhodiola to take?
Usually 200–400 mg of extract with 3% rosavins a day.
How long to take?
In courses of 4–8 weeks, with breaks, as recommended.
Who should not take adaptogens?
Pregnant women and those on medicines, especially with chronic conditions, need a consultation.
Do adaptogens replace sleep?
No, they supplement stress management but do not replace sleep and a healthy lifestyle.