Supplements for Adrenal Support: Addressing HPA Ax…

"Adrenal fatigue" is one of the most searched health terms online and one of the most contested in clinical medicine. Endocrinologists point out — correctly — that adrenal fatigue as classically marketed does not exist as a medical diagnosis. The adrenal glands rarely "burn out" in otherwise healthy people without an identifiable cause.

But this clinical pushback can miss the underlying phenomenon that millions of people are experiencing: a dysregulated stress response, disrupted cortisol rhythms, and a nervous system that has been running in chronic overdrive. This is better understood through the lens of HPA axis dysregulation — and it is both real and measurable.

This post covers what HPA axis dysregulation actually is, how to test for it, and which supplements have meaningful evidence for supporting the stress response system.

Adrenal fatigue vs. HPA axis dysregulation

True adrenal insufficiency (Addison's disease) is a serious medical condition in which the adrenal glands cannot produce sufficient cortisol due to gland damage, often autoimmune in origin. It presents with severe fatigue, weight loss, hyperpigmentation, salt craving, and low blood pressure. It requires medical diagnosis and hormone replacement therapy — not supplements.

HPA axis dysregulation is different. The hypothalamic-pituitary-adrenal (HPA) axis is the body's central stress response system. Chronic psychological stress, poor sleep, overtraining, or dysbiosis can alter the normal cortisol rhythm without causing outright adrenal failure. Common patterns include: elevated morning cortisol with poor nighttime decline, flattened cortisol curve throughout the day, or delayed morning awakening response.

These patterns correlate with fatigue, anxiety, difficulty concentrating, disrupted sleep, and impaired recovery — the same symptoms people attribute to "adrenal fatigue."

How to test before supplementing

Targeted testing reveals far more than guessing from symptoms.

4-point salivary cortisol: The most clinically informative test for HPA axis function. Cortisol is measured four times throughout the day (upon waking, mid-morning, mid-afternoon, and evening). This captures the diurnal rhythm, which is disrupted in HPA axis dysregulation long before absolute cortisol levels become abnormal.

Cortisol awakening response (CAR): A more refined version of the 4-point test, measuring cortisol at waking, 30 minutes, and 60 minutes after waking. The CAR is a distinct neuroendocrine response separate from the diurnal rhythm and reflects HPA axis reactivity.

DHEA-S (serum): DHEA-S is the sulfated, storage form of DHEA — the most abundant adrenal hormone. It declines with age and can decline faster in people with chronic stress. Low DHEA-S alongside dysregulated cortisol provides a more complete picture of adrenal output. See the separate guide on DHEA supplementation for how to interpret and use this marker.

Urinary free cortisol: Captures total daily cortisol output. Useful for ruling out Cushing's syndrome (very high cortisol) but less nuanced than salivary testing for rhythm assessment.

Ashwagandha (Withania somnifera)

Ashwagandha is the most studied adaptogen for cortisol and HPA axis support, with multiple randomized controlled trials specifically measuring cortisol outcomes.

The landmark KSM-66 trials (using a standardized root extract) showed a 27-30% reduction in morning serum cortisol in chronically stressed adults over 8-12 weeks at 300-600mg/day. Participants also reported significant reductions in perceived stress, anxiety, and sleep quality scores.

Proposed mechanism: Ashwagandha's withanolide compounds appear to act on GABAergic pathways and may modulate the HPA axis at the level of the hypothalamus, reducing CRH (corticotropin-releasing hormone) secretion.

Important cautions: Ashwagandha has documented thyroid-stimulating effects and is contraindicated in hyperthyroidism. People on levothyroxine should have thyroid levels rechecked after starting, as doses may need adjustment. Avoid in pregnancy.

Dose: 300-600mg of a standardized extract (KSM-66 or Sensoril) daily. Can be taken in the morning or split morning/evening.

Rhodiola rosea

Rhodiola is classified as an adaptogen — it modulates the stress response in a bidirectional way, reducing excessive cortisol response while supporting energy and resilience. Unlike ashwagandha, it is mildly stimulating rather than calming, making it better suited for people with flattened cortisol (low energy, chronic fatigue) rather than elevated cortisol.

Key trials show improvements in fatigue, mental performance under stress, and burnout symptoms. Rhodiola does not dramatically lower absolute cortisol levels but appears to normalize the cortisol awakening response.

Dose: 200-400mg of a standardized extract (3% rosavins, 1% salidroside) daily. Take in the morning — the mild stimulant effect can interfere with sleep if taken later in the day.

Phosphatidylserine

Phosphatidylserine (PS) is a phospholipid component of cell membranes, particularly abundant in brain tissue. It has some of the most specific evidence for blunting excessive cortisol output.

Studies from the late 1990s and 2000s demonstrated that phosphatidylserine (400-800mg/day) significantly blunted the cortisol and ACTH response to both psychological stress and intense exercise. The mechanism appears to involve modulation of HPA axis feedback at the pituitary level.

Best evidence for: Post-exercise cortisol suppression in athletes; may also be useful for people with elevated evening cortisol disrupting sleep.

Dose: 400-800mg daily. Soy-derived PS is most common and has the most trial data; sunflower-derived PS is available for those avoiding soy.

Note: Lower doses (100-200mg) commonly marketed for cognitive function may have insufficient effect on cortisol specifically.

Vitamin B5 (pantothenic acid)

Pantothenic acid is a cofactor in the synthesis of coenzyme A (CoA), which is required for cortisol biosynthesis in the adrenal cortex. This has led to its inclusion in many "adrenal support" formulas.

The evidence base is thin — most support is mechanistic or from older animal studies. B5 deficiency causing impaired cortisol production is not well documented in humans eating varied diets. However, it is water-soluble and has a very low toxicity profile.

Dose: 250-500mg pantethine (the active form) if including in an adrenal stack. It is a reasonable adjunct rather than a primary intervention.

Building an HPA support stack

For people with confirmed cortisol rhythm disruption or elevated perceived stress:

Foundation level (lifestyle comes first):

Consistent sleep schedule (non-negotiable)
Morning light exposure within 30 minutes of waking
Time-restricted caffeine use (before noon)
Regular exercise that does not cause overtraining

Supplement stack:

Ashwagandha KSM-66, 300-600mg daily
Magnesium glycinate, 300-400mg in the evening
Phosphatidylserine, 400mg if cortisol is elevated (especially post-exercise or in the evening)
Rhodiola, 200-400mg in the morning if fatigue is the primary concern

Retest salivary cortisol at 8-12 weeks to assess response.

When supplements are not enough

HPA axis dysregulation driven by significant sleep disorders, trauma, severe anxiety, or burnout may require more than nutritional intervention. Cognitive behavioral therapy, EMDR, sleep disorder treatment, and appropriate medical care are not replaceable with supplements.

If salivary cortisol testing reveals extreme abnormalities (very high 24-hour output, very flat curve with extremely low values), or if you have symptoms suggestive of Addison's disease (profound fatigue, hyperpigmentation, salt craving, hypotension), see an endocrinologist for serum cortisol and ACTH stimulation testing. True adrenal insufficiency is a medical emergency in some circumstances.

The bottom line

HPA axis dysregulation is real, measurable through salivary cortisol testing, and can be meaningfully supported with adaptogens and targeted nutrients. Ashwagandha, rhodiola, and phosphatidylserine have the strongest evidence. Test first to understand your cortisol pattern, then select supplements that match the dysregulation pattern you have — high cortisol calls for different interventions than flat, low cortisol.

Track your supplement stack and stress symptoms to see what's actually working. Use Optimize free.

Supplements for Adrenal Support: Addressing HPA Axis Dysregulation