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Cortisol is the hormone that mediates waking up and a variety of catabolic (tissue breakdown) reactions; it isn't bad in any way, but many people with elevated cortisol could suffer pathology from it. In these scenarios, it is nice to lower cortisol and supplementation may be effective.

Our evidence-based analysis on cortisol features 54 unique references to scientific papers.

Research analysis led by Kamal Patel.
All content reviewed by the Examine.com Team. Published: Feb 6, 2013
Last Updated:

Frequently Asked Questions about Cortisol

How important is sleep?
Sleep is incredibly important, and can be considered crucial alongside diet and exercise. Proper sleep habits help sustain many biological processes, and bad sleep can cause these processes to be suboptimal or even malfunction.

Human Effect Matrix

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what supplements affect cortisol
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
grade-b Minor High See all 4 studies
In general, cortisol appears to be increased at high doses of caffeine; lower doses may not have an effect.
grade-b Minor Moderate See all 5 studies
Highly unreliable influences on cortisol, with decreases seen in studies where androgens and estrogens are also increased (with no significant influence or possibly an increase in other studies)
grade-b Minor Low See all 4 studies
A possible reducing effect of fish oil supplementation on cortisol
- See all 7 studies
Vitamin C (500-1,500mg daily) appears to be associated with both increases and decreases in exercise-induced cortisol spikes, depending on whether it acts as a prooxidant or antioxidant (respectively). There is no influence on resting cortisol concentrations.
grade-b - Very High See all 4 studies
No effect on cortisol changes associated with sleep deprivation.
grade-b - Very High See all 3 studies
No significant influence on cortisol levels following acute ingestion
grade-b - Very High See all 4 studies
A decrease in exercise-induced cortisol has been noted with the bovine cortex sourced PS only, soy based supplements (which are usually the only ones sold now due to fear of Creutzfeldt–Jakob disease) have been shown to have outright no effect at doses up to 750mg
grade-c Notable Very High See all 4 studies
The decrease in cortisol noted in humans has reached 14.5-27.9% in otherwise healthy but stressed humans, which is significantly larger than many other supplements.
grade-c Minor - See study
At least one study has noted increased in salivary cortisol following acute ingestion of 5-HTP supplementation.
grade-c Minor - See study
In stressed persons, daily supplementation of eurycoma is associated with a 16% reduction in cortisol concentrations.
grade-c Minor - See study
The increase in cortisol seen before a stress test is attenuated with supplementation of ginkgo, secondary to its anti-stress effects
grade-c Minor Very High See all 3 studies
Appears to increase cortisol at higher doses (500mg or more), with no significant influence at lower doses; this is related to the glycyrrhizin content, and would not occur in deglycyrrhizinated supplements
grade-c Minor Moderate See 2 studies
Mixed results, a possible increase when measuring whole-day cortisol levels (when taken in the AM) with no augmentation of stress-induced cortisol increases; may reduce cortisol if taken prior to sleep, however
grade-c Minor - See study
In chronically stressed men, prolonged ingestion of mucuna pruriens appears to be able to reduce cortisol concentrations
- See study
Increases have been noted with intravenous ornithine (not in human trials table) while decreases have been noted following treatment of hangovers. The most practical study of using ornithine as a preworkout supplement failed to find any effect
grade-c Minor - See study
A decrease in cortisol appears to result from the anti-stress response of rose oil inhalation
grade-c Minor - See study
The aroma of saffron has been noted to reduce cortisol concentrations to a mild degree in otherwise healthy women, and this occurred alongside a reduction in state anxiety.
grade-c Minor - See study
A decrease in cortisol may result following inhalation of clary sage, but the magnitude of reduction (2.5%) is very small
- See study
Conditional influences on cortisol, with an apparent increase in cortisol of beginner atheltes at rest with decreases in exercise-induced cortisol in beginners and lower overall cortisol exposure in trained athletes
grade-c Minor - See study
May reduce cortisol during a social stress test at 2g
grade-c Minor - See study
A decrease in exercise-induced cortisol secretions has been noted with theaflavin consumption in high doses (above 1,800mg daily)
grade-c Minor - See study
Cortisol appears to be minimally (6.1%) decreased with two weeks betaine supplementation when measured after exericse in a fasted state.
grade-c Minor Very High See 2 studies
Appears to increase cortisol following ingestion
grade-c - - See study
Cortisol is not influenced by alanylglutamine relative to water during and after an exercise trial.
grade-c - Very High See 2 studies
No significant alterations in cortisol levels seen with alcohol ingestion in moderate levels
grade-c - - See study
grade-c - - See study
No significant influence on circulating cortisol concentrations
grade-c - - See study
grade-c - - See study
No significant interactions with BCAA supplementation and cortisol
grade-c - - See all 3 studies
The increase in cortisol has been buffered in one study where stress was introduced, but otherwise cocoa does not appear to influence resting cortisol concentrations.
grade-c - Moderate See all 3 studies
While one study noted an increase in morning cortisol during multiple day training in elite cyclists (a beneficial response), basal cortisol concentrations and those immediately after standard exercise do not appear to be influenced with colostrum supplementation.
grade-c - - See study
No demonstrated changes in cortisol levels with ecdysterone consumption
grade-c - - See study
No significant influence on cortisol levels following fenugreek ingestion
grade-c - - See study
No significant influence on cortisol levels with prolonged supplementation
grade-c - - See study
No significant influence of garlic supplementation has been found on cortisol in cancer patients.
grade-c - - See study
No significant alterations in cortisol noted
grade-c - - See study
No significant influence on cortisol seen with magnesium supplementation
grade-c - - See study
No significant influence on cortisol levels
grade-c - - See study
No significant reduction in cortisol seen with supplementation of vitamin E relative to placebo.
grade-d Minor Very High See 2 studies
A reduction has been noted in two studies, but more research is needed.
grade-d Minor - See study
A decrease in cortisol has been noted acutely with aromatherapy
grade-d - - See study
Exercise-induced changes in cortisol are not influence by blueberry supplementation
grade-d - - See study
No significant effect on cortisol has been noted with supplemental boron
grade-d - - See study
There does not appear to be a significant influence of marijuana on urinary cortisol.
grade-d - - See study
No significant alterations in cortisol concentrations seen with supplementation of the seeds.
grade-d - - See study
Supplementation of niacin during a fasting period does not appear to influence circulating cortisol concentrations.
grade-d - - See study


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