Can supplements help with stress, cortisol and burnout? A careful, evidence-based look
If you are exhausted, overwhelmed, wired but tired, or feeling like your stress system is constantly switched on, it is understandable to start looking for something that might help.
Social media is full of claims about “lowering cortisol”, “balancing hormones”, or “fixing burnout” with supplements such as vitamin D, magnesium, or adaptogenic herbs. These claims are tempting, but they often oversimplify a very complex system.
This article is about what the evidence does and does not support, and where supplements might sit, sensibly and safely, within a much bigger picture of stress, overload, ADHD, and midlife health.
An important boundary
Supplements do not fix chronic stress.
Cortisol is regulated by the HPA (hypothalamic–pituitary–adrenal) axis, a complex neuroendocrine system influenced by sleep, circadian rhythm, psychological stress, inflammation, illness, and long-term load (Tsigos et al., 2016). Dysregulation of this system is not usually caused by a single nutrient deficiency, and it is very unlikely to be corrected by a single supplement.
The main drivers of stress physiology are:
• Total load
• Recovery and sleep
• Ongoing psychological and physical stress
• Metabolic and inflammatory strain
Supplements can support physiology, particularly where there is a deficiency or increased demand, but they do not replace rest, recovery, or reducing overload.
A brief recap, what cortisol actually is
Cortisol is not a “bad” hormone. It is essential for survival and helps regulate energy, blood pressure, immune activity, and alertness. The problem is not cortisol itself, but chronic activation or dysregulation of the stress system (Tsigos et al., 2016).
If you want a fuller explanation of this, it is worth reading the main article on cortisol, ADHD, and the stress system, as this piece builds on that foundation.
When supplements are actually relevant
Supplements tend to be most helpful when:
• There is a genuine deficiency
• There is increased physiological demand
• There is impaired absorption or higher needs due to stress, illness, or life stage
This is particularly true for nutrients such as vitamin D and magnesium, where deficiency is common in the general population (NICE, 2022; de Baaij et al., 2015).
Vitamin D
Vitamin D is best known for its role in bone and immune health, but vitamin D receptors are widely distributed in the brain and in endocrine tissues involved in stress regulation (Menon et al., 2020).
There is growing interest in the relationship between vitamin D and the HPA axis, and mechanistic research suggests vitamin D may influence stress pathways and inflammatory regulation (Menon et al., 2020). Observational studies show that low vitamin D levels are associated with poorer mental health and greater vulnerability to stress (Casseb et al., 2019).
However, intervention trials show mixed results. While correcting deficiency is clearly beneficial for general health, vitamin D supplementation does not reliably or consistently reduce cortisol levels in people who are not deficient (Choukri et al., 2020).
In practice this means:
• Vitamin D deficiency is common, especially in the UK
• Testing and correcting deficiency is sensible and evidence based (NICE, 2022)
• Vitamin D supports overall resilience and health
• It should not be presented as a direct or reliable “cortisol-lowering” treatment
Vitamin K2
Vitamin K2 is usually mentioned alongside vitamin D because of its role in calcium metabolism and bone health, helping to direct calcium to bones rather than soft tissues (Rønn et al., 2016).
There is currently no good evidence that vitamin K2 affects cortisol or stress physiology directly. Its role is about long-term bone and cardiovascular health when using vitamin D, not stress regulation.
Magnesium
Magnesium plays a key role in nervous system regulation, muscle function, sleep, and neurotransmission. Chronic stress increases magnesium loss, and low magnesium status is associated with greater stress sensitivity and anxiety (de Baaij et al., 2015; Boyle et al., 2017).
A systematic review found that magnesium supplementation can improve subjective measures of anxiety and stress in vulnerable groups, particularly where deficiency is present (Boyle et al., 2017). Direct evidence for large reductions in cortisol is limited, but magnesium appears to support nervous system stability and stress tolerance.
In practice:
• Magnesium deficiency is common
• Supplementation may help sleep, muscle tension, and stress resilience
• It supports the system, rather than “switching off” stress hormones
Omega-3 fatty acids
Omega-3 fatty acids are important for brain function and inflammation regulation. In a randomised controlled trial, omega-3 supplementation was associated with lower cortisol output in response to acute stress compared with placebo (Madison et al., 2021).
This suggests omega-3s can influence stress reactivity and may help buffer physiological stress responses, particularly in people with low baseline intake.
Adaptogens, especially ashwagandha
Ashwagandha is one of the better-studied adaptogens. A systematic review and meta-analysis found that ashwagandha supplementation was associated with significant reductions in stress and cortisol levels compared with placebo in several trials (Pratte et al., 2014; NIH, 2024).
However:
• Study quality varies
• Preparations and doses differ
• It is not suitable for everyone
• It can interact with medications and some health conditions
It should be used cautiously and thoughtfully, not as a blanket recommendation.
The problem with the “supplement mindset”
A very common pattern is trying to supplement your way out of burnout.
This often looks like:
• Adding more and more supplements
• Still sleeping badly
• Still being overloaded
• Still having no real recovery
There is good evidence that chronic stress and allostatic load are driven primarily by sustained life strain, not by single nutrient deficiencies (Tsigos et al., 2016).
Supplements can support a system that is being cared for. They cannot rescue a system that is being continually overrun.
A grounded, honest conclusion
The evidence suggests that:
• Correcting deficiencies (e.g. vitamin D, magnesium) supports overall resilience
• Omega-3s can reduce stress reactivity
• Ashwagandha has evidence for reducing cortisol and perceived stress in some people
But:
• None of these fixes chronic overload
• None replace sleep, rest, pacing, or boundaries
• None override an unsustainable life
The biggest levers for regulating the stress system remain:
• Sleep
• Rest
• Reducing chronic strain
• Recovery time
• And having a life your nervous system can actually cope with
Supplements can support that work, but it’s important to remember that they cannot replace it.
References
Boyle, N.B., Lawton, C. and Dye, L. (2017) ‘The effects of magnesium supplementation on subjective anxiety and stress’, Nutrients, 9(5), 429.
Casseb, G.A.S. et al. (2019) ‘Vitamin D deficiency and its relationship with mental disorders’, Journal of Affective Disorders, 259, pp. 246–254.
Choukri, M.A. et al. (2020) ‘Effect of vitamin D supplementation on cortisol and stress biomarkers’, Clinical Nutrition, 39(4), pp. 1236–1243.
de Baaij, J.H.F., Hoenderop, J.G.J. and Bindels, R.J.M. (2015) ‘Magnesium in man: implications for health and disease’, Physiological Reviews, 95(1), pp. 1–46.
Madison, A.A. et al. (2021) ‘Omega-3 supplementation and stress reactivity’, Molecular Psychiatry, 26, pp. 3662–3672.
Menon, V. et al. (2020) ‘Vitamin D and the HPA axis’, Frontiers in Endocrinology, 11, 341.
NICE (2022) Vitamin D deficiency in adults, treatment and prevention. National Institute for Health and Care Excellence.
NIH (2024) Ashwagandha: Health Professional Fact Sheet. National Institutes of Health Office of Dietary Supplements.
Pratte, M.A. et al. (2014) ‘An alternative treatment for anxiety: a systematic review of human trial results reported for ashwagandha’, Journal of Alternative and Complementary Medicine, 20(12), pp. 901–908.
Rønn, S.H. et al. (2016) ‘Vitamin K2 and cardiovascular and bone health’, Nutrition, 32(2), pp. 133–138.
Tsigos, C. et al. (2016) ‘Stress, endocrine physiology and pathophysiology’, Endotext. South Dartmouth: MDText.