Several supplements have solid clinical evidence for lowering cortisol levels, with ashwagandha showing the strongest results: a 23% reduction in cortisol over 60 days in a randomized trial. But it’s not the only option. A combination of the right adaptogens, minerals, and nutrients can target cortisol from multiple angles, calming the stress signaling chain your brain uses to trigger cortisol release in the first place.
Ashwagandha
Ashwagandha is the most studied natural cortisol-lowering supplement available. In a double-blind, placebo-controlled trial of 60 adults, those taking 240 mg of a standardized extract daily saw a 23% drop in cortisol levels. The effect was consistent across genders: a 22% reduction in men and 25% in women. The extract used in this trial was a concentrated root and leaf form called Shoden, so the specific product matters. Not all ashwagandha supplements are standardized the same way, and lower-quality extracts may not deliver comparable results.
You can take ashwagandha in the morning or evening. It builds up over weeks rather than working acutely, so consistency matters more than timing. If it bothers your stomach, taking it at night with a small snack can help. Some people use it in warm milk before bed to support sleep, which itself helps regulate cortisol rhythms.
Rhodiola Rosea
Rhodiola targets a specific cortisol pattern that many stressed people recognize: the cortisol awakening response, which is the spike in cortisol your body produces within the first 30 to 60 minutes after waking. In people with burnout-related fatigue, 576 mg of rhodiola extract daily for four weeks decreased this morning cortisol surge while also improving concentration and reducing mental fatigue. If your stress feels worst in the morning, with that wired, anxious feeling before the day even starts, rhodiola may be particularly useful.
Magnesium
Magnesium plays a direct role in regulating the hormonal cascade that produces cortisol. When magnesium levels are low, the brain ramps up production of a hormone called CRH, which is the first signal in the chain that ultimately tells your adrenal glands to release cortisol. Supplementing with magnesium helps quiet that chain at its source.
In a 24-week randomized trial, participants taking 350 mg of magnesium daily showed lower 24-hour cortisol output. The effect appears to work by reducing how aggressively your brain signals for cortisol production and by improving how your body processes and clears cortisol once it’s been released. Since roughly half of adults don’t get enough magnesium from food alone, correcting even a mild deficiency can make a meaningful difference.
Omega-3 Fatty Acids
Fish oil works best at higher doses for cortisol. In a dose-response study of midlife adults, 2.5 grams per day of omega-3s (mostly EPA) lowered total cortisol levels during a stressful task by 19% compared to placebo. The lower dose of 1.25 grams per day had no significant effect, which means the standard one-capsule-a-day fish oil supplement probably isn’t enough. You’d typically need four or five standard fish oil capsules to reach the 2.5-gram threshold, or a concentrated EPA formula designed for higher dosing.
One nuance: the omega-3s lowered overall cortisol levels throughout the stressor but didn’t change how sharply cortisol spiked in the moment. Think of it as lowering the baseline rather than blunting the peak. Over time, a lower baseline means your body isn’t swimming in excess cortisol all day.
L-Theanine
L-theanine is the amino acid responsible for the calm-but-alert feeling you get from green tea. A single 200 mg dose reduced salivary cortisol within one hour in a triple-blind, placebo-controlled crossover study, and the effect held even after participants completed a stressful mental task. That makes L-theanine one of the fastest-acting options on this list. It won’t restructure your cortisol patterns over weeks the way ashwagandha does, but it’s useful as a same-day tool when you know stress is coming: before a presentation, a difficult conversation, or a high-pressure workday.
Phosphatidylserine
Phosphatidylserine (PS) is a fat-based compound found in cell membranes that has a specific talent for blunting cortisol spikes during physical and mental stress. The dosing research here is a bit unusual. For exercise-related cortisol, 600 mg daily for 10 days blunted cortisol before and during moderate exercise in healthy men. A higher dose of 800 mg reduced the cortisol response to intense resistance training by 20% and by 30% in another protocol.
For mental and emotional stress, the picture flips: 400 mg per day of a soy-based PS complex blunted cortisol more effectively than 600 or 800 mg doses. If you’re dealing with psychological stress rather than exercise-induced cortisol, a moderate dose may actually work better.
Vitamin C
High-dose vitamin C doesn’t prevent cortisol from rising during acute stress, but it helps your body clear it faster afterward. In a trial of 120 healthy young adults, those taking 3,000 mg daily of sustained-release vitamin C for two weeks recovered their cortisol levels more quickly after a standardized stress test (public speaking and mental math). They also had lower blood pressure spikes and reported feeling less stressed overall. The key word is “recovery.” If your problem is that stress lingers, that your body stays wound up long after the stressor has passed, vitamin C may help shorten that tail.
Probiotics
Your gut bacteria communicate directly with the brain systems that regulate cortisol. A large meta-analysis of 30 randomized trials found that single-strain probiotics produced a modest but statistically significant reduction in cortisol levels. The strains with the best individual evidence include Lactobacillus plantarum 299v (which lowered salivary cortisol during exam stress), Lactobacillus casei Shirota, and a combination of Lactobacillus helveticus R0052 with Bifidobacterium longum R0175. The effects aren’t as dramatic as ashwagandha or high-dose omega-3s, but probiotics offer a supporting role, especially if you already have gut issues that could be amplifying your stress response.
How to Combine These Effectively
These supplements target cortisol through different mechanisms, which means combining two or three can make sense. A reasonable starting stack might pair ashwagandha for long-term cortisol reduction with magnesium for HPA axis support, and L-theanine as needed for acute stressful moments. Add omega-3s if your diet is low in fatty fish.
Give adaptogens like ashwagandha and rhodiola at least four to six weeks before judging results. Magnesium works over a similar timeline for cortisol, though you may notice improvements in sleep and muscle tension sooner. L-theanine and vitamin C have faster, more immediate effects and can be layered in from day one.
Supplements work best alongside the behaviors that drive cortisol regulation: consistent sleep, regular moderate exercise, and time outdoors. No pill fully compensates for chronic sleep deprivation or an unmanaged source of ongoing stress. But when you’re already working on those foundations, the right supplements can meaningfully accelerate the shift toward lower, healthier cortisol levels.