What supplement is best for stress?

None is authorised to reduce stress in the UK. Magnesium, Vitamin B6 and B12 contribute to normal psychological function, which is the closest approved claim.

Most adults tolerate it, but it is not advised in pregnancy, for thyroid conditions or alongside some medicines. Check with your GP or pharmacist first.

Are mushroom supplements good for stress?

Mushrooms such as Maitake and Reishi have long traditional use, but no health claim is authorised for them in the UK.

Buyer's guide · updated 2026-09-24

Supplements for stress in the UK: what the rules allow and what actually helps

What is the best supplement for stress in the UK?

The short answer

No supplement is authorised in the UK to reduce stress or anxiety. The approved claims that come closest: Magnesium, Vitamin B6 and Vitamin B12 contribute to normal psychological function, and Magnesium and B vitamins contribute to the reduction of tiredness and fatigue. Ashwagandha, L-theanine and Maitake have traditional or early research interest but no authorised claim. For everyday stress, sleep, movement, daylight and cutting back on caffeine help most. If stress or anxiety is affecting daily life, speak to your GP.

Common stress ingredients and what they can claim

Common stress ingredients and what they can claim
	Approved UK claim	Notes
Magnesium	Normal psychological function; tiredness and fatigue	Most useful if your diet is short of it
Vitamin B6	Normal psychological function; tiredness and fatigue	Check for overlap with other supplements
Ashwagandha	None	Not for pregnancy or thyroid conditions without advice
L-theanine (green tea)	None	Naturally present in tea
Maitake and Reishi	None	Traditional use only
CBD	None	FSA advises no more than 10mg a day

The trade-offs

Grass & Co. RELAX capsules

Magnesium and B6 with approved claims
Ashwagandha, green tea L-theanine and Maitake in one capsule
Vegan Society registered

Cannot claim to reduce stress
Ashwagandha is not for everyone; check with your GP if pregnant or on medication

Plain magnesium tablet

Cheapest way to get the approved claim
Widely available

No other ingredients
No ritual or story to keep the habit going

The verdict

Start with sleep, movement and less caffeine. If you add a supplement, pick one with magnesium and B vitamins in stated amounts, and treat botanicals as a bonus rather than a treatment.

Where Grass & Co. loses

A plain magnesium tablet is cheaper than RELAX if the approved claim is all you want. And for ongoing anxiety, talking to a GP or therapist is the right step, not a supplement.

Mentioned in this piece

Questions people ask

What supplement is best for stress?: None is authorised to reduce stress in the UK. Magnesium, Vitamin B6 and B12 contribute to normal psychological function, which is the closest approved claim.
Is ashwagandha safe?: Most adults tolerate it, but it is not advised in pregnancy, for thyroid conditions or alongside some medicines. Check with your GP or pharmacist first.
Are mushroom supplements good for stress?: Mushrooms such as Maitake and Reishi have long traditional use, but no health claim is authorised for them in the UK.

More comparisons

Grass & Co. products are food supplements and are not intended to diagnose, treat, cure or prevent any disease. Do not exceed the stated dose. Most products are for adults; CBD is for adults only.