Phosphatidylserine

What it is

Phosphatidylserine (PS) is a phospholipid, a type of fat that makes up part of every cell membrane and is especially concentrated in the brain. You also get small amounts from food such as soy, fish and meat.

Supplements were originally made from cow brain, and that older form is where much of the research comes from. Today they are mostly made from soy or sunflower lecithin, which is chemically similar but has fewer studies behind it.

How it works

PS is involved in nerve cell membrane function and signalling, including neurotransmitter release. In supplements it is thought to support those membranes. Some studies also suggest it blunts the cortisol response to exercise stress, although results are inconsistent.

What the evidence says

• Limited Memory in older adults
  Older trials using bovine-derived PS showed small benefits; soy-derived PS studies are fewer and less convincing.
• Limited Stress and cortisol after exercise
  Some small studies show a lowered cortisol response; the real-world meaning is unclear.
• Weak Attention in children with ADHD
  Small early studies, often combined with omega-3, are not enough to base decisions on.
• Weak Sports performance
  Little consistent evidence of a performance benefit.

Evidence ratings are our plain-English summary of how much good human research exists, not a promise of results. How we rate evidence.

Dosage and timing

• Studies typically use 100 mg three times a day or 300 mg once a day.
• Take with food, ideally a meal with some fat.
• Taking it late in the day may affect sleep for some, so many take it earlier.
• No official UK upper limit; check current guidance.

Forms and what to look for

• Soy-derived PS is the most common; if you have a soy allergy, choose sunflower-derived.
• Bovine-derived PS is no longer sold widely because of concerns about BSE (mad cow disease).
• Look for stated PS content, not just total phospholipid content, on the label.
• Blends with omega-3 or other nutrients make the dose of PS harder to judge.

What to expect, and when

• Studies have usually run 6 to 12 weeks or longer.
• Any change is likely to be subtle.
• Many people notice nothing.

Side effects

• Stomach upset or nausea.
• Insomnia, especially at higher doses or taken late.
• Occasional headache or gas.
• Allergic reaction in those sensitive to soy.

Interactions

• May add to the effect of blood thinners in theory; ask a pharmacist if you take warfarin.
• Possible additive effects with cholinesterase inhibitors and anticholinergic drugs.
• May interact with other supplements that affect cortisol or the nervous system.
• Limited formal interaction data exists.

Who should avoid it

• Soy allergy (for soy-derived products).
• Pregnancy and breastfeeding, as data is limited.
• People on blood thinners without medical advice.
• Anyone with memory concerns should talk to a doctor rather than self-treat.

Risks and safety

• Most of the better research used bovine PS, so soy products may not perform the same.
• Long-term safety data in healthy people is limited.
• Products are variable in actual PS content.

Buying well: quality and testing

• Check the source (soy or sunflower) and PS content per capsule.
• Prefer third-party tested brands.
• Look for non-GMO if that matters to you.
• Be wary of low-dose blends that include a trace of PS for marketing.

Bottom line

Phosphatidylserine has a longer research history than most brain supplements, but the strongest data is on a form that is no longer sold. It suits people curious about a gentle option who accept modest and uncertain benefits. It is not proven to protect against dementia.