Guide
Nitric oxide and the brain: do arginine and citrulline help?
Nitric oxide is a gas the body makes to help blood vessels widen, including in the brain. Arginine and citrulline are building blocks for it, but we found no trial showing that capsules of either one change memory in healthy adults. The one brain-flow study used a vein drip of 500 mg per kg. A MemoHoney capsule holds 400 mg of arginine in total.
Written by the MemoHoney label deskUpdated
The basics
What is nitric oxide, and what does it do in the brain?
Nitric oxide is a small gas that the body makes inside blood vessel walls and nerve cells, and it helps vessels relax and widen.
A physiology review calls it an important regulator of brain blood flow: with more nitric oxide, flow rises and vessel resistance falls (Toda 2009, NO and brain blood flow). That describes how the body works, not what a capsule does.
Knowing that a molecule matters to the brain does not tell you that swallowing its building blocks changes how well you remember a name.
The pathway
Can arginine and citrulline raise nitric oxide in the brain?
In theory, yes: arginine is the raw material for nitric oxide, and citrulline is a step back along the same route.
In a person who takes a capsule, though, we found no study that measured nitric oxide in the brain. Tap the tabs to see where each label ingredient sits on the pathway.
01 / 05 · 200 mg + 200 mg per capsule
L-arginine (base and AKG extract)
An amino acid the body makes and gets from protein foods; AKG stands for alpha-ketoglutarate, and the label does not say how much arginine the 200 mg of extract holds. Sold as a nitric-oxide building block.
- Studied at
- 6.4 g a day by mouth for 30 days in one small pilot in older adults with measured memory problems; 500 mg per kg by vein in a blood-flow study; up to 30 g a day for 90 days in a safety trial
- Evidence
- Very little for memory, focus or brain blood flow
- Watch for
- Nitrates, ED medicines, BP medicines, recent heart attack
02 / 05 · 100 mg + 100 mg per capsule
L-citrulline (HCl and malate)
A non-essential amino acid the body turns into arginine; malate is a salt, and citrulline malate is about 56.6% citrulline by weight. Sold as a nitric-oxide building block that is easier to keep up than arginine.
- Studied at
- No human memory trial of citrulline alone was found; 3 to 9 g a day in exercise and blood pressure trials
- Evidence
- None shown for memory, focus or brain blood flow
- Watch for
- Stomach discomfort
03 / 05 · 40 mg per capsule
Beta-alanine
An amino acid that muscle cells combine with histidine to make carnosine. Sold for stamina; here named among the memory-support rows.
- Studied at
- 4 to 6 g a day for at least 4 weeks (ISSN, exercise); 28 days in the one cognition test we found
- Evidence
- None shown for memory, focus or brain blood flow
- Watch for
- Tingling at high single doses
04 / 05 · 7.5 mg NE (47% DV) per capsule
Niacin (vitamin B3)
Vitamin B3. On the panel in niacin equivalents (NE); the label does not say whether it is nicotinic acid or nicotinamide. A vitamin on the panel; the seller's page links it to cellular energy.
- Studied at
- No trial at the label amount for memory; one food-intake cohort; the RDA for men is 16 mg NE and the upper limit is 35 mg a day
- Evidence
- Very little for memory, focus or brain blood flow
- Watch for
- Flushing, if it is nicotinic acid
05 / 05 · 18 mg (1.5% DV) per capsule
Calcium (as calcium carbonate)
A mineral; the panel lists the weight of the calcium itself, here from calcium carbonate. Listed on the panel; a very small amount.
- Studied at
- Adults need about 1,000 mg a day from all sources; the memory trial we found used 1,000 mg with vitamin D
- Evidence
- None shown for memory, focus or brain blood flow
- Watch for
- Very little; a trace amount
The diagram shows the route that sellers point to. It is not proof that each step happens at capsule doses.
Blood flow
Does arginine increase blood flow to the brain?
One small study found that arginine given by vein raised whole-brain blood flow by 9.5%, and that is the closest evidence we found.
In 12 people, six got a saline drip and six got an intravenous arginine drip of 500 mg per kg of body weight. Flow rose from 34.9 to 38.2 ml per 100 g a minute after arginine and did not move on saline (Reutens 1997, arginine cerebral flow). The study ran no memory test. It also used a vein, and a dose of about 35 g for a 70 kg adult, which is nearly 90 times the 400 mg of arginine in a MemoHoney capsule.
So the brain can respond to a large dose given straight into the blood. That does not show a capsule does the same, or that more flow means better recall.
The memory studies
Do nitric oxide supplements help memory?
We found no trial showing that nitric oxide supplements help memory in healthy adults, and the few small studies that exist used far more than a capsule holds.
Each row below used a different group and dose, so the rows cannot be added together.
| Ingredient | Study | Dose | Result |
|---|---|---|---|
| Arginine | Pilot, older adults with memory complaints, 30 days | 6.4 g a day | Some reached a normal test score, but the placebo group also improved (Teotia 2026, oral arginine pilot) |
| Citrulline | Trial of 12 athletes using a mix with arginine and other amino acids | Mixed formula | Reaction time held up after fatigue; the mix cannot show what citrulline did alone (Chen 2016, BCAA arginine citrulline) |
| Beta alanine | 20 soldiers, 28 days | Gram-level | No change on a thinking test (Hoffman 2014, beta-alanine soldiers) |
The National Institute on Aging says no supplement is recommended to prevent memory decline (NIA, Cognitive health and older adults), and an expert panel could not endorse any ingredient for brain health (GCBH 2019, supplements and brain).
Doses
How far is the capsule dose from the studied doses?
A MemoHoney capsule holds 40 to 200 mg of each amino acid, and the studies used grams a day, so the capsule sits well below every studied dose.
The arginine pilot used 6.4 g, and the label shows 0.4 g across two rows, about 6% of that. Exercise trials of citrulline used 3 to 9 g a day, against 0.2 g on the label (NIH ODS, exercise supplements).
A smaller dose is not a weaker version of a result. It is a dose nobody has tested for memory. The formula page has the full chart.
MemoHoney capsules: 30 to a bottleOne capsule a day · 2, 3 or 6 bottles · price and shipping shown at checkout
See the priceThe label
What does the MemoHoney label say about nitric oxide?
The MemoHoney label does not mention nitric oxide at all; the front says "ADVANCED MEMORY SUPPORT*" and the star leads to the FDA statement.
Phrases such as "boosts nitric oxide" turn up in marketing for this kind of capsule, and we do not repeat them as fact. The panel lists two arginine rows (200 mg each), two citrulline rows (100 mg each) and beta alanine at 40 mg (MemoHoney label). No source tests that mix.
The FDA lets a supplement describe how a nutrient affects normal body function, as long as the label says the FDA has not evaluated the claim (FDA structure/function claims). See the supplement facts for each row.
Safety
Is it safe to take arginine for nitric oxide?
It depends on your health and your medicines, because the same effect on blood vessels that sellers describe can push blood pressure too low.
Mayo Clinic lists a possible fall in blood pressure with nitrates, sildenafil-type medicines and blood pressure medicines, and extra bleeding risk with blood thinners (Mayo Clinic, L-arginine). In one trial, 6 of 153 patients on arginine after a heart attack died, against none on placebo (Schulman 2006, VINTAGE MI). Stomach upset and bloating are common (MSK, Arginine).
Ask your doctor or pharmacist first if you take nitrates, sildenafil-type medicines, blood pressure medicines, blood thinners or diabetes medicines, or if you have had a heart attack. Chest pain, fainting or trouble breathing: call 911. More in arginine and blood pressure medicines.
What helps
What supports healthy brain blood vessels instead of a capsule?
The best-supported steps are the ones that protect blood vessels in general: moving, sleeping, and keeping blood pressure in check.
The Lancet Commission lists high blood pressure and physical inactivity among 14 modifiable dementia risk factors, and no supplement is on the list (Lancet Commission 2024 (AE summary)). Adults need 150 minutes of moderate activity a week (CDC, Adult activity).
Memory problems that are new, getting worse or getting in the way of daily life need a clinician, not a supplement. The forgetting guide lists the signs.
FAQ
Nitric oxide and the brain: common questions
Does nitric oxide help memory?
We found no trial that shows it. Nitric oxide helps regulate blood flow in the brain, but that is a mechanism, not a memory result. The studies of arginine and citrulline used grams a day, and none proved a memory effect in healthy adults.
Can arginine boost nitric oxide levels?
Arginine is the raw material the body uses to make nitric oxide, so in theory more arginine could matter. We found no study that measured brain nitric oxide after a capsule. One vein-drip study of 500 mg per kg raised brain blood flow, which is not the same thing.
Does citrulline increase blood flow to the brain?
We found no human trial of citrulline for brain blood flow or memory. Exercise and blood pressure trials used 3 to 9 g a day, far above 200 mg.
How much arginine is in a MemoHoney capsule?
The label prints L-arginine base 200 mg and L-arginine AKG 2:1 extract 200 mg, so 400 mg at most. The one memory pilot we found used 6,400 mg a day.
Are nitric oxide supplements safe?
Not for everyone. Arginine can drop blood pressure too far with nitrates, sildenafil-type medicines and blood pressure medicines, and it may add to blood thinners and diabetes medicines. Ask your doctor or pharmacist first.
What is the difference between brain blood flow and memory?
Blood flow is how much blood moves through brain tissue. Memory is what a person recalls on a test. A study can move one without the other, so a blood-flow result is not a memory result.
Who wrote this
Written and reviewed by
Pages built from the label, the seller's brief and linked NIH, FDA, CDC, FTC and peer-reviewed sources.
Last updated . Read our editorial standards and how we check reviews. This website is the information site of a USA Authorized MemoHoney Retailer. It is not the manufacturer, and the label names INSTITUTO EXPERIENCE (Ogden, Utah) as the distributor. We earn money when you buy through our order links.
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