L-Citrulline vs L-Arginine: Which Is Better for Blood Pressure, and Why BloodPril Uses Both
Quick answerNeither replaces blood pressure medicine. Citrulline has one practical edge: taken by mouth, it raised blood arginine more efficiently than the same amount of arginine in a 2008 study. Arginine has more blood pressure trials behind it. Both were tested at gram doses, and both can add to blood pressure drugs. BloodPril uses both, with citrulline malate listed first.
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What is the difference between L-citrulline and L-arginine?
Both are amino acids, and both feed the same process. Blood vessel walls use arginine to make nitric oxide, a gas that helps vessels relax.
L-arginine is the direct raw material. L-citrulline is one step back. Your kidneys turn citrulline into arginine, and making nitric oxide also releases citrulline that can be recycled.
So the question is not which one works in a totally different way. It is which one gets more arginine where it is needed, and which has better human data. Our L-arginine research review covers the arginine trials in detail.
Which raises arginine levels better?
Citrulline did better at raising blood arginine in one key study. In healthy volunteers, oral L-citrulline raised blood arginine levels more efficiently than the same amount of oral L-arginine (Schwedhelm et al., 2008).
A common explanation is the trip through the gut and liver. Much of the arginine you swallow is broken down before it reaches the rest of the body. Citrulline mostly passes through and is turned into arginine later, largely in the kidneys.
Higher blood arginine is a lab marker, though. It does not prove lower blood pressure on its own. That still needs trials that measure blood pressure.
L-citrulline vs L-arginine: which is better for blood pressure?
| Question | L-citrulline | L-arginine |
|---|---|---|
| How the body uses it | Converted to arginine, mainly in the kidneys | Used directly to make nitric oxide |
| Raises blood arginine | More efficiently by mouth (Schwedhelm et al., 2008) | Much is broken down in the gut and liver first |
| Blood pressure evidence | Small trials; authors want larger studies (Mirenayat et al., 2018) | 11 trials; about 5/3 mmHg lower than placebo (Dong et al., 2011) |
| Doses studied | Several grams a day | 4 to 24 g a day |
| Common side effects | Stomach upset, bloating, low blood pressure | Stomach upset, bloating, diarrhea, low blood pressure |
| Drug interactions | May add to blood pressure drugs and nitrates (WebMD, L-citrulline) | May add to blood pressure drugs, nitroglycerin, sildenafil (Mayo Clinic, L-arginine) |
| Heart attack history | Little specific data; ask your cardiologist | VINTAGE MI stopped early with more deaths (Schulman et al., JAMA 2006) |
| In BloodPril | Listed first; at least 167 mg as citrulline DL-malate | Two forms; together at most about 417 mg |
There is no clear winner for blood pressure. Arginine has the larger pool of trials. Citrulline has the better path into the blood. A 2019 review of both found modest, mixed results and limited long-term data (Khalaf et al., 2019).
If someone tells you one is proven better, ask to see the study. Most head-to-head claims online come from sports marketing, not blood pressure research.
Citrulline malate vs L-citrulline: what is the difference?
Citrulline malate is L-citrulline bound to malic acid. Malic acid is a natural compound found in fruits like apples. The bond makes a stable powder that mixes well.
The catch is weight. In citrulline malate, part of every milligram is malate, not citrulline. So 500 mg of citrulline malate holds less citrulline than 500 mg of plain L-citrulline.
What do 2:1 and DL mean on a label?
Sports labels often print a ratio. A 2:1 ratio means two parts citrulline to one part malate by weight. "DL" means the malate is a mix of both mirror-image forms of malic acid.
BloodPril lists L-Citrulline DL-Malate but does not print a ratio. Read our L-citrulline malate ingredient page for what the label does tell you.
How do the studied doses compare?
Blood pressure trials of citrulline used several grams a day (Mirenayat et al., 2018). Arginine trials used 4 to 24 g a day (Dong et al., 2011). No agency has set a blood pressure dose for either one.
Honest note: the dose gap
The whole BloodPril blend is 500 mg per capsule, shared by three ingredients and their carriers. That is a small fraction of trial doses. No trial of the capsule itself has been published. The bars below show the gap plainly.
L-Arginine (both forms)Under 10% of 4 g
L-Citrulline DL-MalateGram doses studied
Blood pressure trials of citrulline used several grams a day; one capsule's whole blend is 500 mg. (Mirenayat et al., 2018)
Two capsules a day1,000 mg blend
Whole blend500 mg total
Three amino-acid forms share 500 mg, including the weight of their carriers. (21 CFR 101.36)
Should you take citrulline and arginine together?
Taking both is common in supplements, and the idea makes sense on paper. Citrulline feeds arginine over time, while arginine is available right away. Combined products have been studied less than either one alone, though (Khalaf et al., 2019).
Why people combine them
- Two routes to the same raw material
- Citrulline avoids much of the first-pass breakdown
- Both are familiar amino acids found in food
- One capsule can hold both forms
What to weigh first
- Few trials test the combination for blood pressure
- Both may lower pressure, so effects can stack with medicine
- Blends often hide each amount
- Arginine carries the heart attack warning
Are citrulline and arginine safe?
Both amino acids share similar safety notes. WebMD calls citrulline possibly safe for short-term use, and notes it might add to blood pressure drugs and nitrates (WebMD, L-citrulline). Mayo Clinic gives the same kind of warning for arginine (Mayo Clinic, L-arginine).
Safety checks for citrulline and arginine
- Never stop, skip or change prescribed blood pressure medicine because of a supplement.
- Ask your doctor first if you take nitrates or sildenafil or tadalafil-type drugs.
- Talk to your cardiologist if you have had a heart attack or have heart disease.
- Ask first with kidney or liver disease, pregnancy, nursing or upcoming surgery.
- Watch for stomach upset, bloating, diarrhea or dizziness, and call your doctor if they persist.
- Call 911 for a reading over 180/120 with chest pain, shortness of breath, weakness or vision change.
Our post on supplements with blood pressure medication walks through how to raise this with your doctor or pharmacist.
How do you choose between them?
- 01
Start with your doctor
Share your medicine list and ask whether either amino acid is safe for you.
- 02
Check the amounts
A label that prints milligrams per ingredient tells you more than a blend total.
- 03
Know the form
Citrulline malate and arginine salts include carrier weight, so compare like with like.
- 04
Ignore big promises
Words like cure or replace your medicine are warning signs on any product.
- 05
Track with a cuff
Log home readings before and after you start, and share them at your next visit.
Our buyer's checklist goes through each of these steps with examples.
Why does BloodPril use both?
BloodPril chose not to pick a side. Its 500 mg blend lists L-Citrulline DL-Malate first, then L-Arginine AKG and L-Arginine HCL. That order means citrulline malate is the largest part of each capsule.
The routine is easy: 1 capsule a day with an 8 oz glass of water, in a vegetarian capsule. The how it works page explains each step from capsule to cuff.
L-citrulline vs L-arginine FAQ
Is L-citrulline better than L-arginine for blood pressure?
Not clearly. Citrulline raises blood arginine more efficiently, but arginine has more blood pressure trials. Neither one has strong long-term data.
Does L-citrulline lower blood pressure?
Small trials at gram doses suggest it might lower it a little. The authors of a 2018 meta-analysis asked for larger, longer studies before firm conclusions.
Can you take L-citrulline and L-arginine together?
Many products combine them, and a 2019 review looked at both. Ask your doctor first if you take any blood pressure medicine, since both may lower pressure.
What is the difference between citrulline malate and L-citrulline?
Citrulline malate is citrulline bound to malic acid. Part of its weight is malate, so it holds less citrulline per milligram than plain L-citrulline.
How much L-citrulline should I take for blood pressure?
No official dose exists for blood pressure. Trials used several grams a day, so talk to your doctor before trying amounts like that.
Is L-citrulline safe with blood pressure medicine?
It may add to the effect. WebMD notes citrulline might lower blood pressure and could add to blood pressure drugs and nitrates, so ask first.
Does watermelon have citrulline?
Yes. Watermelon is the best-known food source of citrulline, and the amino acid was named after it. A normal serving gives far less than trial doses.
What are the side effects of L-citrulline?
Reported side effects include stomach upset, bloating, diarrhea and low blood pressure. WebMD calls it possibly safe for short-term use.
Why does BloodPril use both citrulline and arginine?
BloodPril lists citrulline DL-malate first and two arginine forms after it. The brand does not explain the mix, and no trial of the capsule has been published.
Ready to try BloodPril?
1 capsule a day, 60 per bottle, from $49 a bottle on the 6-bottle pack, with a 60-day satisfaction window. Taking blood pressure medicine? Ask your doctor first.
