Milligrams (mg) vs. Fibrin Units (FU)

11/11/2017

As a leading seller of enzyme supplements, a question that we often get is regarding systemic enzymes, in particular. Systemic enzymes are enzyme supplements that work throughout the body, or “systemically”, as a biocatalyst, speeding up the chemical reactions that make up our life. The human body contains nearly 3,000 enzymes, with functions ranging from anti-inflammatory and anti-fibrosis, to blood cleansing and virus fighting. Enzymes play a large role in digestion as well, but for the purposes of this article, we are focusing on systemic enzymes in particular.

Typically, when you purchase your vitamins or other supplements, you look at the label and focus on the number of milligrams (mg) or grams (g) of each ingredient. These are quantitative measurements, showing us how much of “xyz” ingredient is in the product, and this is important because there are recommendations for how much of a particular vitamin or mineral that we as humans should consume on a daily basis. Enzymes are slightly different, however.

The most important measurement to pay attention to when it comes to enzymes is their potency, or biological activity. If you’ve bought a systemic enzyme supplement before, you’ve probably noticed the letters SU, SPU, FU, or IU somewhere on the product label. These letters are all used as a measurement of how active the enzymes are, and how well they will work when introduced to the body. So they are a measurement of quality, not quantity. Specific testing is conducted in order to determine these figures.

SPU and SU stand for Serrapeptase Units, and are used interchangeably between supplement brands when referring to the potency of the specific enzyme, serrapeptase. The best serrapeptase products will contain 100,000 units or higher per capsule.

FU stands for Fibrin Units, and is used for the enzyme, nattokinase. The standard for nattokinase manufacturing is a potency of 2,000 FU per capsule.

The IU designation stands for International Units, and is generally used when showing the potency of a blend of several different enzymes in a product, although FU can be used as well.

Again, all of these abbreviations are just different ways of disclosing the same thing…the "strength" of the enzymes on a per-serving basis. A systemic enzyme supplement with a higher potency will require a smaller dosage in order to produce the desired effect.

When you see enzymes measured in milligrams on a product label, this is simply letting you know how much the enzyme weighs (ie. how much of the enzyme is actually in the formula). It is not telling you anything about the biological activity that it produces. You could have 200 mg of an enzyme that is of poor quality, and likewise, you could have 4,000 FU of an enzyme, but only have 50 mg of it in the formula.

Using nattokinase as an example, some companies will use certain labeling techniques to make it appear as though there is a stronger form of nattokinase in the product, but when we do that math, we see that there is very little, if any difference.

So, in addition to grams and milligrams, be sure to look for the units of activity (SU, SPU, FU, IU) on the label of an enzyme supplement. If you do not find one of these indicators, ask the manufacturer, or find a different product to use.

51 Comments

David Martin

8/27/2018 02:37:56 pm

How many standard 2000 FU nattokinase capsules can a person take each day day if he is not taking other blood thinners like aspirin?

Lyndia Storey link

1/8/2024 10:25:58 am

Answer to the first question of how many 2,000 FU of nattokinase to take daily

Sascha

9/26/2024 02:48:49 pm

Aspirin and k2 increase the positive effect of NK on atherosclerosis. You should not take it with warfarin!
NK must exceed 15k or 20k FU to show any (positive) effect.

Christy Jones

11/3/2024 09:31:35 am

Hi I'm looking at a product that says it has 12,000 FU of nattokinease. And 360, 000 SU of Serrapeptase in liposomal form. My cardiologist has told me for several years my heart was fine. I just found out the three arteries on the left are badly plugged up with plaque and I'm wondering if this is a safe amount to take. They can operate so I have to find something that works for myself. Thank you so much if you have any information I would be terribly grateful.

sascha

11/3/2024 02:47:08 pm

Hey Christ,
I've never seen anywhere a pill more than 4000 FU.
A study showed that NK daily usage of 10.200 FU showed 30% reduction of atherosclerosis in a year while they mentioned amount of < 8000 is not efficient for reverting/healing atherosclerosis.
Adding k2, and d3 make a magic.
I hope this helps.

Gary Webb

4/20/2025 12:39:24 pm

Can natti be used for afib instead of blood thinners like xarelto

Sascha

4/20/2025 08:15:50 pm

A-Fib increases the risk of blood clots. It is very serious and I'd never dare to substitute prescripted medication unless some blood tests show the same result as Natto kinase.

Sascha

4/21/2025 06:11:08 am

After posting my previous comment, I read in iHerbs that Natto kinase is used by many as a blood thinner. A test for calculating blood viscosity should help you to find right dosage.

Admin link

8/28/2018 02:57:44 pm

Hi David,
Dosages are really going to vary from person to person, but it is not recommended to take more than the maximum suggested dosage on the bottle. With that said, the more chronic and serious conditions will generally require the higher dosages.

Kat Wolf

9/27/2018 07:35:09 am

I am wondering about dosage for a UTI. Not preventative, but once I have a UTI & need to treat it. Also, is it okay to take along with D-Mannose if I wanted to do that?
Thanks!

Max

4/27/2020 02:16:15 am

Thank you SO much for all you’re doing to help others!!
I’m confused… Would one label’s
2000 FU’s of nattokinase
be comparable to, say,
200mg of Vit K2-m7 on another ??

Thanks again & God bless you & yours with MORE health & HAPPINESS than ever!!!

Southwest Nutraceuticals link

4/28/2020 05:22:10 pm

Hi Max,
Nattokinase is a different type of ingredient altogether, so it would be tough to compare them and their effectiveness. Some people use both together, while others may take one or the other depending on the benefits that they see. All the best!

ROBERT H W

11/6/2022 09:09:28 pm

Max are you investigating the benefits of taking Peak Cardio Platinum. If so let's talk and maybe exchange info Email me directly.

McNaught

8/7/2024 02:21:57 am

I have been preparing and consuming natto at home. This was one of my first questions when I began investigating.

I was informed to consume 50-100 grams of natto per day. A portion size of 50 grams delivers approximately 1500 FU.

If anyone can relate corrected or additional information, please do!

Sascha

9/26/2024 02:53:57 pm

My investigation shows that commercial Natto products contain 1700 to 3200 (depending on the brand, I guess) per 50g. Homemade Natto is even more difficult to measure. That come as a unpleasant surprise as I'm aiming for 20.000 FU daily.

Benz

5/5/2020 12:53:50 pm

Hi there.
I still not understand something.
If 1 nattokinase capsule is 2000FU, then 2 same capsule is 4000FU. Is it?

Admin link

5/7/2020 01:17:32 pm

That is correct. To get a desired potency, you may take more capsules (it is not recommended to take more than the bottle suggests without consulting a physician), however, your body will use what it needs and flush the rest out.

Benz

5/7/2020 02:49:33 pm

Many thanks, Admin.

Sascha

9/26/2024 02:57:09 pm

Why are you terrifying people by giving them wrong and actually harmful information?
I've come across many studies that show NK must be taken in very high dosages, and less than 4000FU has shown no effect whatsoever.
Do your research before giving people the wrong advice.

Judy link

5/21/2020 04:19:14 am

How many fu's are in 50mg Nattokinase?
Thankyou

Southwest Nutraceuticals link

5/26/2020 01:11:32 pm

Hi Judy,
It will vary, as the two are not correlated. Supplement brands should provide both pieces of information on the bottle, however.

Judy link

5/23/2020 04:35:43 am

I want to wean my husband off Xaralto 20mg. What strength Nattokinase should he take daily (of course monitored by his Specialist) He has no history of clots or thick blood, but due to a bout of pneumonia, developed some clots in February 2020
Thankyou

Southwest Nutraceuticals link

5/26/2020 03:00:10 pm

Hi Judy,
While we cannot prescribe a specific dosage for someone, you will find that most Nattokinase supplements will follow a standard of 2,000 FUs per serving (keep in mind that I said "per serving", not "per capsule"). Different brands may have different serving sizes, so you will want to pay close attention to that, as well as the dosage recommendations on the bottle. I hope that helps!

Alicia

11/13/2020 02:09:03 am

Hi,
So I think I understand the standard nattokinase and serrapeptase conversions, though a particular supplement is confusing to me in terms of the mg amounts of those two enzymes. I have looked on their website and others, but cannot seem to find an answer. It states: nattokinase (20,000 fu/g) and serrapeptase (100,000 su/g) per serving of 2 capsules. And then it provides a 633 mg total including all ingredients (about 10 or so), but the 633 is not divided out. What do those two nattokinase and serrapeptase enzymes equal in milligrams?

I’ve been shopping around for a while now for an enzyme complex including those two among a few other proteolytic enzymes for cardiac health. But I want to make sure there is enough of those two enzymes specifically to be effective for inflammation and overall heart and arterial health. From what I’ve found, there is a range of the amount of mgs included in various heart-specific enzyme supplements. The one I’ve landed on includes all of the enzymes I’m looking for, it’s called Vascuzyme by Empirical Labs. But I needed to verify the mg strength before I shell out over $100 for a bottle.
Thank you so much for your help!

Bradley link

12/1/2020 09:58:39 am

Hi Alicia,
When a company labels a blend of various ingredients in their product(s), it is generally because it is a "proprietary" blend (or secret patented blend) that they do not want known. It's no reason to be too alarmed though, as companies typically do this so that a competitor does not duplicate their exact formula. Soft drinks, like Pepsi and Coca-Cola, do this as well.

As for the measurements of FU and SU (Serrapeptase Units) in the formula, that is a very good question. It is difficult to know, without knowing how many grams or mg of Nattokinase or Serrapeptase are in the product. For this, I would recommend contacting the manufacturer to see if they will tell you how much is in each capsule.

John

12/9/2020 03:16:34 pm

After looking into the Vascuzyme product, it looks like the 20,000 fu is on a per "gram" basis. When you break it down, it's the same amount of FU on a per "milligram" (mg) basis as most other formulas. It is a labeling technique to make it look like a more potent form of nattokinase. Also, as Bradley mentioned above, the nattokinase is just part of a 615 mg blend of ingredients in the product. It doesn’t specify the amount within that blend. There could be 1 mg of 20,000 FU/gm potency nattokinase. Hope that makes sense!

Judith

10/1/2024 09:47:42 am

NEPRINL and advanced fibrin defence..30,000 Fu

Vincent Cruz

12/8/2020 02:10:10 pm

Interested to know difference between 2000 fu's and 20000 fu's of nattokinase.

John

12/10/2020 08:51:25 am

Hi Vincent,
That is a great question, and I will update the article above to try to explain this better.

It all depends on the amount that is in the product. Look to see how the label reads, whether they list it on a per gram (g) basis, or on a per milligram (mg) basis. 1g = 1,000mg, so when you break it down that way...

100mg of a 2,000 FU nattokinase is the same as 1g of a 20,000 FU nattokinase. Some companies will label their product that way to make it look like their formula has more or stronger nattokinase (or any ingredient) in it.

John

4/3/2024 12:36:50 pm

100mg is 1/10th of a gram, so 100 mg of 20000 FU nattokinase is the same enzymatic potency as 1 g of 2000 FU nattokinase.

Mrs S Murray

5/4/2021 09:26:36 am

Can Nattokinase supplements be taken before bedtime on an empty stomach?
I ordered these supplements that states to be taken with food? most other manufacturers say on an empty stomach. ?

Thank you.

Bradley

5/4/2021 09:51:38 am

In order for Nattokinase to work effectively, it should be taken on an empty stomach. So prior to bedtime should be just fine.

Holly

6/26/2021 04:42:12 am

I am taking 1 capsule (2000 fu) in the early AM, and 1 capsule before bed per day. Is this an appropriate dosage or too high?

Susan Murray

9/10/2021 02:12:52 am

Good day,

I would like to ask a question about taking other natural supplements.

Firstly I have recently started taking Spirulina supplements which I used to take a few years back.

I also states that Spirulina is also good for the heart and BP.
I have no Heart issues but used to take Co Q10 or Fish oil supplements for maintenance of the heart but stopped when taking Spirulina.
Is it advisable to continue taking the CoQ10 and Fish Oil when on Nattokinase or even Spirulina? is this unecessary overloading of too many heart supplements?
I just want to get a good overall balance of health benefits from natural supplenemts.

Thank you for your time,
Bediveare.

Can I take Nattokinase and Spirulina together or in between a couple of hours apart ?
I also take Probiotics and Digestive Enzymes but according to Spirulina it has lots of vitamins and minerals within it.
Would it be advisable to may be stop the digestive enzymes and probiotics and carry on with Nattokinase and Spirulina

linda patterson

11/7/2022 03:41:54 pm

As Harry Belafonte said "it's was clear as mud but it covered the ground' Thank you for the lengthy explanation that left me in the dark, My doctor told me to take 200mg of Nattokinase and the bottle only says 2000 FU. I take Xeralto so I don't want to screw around with dosages. Could you please translate. 2000 FU means what in MG? If there is no answer, comparing apples to pears, than, I've got to find a bottle that simply says 200 mg. Thanks for any help

Manny

6/28/2023 06:08:03 pm

With extensive search I found that about 100 mg of the supplement is equivalent to 2000 FU.. . of course it depends also on the purity and quality
Check this site and search that and other issues as how to take.
https://drjessesantiano.com/category/supplements/nattokinase/
You can buy it in BulkSupplements but you need to be precise measuring the dose because it comes as a loose powder.

Karen F

4/24/2023 06:15:45 pm

I am researching (fir my family's health, not professional) the benefits of nattokinase and other natural remedies. Ideally, one would get these types of ingredients through real food, but natto, for example, is not easy to find in the Midwest, my little Asian market has been sold out for a year. Can you please briefly explain how weight/volume ounces calculate into FU's? For example, I used to eat 1 package of real natto each day, and that was just under 2 ounces. How many FU's would that be? If I start taking the tablets instead, would I be getting more nattokinase in the pill form than the fresh bean firm, and if so how much? Thank you in advance.

Sofis Benitez

4/27/2023 02:03:04 pm

I’m on 6 mg Warfarin and hate it. Can I stop and take the Nattokinase?? I had open heart surgery in 2018 five bypasses. Had Lacunar stroke in 2017. Warfarin gives me purple toes and lots of hair loss plus mobility issues. Stopped it for a week and a half for a small surgery and felt great. Pls help!! My cardiologist keeps pushing Warfarin and the Watchmsn procedure. I’m scared. I want to stop warfarin!!

Benz

4/28/2023 02:11:08 am

Hi Dofis,
Let me shed more light from professional knowledge and from personal experience

Firstly, all nattokinase in the market are without from vitamin k2 that contribute to blood thinning, this is by law!

Even if you find (and you don't) original nattokinase, and even if take 20000iu (not 2000iu) it's not come close to warfarin effect!

To get all nattokinase benefit you should eat Natto food and I doubt if you can eat it...

They most disadvantages of warfarin that you need to make blood test every week or two, but there is good substitute in the market, ask your doctor for xarelto or something similar, there is many.

If you still want to go with natural option you can use lumbrokinase, but you have to take it 3-4 times a day since it's have short life

Despite everything that has been said, you must be under medical supervision, which means blood tests every week at least in the beginning

I hope it will help.

Benz

4/28/2023 02:22:44 am

Sorry for misspell your name.

Sofia Benitez

4/28/2023 03:04:53 am

Benz thank you for your reply. I hate being on Warfarin and can’t afford Xarelto or any of those new ones. What about Red Yeast Rice?? There must be something natural I can take. I have a machine at home to test my INR. I have paroxysmal AFib. Hope something else could work. Thanks

Gary Webb

4/20/2025 12:51:11 pm

Want to know how effective natto is at preventing blood clots

Benz

4/28/2023 03:41:15 am

Hello All,
Since, many people don't understand the full benefits of Nattokinase effects, allow me to shed more light.

The only way get the full advantage Nattokinase is to eat Natto food (and it's not easy)

Natto food has Nattokinase, Vitamin K1, and Vitamin K2, unfortunately -by the law- its prohibit to sale Nattokinase with vitamin k1, and k2 FULL STOP !

Vitamin K2, contribute to thin the blood, vitamin K1 contribute to thick the blood, and Nattokinase contribute to dissolve blood thrombosis

Nattokinase, have shelf life of 2 years make sure to use fresh Nattokinase

nevertheless, even if you consume 20000FU Nattokinase its not come close to HIGH dose of warfarin effects!

other nature substitute that dissolve blood thrombin, and its legal and, you can find it in the market is lumbrokinase

some researchers claim lumbrokinase its better then Nattokinase since its only dissolve blood trombone, and have no effect on blood coagulations while Nattokinase have (for more info search the net)

lumbrokinase, is much expensive then Nattokinase, and have half life of 4 hours compare to Nattokinase that have half life of 8 hours.

Nattokinase, lumbrokinase can replace low-mid dose of warfarin but not high dose of warfarin

Warfarin is old, and cheap medicine doctors have a lot experience with it this is why its first line medicine.
The medicine market have lots of substitute to Warfrain, if you don't like it ask your doctor for replacement.

if you already on high dose of Warfarin, and you want to move to Nattokinase I suggest you lower your Warfarin dose then measure your INR, then add Nattokinase and measure again your INR and see if there is a difference

Red Yeast Rice, is the original source for Statin, it's only lower your cholesterol!

Ty Webb

10/24/2023 10:03:18 pm

"blood trombone" ?!? I have blood saxophone.

Dolores

9/21/2023 01:54:07 pm

Can you explain how to determine the potency of 2 different nattokinase products with one using 2000 FUper 100mg capsule vs another 10,000,000 IU per 1 gram capsule

Thank

Angela

12/9/2023 11:52:46 pm

Hello, I was curious if you can help me understand the label on the Neprinol AFD? It lists 30,000 FU per dose with a blend of 3 enzymes, one being the Nattokinase (the other two are Serapeptase & Lipase) but it falls to mention exactly how much Nattokinase is in them. I'm a bit uneasy to take without knowing better exactly how much Nattokinase is in each capsule/dose - especially with the standard dose being 2,000FU of Nattokinase; 30,000 is a huge jump. Any idea how much or where I can find that out? Its confusing since they label it with the "FU" measure, but it's a blend of three enzymes.
Thanks in advance.

Kevin

6/30/2024 05:53:11 am

Hey Angela, The 30,000 FU is for two capsules. Considering one is 15,000 FU, with the enzymes listed in order of decreasing percentage included, one might start with a guestimate of 40%, 35% and 25%...?... giving 6000. 5250, 3750 ?? Trouble is, serrapeptase is generally supplied with SPU or SU..and Lipase with FIP. There really is no way to know how much Nattokinase without the contacting the manufactures and them wanting to give you an idea.. I plan to just use one per day after building up to 3 or 4 per day for a few weeks.

The standard dose of Nattokinase, in my opinion only derived from reading through a few case studys, seems to fall between 5000 and 12000 FU per day.

I feel that if I end up only taking one Neprinol AFD instead of the two recommended, I may end up taking one 4000 FU capsule of Nattovena per day as well.

I am taking this more of a preventative measure with some moderate BP lowering goals as well.

Ray link

2/12/2024 07:09:02 am

I understand your not a Docter but they are not aware of this good stuff Could you please tell me why Nattokinase make me dizzy
should i incorporated serrapeptase ? and what brand to look for there so many.
Thank you.
from CANADA

Jackie

3/13/2024 03:28:27 pm

Hi
First, thank you for this site and for helping people understand the FU to MG correlation or really lack thereof. 😊
According to this paper, doses under 3,600 FU/day are a waste of money. Most supplements are 2000 to 4000 FU.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9441630/
Does any know of any commercial product that gives you the 10,800 FU/day they recommend?

Thanks,
Jackie

marcie webber

8/17/2024 10:14:54 pm

Wonderful explanation answering the baffling dosages i saw in Lumbrokinase Doublewood and Doctor best which was 10,000 FU/g =150mg 2 caps vs doctor best 720000=40mg.respectively. Thank you so much. If I understood it correctly the FU more represented the strength of the supplement.

Marcie

10/20/2024 09:58:45 pm

In my readings of thiese systemic enzymes Serrapeptase Nattokinase & Lumbrokinase consider strength expressed in SPU, FU & LKU respectively..
Also of these be taken 1h before meals or 2h after meals otherwise taken with meals they become digestive enzymes which seem costly.

I just stumbled on these after diagnosed of type 2 MI July this year & was put on Baby ASA Crestor Coreg & CCB ARB combo for BP.
Currently tonight will increase Nattokinase 12K FU from 10K, Serrapeptase 1200000SPU from 960000 SPU tomorrow AM. Just started Dr. Best Lumbrokinase Oct 16 4 days ago 1cap BID. (720K LKU total)

I started low dose 2-3 days & gradually increased dosage if no untoward reaction. Luckily nothing except mucus constantly dripping keep blowing my nose.

I take Serrapeptase & Lumbrokinase early AM.upon waking up
Nattokinase & Lumbrokinase before going to bed about 10p.
I am also on 16-18h Intermittent fast. So the rest of my time are programmed for water/fat soluble supplement & prescribed drugs I take. I did experiment on these enzymes taking off supplements and drugs only BP.. Dropped Crestor ASA & Coreg.

I am 82 years old with lots of health challenges . You name it from trouble sleeping, no appetite, muscle joint pains , stiff , no energy , depressed etc not worth living for. But not fun of drugs..Also I am very outgoing...so opposite!

Barely 2 months since started late August I see improvements in blood sugar, energy, sleep, mood, mental clarity.. Chest pain still there while walking & swelling in my L foot etc. Will see but i am encouraged. Just wary of the brands who are honest in their products. Also want higher dosage to reduce swallowing many. Hope my journey helps.

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