Sulfur in cysteine and methionine

Most of us DIYers have been supplementing sulfur in the form of MSM. I’ve long known that sulfur is bonded to some of the proteins in various foods, although it’s not listed on any nutrition labels. Today I read that both cysteine and methionine contain sulfur. Since the amino acid breakdown of most foods are available to us, I was wondering if anyone could help me figure out what percentage of cysteine and methionine by weight are sulfur?

I figure if this is community knowledge then we’ll be able to reduce our reliance on supplements such as MSM and reduce the prices of all our recipes.

So – how much sulfur is in cysteine or methionine?

Plus, y’know – maybe our farts wouldn’t smell so bad.

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I was thinking about this same issue. I don’t think the Soylent micronutrient breakdown list included sulfur, probably because it’s supplied by the high levels of cysteine or methionine found in rice protein.

Well my hunch is that there’s enough sulfur and also choline in these DIY recipes to hit 100%, but we’re over-supplementing due to unknown nutrition information.

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For my spreadsheet, I set the sulfur content of my protein sources to 0.27 x Cystine mass + 0.21 x Methionine mass. This is based on the molar mass of the molecules as calculated below. I don’t have any sources on the absorbability of sulfuric proteins, but I think it’s a safe assumption.

Sulfur Molar Mass: 32g/mol

Cystine: C6H12N2O4S2, molar mass: 240.3g/mol

Sulfur mass ratio of cystine = 64/240 = 0.2666~

Methionine: C5H11NO2S, molar mass: 149g/mol

Sulfur mass ratio of methionine = 32/149 = 0.21


Brilliant! Thanks Sintax!

It’s hard to find good information for all ingredients. I keep finding different sources for defatted soy flour nutrition facts with different numbers, references on sites to choline in olive oil and canola oil, but no hard facts.

this is possibly slightly off topic, but i did notice that there was no sulfur content listed in the raw whole egg entry in the diy solyent site - ive updated it for my recipe to 75mg per egg as per this information:
for those people doing recipes with whole foods i suspect there are a lot of foods in the database(s) that just ignore sulfur. cocoa for example is supposed to have sulfur in some quantity but i can’t find out exactly how much.


Thanks for the work on this, guys. But before we all go off to the races using these ratios to derive the elemental mass of sulfur from the amino acids in question, let’s make sure we’re measuring the right thing…

From what I’ve read, it appears that all of the nutritional studies done in this area have focused on the dietary requirements of sulfur-containing amino acids (SAA), rather than elemental sulfur.

There’s an SAA requirement recommended by the WHO – 13 mg/kg per 24 h in healthy adults.

Similarly, since 1989 the U.S. RDA for methionine (combined with cysteine) has been 14 mg/kg body weight per day (that recommendation was itself based on a 1955 study of amino acid requirements, “Rose et al”).

From the above article: “When Rose proposed these amounts he suggested that a “safe intake” should be twice that amount or 2.0 g/day, probably acknowledging that his studies had been done on limited numbers of individuals, usually 3–6 for each amino acid.”

So what we should really be looking at here is the SAA content, not the sulfur content.

Note there is no dietary requirement for elemental sulfur. When Rob “forgot to watch his sulfur intake,” what he was really forgetting was the SAA content of his diet. And when “2.0g” was written next to “Sulfur” on the DIY site, it was really referring to SAA in both cases.

To sum up: I agree that many of us have been supplementing sulfur unnecessarily. But reducing implied SAA content by the mass ratio of elemental sulfur is also a mistake, and could result in potentially dangerous levels of supplementation (because it understates the actual intake of SAA by 4-5X). The pubmed article linked above states that “SAA supplementation can be considered safe in amounts exceeding 2-3 times the minimal recommended daily intake,” and also points to potential concerns about oxidative stress arising from excessive SAA supplementation.

What we should be doing is adding up the total mass of methionine and cysteine in all of our ingredients, and recording that as dietary “sulfur” (which should really be labeled “SAA” on the DIY site to avoid this confusion).

While we’re at it, the DIY site should also be updated to do this translation from the USDA database automatically (methionine + cysteine = SAA). It could also fill in the omega-3 and omega-6 PUFA content in those cases where it is specified in the data (as it often is).


Thanks Quid. I actually used this data to reduce the sulfur supplementation. So if anything, we’ve still got too much.

My hunch is further that we’ve got a similar situation with choline and possibly a couple other nutrients that aren’t typically on nutritional labels.

If anything, most of these recipes are over-supplementing things rather than under-supplementing.

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Agreed – but for those who have already calculated a value for “Sulfur” to plug into the nutritional profile using the SAA content of their ingredients, applying the mass ratios calculated by Sintax above would be inappropriate.

In my case, if I were to apply the mass ratios to the dietary “Sulfur” content I’ve already entered for masa harina, whey protein isolate, cocoa powder, flaxseed, and chia seeds (currently equal to their methionine + cysteine content), the true SAA content of those ingredients would be understated by 4-5X, and the result would suggest that sulfur supplementation is required (which would be inappropriate).

I realize this may not have been the case for you (probably because you hand’t already entered a value for “Sulfur”), but you’re still going to be understating the SAA content of your ingredient(s) if you apply the mass ratio of elemental sulfur found here. My suggestion would be to go back and use the higher numbers (i.e., the straight methionine + cysteine).

I think we should collectively take care to get this right – even if it’s not of direct consequence to our respective recipes, we should do what we can to reduce the kind of misunderstanding that could be perpetuated to ill effect elsewhere.


Thanks for the info Quid, it’s weird how little information there seems to be on something that seems relatively important. I think your method of looking at the 13-15mg/kg body weight makes a lot more sense than the alternatives.

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I use the requirements listed here for each of my amino acids. It adds up to 15 mg/kg for the C+M total. I’m not sure how valuable creating a separate SAA requirement would be since all of the amino acids listed are essential anyway. I think we should just make sure we’re getting enough amino acids, period.

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Sintax – understood and agreed, but what I’m suggesting is that the “Sulfur” field in the nutritional profile should be re-labeled as “Sulfur-containing Amino Acids” or “SAA” precisely to avoid this sort of confusion.

There is no dietary requirement for elemental sulfur – only a requirement for SAA.

The 2g daily requirement listed as “Sulfur” on most of the nutritional profiles translates to SAA intake.

I also think the DIY site should be updated to do an automatic tally of the USDA values for methionine & cysteine (where available) when importing an ingredient from the database, and should plug that value into the field for “Sulfur” (SAA).

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Yes, I understand your suggestion, people are confused about what they need. But by that logic shouldn’t we just remove sulfur entirely and replace it with all of the essential amino acids? If the problem is confusion about what’s important, then stressing those 2 amino acids (one of which isn’t even strictly essential) above the others would just contribute to a similar but different misunderstanding.

I suppose I would favor dropping the “Sulfur” entry entirely, then, on the assumption that adequate protein intake will cover the SAA requirement.

But failing that, I think re-labeling it would still be preferable to just leaving “Sulfur” as-is.

If it’s unnecessary, it should be dropped. If it’s important to be kept, then it’s important enough to fix in some manner that encourages people to use it correctly.


another link from IOM that under the Adequate Intake for Inorganic Sulfate list organic sulfates as a source and explicitly lists Methionine and Cysteine. So go ahead and just look up your protein sources for the content of these two amino acids


Good info. Thanks Stoinov!

Awesome source. I am becoming increasingly doubtful of the holistic MSM “detox” stuff.

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Another article that I find interesting (or at least the discussion part of it at the end). Here is an excerpt:

Any excess of SAA is oxidized to inorganic sulfate and excrete in the urine as neither organic nor inorganic excesses of sulfur can be stored. The normal concentration of sulfate in serum is around 3.5 mg/100 ml, roughly 5–10% of that as ether sulfate and the rest as sulfate ions. Sulfur is excreted in the urine as it exists in blood.

So if you take reasonable amount of protein (which you should if you follow the soylent way :wink:) you would get more than enough organic AND inorganic sulfur without supplementing it. One interesting tidbit is at Figure 4:

…SAA intake reduced by 0.9 g/day, to account for the estimated loss of sulfur associated with the consumption of a standard dose of acetaminophen, excreted as a sulfated conjugate.

So after accounting for this, and the RDA of 1.1g, we get at 2g of SAA which coincidentally is the amount recommended by @rob as Sulfur. My guess is that he might actually meant this. Another thing I noticed is that Sulfur is missing from his both post about the recipe. I’m waiting for the third to see what he has to say about it.

As for my recipe, it gives me 5+ g of Methionine + Cysteine, which after the 2g RDA leaves me with enough to spare. So I will not add any MSM but instead will make some blood tests regularly and see if this will have adverse effects on my health.

And save some money in the meantime :wink: