Soylent Macronutrient Overview


As a woman I have never taken iron supplement. not even when I was pregnant and I have never had a problem with being iron deficient as in iron deficient anemia. I eat dark leafy greens and eggs which all provide sufficient iron in my diet. A cup of broccoli only contains 0.7mg of iron. Iron supplementation has never been successful in women or men because of the very unpleasant gastrointestinal effects. In fact there is significant danger from iron overload in the form of hemochromatosis where iron is deposited in the liver leading to liver disease. There is a part of the general population that does require iron supplementation. The amount of iron in an over the counter supplement in fact has minimal absorbable amount. This is mostly so kids can’t accidentally overdose. Only prescription grade iron supplements have significant amounts of elemental iron and need to be in child proof containers and kept out of reach. If Soylent contains 8mg that should be enough for the general public. Those with specific medical conditions should consult their medical professional regarding the need for supplementation.


They need to ABSORB 1-3.4 mg a day. Iron isn’t easy to absorb, especially when it isn’t heme iron (which is mostly found in animal blood). According to Wikipedia, dietary iron absorption varies from 5 to 35 %, depending on the source.

The iron in Soylent comes from the oat flour entirely, according to the micronutrient post. In oat flour, most of the iron is in non heme form. Apparently, the only heme iron there is in plant foods comes from mitochondria… so I assume it’s not a big amount. To ease calculations, let’s say all of the iron is in non heme form.

Non heme iron is absorbed in a percentage of 2 to 20 % according to the website. Let’s assume that they dosed vitamin C and whatever other factors there are perfectly so that everyone gets optimal absorption, 20 %.

Then, in the best case scenario, we would actually absorb 1.6 mg of iron from Soylent. Which appears sufficient for the average menstruating woman. ASSUMING we are in the best case scenario, of course. And even if we are in this scenario, any woman who is above the average will not get enough iron. And if you remember your statistics classes from school, that’s likely to be many women.



then by your worst case scenario, 18mg (0.36) isn’t enough for ANYONE, which leads back to my original statement, the amount of any nutrient is dependent on the individuals needs and lifestyles rather than group or gender. Which is exactly what Rosa Labs said. As is 8mg is sufficient enough to provide for the vast majority of would be Soylent consumers at this time. In the future they may offer individualized/different mixes for people who need a different combination/amounts of specific nutrients.

I would not doubt if there are individuals capable of absorbing 40% or more of the non heme iron.
“Storage levels of iron have the greatest influence on iron absorption.” from .

One thing I haven’t been able to narrow down is the amount lost in menstruating woman. Is said amount an average over the month, or just during said time frame? It should also be kept in mind that their studies usually involve, statistically speaking, relatively few people, and its difficult getting any insight with such small sample size relative to the population.


I believe that the worst case scenario is impossible with Soylent. I may be wrong but I think such low absorption levels would only occur if all factors pushed for low absorption, including vitamin C, which Soylent has plenty of.

And this vast majority isn’t all that vast. Statistically speaking it’s reasonable to think that almost half menstruating women don’t get enough iron from Soylent.


If you look past page 292, you’ll see very detailed explanations of the studies and the reasoning about each recommendation. Some of these tests were made with quite large populations for long periods of time.

As for @Leecauble, I respect her opinion, but this is just that - opinion. We do not know any specifics as to what she is consuming, how often, what is her metabolism like. Also she doesn’t note that she had problems with supplements, only that she has knowledge of it.

So my suggestion is if you cannot provide useful facts and observations for a comment, just note that it’s your personal opinion, so people does not take it for something that is not.


I did read where it said they had a sample size of 100,000 individuals, however that vs the size of the population is arguably insignificant. just the us population is over 300million, assuming that male:female ration is approx 50/50 (think its more accurate at 48:52) so that’s about 150million females in the US alone. Their sample size (if they did indeed use 100k females for some of these tests) is less than a tenth of a percent, and then, they list some where they used groups of less than 100 people for some tests.

We are still learning more about human biodiversity, the end result is its a good guideline, but its still just a best guess, they couldn’t have gotten enough datum to cover the entire population. Ultimately they probably gave 18mg to be on the safe side to cover their ass so someone doesn’t say ‘you said I only needed this much and now I’m sick’.

{ @Tsukimi I don’t think they said where the linear relationship starts or ratio but: “They concluded that iron absorption from meals is increased approximately two-fold when 25 mg of ascorbic acid is added and as much as three- to six-fold when 50 mg is added. There appears to be a linear relation between ascorbic acid intake and iron absorption up to at least 100 mg of ascorbic acid per meal.”

Soylent has 90mg of vitamin C, although they keep stressing that the largest contributing factor is an individuals iron stores. Another line said 900mg of calcium could cut absorption by up to 60%, and there are apparently 2 or 3 formulas they used that took into account different sets of variables, but from what I read, they didn’t include all variables, though there may be one that Rosa Labs and RFI used to determine that the current iron content is plenty for all. }

That being said, if ones iron stores affects the absorption the most, does the 2%-20%, or 5%-35% cover the stores or just the range based on the over all recommended intake list? (i.e. what did they use to come up with those numbers?)

On page 315 ( ) they claim the bio-availability of iron to be 18%, which is used to estimate “the average requirement of iron for children over the age of 1 year, adolescents, and nonpregnant adults consuming the mixed diet typically consumed in the United States and Canada.” Though in their math they don’t appear to take into consideration all the other factors that appear to play a role in affecting iron absorption, just the averaged absorption rate.

Which again takes me back to the beta testers saying they weren’t having any issues with 8mg of iron in Soylent.

@Leecauble I think this paper does say that somewhere, mainly because I feel like I have read that in a few other places. There is apparently some place in sub-Sahara Africa that suffers from iron overload, due to having a large amount (measured in 100’s of mg) in their beer, though I don’t recall the page number.


Again, beta tests are insignificant when it comes to this. As I said before, a person does not know that they are iron deficient until it’s relatively major and it’s been a while. As an anemic person, I know at least it’s that way for me.

Though both of us are speculating a lot when we talk. We’ll never get to an agreement when we say as many answers as questions. I think nothing but a message from @JulioMiles can give us the final word of this.

Why is there 8 mg of iron in Soylent?

Or has blood tests each month that tells them exactly what their iron levels are in the blood, among other things. It would be nice to hear from one of the Soylent crew, though - what was the reasoning that led you to the 8 mg of iron?


@Rob @Juliomiles
Just throwing in my vote for hearing the reasoning behind choosing 8mg of iron. I know you’ve reasoned this out extensively, but it would be nice to share with us so we know you’re not just experimenting on us willy nilly. :wink:


o.o There were blood tests? From what @Matt88 was saying about participants not reporting anything wrong with their iron I figured our only tool was what they said.


You are correct. But on p.351 they mention that due to vegetarianism, the nonheme absorption is twice as low and could go even lower. Since most if not all the iron in soylent is nonheme, we should take this into account.
On p.356 they also note the median intake for a men and women in the us after wide research and compare it to Canada. It seems that 16-18 is not that uncommon. And this seems like a widespread rather than tenth of a percent.

The Sahara quote is on page 359 :wink:


Based on everything I’ve seen from them, it seems to me that their reasoning was simply that the USDA recommends 8mg/day for men… but I would like to be proven wrong.


It’s weird to me that now we’re debating the accuracy of USDA recommendation for iron and only iron. Because I keep seeing DIY Soylent threads where someone’s got too low a count of something-other and people jump on it instantly as wrong, and say it needs to be fixed, and they’ll seriously risk their health if they don’t regularly get so much whatever, but nobody ever comes back with, “Well, how sure are we REALLY that we need that much manganese?”


@Matt88 @Stoinov
It would appear that we have an answer. I’m pinging the two of you because you seem interested in the topic but might not have seen the new thread I started yet.


Thanks, and as far as I know, their beta testers do all sorts of tests, though what they report to Rosa Labs I can’t say for certain. Though if they say their testers didn’t have any issues with 8g, I am more inclined to agree with more recent and more controllable intake. The aforementioned article was released in 2001 and a lot can change in ~13 years.


Thanks @Tsukimi :smile: I’ve noticed the thread list night before going to bed and subscribed to it. Great answer for our discussion.


I agree, coconut oil would be a superior choice—safe, nutritious, and less likely to go rancid. The thing that concerns me now is the use of Sucralose! Artificial sugar is always a BAD idea! Refined sugar, toxic as it is, is still safer.


Lots and lots and lots of discussion on this. If you’re interested in opening up the discussion, please read through those and see if your concerns have already been touched on (good chance they have - they are pretty extensive threads). If after doing so, you discover that you have some new scientific data supporting “Artificial sugar is always a BAD idea” that hasn’t been mentioned yet, please share - this is after all a rational community, and we’re open to being proven wrong, given a display of evidence :smile:

Rob has also responded directly in the applications thread:

(emphasis mine)


Any news on the other two posts and when they are coming? Since we Europeans will be waiting for some time I want to try DIY but be as close to the official recipe as possible.


They’ll be out in… around negative 5 months :wink:
Here you go: micro breakdown, applications overview, DIY thread with the same goal, and one of the DIY recipes with that goal