Have you asked yourself why upper limit of Manganese is 11mg/day?


Whats the harm in keeping it at 2mg or less, the recommended intake i believe?


I doubt there is any harm is keeping it that low. The problem is that it is very hard to keep it that low on a healthy diet. When you start getting into plant (especially herbs) food sources, it is in almost everything. Oat flour is loaded. Pretty much any dark greens (and the dark ones are generally the more healthy ones) are high in manganese. Herbs are absolutely loaded with the stuff (basil and parsley especially, which also happen to be some of the best sources of vitamin K). The problem is not that anyone wants it that high. The problem is that it is so hard to keep it even as low as the 11mg upper limit if you are trying to eat healthy.


It’s not difficult on a soylent diet. Instead of flours and herbs, use “engineered” food products, such as starches (e.g., corn, unmodified potato) for carbohydrates and isolates (e.g., soy, whey) for proteins. Oils (e.g., canola, sunflower, safflower) can be used for fat. That will eliminate the high levels of micronutrients present in some foods. It will also make your diet more “modular” and easier to balance.


If you stick to using engineered food products and synthetically produced vitamins, getting a good balance is trivial. You use low nutritional value components for macronutrients (starches, isolates, and plant oils, as you suggested), and then add each vitamin and mineral in the right amount.

My project was to make soylent recipes that are food stamp (SNAP, now days) friendly. Food stamps are somewhat restrictive on what you can buy. Pharmaceuticals are not considered foods, which means that you cannot buy multi-vitamins or even individual vitamin and mineral supplements with them. This means you are stuck with only real food options and vitamin enriched foods (some protein shakes are enriched with vitamins and minerals, and I actually use one of these as my base).

The problem with real foods is that you can never get just one component in a real food. It is hard to find potassium and vitamin K in dry food form (my goal was to make a dry mix that you mix with water and blend, so it would keep for long periods of time). I ended up using potassium chloride salt substitute for some of the potassium, but if you use too much, it affects the flavor negatively. The big problem was the vitamin K (and maybe phosphorus…). The only foods rich in vitamin K that can be found in dry form are dark green herbs. Unfortunately, all of these have significantly larger amounts of manganese. Since I was using oat flour for some of the other vitamins and minerals, I already had plenty of the stuff. The oat flour is not just for carbs. Oat flour has a very good balance of a large range of vitamins and minerals (it was the second base in my recipes). If I replace some of it with potato starch or something similar, then I have to make up a huge deficit in other things. By reducing the oat flour by a very small amount and adding other carbs (which I actually need to replace with raw potato starch, because the substitute was standard corn starch, which has a glycemic index close to pure sugar), I was able to reduce the manganese to around 11.5mg, which is 0.5mg above the IOM upper limit, but well below the typical content for vegan diets.

Anyhow, I totally agree about the modularity thing. If you can get the micronutrients in their pure forms, that is going to make balancing things trivial. The problem is that this can be expensive (if you are not buying in manufacturing level bulk), and it is not an option for people on food stamps (which is quite possibly the group that needs this the most).

For full disclosure, another one of my goals was to try to get the price per 2000 calorie meal below $1. I think my best so far is $1.12, but the flavor is not perfect (the basil for the vitamin K makes it taste slightly strange and I think the tomato powder was used for something that could be obtained in more expensive dried strawberries; I don’t mind it though). The recipes with dried strawberries are the best ones, but they range from $1.30 to $1.50 a meal, if memory serves. This was around a year and a half ago, so the prices have probably changed a bit. The point of this is that the price thing did influence my ingredient decisions in some degree, though I don’t recall even more expensive alternatives that would have solved the manganese problem.


$1.12 2000kcal meal? Please explain.


I forget which recipe it was that was that low, but I have most of my recipes listed on my blog. The soylent intro post is here: http://makeshifttechnology.blogspot.com/2013/08/soylent-introduction.html All of the soylent posts have titles that start with “Soylent:”.

Ok, I just went through the 6 recipes I have recorded, and the lowest I can find is $1.81 meal. I recall one that was $1.35 a meal and one that was $1.12 a meal, but I don’t have them recorded. My guess is that they did not turn out good enough to be worth keeping. (It has been over a year and a half since I had time to work on this.)

The important thing is that most of the cost comes from two or three especially expensive ingredients (the dried strawberries are the most expensive one). These ingredients are only necessary for a few specific nutrients. If I can find cheaper sources of those nutrients, getting the price to $1 a meal would actually be pretty easy. I don’t know if those cheaper sources exist though.

It is fairly easy to get regular food meals below $1 a meal though. Since I worked on this, I came across some information that prompted me to do the math, and if you pick the right foods, eating cheaply is easy (though, I doubt it is as nutritionally complete as soylent, and it is certainly less convenient). If you get the cheaper kinds of rice, you can cook enough for a meal for less than 40¢ (as low as 20¢ if you hit Costco or Sam’s Club at the right times). If you top that with curry, and if you are light on the meat, you can manage between 30¢ and 50¢ a meal for that component. This leaves a little bit of room for cheap vegetables (a $1 bag of frozen vegetables can provide enough for several meals). Even better, if you are willing to a little over $1 a meal, you can buy a lobster tail on sale (they occasionally get as low as $4 or $5 where I live) and make lobster sauce to put on the rice (the sauce from one tail can give you up to 8 or 10 meals worth). I am actually planning on writing a recipe for the lobster sauce on rice (I may be starting a cheap recipe blog soon). If you are really cheap, you can do beans and rice for about 60¢ a meal (the per meal cost for common herbs is so cheap you can make it taste pretty good within that 60¢ too, and herbs contain tons of vitamins and minerals).


You said “2000 calorie meal” which was confusing. When you say “$1.81 meal”, do you mean with 3 meals per day worth around 2000 daily calories, which would translate to about $5.43 per day?


Oh, right, that is confusing. Give me a moment to check (I think I was confusing myself…).

So yes, you are correct. It is $5.43 a day, for about 2,012 calories, which comes out to $1.81 a meal. That is the cheapest recipe I have on record. (On my blog, it is listed as the “No Strawberry” one, in case anyone cares.)

Obviously, the price is based on local prices where I live, and less obviously, those prices are over a year old. I don’t know what the current prices are. One of these days, I will change how I am storing my data, to make it easier to keep the prices up to date.

Sorry for the confusion. It has been way too long since I worked on this, and I was confusing myself.


It is possible to drive down the price much lower than that. My formulation, at present, is USD$1.71/day. Truckload/tankercar quantities will further lower the price. In the future, prefabbed vertical farms, processing plants, and packing plants will be located adjacent to major metropolitan areas to minimize the acquisition and shipping costs of raw materials and the shipping cost of the finished product.


I think you are right. It is just hard to find the kind of ingredients I need (ones that can be bought on food stamps) at a low enough price. Most of the ingredients are plenty cheap. There are just a few expensive ones that are necessary for getting the right amount of specific nutrients. I just need to find either cheaper sources of those ingredients or cheaper sources of those nutrients. It would be way easier if you could purchase online with food stamps!

I cannot wait to see farming and fabrication decentralized to that level!


I am not sure i agree with this sentence though. We are not absoluetly sure beyond a doubt that even these levels dont cause any harm.


We are not absolutely sure that more than 5mg doesn’t cause any harm. The “study” where they got the 11mg value from was a small sample of women, all from the same place (somewhere in Canada, I think). Essentially the 11mg upper limit comes from the fact that a very small sample of only women did not have any problems that could be attributed to manganese consumption, and the highest intake observed in the sample was 11mg. Not only is this not proof that more than 11mg is unsafe, it is also not even remotely proof that significantly lower values are safe.

The 22mg from vegan diets really holds more weight than the study the 11mg upper limit came from, and it is still not even remotely conclusive. So, it is possible that more than 11mg could be harmful to some people, but there is a pretty large number of vegans on diets with twice that and no reported problems. So a mere 0.5mg over is unlikely to cause any problems. (Notice that I did say “probably.”)

Really, we don’t actually know anything about manganese levels conclusively, except perhaps that 2mg a day seems to be a good amount to consume (I have not looked into why this is the recommended level). No cases of manganese poisoning from food sources have ever been recorded, so we literally know absolutely nothing. The fact that there are no recorded cases does strongly imply that it is far less toxic that the IOM upper limit seems to indicate. (And, there are some nutrients know to be non-toxic even in enormous amounts.)


We are also not absolutely sure beyond a doubt that drinking 8 glasses of water per day doesn’t cause any harm.

I don’t think you’ll find a single study testing whether drinking 8 glasses of water per day doesn’t cause any harm.



That study is referring to environmental exposure (in drinking water).


in drinking water, how is that different to vegan diets?


Manganese dissolved in drinking water does not qualify as a food source. The specific compounds involved are totally different. Industrial and environmental sources are mineral sources. Mineral sources of manganese do have observed toxicity. No toxicity has been observed from food sources.

Here is how it is different: First, I don’t know the exact chemistry for manganese specifically, but I know the general chemistry for metals. Generally, the most common mineral source compounds for metals are oxides or salts. Manganese in drinking water is probably most likely to be in salt form, given that metal oxides are not usually water soluble. Metals in organisms are generally found in much more complex chemical structures. The exception, I believe, is sodium. Sodium salt is used by organic life to help balance water levels. Calcium, on the other hand, is typically found as calcium carbonate (bones and such). To my knowledge, consuming large amounts of calcium carbonate has no ill effects (Tums, or bones found in things like sardines).

The problem is not the element itself. The problem is specific compounds. If a person were to consume pure manganese, it would be toxic, because it would react to produce toxic compounds (and it may be toxic on an elemental level, but most metals are not found in elemental form in nature). Salts can screw up water balance as well as other internal processes. The more complex organic compounds, however, are necessary for many life forms to survive. Plants produce them (probably from salts or oxides, but I am not certain) and retain them.

It is very likely that herbivores and omnivores have evolved to be tolerant of large amounts of these compounds that are so common in plants. They have not evolved to tolerate more simple and reactive compounds though, because those compounds are naturally extremely rare.

What it comes down to is that the manganese compounds found in industrial runoff and mineral formations are very different from manganese compounds found in plants. The human body actually needs the manganese compounds found in plants to survive. The manganese compounds found from mineral and industrial sources are not in a form that is useful to the body, which means that it is either not metabolized (but still absorbed), or it is metabolized in a process that makes it damaging. I would guess its mode of toxicity is displacement. This means it gets metabolized as if it were a similar compound (sodium salt, I would guess), but the body is unable to use it. When it displaces a necessary compound like this, it blocks processes requiring that compound. (This is what makes carbon-monoxide toxic. It attaches to oxygen receptors on blood cells, but the body cannot use it like oxygen, so it starves the cells of oxygen. It displaces oxygen, which causes asphyxiation.)

EDIT: I read through some of that study. One measure it used to determine exposure was Mn concentration in hair. That strongly implies a displacement mechanism as the mode of toxicity. (If it is in the hair, the body is putting it there because it thinks it is something else that belongs in hair.)


Its ingested manganese. Also what makes you assume the manganese in it it has come from industrial run off. Some amount of it is found in drinking water naturally.


I did not say it had to be from industrial runoff. I said mineral sources, which include industrial runoff. Another common source of the mineral (in oxide and salt forms) is rocks and crystals (tiny ones commonly found in rocks). High concentrations of toxic minerals like this in rock is uncommon, but it does happen in some places. Without anything specifically stating that it is from industrial runoff, I would actually assume it is from mineral formations that the water happens to run over or through.

Ingestion is not what makes it a food source. Strictly speaking, “organic” source would be more accurate in this context, however in these forums, people tend to use and understand “food source” better.


It is still ‘ingesting’ manganese, and the study indicates ingesting manganese even in that amounts, whether in oxide or salt form (we are not sure which form/forms of compound soylent has and by how much) can pose problems.