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Amino Acid Rich Foods


Are there any foods out there that contain large amounts of amino acids but not complete proteins? I remember reading something about beans lacking complete proteins. Or am I missing some Biochem 101 about amino acids in foods? A complete protein is defined as containing all 20 amino acids correct?


Basically, with the exception of soy, plant sources (grains, legumes, nuts, seeds) have incomplete proteins; they do not contain all the essential amino acids. Animal sources have complete proteins; they contain all essential amino acids.

Grains and legumes complement each other in that the limiting amino acid in one is high in the other and vice versa. That's why knowledgable vegetarians often eat grains and legumes together.

An interesting Fact I learned: Cerals and legumes are more valuable in the diet if combined with not only each other, but also even a small amount of protein from an animal source.

P.S. There are 22 amino acids, 9 of which are essential (threonine, valine, tryptophan, isoluecine, luecine,lysine, phenylalanine, methionine, and histidine).


beans contain all of the essential amino acids.


and an animal protein is a common source of a incomplete (one of the few) protein.

Hello Gelatin


Beans are still considered incomplete because one or more of the amino acids is in such a small amount, making the biological value is very low.


Soy is not complete. It's missing methionine.



All my nutrition profs and my textbooks tell me it's complete.


read "the whole soy story" by kaayla daniels.

soy is poison. stay away from it.



Here is a general list of which foods are missing which amino acids:

Grains - LYSINE

Nuts and Seeds - PROLINE

Legumes(Beans) - METHIONINE

Soy IS a complete protein although it is low in methionine. Most beans contain none.

Animal MEAT contains all of them (Meat does not include gelatin, skin, bone, hair, etc.)

As you can see by combining different vegetarian foods you can make complete proteins: i.e. Beans and Rice, Peanut Butter and Whole-Grain Bread.


Haha, I wasn't recommending it...just talking about it's protein quality.


They're not missing entirely; they're just in insignificant levels.


Maybe your missing something.

from the USDA food composition database of soy isolate

Methionine 1.130g/100grams

soy bean curd

Soy bean (mature seed) raw

Methionine 0.492g/100g

Soy milk, fluid

Methionine 0.036g/100g

Soy and all beans have all essential amino acids, its just the levels can vary somewhat.


Quantities of amino acids is not what makes the BV, but the food matrix. The quantity of varios essntial amino acids affect the amino acid score, adn ultimately the protien digestibility corrected amino acid score.
Soy isolate has a BV of ~73 vs beef of 80

Amino acid score depends on which reference population you look at, but using the FAO/WHO children ranges (with Histidine at 19mg/g protein) soy isolate has a AAS of 1.04 compared to beef of 0.94 and finally they have PDCAAS values of 0.99 for Soy isolate vs 0.94 for beef.


show us the amino acid composition of beans. Pinto beans contain methionine, lima beans contain methionine, Mungo beans (have no idea what they are, but they are on usda database), mung beans, navy beans and kidney beans. All contain methionine. The levels may not be up to the standards set forth by the FAO/WHO and adapted by the FDA etc for children, but within diets of large quantities of protein (rather than minimal protein) it makes little diffrence anyway.


Soy also contains anti-nutrients that block the absorption of other amino acids.

Also, don't forget there is a huge difference between raw soy beans - which are basically inedible, miso and modern soy protein isolate, soy protein concentrate, and soy lecithin. Those products are manufactured in a chemical plant using stuff like hexane.



so why not show peer reviewed research on the amino acid anti-nutrients

so becuase your concept of no methionine in soy has fallen over you are starting to go off into other concepts? this wasnt a conversation on the relative merits of soy, it was about the amino acid composition of beans.


You're indeed right about the PDCAAS's, but (exceptions aside), animal/complete protein sources have higher PDCAAS's than plant/incomplete sources, anyway. I think the digestibility of animal proteins is from 90-99% whereas plant proteins is somewhere around 70-90%. So it is still safe to associate animal proteins with a high biological value, since they kick butt with both their amino acid composition and digestibility.


What a load of B.S. Soy isn't bad for you. Japan has sued it for over a thousand years and are the longest living race in the world! Those soy studies are funded by the emat and dairy industry,look ,you'll see.Why?Because the meat industry losing millions each year due to soy being sold. I've always drank soy ,my whole life;and I'm living proof,so are my friends,and japan,that it doesn't cause health problems. There are no such thing as anti_nutrients that "block" amino acids.Soy has amino acids.If it "blocked amino acids,people wouldn't be able to digest the amino acids when they mix with stomach acids. the only study done on soy was when it was in baby food.They took certain phytochemicals out of the soy,and the babies were fed no iodine. Well,if you get no iodine then no shit you're gonna have thyroid trouble.but,japan who eats it everyday,too much of it that is,has 63 % less thyroid problems than america does! Thats a fact.


Hey Reaper, there's actually been a lot more research on soy than one study on baby food. Take a look on an online university database (they usually let you search without actually looking at the full article).

Regarding Japan's use of soy - they actually have a larger incidence of prostate cancer formation than western countries. But then, they also have a lower level of prostate cancer mortality. A number of studies I've seen suggest that large ingestion of soy will start uncontrolled prostate growth and then regulate it in turn. It's a strange thing. Also, many of the studies done on Asiatic populations have very poor design, as they didn't account for activity levels, total caloric consumption, micronutrient intake, hell, even air quality, water quality, etc. This isn't to belittle the importance of the studies, but nowhere near all the bases have been covered yet. The jury is definately still out on whether or not soy helps longevity or not.



Sheesh. And I thought I was done with grad school.

OK. Here you go.

Liener IE, Kakade, ML. Protease Inhibitors. In Irvin E. Liener, ed. Toxic Constituents of Plant Foodstuffs (NY, Academic Press, Second edition, 1980) 49,55.

Actually, the argument about soy beans versus how you eat it is very salient because, of course, no one in their right mind would eat an actual soy bean unless they just enjoy gastric distress. Don't tell me about edamame. That's not the same. Those are a different strain of bean and they are also picked while they are still immature.

And no, I don't think you'v proven there's methionone in the thing just because the government says so. Read about food politics and understand how the world beyond your university really works. Why don't you show me some peer reviewed work that states it does have it.