More than you ever wanted to know about phytic acid

[tielfan]

Warning, long thread ahead. Will probably appeal only to nutrition geeks. It's a spinoff from the "update at Cockatiel Cottage" thread at http://talkcockatiels.com/showthread.php?t=8977

Cockatiel Cottage recently updated their nutrition advice at http://www.cockatielcottage.net/diet3.html to include this statement:
"Broccoli contains low levels of phytate or phytic acid, which has the same effects as oxalic acid on the absorption of calcium, but also on the absorption of zinc and iron. Phytates are also found in legumes, nuts, carrots, potatoes, green beans, sweet potatoes and berries. Serve these vegetables in moderation as well."

I'd never heard anything like this before so I did some quick research, and learned that phytic acid does indeed chelate important nutrients including calcium, magnesium, iron, zinc, etc. But it looked like there was something wrong with the Cockatiel Cottage quote, since it was warning against broccoli based on a low level of phytate. It's the high levels that would be expected to cause problems.

So I wrote to the webmaster, who said that the information came from the book "Avian Medicine, Principles and Practices" by Harrison, Ritchie and Harrison, who are avian vets. She also suggested that I consult my avian vet for nutrition information. That wasn't informative enough for me, so I did some more research.

The only site I found talking about the amount of phytate in broccoli was at http://www.healthy-eating-politics.com/phytic-acid.html which said that it's relatively high in it. I don't know how reliable that source is; based on the title alone it may be dubious. But since various reliable-looking sources mention broccoli in discussions of phytic acid, it seems likely that this is correct, and is probably the real reason for the recommendation. However it seems to be universally agreed that seeds, nuts, and grains are much higher in phytates than any vegetable. It is also agreed that phytic acid has some beneficial effects, primarily antioxidant, and there are sites recommending that humans increase their consumption of it.

There are some sources that talk about phytic acid and birds. From http://books.google.com/books?id=tN3pn2PsymAC&pg=PA26&lpg=PA26&dq=phytic+acid+birds&source=bl&ots=yECOak-PL7&sig=X2CkRX5N_8z_x2brGqUNUDCM33c&hl=en&ei=xwLZScOdMo-EtAOG_cmoCg&sa=X&oi=book_result&ct=result&resnum=6 (page 26 of Feeding Your Pet Bird, by Petra Burgmann et al): "Phytic acid, a substance found in whole grains, also binds with calcium and other minerals and prevents their absorption." For what it's worth, Dr Burgmann is quoted on Cockatiel Cottage at http://www.cockatielcottage.net/diet3.html as saying that parsley is not toxic to pet birds, which seems to be generally accepted nowadays, but doesn't mention that it has almost twice as much oxalic acid as spinach. There is at least one outright error in her work. A little further down the page at the google link above, she implies that broccoli is high in oxalic acid. All other sources that I've seen agree that it is not. If you keep scrolling down, she talks a bit more about phytic acid on the next page.

There's an interesting page at http://books.google.com/books?id=S5oCjZZZ1ggC&pg=PA201&lpg=PA201&dq=phytic+acid+broccoli&source=bl&ots=2vKIzZpItC&sig=U5_Ii5_CCg1CXQZAEnP6B_CrhtY&hl=en&ei=qQXZSYD3Lp66tQPLk6yyCg&sa=X&oi=book_result&ct=result&resnum=9 It says that oxalic acid is the most potent inhibitor of calcium absorption and phytic acid is a modest inhibitor. A chart at the bottom shows the amount of bioavailable calcium for several different foods. Broccoli does pretty well on this scale, and the text specifically cites it as a good source of usable calcium.

Here are some scientific papers on phytic acid and birds (chickens). I won't attempt to quote them, but they all indicate that phytic acid reduces the availability of desirable nutrients. The scientific jargon is fairly impenetrable, but it seems likely that the amount of phytate used in the experiment was pretty high.
http://journals.cambridge.org/action/displayAbstract;jsessionid=26AD3B9ECB2C7D7481272BA A1DA8B4D8.tomcat1?fromPage=online&aid=4773440
http://jn.nutrition.org/cgi/reprint/84/2/145.pdf
http://www.ncbi.nlm.nih.gov/pubmed/15115207

Maybe I'm just naive, but it doesn't sound to me as though the phytic acid in broccoli is really that big of a deal. If there's anything to be concerned about, it's the phytic acid in seeds, nuts, and grains, which tend to make up a bigger percentage of our birds diet than broccoli does. However, various sites have noted that sprouting or cooking reduces the amount of phytic acid.

[sweetrsue]

It looks to me as though you have been very busy with your research! Very good information. I always prefer to seek out the scientific papers for the real truth. Far too many sites rely on rumor and myth for their recommendations. Generally accepted knowledge isn't always correct. Often in fact it's information that is not carefully considered or researched but they heard it somewhere. It's like putting "aint" in the dictionary because so many people use it.

[tielfan]

I offer broccoli frequently so it's important for me to know whether there's any problem with doing that. I know this thread is mostly too tedious for this group, and actually I wrote it primarily for cross posting on a nutrition group where they seem to enjoy delving into this sort of thing. The results were interesting, and can be summarized pretty easily.

They agree that the phytic acid in broccoli probably isn't a problem. They had the medical book and could look up the text in question. Some important facts about the book:
1. It was written in 1994 when dry-seed diets were the norm
2. It was compiled and published by Dr. Greg Harrison of the Harrisons pellet company. Virtually everything in the book on the subject of nutrition tends to steer a person toward the use of pellets.
3. The chapter containing the broccoli comment was written by Kaytee's vice president of research and development. That's a potentially biased source.

What the text actually says is "Phytates are most commonly found in nuts, legumes and cereal grains (germ and bran), and in lesser quantities green beans, carrots, broccoli, potatoes, sweet potatoes and berries." In other words, it correctly points out the major sources of phytates, then lists a few vegetables that contain smaller amounts. There's no indication of an intention to steer people away from vegetables, but there probably is an intention to steer them away from seeds, nuts and grains. Pellets are processed, which should neutralize the phytates in the ingredients.

Soaking and sprouting also reduces phytates. Not many people were doing this in 1994 but lots of them are doing it now. Between the increased use of pellets, the increased use of sprouting, and the reduction in the use of the major phytate sources, it's likely that phytate consumption has dropped considerably since the mid-90s. If there was ever an intention to steer people away from the vegetables, it's probably obsolete now.

[sweetrsue]

It almost sounds like a Kaytee/Harrisons conspiracy. I think you are on the right track. You have gathered info from .org's and .gov's rather than .com's which are by nature commercial! You have even paid attention to the author of the medical book in question no doubt have alteriar motives. A conflict of interest as it were. You determined that even the university studies that looked into phytic acid gave it to their subjects in amounts that far exceeded what would normally be consumed. I agree that broccoli is far more beneficial to our babies than harmfull.

[Raven2322]

Wow great research and good to know because I do offer broccoli. Thanks so much for posting this. :)

[skthurley]

I love researching bird diet and nutrition.... but often the more I do, the more frustrated I feel. So much conflicting information! lol!

Thank you for this research, tielfan.

[tielfan]

It almost sounds like a Kaytee/Harrisons conspiracy.

I wasn't suggesting that anybody had ulterior motives. I don't know a lot about Dr Harrison but I have no reason to think he isn't sincere. But our interpretation of information is always influenced by our beliefs, and he's obviously enthusiastic about the benefits of processed foods. His book might have read differently if he distrusted processed foods and was a big fan of natural foods instead.

I love researching bird diet and nutrition.... but often the more I do, the more frustrated I feel.

I know, I feel like banging my head against something right now because there are so many unknown quantities in all this. For instance, how much phytic acid are cockatiels equipped to handle? They're primarily seed eaters in the wild and seeds are a major source, but not all seeds have the same amount and some don't have any. How does their mineral consumption in the wild compare to what they're getting in captivity?

Not everyone shares Dr Harrison's enthusiasm for pellets. A lot of people think that pellets should be fed in moderation, and I tend to agree with their logic. Pellets are based mainly on research that was done for the poultry industry. The poultry industry wants to crank out egg-laying machines and plump, meaty birds, and they're not worried about the birds' long-term health because their birds don't have a long-term future. Obviously, we have different goals for our pet birds, and the poultry formulas might not work as well for us.

Harrisons in particular has made an effort to do research and make pellets more suitable to the needs of pet birds. But there's very little that's species-specific. The word "cockatiel" on a bag of food is usually just an indicator of the size of bird that it's aimed at, it doesn't mean that it's custom-designed for cockatiels based on research into their needs. A lot of different species eat cockatiel food because the industry doesn't market bags of conure food and whatnot.

But how do the nutritional needs of these birds vary? Organisms who live in harsh environments are generally adapted to get by on less than organisms in abundant environments. Cockatiels come from a harsh environment, and I worry a lot about overnutrition because I have a dramatic example of what can happen when desert dwellers get too much of a good thing.

I live in Tucson, which has the Tohono O'odham Indian reservation on the edge of town. These people are physically adapted to the slim pickings of the Sonoran Desert, and diabetes was unknown amongst them in the past. But nowadays they have a typical American diet, and they have the highest rate of diabetes in the world - one half of the adult population. How scary is that?

Strange as it may seem, that's the reason I'd never want to feed my tiels an 80% pellet diet like the manufacturers recommend. I'm worried that this diet might be too rich. There's no doubt that pellets have greatly improved the lives of many birds in the short term, but they haven't been around long enough for the longterm effects to be known. I'm happy that my birds eat some pellets, but I let them choose how much of everything they want to eat and they choose a small amount of pellets. That's fine with me - the pellets scare me more than the broccoli does! The recommendations of veterinarians are mostly based on the pellet manufacturers recommendations, because the vets don't do their own research and don't have anything else to go on. Naturally the pellet companies want you to feed the maximum amount of pellets that won't kill your birds, which seems to be about 80%.

Well, I'm rambling on again. My thanks to everyone who had the patience to wade through all this!

[tielfan]

You have gathered info from .org's and .gov's rather than .com's which are by nature commercial! You have even paid attention to the author of the medical book in question no doubt have alteriar motives. A conflict of interest as it were. You determined that even the university studies that looked into phytic acid gave it to their subjects in amounts that far exceeded what would normally be consumed.

You're giving me too much credit! The connection between the book's authors and the pellet industry was pointed out to me, and I would never have figured it out on my own. I do like to consider the reliability of sources and potential bias, but no source is 100% reliable. Sometimes scientists are wrong, sometimes the wackydoodle crowd is right, and sometimes governments have a political agenda that steamrollers the truth. But the scientific sources do have a higher standard of proof than the nonscientific ones, so you have better odds of getting good information from them.

[skthurley]

I couldn't agree more with you with everything you said about pellets.

I do believe they are an important part of the diet.... but by no means meant to be 80% of the diet like they recommend. That is way too much for sure!

I really think variety is the key when it comes to birds. Offering many different veggies, with fruits and grains surely is the best diet. Even seeds are a good thing.

As Aly has said, everything in moderation, and variety :D

[poppabill]

Damn you got to be a freaking genIus to understand a lot of that stuff, i feed a mixture of seeds ( my own mix) as well as vegetables, pastas cereal and more and have been for over 30 years (actually veggies about the last 20 years) any way i feed as i do and my birds are healthy and seem happy.
I have tried pellets a couple times but my guys pick a bit at the pellets but thats it. As long as folks have animals (birds, dogs etc) there will be folks that read stuff and take it to heart "true or not" and they will believe what they believe no mater what. When a company puts out a statement saying there food is the best then it must be gospel to many. There will allways be the SEED V PELLETS debate and every one is entitled to there own oppinion, how ever not every one will agree with every one. The linkis are very nice and i read most but as i said before ""sometimes you feel like a nut, sometimes you dont"" any way the reading was good and i enjoy all the new information on birds out there as we are allways learning. I'll tell ya before you know it they will put a man on the moon...be happy :D

[sweetrsue]

It just seems to me that if a study is done by a manufacturer of a given product the study will likely find in favor of that product. Better to rely on independent studies. Or at the very least be able to read between the lines

[tielfan]

As far as I know, the manufacturers are the ones doing most of the studies, and some are more involved than others. Harrisons is said to do the most research. The pellet companies have the money and also the motivation, since it's in their own longterm interest to make a quality product. Theoretically they'll make the same amount of money from a person who has one bird for 20 years as they do from a person who has a succession of four birds who live for 5 years each. But the person with the long-lived bird will be thrilled with their product and will recommend it to everyone. The person with the short-lived birds won't actually stick with them for 20 years, because after a couple of birds they'll realize that this is a crappy product that kills birds, and they'll start spreading the word on the internet.

There are organizations that fund avian research, like the American Federation of Aviculture. I don't know how much of their research funds are spent on the subject of diet, but I'm guessing that they don't have as much money as the pellet companies.