Little Feathered Buddies

Small birds, big hearts


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Health & Nutrition


Soybeans are a common ingredient in nutritionally complete pellets because they are the best plant source of lysine, an essential amino acid that is difficult to obtain from plants.  Like all beans, soy has plentiful amounts of other nutrients too.  And like all plant foods, it also contains some anti-nutrients.

Some people say that you should avoid pellets because of claims that soy is dangerous, filled with compounds that disrupt hormone levels and thyroid functioning, interfere with mineral absorption, and cause numerous other problems. The available evidence indicates that these claims are blatantly exaggerated and misleading, with an interesting twist.  There's a lot of wrong information on the internet, and it seems like it's mostly being spread by people who have good intentions but are misinformed. It's possible that this also applies to the anti-soy rhetoric, but it looks very much like someone might be using intentional scare tactics as part of a dirty-tricks marketing campaign.

Where do the anti-soy claims come from?

It looks like virtually all of the anti-soy information on the internet and in print originated from a single source - the Weston A. Price Foundation (WAPF). Everyone else talking about it seems to be following WAPF's lead and using information that came from WAPF.

And what is WAPF? According to numerous sources (most of them with a vegetarian or alternative flavor), Weston Price is a propaganda machine/marketing arm for the dairy and meat industry that promotes dangerous nutrition myths (The Guardian, Share Guide, Aviva, Food Revolution, Vegsource, J Campbell, Freedom from Harm, Zen Habits, Eden Foods, Dr. Dahlman (Some of these links talk about individual WAPF leaders instead of mentioning the organization by name). The Unreasonable Man describes WAPF as shills and quacks whose advocacy for dairy goes far beyond that of the original Weston A. Price, the Cleveland dentist that the organization is named after. 

Weston Price the man traveled the world in the 1920s and 30s looking at which diets seemed to promote the best dental health.  Not surprisingly, he found that cultures that ate calcium-rich milk products tended to have good teeth.  His training was in dentistry, not in medicine, nutrition, or science, and his conclusions about dietary issues in general do not have a sound basis. His ideas about dentistry are questionable too (Wikipedia, Quackwatch).  There is no indication that he had an opinion on soy. He has no association with the Foundation named after him, which was created 50 years after his death and reportedly strays significantly from his ideas (Wikipedia2). Dr. Price was best known for his ideas on holistic dentistry, but the Foundation is focused on other things and doesn't mention dentistry in their mission statement.

I'm not one for conspiracy theories, so I think it's possible that WAPF is sincere and it's coincidental that their activities provide marketing benefits for the dairy and meat industry. But I can't just shrug off these accusations about a connection to Big Dairy and Big Meat, because the WAPF agenda serves them so well. The WAPF mission statement makes it clear that they were founded primarily to promote the consumption of animal products (especially dairy) and this goal is their top priority. They want you to drink milk and eat animal fat (especially butter). They do NOT want you to eat soy, which happens to be a major competitor for dairy and meat products.

There are several groups in the population who are likely to use soy products instead of animal products, like the health-conscious "alternative" community, people concerned about the environment, and people who care about animal welfare. These groups are the natural target for a marketing campaign aimed at preventing people from switching from dairy and meat to soy. But it wouldn't pay for the marketer to be too blatant about what they were doing; they need to look sincere, not like an obvious advertising ploy. That might be the reason that the WAPF mission statement talks about some other objectives that should sound pleasing to these groups.  But the only foods that WAPF thought were worth mentioning were animal products and soy, and the only specific goals that they mention relate to promoting raw milk, banning soy infant formula, and studying butter and the "X factor" (Vitamin K2 which is found primarily in animal products). From the mission statement:

"Dr. Price’s research demonstrated that humans achieve perfect physical form and perfect health generation after generation only when they consume nutrient-dense whole foods and the vital fat-soluble activators found exclusively in animal fats.

The Foundation is dedicated to restoring nutrient-dense foods to the human diet through education, research and activism. It supports a number of movements that contribute to this objective including accurate nutrition instruction, organic and biodynamic farming, pasture-feeding of livestock, community-supported farms, honest and informative labeling, prepared parenting and nurturing therapies. Specific goals include establishment of universal access to clean, certified raw milk and a ban on the use of soy formula for infants.

The Foundation seeks to establish a laboratory to test nutrient content of foods, particularly butter produced under various conditions; to conduct research into the “X Factor,” discovered by Dr. Price; and to determine the effects of traditional preparation methods on nutrient content and availability in whole foods."

The anti-Weston Price sites say that WAPF does not accept funding from industry organizations, but most of their funding comes from individual meat and dairy farmers. This would be difficult to verify so I haven't tried.

What WAPF says about food

WAPF gives their blessing to fermented soy (meaning soy sauce, tempeh, and certain bean pastes used for seasoning). These items don't compete with any other foods. But WAPF is vehemently opposed to the use of non-fermented soy products (including soy milk and most tofu), which make up the bulk of consumption and are serious, direct competition with meat and dairy products. They have devoted some serious effort to trashing non-fermented soy products in an apparent attempt to reduce the demand for them.

There's some interesting stuff in the WAPF Health Topics library illustrating their agenda. There's a long list of anti-soy articles of course, that use heavily distorted information from scientific studies to scare people. For example, breast cancer studies finding that soy has a beneficial, protective effect on hormone levels have been "repurposed" into a claim that soy has a damaging effect on hormone levels and fertility. I looked at a few of the other studies cited as "proof" that soy is evil and found that their results had been twisted as well.

WAPF is anti-vegetarian. They say it's a myth that animal products are bad for you. They encourage you to eat animal fat to lose weight.  Did you know that animal fat protects you against cancer?

Not everything on the site is related to the "eat dairy and meat and for gawds sake don't go vegetarian" theme. There are numerous other articles designed to appeal to their target audience. But if I looked more closely I bet I'd find a lot more subtle and not so subtle encouragement to eat meat and dairy in there, sandwiched in between everything else.

I'm not a vegetarian, and if I ever turn vegetarian you can take it as a sign that the apocalypse is nigh. Humans evolved as omnivores, and it's thought that our meat-eating habit was essential to the development of our exceptional mental capabilities. Animal products are an easy source of some essential nutrients that are difficult to obtain from plant foods. IMO vegetarianism is not a natural way for us to eat, but I don't object to it. It works well when it's done right, and it's superior to meat and dairy in terms of environmental friendliness and animal welfare concerns.

So I can't say that WAPF is entirely wrong about absolutely everything, but in general it looks like their claims are a gross distortion of reality.  They have taken an extremist position, and extremism is never fair and rational.

The James case

An anti-soy claim that's particularly relevant here is the James story, a lurid tale of parrots who suffered tragically from eating pellets containing soy. Click here and scroll down to the section titled "Phytoestrogens - Panacea or Poison?" to read all about it.

There are a few problems with this story. Number one, it is an isolated incident that occurred in the early 1990s. There are no other reports of anything like this happening even though many thousands of birds have been eating soy-containing pellets during the last few decades. WAPF didn't say which brand  was involved but they hinted that it was Roudybush, whose pellets have been widely used since the 1970s.

WAPF tells us that the bird's owners hired a toxicologist who read the existing literature and was horrified at what he learned. The problem with this is that everything he read was already known to the nutrition community and they didn't think that soy was dangerous. BTW The Guardian reports that the toxicologist in the story is on a crusade against soy and is an honorary board member at WAPF. 

The next problem is that WAPF didn't tell us that a dangerous mycotoxin was apparently found in the pellets. This is the single most important detail in the story, since this contamination seems like the most obvious cause for the problems in this flock.  The Parrot Society UK has posted some information provided by the bird owners, including a 1996 article by Valerie James indicating that the pellets contained zearalenone, a toxin produced by several species of fungus. Most zearalenone is produced while fungus-contaminated crops are still in the field, but it can also be produced later if storage conditions are poor. This toxin has estrogenic effects. Zearalenone is of considerable concern to livestock and poultry producers because of the severe problems that it causes. It is heat stable which means that it is not destroyed by cooking or processing.

Zearalenone can occur in beans and even vegetable oil, but it is primarily associated with grain crops including corn, barley, oats, wheat, rice, rye and sorghum (EFSA, Wikipedia). Most pellets contain at least two of these grains. It seems likely that there was tainted grain in this particular batch of pellets and the problem wasn't related to soybeans at all. It's possible that the contamination was caused by mishandling at the factory, but it seems more likely that the pellet manufacturer is innocent and the problem occurred somewhere else. Some contaminated grain may have slipped through the normal agricultural inspection process, and the manufacturer bought it thinking it was safe because it had passed inspection.  Or there may have been improper handling (for example letting the product get wet) that resulted in fungus growth after the pellets had left the factory. 

One can excuse the bird owners for thinking the problem was caused by soy, since that's apparently what the toxicologist told them. Most people don't know what zearalenone is, so they wouldn't realize that its presence was abnormal.  The toxicologist should have known better so it's hard to say why he decided to blame this isolated incident on soy instead of mycotoxin contamination.

The Harrisons website says that the problems in this case were caused by a circovirus infection, which is not related to food. It also states that:

Dr. Kirk Klasing of the University of California Davis [a well-known avian nutrition scientist] is studying the feeding of soybeans as they are normally raised and those that are genetically modified to produce phytoestrogens (specifically genistein), which are used by the pharmacological industry. This latter soybean has a thousand times the phytoestrogen content of regular soybeans. Dr Klasing has found no indication that even this high level has any effect whatsoever. His research subjects are finches, which have the highest metabolism rate and would show problems the soonest. His co-researchers have also set up flocks of finches for breeding, which starts at less than one year of age, and have not seen any effects on fertility, hatchability, chick maturation or illness.

In other words: the anti-soy rhetoric names genistein as the primary villain in their propaganda, but avian nutrition science says it has no effect on birds. 

What science says about soy

The mainstream point of view is that soy is beneficial and safe, although there are certain areas where more research would be useful to help clarify the issues. If there was serious doubt about the safety of soy, governments throughout the world would be taking action against it. The US government is accused of a lot of misbehavior and some of it is probably true, but they do look out for public health to a significant degree. Many European nations pay directly for their citizens' health care so they have an even bigger stake in public health. But far from being afraid of soy, the British government wants imported GMO soybeans so badly that they are defending a foreign corporation (Monsanto) against a lawsuit trying to block importation (Global Research).

This link on The Science of Soy is a nice summary of the current evidence-based understanding of soy. Here are some quotes from it and my comments on them.

"Nevertheless, Americans as a whole still consume very little soy protein. Based on 2003 data from the UN Food and Agriculture Organization, per-capita soy protein consumption is less than 1 gram (g) per day in most European and North American countries, although certain subpopulations such as vegetarians, Asian immigrants, and infants fed soy-based formula consume more. The Japanese, on the other hand, consume an average 8.7 g of soy protein per day; Koreans, 6.2–9.6 g; Indonesians, 7.4 g; and the Chinese, 3.4 g."

The anti-soy rhetoric is coming from populations who don't consume very much of it - Americans and Europeans. Meanwhile, the people in Southeast Asia who eat a lot of soy (most of it non-fermented) appear to be thriving on it.

"populations that consume a lot of soy, particularly those in eastern Asia, have less breast cancer, prostate cancer, and cardiovascular disease, and fewer bone fractures. Additionally, women in these populations report fewer menopausal symptoms, such as hot flashes, and both men and women have a lower incidence of aging-related brain diseases."

What about those estrogenic effects that Weston Price talks about so much?

"Soy isoflavones are frequently referred to as weak estrogens... They are not especially potent, however... [long technical description of what they do]... Such activities have potential benefits—if they occur in the body."

The article goes on to mention that the excessively high concentrations of phytoestrogens used in glass-dish studies are probably not relevant to what actually occurs in the body. This is a fact that Weston Price has ignored, opting instead to use the results of in vitro studies as fuel for scare tactics.

Southeast Asia has a very high population density, so it doesn't look like their high level of soy consumption is interfering with their fertility. IMO it would probably be prudent for a woman experiencing fertility problems to refrain from eating a lot of soy, but it doesn't seem to be an issue for most people. 

Weston Price focuses a lot of attention on the horrors of genistein, a compound found in soybeans.  The science article doesn't provide a short, convenient quote, but in essence says that very little genistein is actually absorbed, and the studies on genistein mostly used injections of it to bypass the normal metabolic pathway, which skewed the results. A professional panel "found little cause for concern about human exposure to genistein".

"the cumulative evidence of numerous biomarker studies has confirmed that [Asian] diets are significantly higher in both isoflavones and lignans (another phytoestrogen) compared to the typical Western diet."

What happens when SE Asians immigrate to Western countries and start eating less soy as they adapt to the local diet?

“it looks like this reliance on plant proteins is one of these things that goes away after [immigrants have] been here a while,” Kaplan says. “What also goes away is any protection from chronic disease that we ascribe to those populations.”

Oh. They become LESS healthy when they eat less soy. That's why some people started calling for Americans and Europeans to start eating more of it. But be wary of sources calling soy a miracle food, because these are overstated too. 

"Approximately 20–25% of U.S. infants receive at least some soy-based formula in their first year... Given the limited evidence for the health effects of soy isoflavones in infants, pediatric and health organizations in several countries suggest caution in feeding soy to infants and young children... However, other experts indicate that soy formula is an adequate source of nutrition for infants with more than 40 years of apparently safe use. 'It’s always true that there could be something subtle that we didn’t look for or didn’t know to look for, but so far we haven’t seen any major health problems'."

What happens when millions of human infants are fed a diet of soy-based formula over the course of several decades? Nothing dangerous evidently. A few minor differences have been found between adults who were fed on soy formula as infants and those who got cow's milk formula, and it's not clear whether those differences are real. Keep in mind that society puts a high value on the health and safety of babies, and that babies fed exclusively on soy formula would probably have a much higher exposure to soy than birds who eat pellets as part of their diet. In addition babies tend to be more sensitive than adults to irritants and toxins. But in spite of all this, no major problems have been observed.

There may be non-essential reasons why a parent would choose to give their baby a soy-based formula, for example wanting to raise a vegetarian child.  But for some parents it's a matter of necessity, since up to 5% of babies may have a milk allergy and don't do well on formula based on cow's milk. Weston Price wants to ban soy formula even though a vast amount of experience indicates that it's safe.  Banning soy formula is so important to Weston Price that it's part of their mission statement.  What do they expect milk-sensitive babies to do?

My opinion on the feeding of infants is that breast-feeding is best, since it was developed by nature specifically to meet the needs of human babies. My second choice would be for a formula based on some kind of animal milk, since we are mammals after all and this milk is expected to be more chemically similar to breast milk than plant sources. The plant-sourced formula would be my last choice.  But plant-based baby formula obviously works pretty well, so I have no objection to it.

The article didn't mention some of the other complaints about soy, such as it's alleged goitrogenic properties and problems associated with its phytic acid content.  These things have simply not been observed to be a problem. Phytic acid is a compound that is plentiful in seeds, nuts, legumes and grains. It can interfere with mineral absorption, but it is also an antioxidant whose health benefits are touted to the extent that you can buy phytate supplements to increase your intake (SelfHacked, Nutrition Diva, Evolutionary Psychiatry). The phytate content in soy isn't terribly out of line with these other common sources, and some nuts like walnuts and almonds have three or four times as much of it as soy does (Authority Nation, Precision Nutrition, Mark's Daily Apple).  It simply isn't a problem for people who eat a varied diet (Andrew Weil), and the balance of nutrients in bird pellets is more than enough to compensate for any interference with mineral absorption.

There's no doubt that eating too much soy could cause problems, because too much of anything is bad.  But at present we don't know how much is too much because it looks like we haven't reached that limit yet with either ourselves or our birds. The extensive real-world experience of veterinarians and bird owners indicates that nutritionally complete pellets are beneficial and safe for most birds, and no problems have been observed that can be blamed on soy or any other specific ingredient. Some birds are sensitive to pellets, just as some birds are sensitive to specific natural foods, and the solution in this case is to use other foods that don't cause problems.


The anti-soy claims do not hold up against the available evidence. The claims that the Weston Price Foundation is churning out propaganda that benefits the dairy and meat industry hold up very well indeed against the available evidence. The biggest question is whether they're intentionally serving these industries.

Copyright 2014-2019 Carolyn Tielfan all rights reserved