If you’ve read our articles or heard us speak, you know we don’t base our nutritional recommendations primarily on what Paleolithic man may or may not have eaten. We care about whether the foods we’re eating here today are making us
more healthy or
less healthy. So the reasons we cite for avoiding legumes, much like our rationale with
grains,
dairy, and sugar, have far more to do with
health than
history. (It just so happens that health and history – and our genetics – are
inextricably linked.)
Legumes are a botanical family of plants that include dozens of varieties of beans, lentils, garbanzos, peas, and
peanuts. Yes, that also includes soybeans, which the multinational agriculture conglomerates have figured out how to grow in (unnatural, unsustainable) monocultures by the megaton – and
market them in a pretty effective way to the American public. (An aside: the coffee , cocoa, and vanilla “beans” are not, botanically speaking, legumes, and thus are excluded from this particular discussion.) Legumes are often used as “cover crops” because of their ability to “fix” nitrogen in the soil, improving fertility of the soil for subsequent crops. Historically, they were primarily used as an
agricultural tool, not as food. Hmmm.
The Case for the Bean
Owing to their nitrogen content (i.e. protein), legumes are often recommended as a healthy dietary choice, especially for vegetarians. Proponents of legumes cite their dietary fiber, vitamins and minerals, and “high” protein content, and may even reference observational studies that “show” that
legumes are healthy. Let’s address the potential benefits of legumes one by one.
First, you might already know that foods
other than beans – such as ample amounts of vegetables and fruit – offer us
plenty of fiber. In addition, dietary fiber isn’t as important as you might think, in the context of a healthy diet that is not promoting gut damage. In summary, eating legumes for fiber is like eating a Mounds bar for the coconut – lots of potential down sides (which we discuss in detail below) for a small potential benefit.
In terms of micronutrient density, legumes come up short when
compared to vegetables and fruit. (The lack of nutrient density in beans compared to green leafy vegetables like kale is so glaring that we can rest our “beans are nutritious” case here.)
Finally, we don’t think we need to make a lengthy argument that legumes are an inferior source of protein compared to meat, seafood, and eggs, and that regularly consuming animal protein is your
best bet to supply dietary protein (i.e. those amino acids that your body builds into your structural “stuff”). Just in case… legumes offer an incomplete amino acid profile, meaning that they do not supply all essential amino acids in
biologically useful amounts. In addition, some of the proteins that are
technically present in the legumes are poorly digestible, and thus not available for use in your body.
Digging Deeper – The Legume Downside
So legumes aren’t as awesome as the marketing might make you think. Is that really a good enough reason to ditch them altogether? Worse than simply being an inferior source of dietary protein and an unnecessary duplication of the dietary fiber supplied by the micronutrient-dense vegetables and fruit we recommend, legumes do have some major downsides – enough that we think you should keep them off your plate.
First, while legumes do contain some protein, they also contain significant amounts of carbohydrate – often several times that of the amount of useable protein. We are certainly not carb-o-phobic, but the amount of carbohydrate you’d take in using legumes as a primary protein source would mean that you were (a) not getting enough (bioavailable) protein in an attempt to limit your carbohydrate intake to a healthy amount, or (b) taking in unhealthfully high amounts of carbohydrate to get as much protein as you need. (Or, potentially, both.) And though the carbs found in beans are
low glycemic index, your body still has to secrete significant amounts of insulin to manage the relatively large amounts of blood sugar – and with insulin, like many things in your body, a little is good, but lots is…
not.
Second, legumes as a general botanical category are toxic if consumed raw. Literally…
toxic. The problem is that usual preparation methods of prolonged soaking and rinsing, cooking, sprouting, or fermenting only
partially neutralizes those toxic substances, generally referred to as lectins. (There are other
harmful substances in legumes, but we’ll stick with lectins for now.) Lectins are plant proteins that are very resistant to digestion in the stomach and small intestine. They arrive (and hang out) in the small intestine largely intact, and do some pretty dirty work there. Lectins such as phytohaemagglutinin
create damage to the wall of the small intestine (which increases gut permeability) and causes an
imbalance of gut bacteria. P.S. Increased gut permeability is
never a good thing.
If your gut integrity is compromised, that means that the immune tissue located in your gut is exposed to large amounts of potentially inflammatory substances, including those lectins. Regular exposure to lectins can promote inflammation in the digestive tract, but also elsewhere in the body (since those little buggers punched holes in your gut and can get virtually
everywhere via your bloodstream). Long story short: the fewer intact foreign proteins (including lectins) circulating in your bloodstream, the better. Foreign proteins in your bloodstream cause
systemic inflammation. Boooo.
Specific to Soy
A third concern, specific to soybeans and even moreso with processed soy products, is the content of compounds that behave like estrogen (that female sex hormone) in the human body. These compounds, classified as phytoestrogens (or “isoflavones”), bind to and stimulate – or, in some tissues, block – estrogen receptors. And while the overall research on soy products is conflicting and inclusive due to the gender-and tissue-specific effects of phytoestrogens, there are, in our view, some alarming issues related to the consumption of soy and soy products. In women, phytoestrogens have been linked to
longer and more painful menstrual periods. For guys, soy intake
decreases sperm count. And studies suggest that children fed soy-based formulas may be at risk for
compromised immune systems later in life. So while the research may not be cut and dried, we think you shouldn’t mess with your delicate sex hormone balance at
any age, and ingesting phytoestrogens in an unknown “dose” via soy products do just that.
As an aside, edamame (the unprocessed soybean) is not your best choice for everyday consumption, but processed soy products, including soy protein concentrate/isolate and “texturized vegetable protein”, are extra-bad choices for multiple reasons. In fact, the more processed forms of soybeans, like tofu, are an even more dense source of the phytoestrogens and other antinutrients than their unprocessed counterparts.
For Vegetarians
For
vegetarians who are morally or ethically opposed to using animal proteins for their amino acid supply, legumes might be a “necessary evil”, since legumes – specifically soy – are some of the densest plant source of protein. However, understand that from our view, legumes won’t come anywhere close to supplying the right amount and proportion of amino acids for
optimal health. (The argument is often made that some groups of people
survive while eating legumes, but that doesn’t mean that legumes are
your best choice to thrive.) If you’re a strict vegan, your best bet is to practice traditional preparation methods of soaking, rinsing, sprouting, fermenting and prolonged cooking, to partially break down some of those inflammatory lectins, and to rely on more dense sources of protein (less processed soy products like tofu and tempeh) that offer more grams of protein without so many accompanying carbohydrates.
The Wrap-Up
In summary, the claimed benefits of legumes aren’t quite what they’re heralded to be, and there are significant downsides to legume consumption. Yes, there are ways to make them “less bad”, but why work so hard to continue to eat things that in the end still aren’t that healthy? While prolonged soaking, rinsing, cooking and fermenting legumes neutralizes
some of the lectins, we still don’t think that they offer enough in terms of micronutrition (vitamins, minerals, and beneficial phytochemicals) to justify regular consumption. And while the jury may be out on the long-term effects of phytoestrogens, we recommend generally avoiding legumes as part of your healthy, Eat-Good-Food diet.
http://whole9life.com/2011/04/legume-manifesto/
