Beans, Beans the Magical Fruit?

Legumes are an adjunct to many traditional diets, and like cereal grains, are a product of agrarian civilization. They are derived from the Fabaceae family, formerly known as the Leguminosae, and contain a variety of edible species including soy (Glycine max), beans (Phaseolus spp.), pea (Pisum sativum), chickpea (Cicer arietinum) and peanuts (Arachis spp.).

Legumes are a good source of protein, and in vegetarians help to mediate the glycemic load of an otherwise high carbohydrate diet. Whole legumes are rich in fiber and can promote a healthy gut flora, assisting in problems such as constipation. Epidemiological research suggests that some legumes such as soy may have preventative effects in prostate, gastric and colorectal cancer, and may assist in menopausal symptoms by virtue of its estrogenic activity. Consumed in small amounts most legumes will not raise blood sugar levels excessively, although some legumes such as fava beans are quite starchy and should be avoided by diabetics.

On the negative side, legumes have been shown to contain potentially toxic or health damaging constituents such as lectins, phytates and enzyme inhibitors. One large epidemiological study found that soy accelerated age-related declines in mental function. Other research has suggested a potential link between soy and reproductive issues in both men and women. And while soy may have preventative effects in some types of cancer, soy and soy protein isolates appear to promote the growth of estrogen-dependent tumors in a dose dependent manner. All of this would be less worrisome if soy and soy isolates weren’t so common in our diet, often hidden in foods we might not anticipate, such as infant formula, processed meat, baked goods, non-dairy substitutes, energy bars, snack foods, candy, margarine, vegetable shortening, mayonnaise and salad dressings. At one time in Asia soy was rarely consumed without first being fermented, such as natto, tempeh or miso, a process which deactivates its health-damaging constituents and enhances digestibility. About 1000 years ago the Chinese developed tofu or bean curd, made by curdling a soybean broth with gypsum dust – but there is no evidence that this properly denatures the problematic constituents of soy. Neither is there sound evidence that modern soy foods such as soy protein isolate, texturized soy (vegetable) protein (TSP/TVP) or soy “milk” are any safer, even discounting the fact that most of the soy grown in North America is genetically modified (and due to “pollen drift”, non-GMO soy may soon become an oxymoron).

In Ayurveda legumes are considered dry, light and cold in quality, and thus all with the exception of black gram (urad) are contraindicated in deficiency conditions. As legumes typically provoke gas and bloating (vata) they should be soaked overnight, cooked with fresh water, ginger and other spicy herbs, and be eaten with fats such as ghee. Gas and bloating can also be caused by eating too many beans at one meal. In places like India where legumes are a staple they are almost always prepared as a thin watery stew called dahl, cooking only one-small handful per person. Frying the beans in fat after they have been boiled is another practice that helps to balance out their dry, light and cold quality, practiced in India as well as in other regions such as Central and South America.

There are a large variety of legumes, and all have different properties and effects. Processing methods such as splitting (e.g. split peas, split chana etc) and washing, thereby removing the skins entirely, does make legumes more digestible. This increase in digestibility however sacrifices some of the purported benefits of legumes, such as fiber. As a general rule, I recommended whole legumes for healthy individuals, and split and washed legumes for people with weak digestion. The following is a list of what I have observed to be the best tolerated legumes and legume products for occasional or regular consumption:

• mung, adzuki, moth, urad, black-eyed pea
• chickpea (chana)
• pigeon pea (toor)
• lentil
• peas: dried green or yellow
• common beans, e.g. navy, pinto, kidney
• refried beans (homemade)
• fermented beans: black bean (douchi), tempeh, natto, miso
• soft tofu

In Ayurveda legumes are generally indicated to reduce inflammation, weight gain, edema and excess greasiness of body. Legumes are also indicated to remove wastes and toxins from the body, often prepared as a rice and bean soup called kitchari that is used as the primary dietary article during an intensive detoxification procedure called pancha karna. The one exception to this general rule is black gram or urad, which is used to enhance fertility, boost breast milk production and promote weight gain. Various Ayurvedic texts talk about urad and its ability to produce “insatiable erections”, but I’ll let readers experiment and confirm the hard truth of it. Urad is hard to digest however and is best cooked half and half with complementary legumes such as mung, and prepared with spicy, digestion-enhancing herbs.

Often I am asked about protein powders formulated yellow pea and soy protein isolates that many vegans rely upon as a primary source of protein. From the research I have seen yellow pea protein is pretty well digested, and combined with rice protein isolate forms a relatively balanced protein in terms of amino acid balance. I do however have some concern about the high concentration of phytoestrogens in the soy protein isolate, which as I mentioned is linked to the issues of cognitive decline and estrogen-receptor stimulation. Yellow protein isolate appears to be safer than the soy, but in my review I still found reference to the presence of antinutrient and potentially allergenic substances. And in contrast the “whole food” marketing noise that accompanies these products, it should be perfecting clear that legume protein isolates are highly purified chemical extracts, unlike anything humans have consumed in the 10,000 years we have chosen to eat legumes. What this ultimately means to vegan nutrition only time will tell, but in the meantime these products fill a significant gap in the vegan’s diet – even if they do taste like crap. In a later column I’ll share my thoughts on the long-term sustainability of the vegan diet from both a scientific and traditional medical perspective.

~ Todd Caldecott

ToddCaldecott.com