Legumes + Soy + Peanuts:
a nutrient-intake dilemma
What’s the controversy over legumes and how should we address it?
Legumes are controversial ingredients in ancestral-based diets. While some specialized diets recommend eating legumes in moderation, other Paleo or Primal-style diets suggest foregoing them altogether. To us, diets are just a part of the exploration to finding out what foods fuel your best performance so we have outlined the basics to how legumes, soy, and peanuts affect digestion as an approachable tool to help you decide what role you want them to take in your diet.
When people voluntarily choose to leave legumes out of their diet, it is mainly because legumes have high levels of antinutrient factors. These factors include digestive enzyme inhibitors, phytic acid, and flatulence-promoting oligosaccharide carbohydrate chains. While relatively high in protein, B vitamins, and essential minerals like magnesium and potassium, legumes are less nutrient-dense than most animal products, and therefore not a necessary food in a well-balanced omnivorous diet.
On the other hand, many of the antinutrient factors can be eliminated via sprouting, soaking, and long, slow cooking. Legumes are a cheap source of protein for those on a budget, and when cooked properly and eaten as a supplement (not a substitute) to more nutrient-dense foods, they are safe to eat for those who do not have sensitive digestions.
Remember, the most important consideration is your own individual biochemistry! If you’re experimenting with legumes, pay attention to how you feel. Bloating and gas are signs that the legumes either haven’t been prepared properly or that you can’t tolerate them. Also, the whole category of legumes is quite large, certain legumes are better to eat than others, so it is worth diving deeper to explore the science behind the bean!
What's a legume, anyway?
Legumes are all members of the plant family Fabaceae, which is the third largest flowering plant family. Legume plants are grown for food (in which case they’re often called pulses), livestock forage, industrial oil production, and soil enhancement. Legumes have a notable protein content, at two to three times that of cereal grasses, and are important for their unique ability to fix nitrogen from the air into the soil.
When legume plants are prepared for people to eat, the primary focus is on the seed. Legume seeds are structurally similar to other seeds and grains with each legume consisting of an embryo and a protective seed coat. The embryo’s nutrient storage center is called the cotyledon — it’s the creamy center of the cooked bean. The cotyledon is made up of mostly protein and starch, except in the case of peanuts and soybeans. In addition, some legumes (like peas) contain significant levels of sucrose, giving them a distinctively sweet taste once cooked.
Depending on the species, legume seed coats can be very thin (like peanuts) or as much as 15% to 30% of the legume’s weight (like chickpeas). The seed coat is made up almost entirely of carbohydrates, and is the primary source of the legume’s indigestible fiber. Colorful seed coats, like those of the cranberry bean, get their vibrancy from antioxidant anthocyanin pigments and phenolic compounds. These compounds are often leached out into the cooking water, so if you’re cooking these beans, be sure to keep the cooking liquid!
So, what's the problem with legumes?
Like other seeds, most legumes are high in defensive compounds. These defensive compounds contain antinutrient properties and protect the seed from germinating or sprouting until the conditions are right to grow into a new plant--an important role of the plant’s natural defense mechanisms. So legumes can resist digestion after being eaten in order to protect the seed. Consequently, legumes cause digestive distress and poor nutrient absorption if they are not properly prepared.
Including legumes into a diet intended to heal your gut should be carefully thought about. In this day and age where we are overloaded with processed foods, chemicals, foods made from cutting corners, our digestive tracks are particularly sensitive. Giving legumes a break in a healing protocol diet can contribute to healthily restoring your gut health. After allowing some time to heal, potentially reintroducing legumes into a diet in the near future is a plausible option for many.
Mission Heirloom is a platform for all health journeys. We consider many types of health ailments a customer could have and create dishes that even the most sensitive individual can have. To facilitate this exploration into what fuels oneself best, we pay close attention to those healing their guts. That is why you will not find legumes in our menu.
The two most common defensive compounds found in legumes are enzyme inhibitors and lectins. Legumes contain both protease enzyme inhibitors and amylase enzyme inhibitors. They prevent the enzymes that digest proteins (proteases) and starches (amylases) from breaking down large molecules into smaller, easier to absorb amino acids and sugars. Lectins are large proteins that can also interfere with digestion. Legumes contain relatively high amounts of lectin agglutinin, with the highest levels found in soy, kidney, and lima beans. These can bind to intestinal cell walls, preventing them from absorbing nutrients. Because they are large and difficult to digest, agglutinins are also capable of moving through the gut wall, entering the bloodstream, and triggering an immune response. Both enzyme inhibitors and lectins can be inactivated by soaking the beans and by cooking them for a long time over low temperature.
One study looked into the benefits of spouting black eyed peas (also known as cowpea and southern peas), finding substantial changes to the nutritional quality of the peas such as: phytic acid decrease by 4-16 times; protein increase by 9-12%; vitamin C increase by 4-38 times; trypsin inhibitor activity decrease by 28-55%; ect. However, the burden often remains on the food preparer to prepare the legumes properly. Without decent soaking times, sprouting time and temperature, the defensive compounds remain intact.
While all beans have some level of defensive compounds, certain plants have higher levels than others. Lentils, mung beans, and black gram (or urad dal) are all relatively low in all defensive compounds. They also have thin seed coats and therefore contain fewer flatulent compounds. If you choose to experiment with legumes, these are good places to start!
Once they’re in the pot, cook them low and slow. The cooking liquid should remain at a gentle simmer (keep the heat on low). Depending on the legume, they will take anywhere from 30 minutes to 2 hours to cook. Because some of the nutrients will be leached out into the cooking liquid, it is best to cook legumes in as little liquid as possible. Save any cooking liquid and serve it in the dish.
Phytic acid is another defensive compound found in legumes. Phytic acid binds to minerals in the legume to form phytates. When a mineral is bound up with phytic acid, it cannot be absorbed in the body. Our digestive systems have a very difficult time breaking down phytates, which means that we often do not absorb the minerals in legumes. Sprouting legumes before cooking them will free the minerals from the phytic acid, making them absorbable by the body.
The other common problem with legumes is that they contain carbohydrate molecules that are impossible for our digestive enzymes to break down. These compounds are then transported to our lower digestive system, where our gut bacteria feast on the sugars in the carbohydrates and produce gas. This gas is then expelled as flatulence. Oligosaccharides in the cotyledon and the compounds that hold together the legume seed coat are both hard to digest. Beans with thicker seed coats will often create more flatulence than those with thin seed coats. Soy, navy, and lima beans are particularly problematic.
In order to make the nutrients in legumes as bioavailable as possible, sprouting and/or soaking them before cooking is crucial.
A Problematic Pair: Peanuts and Soy
No Peanuts in the Shop
So if we’re talking about antinutrient properties, we want to emphasize a couple of heavy hitters we think should be avoided completely--peanuts and soy.
Surprise (maybe), peanuts are a legume! They are notable for their fat content compared to other legumes. (They are about 25% oil by weight.) Peanuts are also relatively high in protein. Typically loved for their roasted & salted flavor, they’re embedded in United States’ traditional eating. Think of those iconic tin buckets filled with boiled peanuts for all your de-shelling pleasure, or peanut butter, and all of various trail mixes! Sure they’re a mess, sure they’re tasty, and while they’re notable for their high fat content and protein, they’re actually quite problematic.
There is a long laundry list of problems with peanuts even if you’re not allergic to them. First, they are highly susceptible to e. coli and salmonella bacteria, which can only be destroyed when roasted at a high enough temperature over a long enough time period. Additionally, peanuts have strong defensive compounds that the body can’t all break down, unfortunately, not even roasting peanuts at high temperatures. Finally, peanuts are highly susceptible to mold contamination. The fungus Aspergillus flavus is the most common mold that grows on peanuts and it releases a potent carcinogen called aflatoxin.
Peanuts are well known as a relatively common food allergy, but still only affects a small number of people. A more statistically relevant issue with peanuts is their effect on autoimmune disorders and thyroid conditions. According to Dr. Kharrazian, a leader in chronic illnesses and autoimmune disorders, an invaluable treatment for quality health is a proper diet. Peanuts increase inflammation in the gut, putting more stress on the body and brain.
Peanuts are considered to be among the most highly allergenic foods. In the United States, the leading cause of fatal allergic reactions are actually caused by peanuts and tree nuts. Indeed, many peanut allergies are severe enough to cause anaphylaxis--a rapid reaction resulting in a constricted airway, swelling of the throat and tongue, low blood pressure, and cardiac arrest--a fatal ending if anaphylaxis is not treated quickly. Globally, peanut allergies are becoming more apparent in Asia and Africa while Western countries have the highest rates, with between 1.4% and 3% of people showing signs of peanut allergies. Even more, this number is on the rise and there is particular concern with the increase of children with peanut allergies.
Peanut allergies occur when the antibody immunoglobulin E (IgE) encounters the peanut protein and releases histamine into the body. Histamine sets off a cascade of reactions, including the dilation of blood vessels and simultaneous constriction of the air passageways in the lungs. In terms of how someone develops a peanut allergy, research indicates various possibilities. George Du Toit & Colleagues found in their 2015 study, that the frequency of developing a peanut allergy decreased with the early introduction of them. Some believe that the increase in peanut allergies is correlated with the increase of soy milk formula use, while others believe that the risk of allergy decreases depending on the number of peanuts the mother eats while pregnant. For example, research published in 2014 looking at allergies among 8,205 children born between 1990 and 1994 found the presence of a peanut and/or tree nut allergy significantly decreased when non-allergic mothers ate them throughout the pregnancy. Still, there are other theories being researched. Clearly, more needs to be done before we draw any conclusions!
At this point, it’s best to opt out of that PB & J, replacing peanut butter with a more nutrient dense and healthy alternative like almond butter.