DISCLAIMER: Before we get into this hot topic, I wanted to say that the point of this blog post is not to deter you from eating plant foods. That is an informed decision you need to make on your own. I am simply trying to bring awareness to some nutritional areas that may challenge status quo. It is a fact that there are anti-nutrients in vegetables and in all plants. It is also a fact that a high oxalate (spinach, nuts) diet causes kidney stones. I have cited all the clinical studies in this article but I am adding additional resources, if you want to read more.
My advice to you: learn as much as you can on any topic and make your own informed decision based on your research, your understanding of the matter and even add adding a little bit of gut feeling. Figure out what works best for you and your family. That’s probably the best route to take. Nothing’s set in stone. If anything, you can always pivot.
Weston A. Price is the father of nutrition. I have linked to a page that is all things children’s nutrition. Our ancestors soaked and sprouted plant food in order to remove some of the toxins, as well as allow for more bioavailability in our foods.
Sally Norton received a Bachelor of Science in Nutrition, from Cornell University, and a Master of Public Health Degree, from the University of North Carolina (UNC) Chapel Hill. You can search her name for many, many discussions on oxalate crystals and oxalate dumping.
Dr. Georgia Ede is a psychiatrist and nutritionist from Harvard University. She has written vastly about plants and the potential dangers of anti-nutrients. I have linked her vegetable section but she has one for nuts and seeds, as well as other food groups.
I was a vegetarian for 12 years and so I understand the resistance this topic can receive. I simply ask that you stay a little open and do your own research before dismissing the absurdity that vegetables can be “bad” for us. We’re all just trying to be our best selves and sometimes it’s not as easy with all the misinformation we’ve been fed. I’m hoping I can shed light on some nutritional areas that may need a little more questioning.
Did you know that most plant foods have anti-nutrients? They are compounds that essentially protect the plants from bacterial infections and from being eaten by bugs. Since plants can’t run from predators, anti-nutrients are essentially plants’ self-defense mechanism.
Anti-nutrients are found in grains, legumes, beans, nuts, plant roots, vegetables, leaves and fruits.
The bigger concern is that these anti-nutrients affect the absorption of nutrients from other foods eaten at the same time. There is no exact science to figure out how many nutrients are lost with anti-nutrient foods. The answer will also vary on the individual as well as how the food is prepared.
Not all anti-nutrients are bad, as long as they are consumed in moderation. Let’s get into some of the anti-nutrients and I’ll help paint the picture.
Polyphenols known as phytochemicals are anti-nutrients that are touted for their health benefits. Dark chocolate, flaxseed meal, cocoa powder and many fruits and vegetables contain polyphenol compounds. Polyphenols may have some health benefits, such as possible body weight regulation and decreasing blood pressure, but there are studies on high doses of polyphenols causing kidney damage, tumor development and altered thyroid hormone production. You can read the details of the study here.
Flavonoids are part of the polyphenol family. They are found in tea, coffee and some whole plants. We all know there are benefits to drinking green tea and some perks with coffee consumption, but even these “good” flavonoids do inhibit mineral absorption. They can be relatively harmless as long as you don’t overconsume.
Gluten causes gut distress for many as it is one of the most difficult plant proteins to digest. Almost everyone does better without gluten. I’ve talked about why it’s better to go without grains and you can find the post here.
4. Phytic Acid (Phytate)
Phytic acid is primarily found in whole grains, legumes, seeds and some nuts. Phytic acid can decrease the absorption of iron, zinc, magnesium, copper, phosphorous and calcium. Studies show that 80% of zinc-rich foods (cashews, chickpeas), 80% of phosphorous-rich foods (pumpkin seeds, sunflower seeds) and 40% of magnesium-rich foods (spinach, almonds, avocado) can be blocked by phytates.
You can read a study here that shows less phytic acid in porridge (oatmeal) improves iron absorption. If you are feeding your infant oatmeal, try to swap oatmeal for some soft protein or fat. Your child may become iron deficient (anemic). You can also read a study done here that shows phytic acid added to white-bread inhibits magnesium absorption.
Lectins are found in legumes (beans, peanuts, soybeans) and whole grains (wheat). They can interfere with nutrient digestion and absorption of calcium, iron, phosphorous and zinc. Lectins are notorious for surviving GI tract digestion. They can then penetrate cell lining in the digestive tract and cause damage to gut epithelial cells and membrane lining, change bacterial flora and trigger autoimmune reactions. You can read the study here.
An immune response from lectin can look like hives, rashes and joint pain. You can read about lectins in more detail here.
Oxalates are found in green leafy vegetables (spinach), sesame seeds, teas, and soybeans. Oxalates can bind to calcium and iron and prevent it from being absorbed. You can read more here. Oxalates are enzyme inhibitors that can prevent proper digestion, cause gut problems and protein deficiencies. Enzymes create chemical reactions in the body that help support our bodies to function properly. Enzymes are especially important in the digestive process. Without the enzymes to properly metabolize food, GI issues can occur, such as bloating and constipation.
Tannins are similar to oxalates as they are also enzyme inhibitors. Tannins are found in teas, coffees, wines and legumes. They can interfere with iron absorption.
Glucosinolates are found in cruciferous vegetables (broccoli, kale, brussels sprouts) and can interfere with the absorption of iodine, which can then interfere with thyroid function. You may be more susceptible if you have hypothyroidism or are iodine deficient.
Saponins are found in legumes (green lentils) and whole grains (seeing a pattern with legumes and grains?!). They can interfere with normal nutrient absorption (iron, zinc) and similar to lectins, can affect the GI lining, causing leaky gut and autoimmune responses. You can read more here.
Solanine is found in nightshades (potatoes, eggplants, tomatoes, peppers). For some, these can cause inflammatory bowel disease and autoimmune conditions. Others may feel a slight feeling of poisoning. (nausea, throat burning, headaches, etc.) Not everyone is adversely affected by nightshades. You can learn more about nightshades and decide for yourself, here.
11. Trypsin Inhibitors
Trypsin inhibitors are found in grain products (cereals, porridge, baby foods). Studies show that heat can remove some of the trypsin inhibitors but these foods can cause mineral deficiencies in infants, children and people with pancreatic disease.
Isoflavones are another polyphenol antinutrient and found in soybeans. Isoflavones are classified as phytoestrogens as they can have estrogen-like effects. They are endocrine disruptors, causing adverse effects to hormone regulation and hormone changes. You can read a study on soy isoflavones consumption and the risk of breast cancer here and other disease risks, here.
Great… so what can I eat?
The first time I read about anti-nutrients, I felt a little disheartened, thinking there’s nothing left to eat.
Here are some tips to reduce your anti-nutrient load.
1) Food preparation is critical. Soaking and sprouting foods and boiling vegetables can remove some of the anti-nutrients. Not all anti-nutrients will be removed but proper food preparation will help absorb more of the nutrients. Here’s a resource for soaking and sprouting legumes, grains and seeds. Here’s one all about phytates and a general guide for optimal ways to cook vegetables. The key here is: don’t eat vegetables raw! (wow, right? I ate salads for 12 years as a vegetarian with some fish.)
2) Break up the foods that have anti-nutrients so you are not consuming too many anti-nutrients at once.
3) Eat anti-nutrients separate from meals. For example, drink tea between meals to reduce iron being poorly absorbed or take a calcium supplement a few hours before eating phytates.
4) Avoid grains and legumes. Please stop the oatmeal — especially with kids!
Ever since becoming a nutritional therapist, I focus more on essential fats and essential proteins with my kids and less on non-essential carbohydrates. (There is no essential carbohydrate!) I also don’t worry too much about vegetables as I know my children can get more bio-available (readily absorbed) nutrients from other food groups (e.g., organ meat, eggs, salmon).