10 reasons to avoid grains
on the Paleo diet

The Paleo diet is a gluten-free and grain-free diet. 
Here are 10 reasons why.

1. Gluten

    Gluten, or rather its gliadin fraction, is a type of protein found in most, but not all, grains, such as wheat, barley, rye and most oats. Although gluten-free diets used to be prescribed solely to people diagnosed with celiac disease, we now know that there are other forms of gluten intolerance and gluten sensitivity that can benefit from a gluten-free diet. (5, 6)

    Gluten is very hard to digest and can damage your gut lining, whether you experience gastrointestinal symptoms or not. (7) Gluten increases the permeability of your intestines, causing a leaky gut, which can make it easier for incompletely digested compounds and other harmful substances that should stay in your gut (pooh!) to enter your bloodstream and cause problem.

    Some of the most common conditions and symptoms associated with gluten are:

    • Gastrointestinal issues (GI issues), such as IBS (irritable bowel syndrome), bloating, constipation, diarrhea, abdominal pain, heartburn (including GERD, or gastro-esophageal reflux disease), gluten intolerance, celiac disease;
    • Autoimmune diseases, including Hashimoto's thyroiditis (the most common form of hypothyroidism), rheumatoid arthritis, psoriasis, lupus, vitiligo, multiple sclerosis;
    • Skin problems, including eczema, acne and hives;
    • Mental health issues, including depression, attention-deficit hyperactivity disorder (ADHD), autism, anxiety, mental ups and downs and schizophrenia;
    • Many other conditions affecting different body parts, such as headaches and migraines, insomnia and poor sleep, hypoglycemia, infertility, fatigue, lack of concentration, mental fogginess, anemia (iron deficiency), asthma, weight problems, including inability to lose or gain weight and failure to thrive, muscle aches, joint pain, osteoporosis, various nutritional deficiencies, leaky gut (intestinal permeability) and more…

    Unfortunately, current testing for gluten intolerance/sensitivity is not as reliable as the ones used for diagnosing celiac disease. The best (and least expensive) way to figure out if gluten may be a problem for you is to follow an elimination diet, as suggested when getting started with the Paleo diet. Cut out gluten and grains from your diet for at least a month and then reintroduce them again. If your symptoms decrease while eating gluten-free and come back after the elimination diet, you will know that a gluten-free and grain-free diet is optimal for you.

 2. Phytic Acid / Phytates

    Phytic acid, or phytates, is an antinutrient that is only found in plant-based foods, which use it as a way to store energy in the form of phosphorus. Ruminants, like cows, have the enzyme, phytase, required to break it down, but we do not.

    Grains and legumes have the highest phytic acid content, although this antinutrient is also found in nuts and seeds. Fruits and vegetables have almost none. For example, wheat bran muffin, oatmeal and wheat bran respectively have 498 mg, 943 mg and 3,011 mg of phytic acid per 100 g, while avocado, broccoli and collard greens have less than 18 mg per 100 g. (3,8)

    The main problem with phytic acid is that it binds to the precious minerals you consume, especially calcium, iron, magnesium and zinc, preventing you from absorbing them properly. (9)

    Avoiding grains with the Paleo diet is an effective way to decrease your phytic acid intake and allows you to correct or prevent mineral deficiencies, which are associated with muscle cramping, skin problems, osteoporosis, PMS (pre-menstrual syndrome), fatigue, anemia, osteoporosis, reproduction, poor immunity (more infections and illnesses) and many other ailments.

 3. Lectins

    Lectin is another type of antinutrient found in especially high amounts in grains, legumes, nuts and seeds. (3,10)

    When you eat plant-based foods, you eat their reproductive systems. Animals have a chance to defend themselves by running away from you, but plants had to come up with a different kind of defense system to allow them to survive. Lectin is part of plants’ biological arsenal.

    Lectin has a protective role for the plant by irritating your digestive system so you don’t digest its seeds, which is needed for the reproduction and survival of their specie. Some people may experience diarrhea, bloating, nausea, reflux or vomiting when ingesting lectins. Whether you experience symptoms or not, lectins can damage your gut lining, impair nutrient absorption, compromise your gut flora and interfere with your immune system. (11) Lectins are also involved in impaired intestinal permeability, or leaky gut, which allows undigested particles (pooh!) to pass from your intestines into your blood and causing problems. (3)

    Some types of lectins, such as wheat germ agglutinin or WGA, can also trigger an autoimmune response, which means that your body starts attacking its own organs and tissues, leading to or worsening autoimmune diseases like most cases of hypothyroidism (Hashimoto's thyroiditis) and rheumatoid arthritis. (12)

 4. Other Antinutrients

    Phytic acid and lectins are not the only antinutrients found in grains. Alpha-amylase inhibitors and protease inhibitors are two others that can interfere with the enzymes your digestive system produces to properly digest food. (3)

    Alpha-amylase is the enzyme required to break down starch and although it may appear like a good thing for people with blood sugar issues or diabetes, alpha-amylase inhibitors can have negative effects on the health of your pancreas in the long-term. (3)

    Protease is the enzyme required to break down proteins into amino acids your body is able to use. Protease inhibitors in grains can compromise your protein digestion and absorption.

    Chronic exposure to these antinutrients has been poorly studied and is not known. (3)

5. Poor Nutrient Density

    In addition to preventing you from absorbing the nutrients found in the food you eat because of their mineral-binding phytic acid, gut-irritating lectins and gluten and other problematic antinutrients, grains are a poor source of bioavailable nutrients compared to meat, seafood, vegetables and fruits. (13)

    Vitamins: Grains lack vitamin A and beta-carotene, vitamin C and many B vitamins (especially vitamin B12).

    Minerals: The high phosphorus to calcium ratio of grains and food products made from grains and flour can promote bone loss. Although some grain products are enriched with iron, it is the non-heme form, which is not as readily available for your body. The bioavailablity of other important minerals like zinc, copper and magnesium is also lower in grains compared to animal foods. (3)

    Protein: The protein found in grains is incomplete because it lacks lysine and is low in threonine, two essential amino acids your body needs. (3) Animal protein on the other hand is always complete with the right proportion of amino acids.

    Unhealthy fats: The high omega-6 content of grains can also contribute to a high omega-6 to omega-3 ratio in your diet, which is associated with inflammation. Inflammation is the root cause of many of today’s chronic diseases, including cardiovascular diseases, some cancer, arthritis and various autoimmune diseases. (14)

    The basic principle of the Paleo diet is to eat real food. Real food is nutrient-dense and can help you meet all of your dietary requirements to stay healthy and prevent diseases.

6. High Carbohydrate Content

    Carbohydrates are the main source of energy and calories in grains and food products made from flours. Many Americans get over 300 grams of carbohydrates in their diet every day, which corresponds to over half of their calories, mostly from grains and sugar as found in breads and baked goods.

    Carbohydrates offer a quick source of non-lasting energy.

    The digestion process

    • When you eat carbohydrates, such as a muffin, granola bar or breakfast cereals, they are broken down into sugars. Whether your carbohydrates are in the form of sugar or starch, they all end up as simple sugars, mostly glucose, after being digested.
    • This glucose then enters your bloodstream to be used as energy. Glucose and other sugars cannot stay in your blood for too long because they are very damaging to your body.
    • To get this sugar out of your blood, your pancreas produces insulin, which has the role of helping your cells open their doors to let glucose enter. Because most people have a fairly sedentary job or are not very physically active, your cells only burn a small amount to get the energy they need.
    • Some of the leftovers can be stored in limited amounts in the form of glycogen (in your muscles and liver), but most of the carbohydrates you eat will end up stored as triglycerides, or fat, in your fat cells around your waist, hips, thighs, arms and even in your cheeks.

    A high-carbohydrate diet can contribute to insulin resistance, weight gain, obesity, metabolic syndrome, prediabetes, type 2 diabetetes, some cancers and PCOS (polycystic ovarian syndrome). (15, 16) Learn more about carbohydrates on the Paleo diet.

    The Paleo diet is not necessarily a low-carb diet, but it is lower in carbs compared to the standard American diet. The Paleo dietitian can help you find the right amount for YOUR body.

    Read more about carbohydates on the Paleo diet
    and how to find you personal carb target.

    Click here to learn about how to manage your PCOS
    with real food
    with the help of the Paleo dietitian.


    Contrarily to popular beliefs, carbohydrates are not essential. (17) There is no such thing as carbohydrate deficiency. We do need glucose, but it can be obtained either from vegetables, fruits and tubers or synthesized from protein (neoglucogenesis).

    Limiting carbohydrates by avoiding grains is a safe and effective approach to lose weight, improve your blood pressure, cholesterol levels, blood sugars, insulin resistance and other metabolic problems. (15, 16)

7. Appetite Dysregulation

    Grains, especially refined ones, can stimulate your appetite and stimulate food cravings by making your blood sugar levels fluctuate and disrupting the fragile balance between your hunger and satiety hormones (leptin, grehlin, peptide YY or PYY, and cholecystokinin or CCK). (18)

    Going grain-free by adopting the Paleo diet could help you
    get closer to your ideal weight
    .

8. Addiction

    Grains contain opioid peptides, similar to those found in drugs, that can create an addiction. (19) Although the effect is mild, eating grains at every meal every day may make you eat enough opioids to make you think that you couldn’t live without bread, pasta or cookies.

9. Short-Chain Fermentable Carbohydrates (FODMAPs)

    Some grains, especially wheat and rye, and most legumes contain short-chain fermentable carbohydrates, mainly fructans and galactans, also known as FODMAPs, which can be very problematic if you have IBS, fructose malabsorption or suffer from any gastrointestinal problems. (20)
Learn more about how to adopt a grain-free
Paleo diet to manage your IBS symptoms,
fructose malabsorption or SIBO

10.  Non-Sustainable Agriculture

    Grains are not produced and could never be produced in a sustainable manner. Immense fields with monocultures of wheat, corn and other grains are detrimental to the biodiversity and health of our planet. (21, 22)

    The Paleo diet emphasizes the importance of chooosing environment-friendly and sustainable food sources.


The Paleo diet recommends getting your fiber, carbohydrates and other important nutrients from vegetables, fruits and tubers.

The Paleo dietitian can help you
transition more smoothly to the Paleo diet
when eliminating grains.



More info about grains from the Paleo dietitian:
What about gluten-free grains?
If you think that giving up gluten-containing grains is enough, think again! Including gluten-free grains in your Paleo diet could be holding your back.

What about fiber on the Paleo diet?
Are you worried that you won't get enough fiber on the Paleo diet without your "healthy whole grains"?


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References: (1) United States Department of Agriculture. ChooseMyPlate.gov. (accessed January 2012)(2) Cordain L. The Paleo Diet: Lose Weight and Get Healthy by Eating the Foods You Were Designed to Eat. 2002: 42.(3) Cordain L. Cereal Grains: Humanity’s Double-Edged Sword. World Rev Nutr Diet. 1999; 84: 19–73.(4) Allam AH, et al. Atherosclerosis in Ancient Egyptian Mummies - The Horus Study. J Am Coll Cardiol Img. 2011; 4: 315-327.(5) Sapone A, et al. Divergence of Gut Permeability and Mucosal immune Gene Expression in Two Gluten-Associated Conditions: eliac Disease and Gluten Sensitivity. BMC Medicine. 2011; 9: 23.(6) Wangen W. Healthier Without Wheat – A New Understanding of Wheat Allergies, Celiac Disease, and Non-Celiac Gluten Intolerance. 2009.(7) Drago S, et al. Gliadin, Zonulin and Gut Permeability: Effects on Celiac and Non-Celiac Intestinal Mucosa and Intestinal Cell Lines. Scandinavian Journal of Gastroenterology. 2006; 41: 408.419.(8) Rose A. Phytic Acid – Tips for Consumers from Food Science. 2012. (accessed January 2012)(9) Reddy NR and Sathe, SK. Food Phytates. 2001(10) Nachbar MS and Oppenheim JD. Lectins in the United States diet: a Survey of Lectins in Commonly Consumed Foods and a Review of the Litterature. Am J Clin Nutr. 1980; 33: 2338-2345.(11) Vasconcelos IM and Oliveira JTA. Antinutritional Properties of Plant Lectins. Toxicon. 2004; 44: 385-403.(12) Lavelle EC, et al. The Identification of Plant Lectins With Mucosal Adjuvant Activity. Immunology. 2001; 102: 77-86.(13) Cordain L, et al. Origins and Evolution of the Western Diet: Health Implications for the 21st Century. Am J Clin Nutr. 2005; 81:341-54.(14) Simopoulos AP. The Importance of the Ratio of Omega-6/Omega-3 Essential Fatty Acids. Biomedicine & Pharmacotherapy. 2002; 56(8): 365-79.(15) Hite AH, et al. Low-Carbohydrate Diet Review: Shifting the Paradigm. Nutr Clin Pract. 2011; 26: 300-308.(16) Phinney SD and Volek JS. The Art and Science of Low Carbohydrate Living: An Expert Guide to Making the Life-Saving Benefits of Carbohydrate Restriction Sustainable and Enjoyable. 2011.(17) Institute of Medicine Food and Nutrition Board. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. 2005: 275.(18) Wolf, R. The Paleo Solution – The Original Human Diet. 2010.(19) Zioudrou C, et al. Opioid Peptides Derived from Food Proteins. J Biol Chem. 1979; 254(7): 2446-2449.(20) Gibson PR, et al. Review Article: Fructose Malabsorption and the Bigger Picture. Aliment Pharmacol Ther. 2006; 25: 349–36.(21)  Keith L. The Vegetarian Myth: Food, Justice and Sustainability. 2009.(22) Manning R. Against the Grains – How Agriculture has Hijacked Civilization. 2005.(23) Cordain L. The Nutritional Characteristics of a Contemporary Diet Based Upon Paleolithic Food Groups. JANA. 2002; 5(3): 15-24.(24) Stephen AM and Cummings JH. The Microbial Contribution to Human Faecal Mass. J Med Microbiol. 1980; 13: 45-56.(25)  Schmidt RF and Thews G. Colonic Motility. Human Physiology. 1989; 29.7:731.(26)  United States Department of Agriculture. USDA National Nutrient Database Food Search for Windows, Version 1.0, Database Version SR23.

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