The paleo diet excludes grains, legumes, dairy, refined sugars, processed foods, and industrial seed oils. If a food couldn’t have been hunted or gathered before agriculture existed (roughly 10,000 years ago), it’s off the list. That’s a surprisingly large chunk of the modern grocery store, so here’s a detailed breakdown of what’s excluded and why.
Grains and Cereals
All grains are excluded from the paleo diet. That includes wheat, rice, oats, barley, rye, corn, millet, sorghum, and anything made from them: bread, pasta, tortillas, cereal, crackers, and beer. Pseudocereals like quinoa, amaranth, and buckwheat are also off limits despite often being marketed as health foods.
The reasoning centers on compounds called antinutrients, particularly lectins and phytates. Phytates in cereal grains can reduce your body’s absorption of iron, zinc, magnesium, and calcium. Lectins, found in both grains and legumes, may interfere with gut function and trigger inflammation in some people. Tannins in whole grains can also inhibit iron absorption. Paleo proponents argue that because humans spent most of their evolutionary history without cultivated grains, our digestive systems aren’t well adapted to handle these compounds in large amounts.
Legumes, Beans, and Peanuts
Beans, lentils, chickpeas, peas, soybeans, and peanuts are all excluded. Yes, peanuts. Despite being called nuts, peanuts are botanically legumes and carry the same antinutrient profile.
Legumes contain lectins, phytates, saponins, and tannins. Soybeans have the highest lectin activity among common legumes, followed by common beans, lentils, and peas. Phytate content is also substantial: soybeans contain about 23 mg/g, fava beans around 20–23 mg/g, and common beans 16–19 mg/g. Saponins in legumes can interfere with normal nutrient absorption.
Soy gets extra scrutiny. It contains isoflavones, a type of phytoestrogen, in concentrations far higher than other plant foods. These compounds can inhibit thyroid peroxidase, an enzyme your thyroid needs to produce its hormones. Research has raised concerns that soy isoflavones may be particularly problematic for people with subclinical hypothyroidism. Goiter has been documented in infants fed soy formula, though it typically reverses once the diet changes.
Dairy Products
Milk, cheese, yogurt, butter, cream, and ice cream are all off the standard paleo list. The logic is straightforward: dairy farming didn’t exist in the Paleolithic era, and a large percentage of the global population still can’t digest lactose properly. People who are lactose intolerant lack enough of the enzyme lactase to break down milk sugar, which then passes through the digestive tract undigested and causes bloating, gas, and cramping.
Beyond lactose, paleo advocates also point to casein and whey, the two major proteins in milk, as potential sources of inflammation and immune reactions in sensitive individuals. These are separate from the lactose issue. Someone who tolerates lactose-free milk could still react to casein.
Eliminating dairy does come with a nutritional cost. Short-term studies on the paleo diet show calcium intake averaging around 628 mg per day, well below recommended levels for healthy adults. The diet also provides virtually no dietary vitamin D, which compounds the calcium problem since vitamin D is essential for calcium absorption. Iodine deficiency is another risk, since dairy and iodized salt (also excluded) are primary sources of iodine in most Western diets.
Refined Sugars and Sweeteners
White sugar, brown sugar, high-fructose corn syrup, agave nectar, and all artificial sweeteners are excluded. So are candy, soft drinks, most commercial baked goods, and anything with added sugar on the label.
The metabolic case against refined sugar is well established. Concentrated sugars cause rapid spikes in blood glucose and insulin, and the paleo diet’s emphasis on foods with a low glycemic index is one of its more evidence-backed features. A meta-analysis of randomized controlled trials found that the paleo diet may have beneficial effects on carbohydrate metabolism and insulin homeostasis compared to standard dietary guidelines.
Small amounts of honey and maple syrup exist in a gray zone. Some paleo followers allow them as natural sweeteners in moderation, while stricter versions exclude all concentrated sugars regardless of source.
Industrial Seed Oils
Soybean oil, corn oil, canola oil, safflower oil, sunflower oil, and cottonseed oil are all excluded. These oils are relatively new in human diets, becoming widely available only in the last century through industrial processing.
The core concern is their omega-6 to omega-3 fatty acid ratio. Corn oil has an omega-6 to omega-3 ratio of roughly 60:1. Safflower oil is even more skewed at 77:1. For most of human history, the dietary ratio of omega-6 to omega-3 fats was around 4:1 or lower. The typical Western diet now runs about 20:1 in favor of omega-6, driven largely by these seed oils. Excess omega-6 consumption creates what researchers describe as a pro-inflammatory, pro-allergic state in the body. Paleo-approved cooking fats include olive oil, coconut oil, avocado oil, and animal fats like lard and tallow.
Processed and Packaged Foods
Beyond the major food groups above, most processed foods are excluded simply because they contain some combination of prohibited ingredients. Chips combine grains or potatoes with seed oils. Salad dressings typically contain soybean oil and sugar. Deli meats often include sugar, soy, and preservatives. Even “healthy” packaged snacks frequently rely on grains, legumes, or dairy.
Common food additives are another reason to avoid processed foods on paleo. Ingredients like carrageenan, xanthan gum, maltodextrin, soy lecithin, and carboxymethylcellulose are found in everything from almond milk to salad dressing. These additives have been linked in preclinical research to changes in gut bacteria and intestinal inflammation. A study examining children with Crohn’s disease found frequent daily exposure to xanthan gum, maltodextrin, soy lecithin, and carrageenan from processed foods.
Alcohol and Beverages
Most alcohol is off limits. Beer is made from grains. Many spirits are grain-based. Sweet cocktails, liqueurs, and mixers are loaded with sugar. Strict paleo eliminates alcohol entirely.
In more relaxed interpretations, a few options are considered less problematic. Dry red and white wines (lower in residual sugar), potato or grape-based vodka, and 100% agave tequila are sometimes accepted in moderation. The key is avoiding grain-derived spirits and anything with added sugar. Coffee and tea are generally allowed in most modern paleo frameworks, though neither would have been available in the Paleolithic era.
Foods That Fall in Gray Areas
White potatoes are one of the most debated foods in paleo circles. They’re a whole, unprocessed food that humans have eaten for thousands of years, but they belong to the nightshade family. Some stricter paleo protocols, like the Wahls Elimination diet designed for autoimmune conditions, exclude all nightshades including white potatoes, tomatoes, eggplant, and peppers to reduce lectin exposure. More moderate paleo approaches allow white potatoes, especially for active people who need the carbohydrates. Sweet potatoes are universally accepted on paleo.
Other gray-area foods include ghee (clarified butter with milk proteins removed), white rice (lower in antinutrients than other grains), and certain fermented foods. Where you draw these lines depends on whether you’re following a strict template or a more practical, personalized version of the diet. The non-negotiable exclusions, the ones virtually all paleo frameworks agree on, are grains, legumes, refined sugar, dairy, and industrial seed oils.