Short answer: There is almost no direct evidence that paleo helps the brain. In the one small trial of memory, a Nordic diet worked equally well. Paleo’s emphasis on whole foods and fish fits brain research, but its bans on legumes, whole grains and dairy don’t. Keep paleo’s strengths and add those foods back.

The paleo diet has not been shown to improve thinking or memory, so the evidence is insufficient. Small trials show short-term metabolic gains, such as better glucose control and lower triglycerides. But other whole-food diets achieve the same and have more direct brain evidence.

Paleo typically includes meat, poultry, fish, eggs, vegetables, fruit, nuts, seeds and fats such as olive oil. It excludes grains, legumes (including peanuts and soy), dairy, refined sugar, seed oils and processed food.

How to eat: paleo’s best parts, without the bans

  1. Eat whole, unprocessed food. This is paleo’s strongest element. Cut ultra-processed food, refined sugar and packaged snacks.
  2. Eat fish and seafood two to three times a week. Fatty fish such as salmon, sardines, mackerel, herring and anchovies provide DHA and EPA, omega-3 fats the brain relies on.
  3. Keep legumes. Lentils, chickpeas and beans are a staple of the Mediterranean diet. They provide folate, magnesium, fiber and protein. Cook them properly.
  4. Keep whole grains unless you have a medical reason to avoid them. Oats, quinoa and brown rice provide B vitamins and fiber. Avoid refined grains.
  5. Consider fermented dairy. Yogurt and kefir supply probiotics, calcium, protein and vitamin K2. If you tolerate dairy, there is no good evidence for excluding it.
  6. Eat plenty of vegetables and fruit, especially berries and leafy greens.
  7. Get enough protein. It supplies building blocks for neurotransmitters. Animal sources also supply creatine and B12.
  8. Cook with extra-virgin olive oil. Its polyphenols have shown anti-inflammatory and neuroprotective effects, mainly in laboratory studies.

The evolutionary argument

Paleo rests on the idea that our bodies evolved over millions of years on wild game, fish, plants and tubers. Agriculture began only about 10,000 to 12,000 years ago, and industrial processing is about a century old. Cordain and colleagues argued in 2005 (Cordain 2005) that this mismatch drives much modern chronic disease.

For the brain, parts of this hold. The modern Western diet harms the brain through high blood sugar, inflammation, nutrient shortfalls and gut disruption. Ancestral diets almost certainly had more omega-3s, micronutrients, fiber and polyphenols and far less refined carbohydrate.

Diet may also explain how we got big brains. The brain is about 2 percent of body mass but uses about 20 percent of resting energy. Aiello and Wheeler (1995) proposed that richer food, including more animal food, let our ancestors afford a smaller gut and a larger brain. Crawford (1999) argued that fish and shellfish, rich in ready-made DHA, helped drive brain growth. Adults convert plant omega-3 (ALA) into DHA very poorly, typically less than 5 percent. This idea is still debated.

But the argument breaks down when applied rigidly:

  • There was no single paleo diet. Arctic groups ate mostly animals. Tropical groups ate far more plants, including tubers and wild grains. The Hadza of Tanzania eat lots of honey and fibrous tubers.
  • 10,000 years is long enough for some adaptation. The ability to digest milk as an adult evolved separately in at least five populations. Farming populations also carry extra copies of a starch-digesting gene (AMY1).
  • Grains and legumes are older than paleo admits. There is evidence that humans ground wild grains at least 30,000 years ago, and that Neanderthals ate legumes and starchy plants.
  • Cooking is processing. Cooking made food far more digestible, and it may have supplied the energy for brain growth (Wrangham 2003).

What paleo gets right

Cutting ultra-processed food. This is probably paleo’s biggest contribution. A study followed 10,775 Brazilian adults (Gonçalves 2023). Those who got more than about a fifth of their calories from ultra-processed food had 28 percent faster cognitive decline over a median of 8 years. This was observational, so it can’t show cause. Any whole-food diet cuts these foods too. See ultra-processed food and the brain.

Fish. A meta-analysis (Zhang 2016) pooled 21 cohort studies. Each extra weekly serving of fish was linked to a 5 percent lower risk of dementia and a 7 percent lower risk of Alzheimer’s. These are observational findings.

Protein and creatine. Animal protein supplies tryptophan and tyrosine, which the brain uses to make serotonin and dopamine. Meat is also the main food source of creatine. In 45 young vegetarians (Rae 2003), who get little creatine from food, creatine supplements improved working memory and reasoning.

Vegetables and fruit. Flavonoid-rich foods such as berries and leafy greens are linked to better cognitive aging in large cohorts, including the Nurses’ Health Study and the Rush Memory and Aging Project.

Steadier blood sugar. Dropping refined grains and sugar tends to steady blood glucose. In a cohort of over 2,000 older adults (Crane 2013), higher blood glucose, even below the diabetic range, was linked to higher dementia risk. Our page on blood sugar and brain function explains why.

What paleo gets wrong

Excluding legumes. Paleo bans them for their “antinutrients” (lectins, phytates). But cooking destroys most lectins, and phytates matter little in a varied diet. Legumes are a staple of the Mediterranean diet, and beans are one of the MIND diet’s food groups. The Blue Zones, regions with the most centenarians, all feature legumes.

Excluding whole grains. Refined grains spike blood sugar and offer little nutrition. Whole grains are different: they supply fiber, B vitamins, magnesium and polyphenols, and the MIND diet includes them. A meta-analysis (Aune 2016) found dose-response links between whole grain intake and lower risk of heart disease, cancer and death from any cause. For people with celiac disease (about 1 percent of the population) or documented gluten sensitivity, avoiding grains makes sense. For everyone else, there is no evidence that whole grains harm the brain.

Excluding all dairy. Fermented dairy such as yogurt, kefir and aged cheese has little lactose and is well tolerated by most people, including many who are lactose intolerant. Its gut effects are being studied for their relevance to the brain. See fermented foods.

What the trials show

Thinking. In the only trial to measure cognition (Boraxbekk 2015), 20 overweight postmenopausal women followed a modified paleo diet or a standard Nordic diet for six months. Episodic memory improved on both, with no difference, and the gain was linked to weight loss.

Metabolic health. No major paleo trial has measured cognition, but several measured metabolic markers linked to dementia risk:

  • Jönsson 2009: This crossover trial included 13 people with type 2 diabetes. Paleo beat a standard diabetes diet on HbA1c (long-term blood sugar), triglycerides, diastolic blood pressure, weight, waist size and HDL cholesterol.
  • Lindeberg 2007: In 29 people with heart disease and glucose intolerance or diabetes, paleo improved glucose tolerance more than a Mediterranean-like diet. A follow-up (Jönsson 2010) found the paleo group felt as full while eating less energy.
  • Boers 2014: In a two-week pilot of 34 adults with metabolic syndrome features, paleo lowered blood pressure, total cholesterol and triglycerides and raised HDL compared with a healthy reference diet. Inflammation markers did not change.
  • Manheimer 2015: A meta-analysis of four trials with 159 people found greater short-term drops in waist size and triglycerides. Differences in blood pressure, HDL and fasting blood sugar favored paleo but were not statistically significant. The trials were small and short.

Insulin resistance, high blood pressure and abnormal blood fats are established risk factors for dementia. So these gains could plausibly help the brain over time, but that is inference. The Mediterranean and DASH diets produce similar metabolic gains, and some have been tested directly for cognition.

Paleo versus Mediterranean

Both diets emphasize whole food, vegetables, fruit, fish, nuts and good fats, and both limit refined sugar and processed food. The Mediterranean diet adds whole grains, legumes and moderate dairy.

The Mediterranean diet also has more brain evidence. In a sub-study of the PREDIMED trial with 334 participants (Valls-Pedret 2015), the olive-oil group scored better than controls on some cognitive tests after about four years. The MIND diet, a Mediterranean-DASH hybrid, was linked to slower decline in a cohort study (Morris 2015). But in a 3-year trial of 604 older adults (Barnes 2023), it did not improve cognition more than a control diet with the same mild calorie restriction. Paleo has almost none of this direct evidence.

For brain health, the Mediterranean diet is the better-supported choice. It is less restrictive and keeps the legumes and whole grains that paleo drops.

Frequently Asked Questions

Can the paleo diet help with brain fog?

Many people report less brain fog on paleo, and that is plausible. The likely reason is cutting ultra-processed food, refined sugar and blood sugar swings, not anything specific to paleo. Any whole-food diet that does the same should help similarly.

Is the paleo diet anti-inflammatory?

Compared with a Western diet, it can be, because it drops refined sugar, processed food and seed oils and adds vegetables and omega-3s. But in a two-week trial, inflammation markers did not change on paleo (Boers 2014). The Mediterranean diet has far more evidence.

Sources

  • Cordain, L., Eaton, S. B., Sebastian, A., Mann, N., Lindeberg, S., Watkins, B. A., O’Keefe, J. H., & Brand-Miller, J. (2005). Origins and evolution of the Western diet: health implications for the 21st century. American Journal of Clinical Nutrition, 81(2), 341–354. doi:10.1093/ajcn.81.2.341

  • Aiello, L. C., & Wheeler, P. (1995). The expensive-tissue hypothesis: the brain and the digestive system in human and primate evolution. Current Anthropology, 36(2), 199–221. doi:10.1086/204350

  • Crawford, M. A., et al. (1999). Evidence for the unique function of docosahexaenoic acid during the evolution of the modern hominid brain. Lipids, 34(Suppl), S39–S47. doi:10.1007/BF02562227

  • Wrangham, R., & Conklin-Brittain, N. (2003). Cooking as a biological trait. Comparative Biochemistry and Physiology Part A, 136(1), 35–46. doi:10.1016/s1095-6433(03)00020-5

  • Jönsson, T., Granfeldt, Y., Ahrén, B., Branell, U. C., Pålsson, G., Hansson, A., Söderström, M., & Lindeberg, S. (2009). Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study. Cardiovascular Diabetology, 8, 35. doi:10.1186/1475-2840-8-35

  • Lindeberg, S., Jönsson, T., Granfeldt, Y., Borgstrand, E., Soffman, J., Sjöström, K., & Ahrén, B. (2007). A Palaeolithic diet improves glucose tolerance more than a Mediterranean-like diet in individuals with ischaemic heart disease. Diabetologia, 50(9), 1795–1807. doi:10.1007/s00125-007-0716-y

  • Jönsson, T., Granfeldt, Y., Erlanson-Albertsson, C., Ahrén, B., & Lindeberg, S. (2010). A paleolithic diet is more satiating per calorie than a mediterranean-like diet in individuals with ischemic heart disease. Nutrition & Metabolism, 7, 85. doi:10.1186/1743-7075-7-85

  • Boers, I., Muskiet, F. A., Berkelaar, E., Schut, E., Penders, R., Hoenderdos, K., Wichers, H. J., & Jong, M. C. (2014). Favourable effects of consuming a Palaeolithic-type diet on characteristics of the metabolic syndrome: a randomized controlled pilot-study. Lipids in Health and Disease, 13, 160. doi:10.1186/1476-511X-13-160

  • Manheimer, E. W., van Zuuren, E. J., Fedorowicz, Z., & Pijl, H. (2015). Paleolithic nutrition for metabolic syndrome: systematic review and meta-analysis. American Journal of Clinical Nutrition, 102(4), 922–932. doi:10.3945/ajcn.115.113613

  • Gomes Gonçalves, N., et al. (2023). Association between consumption of ultraprocessed foods and cognitive decline. JAMA Neurology, 80(2), 142–150. doi:10.1001/jamaneurol.2022.4397

  • Crane, P. K., et al. (2013). Glucose levels and risk of dementia. New England Journal of Medicine, 369(6), 540–548. doi:10.1056/NEJMoa1215740

  • Zhang, Y., Chen, J., Qiu, J., Li, Y., Wang, J., & Jiao, J. (2016). Intakes of fish and polyunsaturated fatty acids and mild-to-severe cognitive impairment risks: a dose-response meta-analysis of 21 cohort studies. American Journal of Clinical Nutrition, 103(2), 330–340. doi:10.3945/ajcn.115.124081

  • Aune, D., et al. (2016). Whole grain consumption and risk of cardiovascular disease, cancer, and all cause and cause specific mortality: systematic review and dose-response meta-analysis of prospective studies. BMJ, 353, i2716. doi:10.1136/bmj.i2716

  • Rae, C., Digney, A. L., McEwan, S. R., & Bates, T. C. (2003). Oral creatine monohydrate supplementation improves brain performance: a double-blind, placebo-controlled, cross-over trial. Proceedings of the Royal Society B: Biological Sciences, 270(1529), 2147–2150. doi:10.1098/rspb.2003.2492

  • Boraxbekk, C. J., Stomby, A., Ryberg, M., Lindahl, B., Larsson, C., Nyberg, L., & Olsson, T. (2015). Diet-induced weight loss alters functional brain responses during an episodic memory task. Obesity Facts, 8(4), 261–272. doi:10.1159/000437157

  • Valls-Pedret, C., et al. (2015). Mediterranean diet and age-related cognitive decline: a randomized clinical trial. JAMA Internal Medicine, 175(7), 1094–1103. doi:10.1001/jamainternmed.2015.1668

  • Morris, M. C., Tangney, C. C., Wang, Y., Sacks, F. M., Barnes, L. L., Bennett, D. A., & Aggarwal, N. T. (2015). MIND diet slows cognitive decline with aging. Alzheimer’s & Dementia, 11(9), 1015–1022. doi:10.1016/j.jalz.2015.04.011

  • Barnes, L. L., et al. (2023). Trial of the MIND diet for prevention of cognitive decline in older persons. New England Journal of Medicine, 389(7), 602–611. doi:10.1056/NEJMoa2302368