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If you are living with a mental health problem of any kind, there are many dietary strategies you can use to try to address the root causes of your symptoms, and the so-called paleo diet is an excellent place to start for just about everyone.

While definitions can vary, I define a paleo diet as a pre-agricultural whole foods diet. Pre-agricultural because it excludes the grains, legumes and dairy products that only became staple foods in most cultures after the birth of agriculture, and whole foods because it excludes the dizzying array of modern processed “foods” which began flooding our markets with the industrialization of our food supply in the mid-20th Century. A paleo-style diet consists therefore of meat, seafood, and/or poultry, fruits and vegetables, nuts and edible seeds, and may also include eggs.

A paleo-style diet has the potential to improve your physical health, but how might it benefit your brain? I am not aware of any clinical studies testing the effects of a paleo-style diet on mental health, but in my consultation service, I have witnessed significant improvements, particularly in certain individuals with , , and ; and I am not alone. -edge nutritional psychiatrists who recommend paleo style diets include Ann Childers MD in Oregon, Ignacio Cuaranta MD in Argentina, Emily Deans MD in Massachusetts and Kelly Brogan MD in New York.

How might these whole foods dietary patterns work to improve disorders in some people? Let’s take a look at how the removal of specific food groups may work to support better brain health.

No Grains or Legumes

Grains and legumes have only been major staple foods in most human diets for about 10,000 years, which in the grand scheme of nearly two million years of human evolutionary history is actually a very short period of time.

Grains and legumes have a lot in common. All grains and legumes are seeds, most of which are considered inedible in their natural state. Eaten raw, most grains and legumes are poor sources of nutrients and can even make you very sick. Why is that?

No self-respecting creature wants to be eaten—and plants are no exception. Plants defend themselves with sophisticated chemical weapons designed to maim or kill animal cells. All seeds contain plant embryos—the future generation of the parent plant, therefore seeds typically contain high concentrations of the fiercest defensive chemicals in the plant’s arsenal. These include a wide variety of lectins, which can poke holes in animal cells and aggravate the immune system, phytoestrogens which disrupt normal activity, goitrogens which interfere with thyroid function, and many others.

Furthermore, all seeds contain special substances designed to help them hold on to the nutrients needed for future successful sprouting. These so-called antinutrients include protease inhibitors which interfere with our ability to digest seed proteins, and phytic acid, a mineral magnet that significantly interferes with our ability to absorb iron, zinc, magnesium, and calcium—all vital to brain function. The following graph illustrates the rather significant impact of phytic acid on zinc absorption in human subjects. The blue line shows how nicely blood zinc levels rise after consuming zinc-rich oysters alone. Notice that if you eat that same amount of oysters with black beans (legumes), you absorb only about half the amount of zinc, and if you eat them with corn tortillas (corn being a grain), you absorb virtually none of the zinc from the oysters.

Source: Suzi Smith, used with permission

Soaking, sprouting, fermenting, or boiling can all help make grains and legumes easier on the body and improve their nutritional value, but none of these processes completely neutralizes all of the problematic compounds in these foods. (To learn more, click here.)

No Gluten

Beyond gluten-free, the Paleo diet is free of all grains, not just glutinous grains like wheat. Corn, oats, rice, quinoa, buckwheat, bulgur, and all other grains are off the menu. While all of these grains pose risks, grains that contain gluten bear special mention—particularly when it comes to mental health. Strictly speaking, gluten is neither a toxin nor an antinutrient—it is simply a seed storage protein found in wheat, barley, rye, and triticale. We are clearly not well equipped to use this protein for food, as evidenced by the fact that we can’t completely break it down into individual amino acids.

There seem to be important connections between gluten and neuropsychiatric disorders. The book Grain Brain by neurologist David Perlmutter helped introduce the public to the risks to brain health of gluten and other grains. While the relationship between gluten and psychiatric disorders remains poorly understood, and more research is clearly needed, the information we do have suggests clear risks to mental health—at least in susceptible individuals.

Gluten can cause Celiac disease, an autoimmune disease characterized by the production of antibodies against proteins in the small intestine. It is well established that Celiac disease, which affects about 1% of the population, is often accompanied by psychiatric symptoms, particularly depression and . However, some people without Celiac disease appear to have an abnormal immune reaction to gluten which may also be associated with psychiatric symptoms. For example, people with , spectrum disorder, and are more likely to have antibodies against gluten-derived peptides (short chains of amino acids resulting from the incomplete digestion of gluten) in their bloodstream than those in the general population. Levels of antibodies can be up to four times higher in people with schizophrenia compared to people without schizophrenia. There have been a number of published case reports of people with schizophrenia and autistic spectrum disorders improving on gluten-free diets. This 2015 paper meticulously and convincingly documents the case of a 14-year-old Sicilian girl with severe psychotic symptoms including , , and thoughts due entirely to non-Celiac gluten sensitivity.

Several studies suggest that gluten may contribute to depression symptoms in some people and in my own clinical experience, I have witnessed several cases of depression, including at least one case of severe bipolar depression, which resolved when gluten was removed from the diet. This certainly does not mean that everyone who eliminates gluten will see their psychiatric symptoms disappear, but if you or someone you love is suffering from mental health problems, it is good to know that this is a distinct possibility in some cases; therefore a gluten-free diet is well worth a try. If you embark on a gluten-free trial, I would recommend abstaining from gluten for a period of at least six weeks and avoiding gluten-free processed foods made with refined carbohydrates such as baked goods and breakfast cereals.

No Refined Carbohydrates

One of the things that all healthier diets share is the avoidance of refined carbohydrates such as added sugars and processed cereals. Eating too many of the wrong carbohydrates too often can cause high blood sugar and insulin levels, which promote inflammation, , and instability throughout the body and brain. These damaging forces can drive imbalances in the activity of neurotransmitters such as serotonin, , glutamate, and GABA—the very same neurotransmitter imbalances most psychiatric medications are designed to try to correct. If your insulin levels run too high too often, your brain can become insulin resistant, making it harder for insulin to cross into the brain where it is needed to help brain cells generate energy and the vital components they need for daily operations. We are gradually coming to understand that inflammation, oxidative , and insulin resistance represent important root causes of many chronic brain illnesses, including many psychiatric disorders.

Note that if you have a significant degree of insulin resistance, a Paleo diet may contain too many carbohydrates from fruits and starchy vegetables for your metabolism. If so, you may need to switch to a low-carbohydrate version of this same diet. Click here to learn more about whether you might have insulin resistance. To learn more about the connection between refined carbohydrates and mental health, including a diagram of what happens to adrenaline levels after drinking sugary soda, see “Stabilize Your Mood with Food.”

No Refined Seed Oils

The so-called “vegetable” oils are industrially extracted from seeds, some of which we don’t typically think of as foods such as canola (rapeseed), cottonseed, and safflower seeds, as well as some that we do think of as foods such as corn, peanuts, and sunflower seeds. These oils were not available to any significant extent prior to the industrialization of our food supply in the mid-20th century, but you can now find them in nearly every processed and prepared food in the grocery store. Most of these oils are exceedingly high in linoleic acid, an omega-6 important to our immune system. Omega-6 fatty acids exist in delicate balance with omega-3 fatty acids to regulate the processes of inflammation and healing. Diets too high in omega-6 fatty acids tip the scales too far towards inflammation and away from healing, reduce the brain’s access to DHA (an omega-3 fatty acid critical to brain function) and upset endocannabinoid signaling in the brain, increasing risk for and other inflammatory conditions. This randomized clinical trial found that eliminating vegetable oils from the diet reduced pain and psychological distress in people with chronic daily headaches. This post includes a table listing the omega-6 content of common vegetable oils in comparison to other edible oils to help you make healthier choices.

No Dairy

A true Paleo-style diet is dairy-free. We have very little scientific research to help us understand how dairy products affect mental health, but what we do have is intriguing. It has been shown for example in a number of studies that people with autistic spectrum disorders, bipolar disorder, and schizophrenia tend to have higher levels of antibodies against dairy proteins.

In a 2015 study jointly conducted by researchers at Johns Hopkins, Columbia and Heidelberg Universities, similar levels of anti-casein antibodies [casein is the primary protein in milk] were found in the bloodstream of people with and without schizophrenia, but those with schizophrenia tended to have higher antibody levels in the brain. [

This does not necessarily mean that dairy products cause schizophrenia, it could simply suggest that people with schizophrenia may have “leakier” blood-brain barriers that allow unwanted substances into the brain.

Includes Animal Foods

Central to the Paleo diet is not just the absence of post-agricultural ingredients, but also the presence of meat, seafood, and/or poultry. These nutritious animal foods provide complete proteins in easily digestible forms and vital nutrients in their most highly bioavailable forms (the forms easiest for us to absorb and utilize). Eggs can also be included and are essential for those preferring a vegetarian whole foods diet. It is rather challenging (although not impossible) to construct a vegan Paleo diet because typical vegan diets rely heavily on legumes such as soy, lentils, and chickpeas—often in combination with grains— for protein. My fully referenced article “Your Brain on Plants: Micronutrients and Mental Health” explains how plant and animal foods affect our ability to access essential nutrients and discusses how specific nutrient deficiencies influence our risk for mental health disorders.

The Bottom Line

If you currently eat a typical modern diet high in grains, legumes, dairy products and processed foods, and you have any problems with your mood, , energy, sleep or stress levels, you owe it to yourself to try a pre-agricultural whole foods diet for a month to see whether it helps you feel better. Just beware of processed ingredients in trendy “Paleo-friendly” convenience foods, particularly snack bars. Examples include coconut sugar, whey protein isolate, and fruit juice concentrates. For more information and to help you get started, I highly recommend the excellent work of Paleo health and fitness expert Robb Wolf, a trustworthy pioneer in this field, as well as the popular Whole 30 program. [I have no financial relationship with these entities.]

What do you have to lose? This diet is safe and requires no special monitoring or medical supervision. It may even help you avoid psychiatric medications or allow you to work with your psychiatrist to reduce or eliminate psychiatric medications in some cases. Compared to most modern diets, a paleo-style diet contains more bioavailable nutrients and far fewer antinutrients, and therefore is more nourishing for the brain. For more information, watch my half-hour video presentation “Our Descent into Madness: Modern Diets and the Global Mental Health Crisis.”

A paleo-style diet is not a special diet, a fad diet, or a radical diet. In fact, it isn’t really a diet at all. Eating whole plant and animal foods is the way our species evolved to eat over nearly two million years of our evolutionary history—simply put, it is common sense nutrition for humans.

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