Does a Bad Diet Cause Bad Behavior?

Bad Eating Behavior

Story at-a-glance

  • Your gut is quite literally your second brain, with the ability to significantly influence your mind, mood and behavior. A wide variety of nutrients found in whole foods are also critical for brain health and mood control
  • For example, niacin may be a "secret" treatment for a variety of psychological disorders, including schizophrenia, which can be notoriously difficult to address
  • Polyamines, found in foods such as wheat germ, fermented soy and matured cheeses, have been shown to stave off memory decline in fruit flies
  • Further research will investigate whether a polyamine-rich diet might have the same effect on humans
  • According to recent research, a quarter of the participants were found to have 40 percent fewer gut bacteria than the average needed for optimal health


This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.

By Dr. Mercola

Your gut is quite literally your second brain, with the ability to significantly influence your mind, mood and behavior. Again and again, researchers find that depression and a wide variety of behavioral problems appear to stem from nutritional deficiencies and/or an imbalance of bacteria in your gut.

At this point, there's simply no denying the powerful influence of the gut on both your physical and mental health. This is great news, since this places you in a distinct position of power over your and your children's psychological health.

A recent article by the Weston A. Price Foundation,1 titled: "Violent Behavior: A Solution in Plain Sight", highlighted the impact of nutrition on brain health and behavior, reviewing the importance of a number of dietary factors, such as:

  • Fat-soluble vitamins, such as vitamins A, D3 and K2
  • Water-soluble vitamins like B1, B6 and B12
  • Minerals such as iodine, potassium, iron, magnesium, zinc, chromium, manganese
  • Specific brain nutrients like choline, ARA and DHA

The article is quite extensive and well worth reading in its entirety as it covers the nutrition-behavior connection from several different angles. In short, however, the evidence is overwhelmingly clear that our current problems with violence and other behavioral problems are rooted in our diet...

As stated by Sylvia Onusic, PhD, CNS, LDN in her article:

"[T]he fact is that a large number of Americans, living mostly on devitalized processed food, are suffering from malnutrition. In many cases, this means their brains are starving...

Making things worse are excitotoxins so prevalent in the food supply, such as MSG and aspartame. People who live on processed food and who drink diet sodas are exposed to these mind-altering chemicals at very high levels.

... Modern commentators are blind to the solution, a solution that is in plain sight: clearly defining good nutrition and putting it back into the mouths of our children, starting before they are even conceived... because food is information and that information directly affects your emotions, nervous system, brain and behavior."

How Chronic Niacin Deficiency Can Cause Violent Behavior

Few people realize just how potent a factor nutritional deficiencies can be when it comes to behavioral difficulties and violence. Last year, I interviewed Dr. Andrew W. Saul on the topic of niacin and psychiatric health.

He has over 35 years of experience in natural health education and is currently serving as editor-in-chief of the Orthomolecular Medicine News Service. He's authored over 175 publications and 11 books, and has been named as one of the seven health pioneers by Psychology Today. He's also featured in the movie Food Matters, which I'm sure many of you have seen.

Dr. Saul is co-author of the excellent book, Niacin: The Real Story, along with one of the leading niacin researchers in the world, Dr. Abram Hoffer. Niacin, Dr. Hoffer found, may in fact be a "secret" treatment for psychological disorders, including schizophrenia, which can be notoriously difficult to address.

He performed the first double-blind, placebo-controlled nutrition studies in the history of psychiatry in the mid-1950s. Giving patients extremely high doses of niacin—as much as 3,000 mg per day—his cure rate for schizophrenia was 80 percent! At that point, the American Psychiatric Association blacklisted him, which may in part be why you've probably never heard of him, or his invaluable research...

A key point Dr. Saul brings up in the full interview is that certain people have what Dr. Hoffer referred to as niacin dependency, meaning they need more niacin on a regular basis. Essentially, they're beyond deficient—they're dependent on high-doses of niacin in order to remain well.

This particularly appears to be the case with mental disorders. Other researchers have since confirmed Dr. Hoffer's findings, and found that niacin can also be successfully used in the treatment of other mental disorders, such as:

Attention deficit disorder Anxiety Obsessive-compulsive disorder
General psychosis Depression Bipolar disorder

Might Fermented Foods Help Prevent Memory Loss in the Elderly?

Fermented foods have been a staple in virtually all native diets, and the more I learn about fermented foods and the importance of gut health, the more convinced I get that many of our "age-related" health problems stem from lack of protective intestinal microbiota.

We have, en masse in the Western world, abandoned traditionally fermented foods and replaced them with processed foods high in sugar and grains—which feed harmful bacteria instead and promote chronic inflammation.

The effects of this dietary trade-off can be seen in our worsening rates of behavior problems in children, depression, and mental decline in the elderly. It's worth reiterating that memory loss is NOT a "normal" part of aging at all. It used to be quite normal for seniors to be "sharp as tacks."

In a recent study, polyamines, found in foods such as wheat germ, fermented soy, and matured cheeses,2 were shown to stave off memory decline in fruit flies.3 The researchers are now embarking on studies to see whether a polyamine-rich diet might have the same effect on humans. I believe chances are, they'll find that this is indeed the case... Polyamines are aliphatic amines4 believed to be essential components of all living cells. Your body gets polyamines from three sources:

  1. Endogenous biosynthesis
  2. Intestinal microorganisms, and
  3. Through your diet

 As described in a 2011 report5 on polyamines in food:

"[P]olyamines are involved in the differentiation of immune cells as well as in regulation of inflammatory reactions, and they exert a suppressor effect on pulmonary immunologic and intestinal immunoallergic responses. In children, high polyamine intake during the first year has been significantly correlated to food allergy prevention...

Diet can to a certain extent regulate biosynthesis of polyamines. Thus, dietary polyamines have several important roles to play in this regard; supporting a normal metabolism and maintaining optimal health as well as regulating the intracellular polyamine synthesis. These seem to be of importance for maintaining the normal growth, maturation of the intestinal tract. Since the level of polyamines decreases with age in animal organs (brain, kidney, spleen, and pancreas), it has been suggested that maintenance of polyamine level from the diet is important to keep the functioning of various organs in the elderly."

At Least One-Quarter of Population Have Too Little Gut Bacteria

According to recent research6, 7 from Denmark, in which they analyzed the human gut microbial composition on 292 people (169 of them obese and 123 of healthy weight), a quarter of the participants were found to have 40 percent fewer gut bacteria than the average needed for optimal health. Obese participants were particularly at risk of having too little beneficial bacteria to maintain health. Oluf Pedersen, professor and scientific director at the Faculty of Health and Medical Sciences at the University of Copenhagen told Medical News Today:8

"Not only has this quarter fewer intestinal bacteria, but they also have reduced bacterial diversity and they harbor more bacteria causing a low-grade inflammation of the body...

Our study shows that people having few and less diverse intestinal bacteria are more obese than the rest. They have a preponderance of bacteria which exhibit the potential to cause mild inflammation in the digestive tract and in the entire body, which is reflected in blood samples that reveal a state of chronic inflammation, which we know from other studies to affect metabolism and increase the risk of type 2 diabetes and cardiovascular diseases.

...Our intestinal bacteria are actually to be considered an organ just like our heart and brain, and the presence of health-promoting bacteria must therefore be cared for in the best way possible."

Recent studies have repeatedly demonstrated that the makeup of your intestinal flora can have a powerful impact on your weight, and your propensity to gain or lose weight. For example, lean people tend to have higher amounts of various healthy bacteria compared to obese people. One 2011 animal study9 even suggested that daily intake of a specific form of lactic acid bacteria could help prevent obesity and reduce low-level inflammation. Probiotics have also been found to benefit metabolic syndrome, which often goes hand-in-hand with obesity. This makes sense since both are caused by a diet high in sugars, which leads to insulin resistance, fuels the growth of unhealthy bacteria and promotes chronic inflammation, and packs on excess weight.

Diet and Environmental Factors Affect Your Gut Flora

I have long been convinced of the value of regular probiotic supplementation. For nearly 20 years, I took a daily probiotic supplement but now I eat about four ounces of fermented vegetables a day that are started with our new high vitamin K2 starter culture, which will soon be available for sale. I sincerely believe that it is a profoundly wise health habit to either regularly supplement with a high quality probiotic or eat non-pasteurized, traditionally fermented foods such as:

Ideally, you want to eat a variety of fermented foods to maximize the variety of bacteria. Keep in mind that eating fermented foods may not be enough if the rest of your diet is really poor. Your gut bacteria are an active and integrated part of your body, and as such are vulnerable to your overall lifestyle. If you eat a lot of processed foods for instance, your gut bacteria are going to be compromised because processed foods in general will destroy healthy microflora and feed bad bacteria and yeast. Your gut bacteria are also very sensitive to:

  • Antibiotics
  • Chlorinated water
  • Antibacterial soap
  • Agricultural chemicals
  • Pollution

Are You Getting Enough "Brain Food"?

One nutrient in particular that is essential for optimal brain functioning is omega-3 fat. Along with probiotics for those who refuse to eat fermented foods, an omega-3 supplement is one of the few supplements I had recommended to all the patients at my clinic.

In terms of brain health, omega-3 deficiency is known to change the levels and functioning of both serotonin and dopamine (which plays a role in feelings of pleasure), as well as compromise the blood-brain barrier, which normally protects your brain from unwanted matter gaining access. Omega-3 deficiency can also decrease normal blood flow to your brain, an interesting finding given that studies show people with depression have compromised blood flow to a number of brain regions.

Could rampant omega-3 deficiency be a contributing factor to deteriorating mental health? I believe so—along with vitamin D deficiency, which also plays an important role.

Making matters worse, a number of foods that contain critical nutrients for optimal brain function and mood control have been "demonized" in our culture. B3- and protein-rich foods such as raw dairy products, eggs and meat have been more or less blacklisted, accused of being too high in cholesterol and fat...

I couldn't agree more with the Weston A. Price Foundation's sentiment that the answer to so many of our health problems, both physical and psychological, are right in front of our noses—in our fridge and pantry. In addition to consuming fermented foods, eliminating most sugars and grains from your diet is also of critical importance as these will increase your risk of insulin resistance, which is also linked to psychological problems such as depression and violent behavior.


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