Noted British psychiatric researcher Malcolm Peet conducted a provocative cross-cultural analysis of the relationship between diet and mental illness. His primary finding was a strong link between high sugar consumption and the risk of both depression and schizophrenia.

There are at least two potential mechanisms through which refined sugar intake could exert a toxic effect on mental health. First, sugar actually suppresses activity of a key growth hormone in the brain called BDNF. BDNF levels are critically low in both depression and schizophrenia.

Second, sugar consumption triggers a cascade of chemical reactions in your body that promote chronic inflammation. In the long term, inflammation disrupts the normal functioning of your immune system, and wreaks havoc on your brain. Once again, it's linked to a greater risk of depression and schizophrenia.

Dr. Mercola's Comments:

It's already known that many additives, preservatives and food colorants can cause behavioral changes, and sugar should definitely be on this list as well. One of the most recent and highly plausible theories that explain sugar's impact on your mood and mental health is the connection between sugar and chronic inflammation.

The Central Role of Inflammation in Depression

Chronic inflammation in your body disrupts the normal functioning of your immune system and can wreak havoc on your brain.

Chronic inflammation is also associated with heart disease, diabetes, arthritis, and cancer. So consuming excessive amounts of sugar can truly set off an avalanche of negative health events - both mental and physical.

Keep in mind that "sugar" refers not only to refined sugar, but to many other sources as well, including high fructose corn syrup (HFCS) and starches in the form of grains and potatoes. (Following my nutrition plan is a simple way to automatically reduce your intake of all these sugar sources.)

Another major culprit that encourages inflammation in your body is rancid or oxidized omega-fats (think trans fats), whereas a diet rich in omega-3 fats helps to reduce inflammation. Healthy omega-6 fats like gamma linoleic acid (GLA), found in evening primrose, black currant seed and borage oil can also help counteract inflammation.

As you may already know, I recommend taking animal-based omega-3 supplements for many types of inflammation, and for optimal brain health. Most alternative health practitioners are also well aware of the benefits of omega-3's for depression.

While all omega-3 fats possess immune-boosting qualities, omega-3 fats from marine sources (EPA and DHA) are more biologically potent than omega-3 fat ALA found in plant sources such as flax seeds, and are more potent inflammation fighters.

My favorite source of omega-3 fats is krill oil, as it has several advantages over fish oil.

The importance of reducing inflammation when dealing with mental health issues is also evidenced by another recent study.

Published in the International Breastfeeding Journal, the study entitled "A new paradigm for depression in new mothers: the central role of inflammation and how breastfeeding and anti-inflammatory treatments protect maternal mental health" discovered that inflammation may be more than just another risk factor. It may in fact be THE risk factor that underlies all others.

The researchers' stated:
"The old paradigm described inflammation as simply one of many risk factors for depression. The new paradigm is based on more recent research that has indicated that physical and psychological stressors increase inflammation. These recent studies constitute an important shift in the depression paradigm: inflammation is not simply a risk factor; it is the risk factor that underlies all the others.

Moreover, inflammation explains why psychosocial, behavioral and physical risk factors increase the risk of depression. This is true for depression in general and for postpartum depression in particular.

Puerperal women are especially vulnerable to these effects because their levels of proinflammatory cytokines significantly increase during the last trimester of pregnancy - a time when they are also at high risk for depression.

Moreover, common experiences of new motherhood, such as sleep disturbance, postpartum pain, and past or current psychological trauma, act as stressors that cause proinflammatory cytokine levels to rise. "
In the case of post partum depression, breastfeeding is the most obvious remedy of choice as it naturally eases stress and modulates the inflammatory response.

Improve Your Mental Health by Ditching Sugar

Other studies have also found significant links between high-sugar diets and mental health problems such as depression and schizophrenia, even though they were not focused on the presence of inflammation per se.

For example, a 2004 study published in the British Journal of Psychiatry found that a higher dietary intake of refined sugar and dairy products predicted a worse 2-year outcome of schizophrenia.

In addition, a low dietary intake of fish and seafood (sources of healthy omega-3 fats) predicated high prevalence of depression.

The authors also pointed out the link between depression and physical illnesses such as heart disease and diabetes, stating that they all share epidemiological features.

And what do diabetes and heart disease have in common?

Both are caused by and/or worsened by a high intake of sugary foods.

It is a proven fact that sugar increases your insulin levels, which can lead to high blood pressure, high cholesterol, heart disease, diabetes, weight gain, premature aging, and many more negative side effects.

Sugar can also cause a rapid rise of adrenaline, which leads to hyperactivity, anxiety, and difficulty concentrating.

Reduced-Sugar Diet Also Shown to Decrease Anti-Social Behavior

As explained by Dr. Russell Blaylock, high sugar content and starchy carbohydrates lead to excessive insulin release, which can lead to falling blood sugar levels, or hypoglycemia. Hypoglycemia, in turn, causes your brain to secrete glutamate in levels that can cause agitation, depression, anger, anxiety, panic attacks and an increase in suicide risk.

Two studies that confirm this theory go back several years.

A 1985 study published in the Journal of Abnormal Psychology found that reducing sugar intake had a positive impact on emotions:
"... Subjects reported many symptoms and/or presented a distressed profile during baseline assessment. However, following a 2-wk dietary change symptoms declined, and the MMPI or POMS profiles reflected a more stable and less distressed individual.

Results suggest that a dietary change can remediate the emotional distress exhibited by some individuals..."
The dietary change consisted of a high protein, low carbohydrate diet void of sucrose and caffeine.

The other, the Los Angeles Probation Department Diet-Behavior Program: Am Empirical Analysis of Six Institutional Settings, was published in 1983.

This study included a before and after comparison of 1,382 juveniles who were detained in three juvenile halls, and a before-after comparison of 289 juveniles who were confined in three juvenile camps.

The dietary modifications were designed to lower the daily consumption of sugar in all six settings to see if it had an impact on behavior.

In the three juvenile halls, a 44 percent reduction in the incidence of antisocial behavior was found during the subsequent 3 months. And the 289 juveniles in the probation camps showed a 25 percent reduction in the incidence of antisocial behavior during the 9 months after the implementation of the revised diet.

The authors concluded:
"Although it is clear that the diet change caused the improvement in behavior, it remains to be determined if the relationship between sugar and antisocial behavior is causative."
The Most Powerful "Drug" to Heal Depression

If you are following the traditional paradigm you will most likely receive a prescription for antidepressants. Unfortunately, most of the time they simply don't work any better than placebos, and there are many studies that clearly document this.

Physical exercise, on the other hand, is one of the most powerful anti-depressants there is. Numerous studies show that aerobic exercise can improve your mood and is an antidote for mild depression and anxiety.

Dr. James S. Gordon, a world-renowned expert in using mind-body medicine to heal depression, uses exercise extensively when treating depression.
"What we're finding in the research on physical exercise is that physical exercise is at least as good as antidepressants for helping people who are depressed. And that it's even more important for older people," Dr. Gordon says.

Physical exercise changes the level of serotonin in your brain. It changes, increases your levels of "feel good" hormones, the endorphins. And also, it can increase the number of cells in your brain, in the region of the brain called the hippocampus.

These studies have been first done on animals, and it's very important because sometimes in depression, there are fewer of those cells in the hippocampus, but you can actually change your brain with exercise. So it's got to be part of everybody's treatment, everybody's plan."
If you're not sure how to use exercise like a drug, including the correct variety, intensity, and frequency, please review my Exercise page for more in-depth recommendations and guidelines on how to incorporate it into your life.

Please, don't delay starting an exercise routine. Many Americans don't get enough exercise, but this problem is easily remedied if you view exercise as a crucial part of getting healthier and happier.

Other Key Factors to Overcoming Depression

Clearly by now you will have realized that radically reducing or eliminating all forms of sugar is an important step to address the root problem in your body that may be significantly contributing to your depression.

That, plus exercising, may bring you a lot more relief than most conventional strategies used against mild to moderate depression.

Here are four additional strategies that can help you even further:

1. Address your stress - Depression is a very serious condition, however it is not a "disease." Rather, it's a sign that your body and your life are out of balance.

This is so important to remember, because as soon as you start to view depression as an "illness," you think you need to take a drug to fix it. In reality, all you need to do is return the balance to your life, and one of the key ways to doing this is by addressing your stress levels.

Stress can produce depression of all kinds by affecting your neurotransmitters, but stress is also a contributor to inflammation, which may be one of the most significant risk factors for depression.

There are many ways to address stress. Meditation or yoga works for many. Sometimes all you need to do is get outside for a walk. But in addition to such stress reduction strategies, I also recommend using an energy psychology system that can help you address buried emotional issues that you may not even be consciously aware of. For this, my favorite is the Meridian Tapping Technique (MTT).

2. Eat a healthy diet - As discussed, foods have an immense impact on your mood and ability to cope and be happy, and eating whole foods as described in my nutrition plan will best support your mental health.

3. Support optimal brain functioning with essential fats - Again, I strongly recommend supplementing your diet with a high-quality, animal-based omega-3 fat like krill oil. This may be the single most important nutrient to battle depression.

4. Get plenty of sunshine - Making sure you're getting enough sunlight exposure to have healthy vitamin D levels is also a crucial factor in treating depression or keeping it at bay.

One previous study found that people with the lowest levels of vitamin D were 11 times more prone to be depressed than those who had normal levels. Vitamin D deficiency is actually more the norm than the exception, and has previously been implicated in both psychiatric and neurological disorders.

These six primary strategies - avoiding sugar, exercising, addressing emotional stress, eating right, and optimizing your omega-3 and vitamin D levels -- are the lifestyle changes that offer you the greatest chance of restoring and maintaining your mental health.


Psychology Today July 23, 2009

The British Journal of Psychiatry May 2004;184:404-8