WARNING!
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
Foods have an immense impact on your brain, and eating whole foods as described in my nutrition plan is the best way to support both your physical and mental health. Based on the evidence, avoiding sugar (particularly fructose) is an important prevention and treatment strategy for anxiety and depression, both of which are rising in prevalence.
A number of studies have linked high-sugar diets to a higher risk of depression. Most recently, men consuming more than 67 grams of sugar per day were found to be 23 percent more likely to develop anxiety or depression over the course of five years compared to those whose sugar consumption was less than 40 grams per day.1,2,3
This held true even after accounting for other contributing factors, such as socioeconomic status, exercise, alcohol use, smoking, other eating habits, body weight and general physical health. As noted by lead author Anika Knüppel,4 a Ph.D. student at the Institute of Epidemiology and Public Health at University College London: 5
"Sweet food has been found to induce positive feelings in the short-term. People experiencing low mood may eat sugary foods in the hope of alleviating negative feelings. Our study suggests a high intake of sugary foods is more likely to have the opposite effect on mental health in the long-term."
Other Research Showing High-Sugar Diets Promote Depression
While the featured study could neither ascertain a mechanism for the link between sugar consumption and depression risk, nor could it establish causation, it adds support to other studies that have found the same link. For example, research6 published in 2002, which correlated per capita consumption of sugar with prevalence of major depression in six countries, found "a highly significant correlation between sugar consumption and the annual rate of depression."
A Spanish study7 published in 2011 linked depression specifically to consumption of baked goods. Those who ate the most baked goods had a 38 percent higher risk of depression than those who ate the least.
Similarly, a 2016 study,8 summarized in the video above, found a strong link between high-sugar diets (high-glycemic foods such as processed foods, sweetened beverages and refined grains) and depression in postmenopausal women. The higher the women's dietary glycemic index, the higher their risk of depression. A diet high in whole fruit, fiber, vegetables and lactose was associated with lowered odds of depression.
How Sugar Raises Your Depression Risk
A number of other studies have also identified mechanisms by which excessive sugar consumption can wreak havoc with your mental health. For example, eating excessive amounts of sugar:
• Contributes to insulin and leptin resistance and impaired signaling, which play a significant role in mental health.
• Suppresses activity of brain derived neurotrophic factor (BDNF), a key growth hormone that promotes healthy brain neurons. BDNF levels tend to be critically low in both depression and schizophrenia, and animal models suggest this may actually be a causative factor.
• Affects dopamine, a neurotransmitter that fuels your brain's reward system9 (hence sugar's addictive potential10,11,12) and is known to play a role in mood disorders.13
• Damages your mitochondria, which can have body-wide effects. Your mitochondria generate the vast majority of the energy (adenosine triphosphate or ATP) in your body. When sugar is your primary fuel, excessive reactive oxygen species (ROS) and secondary free radicals are created, which damage cellular mitochondrial membranes and DNA.
Needless to say, as your mitochondria are damaged, the energy currency in your body declines and your brain will struggle to work properly. Healthy dietary fats, on the other hand, create far fewer ROS and free radicals. Fats are also critical for the health of cellular membranes and many other biological functions, including and especially the functioning of your brain.
Among the most important fats for brain function and mental health are the long-chained animal-based omega-3 fats DHA and EPA. Not only are they anti-inflammatory, but DHA is actually a component in every cell of your body, and 90 percent of the omega-3 fat found in brain tissue is DHA.
• Promotes chronic inflammation which, in the long term, disrupts the normal functioning of your immune system, thereby raising your risk of depression. A 2004 cross-cultural analysis14 of the relationship between diet and mental illness found a strong link between high sugar consumption and the risk for depression and schizophrenia.
It also concluded that dietary predictors of depression are similar to those for diabetes and heart disease. One of the hallmarks of these diseases is chronic inflammation, which sugar is a primary driver of. So, excessive amounts of sugar can truly set off an avalanche of negative health events — both physical and mental.
Inflammation May Be the No. 1 Risk Factor for Depression
Another previous study published in the International Breastfeeding Journal15 found inflammation may be more than just another risk factor. It may actually be the primary risk factor that underlies all others. According to the researchers:
"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."
In another study,16 the researchers suggested "depression may be a neuropsychiatric manifestation of a chronic inflammatory syndrome." Here, they refer specifically to inflammation of the gastrointestinal tract. Studies have also found depression is closely linked to dysfunction in the gut-brain axis, in which gut inflammation plays an important role.
Artificial Sweeteners Are Also Strongly Associated With Depression
Unfortunately, many are under the mistaken belief they can protect their health by swapping refined sugar for artificial sweeteners. Nothing could be further from the truth, as research suggests artificial sweeteners may actually be more detrimental to your health than regular sugar. For example:
• In a 1986 evaluation of reactions to food additives,17 aspartame (in commonly consumed amounts) was linked to mood alterations such as anxiety, agitation, irritability and depression.
• A 1993 study18 found that individuals with mood disorders are particularly sensitive to aspartame, suggesting its use in this population should be discouraged. In the clinical study, the project was halted by the Institutional Review Board after a total of 13 individuals had completed the study because of the severity of reactions within the group of patients with a history of depression.
• In 2008, researchers asserted that excessive aspartame ingestion might be involved in the pathogenesis of certain mental disorders and may compromise emotional functioning.19
• Research presented at the annual meeting of the American Academy of Neurology in 2013 found that consumption of sweetened beverages — whether they're sweetened with sugar or artificial sweeteners — was associated with an increased risk of depression.20,21 The study included nearly 264,000 American adults over the age of 50 who were enrolled in an AARP diet and health study.
At the outset, participants filled out a detailed dietary survey. At a 10-year follow-up, they were asked whether they'd been diagnosed with depression at any point during the past decade.
Those who drank more than four cans or glasses of diet soda or other artificially sweetened beverages had a nearly 30 percent higher risk of depression compared to those who did not consume diet drinks. Regular soda drinkers had a 22 percent increased risk.
To Cure Depression, Be Sure to Address Root Causes
According to the World Health Organization, depression is now the leading cause of ill health and disability worldwide,22,23 affecting an estimated 322 million people, including more than 16 million Americans. Globally, rates of depression increased by 18 percent between 2005 and 2015.24 According to the U.S. National Institute of Mental Health, 11 percent of Americans over the age of 12 are on antidepressant drugs. Among women in their 40 and 50s, 1 in 4 is on antidepressants.25
While a number of different factors can contribute to depression, I'm convinced diet plays an enormous role. There's no doubt in my mind that radically reducing or eliminating sugar and artificial sweeteners from your diet is a crucial step to prevent and/or address depression.
One simple way to dramatically reduce your sugar intake is to replace processed foods with real whole foods. Eating plenty of fruits and vegetables is associated with lower odds of depression and anxiety,26,27 an effect ascribed to antioxidants that help combat inflammation in your body. Certain nutrients are also known to cause symptoms of depression when lacking, so it's important to eat a varied whole food diet.
Another major contributor to depression and anxiety is microwave exposure from wireless technologies, which I address below. To suggest that depression is rooted in poor diet and other lifestyle factors does not detract from the fact that it's a serious problem that needs to be addressed with compassion and non-judgment. It simply shifts the conversation about what the most appropriate answers and remedies are.
Considering the many hazards associated with antidepressants (the efficacy of which have been repeatedly found to be right on par with placebo), it would be wise to address the known root causes of depression, which are primarily lifestyle-based. Drugs, even when they do work, do not actually fix the problem. They only mask it.
Antidepressants may also worsen the situation, as many are associated with an increased risk of suicide, violence and worsened mental health in the long term. So, before you resort to medication, please consider addressing the lifestyle strategies listed below.
Nondrug Solutions for Depression
✓ Limit microwave exposure from wireless technologies
Studies have linked excessive exposure to electromagnetic fields to an increased risk of both depression and suicide.28 Power lines and high-voltage cables appear to be particularly troublesome. Addiction to or "high engagement" with mobile devices can also trigger depression and anxiety, according to recent research from the University of Illinois.29
Research30 by Dr. Martin Pall reveals a previously unknown mechanism of biological harm from microwaves emitted by cellphones and other wireless technologies, which helps explain why these technologies can have such a potent impact on your mental health.
Embedded in your cell membranes are voltage gated calcium channels (VGCCs), which are activated by microwaves. When that happens, about 1 million calcium ions per second are released, which stimulates the release of nitric oxide (NO) inside your cell and mitochondria. The NO then combines with superoxide to form peroxynitrite, which in turn creates hydroxyl free radicals, which are the most destructive free radicals known to man.
Hydroxyl free radicals decimate mitochondrial and nuclear DNA, their membranes and proteins. The end result is mitochondrial dysfunction, which we now know is at the heart of most chronic disease. The tissues with the highest density of VGCCs are your brain, the pacemaker in your heart and male testes.
Hence, health problems such as Alzheimer's, anxiety, depression, autism, cardiac arrhythmias and infertility can be directly linked to excessive microwave exposure.
If you struggle with anxiety or depression, be sure to limit your exposure to wireless technology. Simple measures include turning your Wi-Fi off at night, not carrying your cellphone on your body and not keeping portable phones, cellphones and other electric devices in your bedroom.
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✓ Get regular exercise
Studies have shown there is a strong correlation between improved mood and aerobic capacity. Exercising creates new GABA-producing neurons that help induce a natural state of calm. It also boosts your levels of serotonin, dopamine and norepinephrine, which help buffer the effects of stress.
Animal research also suggests exercise can benefit your mental health by allowing your body to eliminate kynurenine, a harmful protein associated with depression.31 |
✓ Spend more time outdoors
Spending time in nature has been shown to lower stress, improve mood and significantly reduce symptoms of depression.32 Outdoor activities could be just about anything, from walking a nature trail to gardening, or simply taking your exercise outdoors. |
✓ Get plenty of restorative sleep
Sleep and depression are so intimately linked that a sleep disorder is actually part of the definition of the symptom complex that gives the label depression. Ideally, get eight hours of sleep each night, and address factors that impede good sleep. |
✓ Address negative emotions
I believe it's helpful to view depression as a sign that your body and life are out of balance, rather than as a disease. It's a message telling you you've veered too far off course, and you need to regain your balance. One of the ways to do this involves addressing negative emotions that may be trapped beneath your level of awareness. My favorite method of emotional cleansing is Emotional Freedom Techniques (EFT), a form of psychological acupressure.
Research shows EFT significantly increases positive emotions, such as hope and enjoyment, and decreases negative emotional states.33,34,35 It's particularly powerful for treating anxiety because it specifically targets your amygdala and hippocampus, which are the parts of your brain that help you decide whether or not something is a threat.36
For serious or complex issues, seek out a qualified health care professional that is trained in EFT37 to help guide you through the process. That said, for most of you with depression symptoms, this is a technique you can learn to do effectively on your own. In the video below, EFT practitioner Julie Schiffman shows how you can use EFT to relieve symptoms of depression.
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✓ Optimize your gut health
Your mental health is closely linked to your gut health. A number of studies have confirmed gastrointestinal inflammation can play a critical role in the development of depression.38 Optimizing your gut flora will also help regulate a number of neurotransmitters and mood-related hormones, including GABA and corticosterone, resulting in reduced anxiety and depression-related behavior.39
To nourish your gut microbiome, be sure to eat plenty of fresh vegetables and traditionally fermented foods. Healthy choices include fermented vegetables, lassi, kefir and natto. If you do not eat fermented foods on a regular basis, taking a high-quality probiotic supplement is recommended.
Also remember to severely limit sugars, especially fructose, as well as grains, to rebalance your gut flora. As a standard recommendation, I suggest limiting your daily fructose consumption from all sources to 25 grams per day or less. |
✓ Optimize your vitamin D with sensible sun exposure
Studies have shown vitamin D deficiency can predispose you to depression, and that depression can respond favorably to optimizing your vitamin D stores, ideally by getting sensible sun exposure.40,41,42
In one such study, people with a vitamin D level below 20 nanograms per milliliter (ng/mL) had an 85 percent increased risk of depression compared to those with a level greater than 30 ng/mL.43 For optimal health, you'll want to make sure your vitamin D level is between 40 and 60 ng/mL year-round, so be sure to get a vitamin D test at least twice a year. |
✓ Optimize your omega-3
The animal-based omega-3 fat DHA is perhaps the single most important nutrient for optimal brain function and prevention of depression. While you can obtain DHA from krill or fish oil, it is far better to obtain it from clean, low-mercury fish such as wild Alaskan salmon, sardines, herring, anchovies and fish roe.
In addition to getting your vitamin D checked, I recommend getting an omega-3 index test to make sure you're getting enough. Ideally, you want your omega-3 index to be 8 percent or higher. |
✓ Make sure your cholesterol levels aren't too low for optimal mental health
You may also want to check your cholesterol to make sure it's not too low. Low cholesterol is linked to dramatically increased rates of suicide, as well as aggression toward others.44 This increased expression of violence toward self and others may be due to the fact that low membrane cholesterol decreases the number of serotonin receptors in the brain, which are approximately 30 percent cholesterol by weight.
Lower serum cholesterol concentrations therefore may contribute to decreasing brain serotonin, which not only contributes to suicidal-associated depression, but prevents the suppression of aggressive behavior and violence toward self and others. |
✓ Increase your B vitamin intake
Low dietary folate is a risk factor for severe depression, raising your risk by as much as 300 percent.45,46 If you're using a supplement, I suggest methylfolate, as this form of folic acid is the most effective. Other B vitamin deficiencies, including B1, B2, B3, B6, B8 and B12 also have the ability to produce symptoms of neuropsychiatric disorders. Vitamin B12 deficiency, in particular, can contribute to depression and affects 1 in 4 people.
One of the most recent studies47,48 showing the importance of vitamin deficiencies in depression involved suicidal teens. Most turned out to be deficient in cerebral folate. One of the 33 subjects was also severely deficient in CSF tetrahydrobiopterin, a critical cofactor for monoamine neurotransmitter synthesis.
According to the authors, "All patients with cerebral folate deficiency, including one with low CSF levels of 5-MTHF and tetrahydrobiopterin intermediates, showed improvement in depression symptom inventories after treatment with folinic acid; the patient with low tetrahydrobiopterin also received sapropterin … Treatment with sapropterin, a tetrahydrobiopterin analogue, led to dramatic and long-lasting remission of depression." |
✓ Helpful supplements
A number of herbs and supplements can be used in lieu of drugs to reduce symptoms of anxiety and depression. These include:
- St. John's Wort (Hypericum perforatum). This medicinal plant has a long historical use for depression, and is thought to work similarly to antidepressants, raising brain chemicals associated with mood such as serotonin, dopamine and noradrenaline.49
- S-Adenosyl methionine (SAMe). SAMe is an amino acid derivative that occurs naturally in all cells. It plays a role in many biological reactions by transferring its methyl group to DNA, proteins, phospholipids and biogenic amines. Several scientific studies indicate that SAMe may be useful in the treatment of depression.
- 5-Hydroxytryptophan (5-HTP). 5-HTP is another natural alternative to traditional antidepressants. When your body sets about manufacturing serotonin, it first makes 5-HTP. Taking 5-HTP as a supplement may raise serotonin levels. Evidence suggests 5-HTP outperforms a placebo when it comes to alleviating depression,50 which is more than can be said about antidepressants.
- XingPiJieYu. This Chinese herb, available from doctors of traditional Chinese medicine (TCM), has been found to reduce the effects of "chronic and unpredictable stress," thereby lowering your risk of depression.51
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