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
Your diet plays an intricate role in your mood. While excess sugar has been linked to depression, certain foods, like dark leafy greens, mushrooms and turmeric, are linked to positive emotions. In the longer term, what you eat, or don't eat, may also affect your mood by altering your body's levels of certain vitamins, minerals and fatty acids involved in brain health and mood.
While many people choose to eat a vegetarian or vegan diet for health reasons, this is an important factor to consider, as research suggests doing so may be associated with depression.
In fact, in a study of 9,700 vegetarians (including a small number of vegan) men, vegetarians were nearly twice as likely to suffer from depression as meat eaters, even after adjusting for variables like job status, family history and number of children.1 The study couldn't show causation, but it did have a number of theories for why the association may exist.
Why Might Being Vegetarian Increase Depression Risk?
The association may exist because people with depression may be more likely to change their dietary preferences, or it could be related to higher blood levels of phytoestrogens, particularly among those who eat a lot of soy, or even pesticides, a consequence of consuming a lot of nonorganic produce, the researchers said. But, more likely, it has to do with nutrient levels. Vegetarians tend to have lower intakes of omega-3 fats, vitamin B12 and folate, which could affect depression risk as follows:
Omega-3 Fats
Many Americans' diets are lacking in healthy fats, including the animal-based omega-3 fats EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Although omega-3s are most well known for their role in heart health, they also play an integral role in brain health and mental health.
The 2001 book, "The Omega-3 Connection: The Groundbreaking Anti-depression Diet and Brain Program," by Harvard psychiatrist Dr. Andrew Stoll, was among the first works to bring attention to, and support the use of, omega-3 fats for depression.
There is no set recommended standard dose of omega-3 fats, but some health organizations recommend a daily dose of 250 to 500 milligrams (mg) of EPA and DHA for healthy adults. If you suffer from depression, higher doses may be called for.
In one study, an omega-3 supplement with a dose range of 200 to 2,200 mg of EPA per day was effective against primary depression.2 Good dietary sources of animal-based omega-3s include anchovies, sardines, mackerel, herring and wild-caught Alaskan salmon.
Vitamin B12
Vitamin B12 has made headlines for its powerful role in preventing cognitive decline and more serious dementia such as Alzheimer's disease. Mental fogginess and problems with memory are actually two of the top warning signs that you have vitamin B12 deficiency, indicating its importance for brain health.
However, anxiousness and depression may also occur alongside a B12 deficiency because it depresses the brain chemical serotonin, a neurotransmitter linked to your brain's pleasure centers, and dopamine, the mood regulator registering memory and mood.
Vegetarians and vegans are especially susceptible to B12 deficiency because it's derived from animal products like beef, seafood, eggs and dairy products. Vegans are urged to augment their B12 intake by stocking up on nutritional yeast, coconut oil and fortified coconut milk, but even still a strict vegan or even vegetarian diet is not recommended.
Folate
Folate helps your body produce mood-regulating neurotransmitters, including serotonin and dopamine. One 2012 study found people who consumed the most folate had a lower risk of depression than those who ate the least.3 Another study revealed that when stroke survivors took a daily supplement of B vitamins, including folic acid (synthetic folate), vitamin B6 and vitamin B12, their risk of depression was significantly reduced.4
This is one deficiency that should be easy for vegetarians and vegans to correct, as folate is found in dark leafy greens like spinach, avocados and other fresh vegetables.
Increased Consumption of Omega-6 Fats May Also Play a Role
According to the featured study, vegetarians are also known to have a higher intake of omega-6 fats, which are also associated with a greater risk of depression. A major source of omega-6 fats for many vegetarians is vegetable oil, which is linked to a host of health problems, including heart attack.
These omega-6 polyunsaturated fats, when taken in large amounts, cannot be burned for fuel. Instead, they're incorporated into cellular and mitochondrial membranes where they are highly susceptible to oxidative damage, which damages the metabolic machinery. Worse, most of these vegetable oils are highly processed and grown as GMO crops, loaded with toxic herbicide residues like Roundup.
While your body does need some omega-6, most get far too much of it compared to omega-3, and this lopsided ratio can also have adverse health consequences. Further, when heated, vegetable oils tend to oxidize. According to Dr. Fred Kummerow,5 who researched lipids and heart disease for eight decades before he died a few months ago at 102 years old, oxidized cholesterol is the real culprit that causes heart disease.
By triggering inflammation, they also trigger heart problems as well as, likely, depression. While other factors may also be involved, inflammation can have a profound impact on your mental health. As noted in one 2012 study in the journal Neuropsychopharmacology:6
"Elevated biomarkers of inflammation, including inflammatory cytokines and acute-phase proteins, have been found in depressed patients, and administration of inflammatory stimuli has been associated with the development of depressive symptoms.
Data also have demonstrated that inflammatory cytokines can interact with multiple pathways known to be involved in the development of depression, including monoamine metabolism, neuroendocrine function, synaptic plasticity, and neurocircuits relevant to mood regulation …
Psychosocial stress, diet, obesity, a leaky gut and an imbalance between regulatory and pro-inflammatory T cells also contribute to inflammation and may serve as a focus for preventative strategies relevant to both the development of depression and its recurrence."
Be Wary of Eating a Diet Too High in Grains and Beans, Devoid of Animal Products
Eating a plant-based diet can certainly be healthy, especially if it's properly balanced with healthy fats. However, the absence of all animal-based foods can take a toll over time, as certain nutrients cannot be obtained from the plant kingdom — carnosine, carnitine, taurine, vitamin B12 and animal-based omega-3 fats to name just a handful.
As noted by Dr. Steven Gundry, author of "The Plant Paradox" (who was a vegetarian himself for 15 years, during which he said he was "never sicker"), many vegetarians and vegans run into health issues because are not vegetable eaters but rather grain and bean eaters, and grains and beans are very high in inflammatory lectins — plant proteins that cause harm through molecular mimicry.
Surprisingly, lectins such as wheat germ agglutinin (WGA), found in wheat, and galactans, found in beans, even promote fat storage — despite their source being the plant kingdom. Even more surprising, considering the heart health claims allowed for whole wheat, WGA is one of the most efficient ways to induce heart disease in experimental animals.7
I'm not opposed to vegetarianism. I eat very small amounts of animal protein; mostly fish. Occasionally, I'll have some organic American grass fed certified meat. But meats are not a cornerstone staple in my diet, and I believe most people could benefit from lowering their meat consumption. I don't believe it should be entirely excluded, however, because animal foods do contain very valuable nutrients your body needs for optimal health. Organic pastured eggs and raw butter are additional source of incredibly healthy nutrients.
If you're leading a vegetarian or vegan diet for ethical reasons, consider that organic grass fed animals serve a very important role in regenerative agriculture and are an ethical choice, as they're not abused or mistreated. If, however, you choose to remain strictly vegetarian or vegan, be mindful of the nutrients you may need to supplement in your diet, as well as how to avoid the complications associated with an all-plant diet weighted toward grains and legumes loaded with autoimmune-stimulating lectins.
Can an Online Test Tell You If You're Depressed?
In related news, if you do a Google search for information about depression on a mobile device, you'll notice a screening questionnaire called PHQ-9 pop up in the search results. If you click on "check if you're clinically depressed," it will take you to a self-assessment that's supposed to tell you if you're depressed or not. It sounds like it would be a useful tool, but remember we've seen these types of screenings in the past.
WebMD's online depression screening was sponsored by drugmaker Eli Lilly, maker of the antidepressant Cymbalta, and directed users to discuss treatment with their doctors. In the case of Google, they recently partnered with the National Alliance on Mental Illness (NAMI).
As noted by PsychCentral, nearly 75 percent of NAMI's funding comes from drug companies8 and, while it bills itself as a patient advocacy group, it's actually more of a front group for the pharmaceutical industry. So be very wary of taking advice about your mental health from an online assessment, especially one put out by Google, which is in the business of capturing user data and has repeatedly been caught infringing on privacy rights.
That being said, when depression goes untreated, it can be both debilitating and life threatening. Depression may interfere with personal and work relationships, reduce work or academic performance and may affect your physical health as well. Depression reduces your ability to care for yourself properly and make adequate decisions about your health, including nutrition and sleep. Imbalances in nutrition, weight fluctuations and poor sleep habits may lead to compromised immune function as well.
It's estimated that half of people with depression do not get treatment,9 so this is an important step if you or a loved one is struggling. However, be sure the treatment you seek is appropriate for you — many can be helped without the use of antidepressants. Yoga, exercise and cognitive behavioral therapy (CBT) are examples of some non-drug-based treatments that have been proven effective at reducing symptoms of depression. Addressing your diet, as mentioned, is also important.
Be Sure to Address Your Diet for Better Mental Health
Men consuming more than 67 grams of sugar per day were 23 percent more likely to develop anxiety or depression over the course of five years than those whose sugar consumption was less than 40 grams per day, for instance, so limiting sugar is one strategy.10 This will help you support your gut health, another important factor for mental health. Eating fermented foods regularly, or taking a probiotic supplement can also help toward this end.
Consider a small study involving adults diagnosed with IBS (irritable bowel syndrome) and depression that found the probiotic Bifidobacterium longum provided depression relief. At six weeks, 64 percent of the treatment group had reduced depression scores compared to 32 percent of the control group that received a placebo.11
Further, you needn't wait to find out if the featured study's finding — that a vegetarian diet increases depression risk — is, indeed, a causative one. If you're a vegetarian or vegan, be sure you make a point to increase the animal-based omega-3s, folate and vitamin B12 in your diet to protect your mental and overall health.