Can We Fight Blues with Greens?

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Can We Fight the Blues with Greens?

Why does frequent consumption of vegetables appear to cut one’s odds of depression by more than half? And “frequent” was defined as eating vegetables not 3 or more times a day, but just 3 or more times a week.

A 2012 study was found that eliminating animal products improved mood within two weeks. The researchers blamed arachidonic acid, found primarily in chicken and eggs, which might adversely impact mental health via a cascade of brain inflammation. More on this inflammatory omega-6 fatty acid in:

But better moods on plant-based diets could also be from the good stuff in plants—a class of phytonutrients that cross the blood brain barrier into our heads. A recent review in the journal, Nutritional Neuroscience, suggests that eating lots of fruits and vegetables “may present a noninvasive natural and inexpensive therapeutic means to support a healthy brain.” But how?

To understand the latest research, we need to understand the underlying biology of depression—the so-called monoamine theory of depression. It’s the idea that depression may arise out of a chemical imbalance in the brain. In my video Fighting the Blues with Greens? I run through an oversimplified version.

One of the ways the billions of nerves in our brain communicate with one another is through chemical signals called neurotransmitters. Two nerve cells don’t actually touch—there’s a physical gap between them. To bridge that gap, when one nerve wants to tap the other on the shoulder it releases chemicals into that gap, including three monoamines: serotonin, dopamine and norepinephrine. These neurotransmitters then float over to the other nerve to get its attention. The first nerve then sucks them back in to be reused the next time it wants to talk. It’s also constantly manufacturing more monoamines, and an enzyme, monoamine oxidase, is constantly chewing them up to maintain just the right amount.

The way cocaine works is by acting as a monoamine re-uptake inhibitor. It blocks the first nerve from sucking back up these three chemicals and so there’s a constant tapping on the shoulder—constant signaling—to the next cell. Amphetamines work in the same way but also increase the release of monoamines. Ecstasy works like speed, but just causes comparatively more serotonin release.

After awhile, the next nerve may say “enough already!” and down-regulate its receptors to turn down the volume. It puts in earplugs. So we need more and more of the drug to get the same effect, and then when we’re not on the drug we may feel crappy because normal volume transmission just isn’t getting through.

Antidepressants are thought to work along similar mechanisms. People who are depressed appear to have elevated levels of monoamine oxidase in their brain. That’s the enzyme that breaks down those neurotransmitters. In the video mentioned previously, I show the levels of monoamine oxidase in the brains of depressed individuals versus healthy individuals. If the levels of our neurotransmitter-eating enzyme is elevated, then our levels of neurotransmitters drops, and we become depressed (or so the theory goes).

So a number of different classes of drugs have been developed. The tricyclic antidepressants, named because they have three rings like a tricycle, appear to block norepinephrine and dopamine re-uptake, and so even though our enzymes may be eating these up at an accelerated rate, what gets released sticks around longer. Then there were the SSRIs (the selective serotonin reuptake inhibitors) like Prozac. Now we know what that means—they just block the re-uptake of serotonin. Then there are drugs that just block the re-uptake of norepinephrine, or block dopamine re-uptake, or a combination. But if the problem is too high levels of monoamine oxidase, why not just block the enzyme? Make a monoamine oxidase inhibitor. They did, but monoamine oxidase inhibitors are considered drugs of last resort because of serious side effects—not the least of which is the dreaded “cheese effect,” where eating certain foods while on the drug can have potentially fatal consequences. If only there was a way to dampen the activity of this enzyme without the whole bleed-into-our-brain-and-die thing.

Now we can finally talk about the latest theory as to why fruits and vegetables may improve our mood. There are inhibitors of the depression-associated enzyme in various plants. There are phytonutrients in spices, such as clove, oregano, cinnamon, and nutmeg, that inhibit monoamine oxidase, but people don’t eat enough spices to get enough into the brain. A certain dark green leafy has a lot, but its name is tobacco, which may actually be one of the reasons cigarettes make smokers feel so good. OK, but what if we don’t want brain bleeds or lung cancer? Well, there is a phytonutrient found in apples, berries, grapes, kale, onions, and green tea that may indeed affect our brain biology enough to improve our mood, which may help explain why those eating plant-based diets tend to have superior mental health.

For other natural treatments for mental illness, check out:

-Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my videos for free by clicking here and watch my full 2012 – 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

13 responses to “Can We Fight the Blues with Greens?

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  1. This is fascinating. Once again a one minute eduction improves my resolves to eat the right things (plants) and eschew the wrong things (animals). Thank you!

  2. I live in Seattle so there’s a constant fight with weather-related mood issues to add to whatever you bring. The lowering or stopping of meat eating does seem to make mood less solidly grey. I am wondering if some of it is chemistry (you need lots of acid to digest it). And possibly some is also blood flow reduction (the saturated fat). There can be good effects on mood from taking nitric oxide supplements such as Arginine-citrulline formulas, and Neo40 lozenges. I’m over 40 so have to take both of these to get an effect. But comparing these supplements to antidepressants, these supplements affected a larger area of energy in the body than just the brain–they pour the life back into everything, it seems to me. So if you examine spinach and beets, two outstanding sources of nitrates, there’s strong direct chemical creation of nitric oxide from plant-derived nitrates. Nitrates become nitrites from action of bacteria in saliva, then pass on to the acidic stomach and become nitric oxide right there. But nitrates also are recycled from gut back to the saliva in an endless loop. This is the backup mechanism for older people whose arterial linings are shot and can’t make nitric oxide from arginine as would younger people. The use of both arginine and sodium nitrite supplements like Neo40 ( effectively raises my nitric oxide levels to a good high target range in just a day or two, with great effect on mood and energy levels. It’s really quite amazing. But…I also include beets and greens in fairly steady amounts through the week, higher than the average American by far would probably eat. I juice them and blend them, etc. The turmeric supplement can elevate mood for me, also, but not provide much energy release in the body. It’s got some benefits so I add that too! :)

  3. Kaniwa

    Please post info about Kaniwa or
    Chenopodium pallidicaule, this was featured on Dr. Oz. How much phytates does it have?

    Thanks. :)

  4. What about these findings: “Vegetarians displayed elevated prevalence rates for depressive disorders, anxiety disorders and somatoform disorders. Due to the matching procedure, the findings cannot be explained by socio-demographic characteristics of vegetarians (e.g. higher rates of females, predominant residency in urban areas, high proportion of singles). The analysis of the respective ages at adoption of a vegetarian diet and onset of a mental disorder showed that the adoption of the vegetarian diet tends to follow the onset of mental disorders. Conclusion: vegetarian diet is associated with an elevated risk of mental disorders”.

    1. “the adoption of the vegetarian diet tends to follow the onset of mental disorders”

      So wouldn’t this imply that if there IS any causation here, it could not be that vegetarian diets cause mental disorders?

  5. Toxins, I value your opinion, could you please also comment on the following?

    It is based on several studies.

    Why I’m asking, 4 weeks ago I switched to a low fat vegan
    diet (whole foods, plenty of flax seeds, nuts, green veggies, fruits, lentils, peas, etc.) and feel like crap – weakness, fatigue, brain fog, sleepiness, very low mood, etc. My doctor insists that I should switch to high fat paleo-like diet instead…

  6. Toxins, or somebody else from the NF Team, please, what is you opinion about deficiency in a vegan diet of:

    1. Creatine. Studies show that vegetarians have a deficiency in creatine that leads to adverse effects on muscle and brain function.”

    2. Carnosine. Found strictly in animal tissues. Many researchers have speculated that animal foods may protect the brain and body against aging due to their large amount of carnosine.

    3. Taurine. Amino acid found only in animal foods, and it plays an important role in brain development, maintaining healthy blood pressure, controlling blood glucose, reducing oxidative stress, and preventing damage to your retinas. Although your body can synthesize some taurine most individuals can’t produce enough of it to satisfy their needs without a direct dietary source, and at least one study has shown that vegan men have much lower levels of plasma taurine than nonvegetarians.

    4. DHA. Critical for proper function of the brain. Many people who avoid animal products, supplement with flax seed instead, which is a great source of ALA… a plant form of Omega-3. However, ALA needs to be converted to DHA. Studies show that this conversion process is notoriously ineffective in humans. For this reason, vegans and vegetarians are deficient in this very important fatty acid.

    5. Vitamin K2. Critical for a healthy heart and skeletal system. Among other things, it helps shuttle calcium out of your arteries (where it contributes to plaque formation) and into your bones and teeth. Unlike vitamin K1, which is abundant in some vegan foods like dark leafy greens, vitamin K2 is only found in certain bacteria and animal products such as dairy, organ meats, and eggs.

    And that’s without mentioning B12 and D). How can be a whole plants vegan diet be sustainable if you need to take at least 7 supplements daily??? (B12, D, DHA, creatine, carnosine, taurine, K2), not mentioning calcium, iodine, iron and selenium. Help!

  7. Do you have any further suggestions for someone who is already on a vegan diet? I have been vegan for 2 years and eat large amounts of fruits and vegetables, nuts, spirulina, chlorella, maca, turmeric, cardamom etc; I do yoga and also work out consistently, but am increasingly struggling with depression. Reading that my diet is supposed to be helpful for depression combined with my worsening symptoms makes my state feel hopeless. I have also recently given up on relying on diet and begun taking anti-depressants but I would prefer to treat this with alternative methods. Do you have any suggestions?

    1. Sounds like you’re incorporating a lot of really wonderful things into your daily routine! Regular exercise, a healthy diet, and adequate sleep are a great place to start. In some cases, medication management may be necessary. Talk with your health care providers to see if there are any additional alternative therapies that you could explore – light therapy, support groups, mindfulness meditation classes, etc. Here’s another video you might be interested in: Anti-inflammatory Diet for Depression. Best wishes!

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