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Can We Fight the Blues With Greens?

March 27, 2014 by Michael Greger M.D. in News with 5 Comments

Can We Fight 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.

If you haven’t yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death and More Than an Apple a Day.

Image credit: liz west / Flickr

Starving Tumors of Their Blood Supply

March 25, 2014 by Michael Greger M.D. in News with 15 Comments

How Plants May Help Stop Cancerous Tumors

About a third of common cancers may be prevented by eating a healthy, plant-based diet; being physically active; and maintaining a healthy weight. One of the ways plants may help is by cutting off the supply lines to cancerous tumors.

A tumor cannot grow without a blood supply. Currently, it is believed that a tumor mass cannot exist in a volume greater than about the size of the ball at the tip of a ballpoint pen without a proper blood supply. This indicates that angiogenesis, the creation of new blood vessels, is critical to tumor growth.

Each one of us has cancer cells in us right now. One study describes how “by age 70, microscopic cancers are detected in the thyroid glands of virtually everyone. Most of these tumors never cause problems or become clinically significant, leading to the concept of ‘cancer without disease’ as a normal state during aging.” Cancer cells are commonly present in the body, but they can’t grow into tumors any bigger than that tiny dot size–no more than 10 million cancer cells–before needing to get hooked up to a blood supply. One way cancer turns on the tap is silencing certain tumor suppressor genes. How do we turn them back on? See, for example, Apple Skin: Peeling Back Cancer.

Another way tumors commandeer a blood supply is by diabolically releasing angiogenic factors, chemicals that cause new blood vessels to sprout into the tumor. The most important one is called vascular endothelial growth factor (VEGF). But we may be able to suppress VEGF with veggies.

Many of the phytonutrients we know and love in tea, spices, fruit, berries, broccoli, and beans can block cancer’s stimulation of new blood vessels. They’re ideal for prophylactic long-term use against breast cancer because of their reliability, availability, safety, and affordable price. A recent review concluded that we now have “convincing evidence that dietary plant constituents possess the unique ability to affect tumor angiogenesis, which may be deemed advantageous in the prevention and treatment of human breast cancer and other tumors.”

Most of these studies have only been done in a petri dish, though. Researchers stimulate human blood vessel cells and they start forming tubular structures trying to make new capillaries to feed the tumor. This tube formation can be substantially blocked by adding add plant compounds such as apigen or luteolin, found throughout the plant kingdom in foods such as citrus, celery, and peppers. In a study outlined in my video, Anti-Angiogensis: Cutting Off Tumor Supply Lines, you can see the effect of fisitin, a phytonutrient found in strawberries, shrinking the beginnings of new blood vessel formation. How else can strawberries smack on the cancer kibosh? See Strawberries versus Esophageal Cancer and Cancer Fighting Berries.

Where do researchers get their hands on human blood vessels? They get them from discarded umbilical cords or, more controversially, from the eyes of aborted fetuses. Either way, we can stimulate blood vessel formation with the tumor compound VEGF and then abolish that effect with plant compounds. Therefore, “the daily consumption of natural foods containing adequate flavonoids could be beneficial for the prevention of cancer metastasis or could improve cancer prognosis.” Given the power of plants, one might speculate that the foundation of an anti-angiogenic approach to cancer might be a whole food vegan diet.

Because we all likely have cancer cells inside us, Cancer Prevention and Treatment May Be the Same Thing. To die with cancer rather than from cancer, we need to slow down cancer doubling time. Check out one of my oldie-but-goodie video Slowing the Growth of Cancer.

The cancer-promoting growth hormone IGF-1 is another angiogenic factor, helping tumors turn on the gravy train. This may be another reason plant-based diets protect against cancer, since as few as two weeks on a healthy diet can lower IGF-1 levels. If you’re interested, check out my video series on the elegant experiments that discovered this:

-Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death and More Than an Apple a Day.

Image credit: David Eriksson-Wigg / Flickr

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