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Two Kiwifruit an Hour Before Bedtime

April 1, 2014 by Michael Greger M.D. in News with 9 Comments

Kiwis Might Improve Your Sleep!

The number one question in sleep research is “Why do we sleep?” followed by the question,“How much sleep do we need?” After literally hundreds of studies, we still don’t know the best answer to either question. A few years ago, I featured a large, 100,000-person study which suggested that both short and long sleep duration were associated with increased mortality, with people getting around seven hours of sleep living longest (See Optimal Sleep Duration). Since then, a meta-analysis that included over a million people was published, and found the same thing.

We still don’t know, however, whether “sleep duration is a cause or simply a marker of ill health.” Maybe sleeping too little or too long does make us unhealthy—or maybe we see the associated shortened lifespan because being unhealthy causes us to sleep shorter or longer.

Similar work has now been published on cognitive function. After controlling for a long list of factors, men and women in their 50s and 60s getting seven or eight hours appeared to have the best short-term memory compared to those that got much more or much less. The same thing was just demonstrated with immune function where “both reduced and prolonged habitual sleep durations were associated with an increased risk of pneumonia.”

It’s easy to not get too much sleep—just set an alarm. But what if we’re having problems getting enough? What if we’re one of the one in three adults that suffer symptoms of insomnia? There are sleeping pills like Valium that we can take in the short term, but they have a number of adverse side effects. Non-pharmacological approaches such as cognitive behavioral therapy are often difficult, time-consuming, and not always effective. Wouldn’t it be great to have “natural treatments that can improve both sleep onset and help patients improve the quality of sleep while improving next-day symptoms over the long term?”

What about a study on kiwifruit, featured in my video, Kiwifruit for Insomnia? Participants were given two kiwifruit an hour before bed every night for four weeks. Why kiwifruits? Well, people with sleep disorders tend to have high levels of oxidative stress, so maybe antioxidant rich foods might help? But all fruits and vegetables have antioxidants. Kiwifruits contain twice the serotonin of tomatoes—but it shouldn’t cross the blood-brain barrier. Kiwifruit has folate, and a deficiency might cause insomnia—but there’s a lot more folate in some other plant foods.

The reason they studied kiwifruits is because they got grant money from a kiwifruit company. And I’m glad they did because they found some really remarkable results: significantly improved sleep onset, duration, and efficiency using both subjective and objective measurements. Participants went from sleeping an average of six hours a night to seven—by just eating a few kiwifruits.

More on the power of kiwis in my videos Kiwifruit and DNA Repair and Kiwifruit for Irritable Bowel Syndrome, and more on sleep in Sleep & Immunity.

Videos on other natural remedies for various conditions include:

-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: Peter Miller / Flickr

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

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