Full Transcript Nutrition and Psychological Well-Being 0:00 Doesn't it seem like when it comes to nutrition, there are more opinions than 0:04 facts to go around? Every day we hear new [music] theories 0:08 about diets and supplements and best foods to eat. Well, my role is to take 0:13 the mystery out of good nutrition and look at the science. Welcome to the 0:18 NutritionFacts Podcast. I'm your host, Dr. [music] Michael Greger. Today we 0:22 look at the connections between diet and psychological well-being. 0:27 There are two components of psychological health, the absence of 0:31 mental health disorders such as depression, as well as the existence of 0:35 positive psychological well-being. That's the focus of an emerging field of 0:39 positive psychology focusing on happiness, life satisfaction, and 0:43 flourishing, which may translate to physical benefits such as improvements 0:47 in blood pressure, immune function, and longevity. 0:51 What is the contribution of food consumption to well-being? Well, studies 0:55 have linked the consumption of fruits and vegetables with enhanced well-being. 0:59 A systematic review of research found evidence that consuming fruits and 1:02 vegetables was associated with increased psychological well-being. Okay, but 1:07 that's just an association. A famous criticism in this area of 1:12 research is that maybe there's just some inherent personality trait or type of 1:16 family upbringing that might lead people simultaneously to eat in a healthy way 1:21 and also to have better mental well-being. So, the diet is merely 1:26 correlated [snorts] with but incorrectly gives the appearance of helping to cause 1:30 the level of well-being. But recent research circumvented this 1:35 problem by seeing if changes in diet are correlated with changes in mental 1:40 well-being. In effect, studying the evolution of well-being and happiness 1:44 after increases in the consumption of fruits and vegetables. Increased fruit 1:48 and vegetable consumption appeared predictive of increased happiness, life 1:52 satisfaction, and well-being up to 0.24 life satisfaction points for an increase 1:58 of eight portions a day. What does that mean? Is that a lot? Is 2:02 that a little? That's a lot, equal in size to the 2:06 psychological gain of going from unemployed to getting a job. 2:12 My daily dozen recommendations are for at least nine servings of fruits and 2:16 veggies a day. This study was done in Australia. It was 2:20 repeated in the UK and researchers there found that same thing, though the Brits 2:25 may need to bump up their daily minimum to more like 10 or 11 servings a day. 2:30 Okay, but does eating fruits and veggies also reduce the risk of depression and 2:34 anxiety? I mean, well-being is nice, but governments and medical authorities are 2:39 often interested in the determinants of major mental illness, not life 2:43 satisfaction. And indeed, using the same data set, but instead looking for mental 2:48 illness, eating fruits and vegetables may help to protect against future risk 2:52 of clinical depression and anxiety as well. 2:56 A systematic review and meta-analysis of dozens of studies found that every 100 g
Fruit, Vegetables, and Happiness 3:02 increased intake of fruit was associated with a 3% reduced risk of depression. 3:07 That's about half an apple. Yet less than 10% of most Western 3:12 populations even consume a bare minimum. Maybe the problem is we're just telling 3:18 people about the long-term benefits of fruit intake for chronic disease 3:21 prevention rather than the near immediate improvements in well-being. 3:26 So, maybe we should be advertising the happiness gains, but first we need to 3:31 make sure they're real. We've been talking about associations. 3:38 Yes, a healthy diet may reduce the risk of future depression or anxiety, but 3:42 being diagnosed with depression or anxiety today could also lead to lower 3:47 fruit and vegetable intake. Now, in these studies you can indeed show that 3:51 the increase in fruit and vegetable consumption came first and not the other 3:55 way around. But as a great enlightenment philosopher 3:59 pointed out, just because the crows before dawn doesn't mean the caused 4:04 the sun to rise. To prove cause and effect, you need to put it to the test 4:10 with an interventional study. Unfortunately, to date many studies were 4:14 like this, where those randomized to eat fruit showed significant improvements in 4:20 anxiety and depression, fatigue, and emotional distress. Wow, amazing. But 4:26 that was compared to chocolate and potato chips. 4:31 Apples, clementines, and bananas making people feel better 4:35 than a sort of potato chips and chunky chocolate wafers. Not exactly 4:39 [clears throat] a revelation. This is the kind of study I've been waiting for, 4:44 a randomized controlled trial in which young adults were randomized to a diet 4:49 as usual group, encouragement to eat more fruits and veggies, or a third 4:53 group given two servings of fruits and vegetables a day to eat over and above 4:58 their regular diet. And the ones given fruits and veggies 5:01 showed improvements in their psychological well-being with increases 5:05 in vitality, flourishing, and motivation within just two weeks. 5:10 However, simply educating people to eat their fruits and vegetables may not be 5:14 enough to reap the full reward. So, perhaps greater emphasis needs to be 5:19 placed on actually providing people with fresh produce. For example, offering 5:23 free fruit for people when they shop. I know that would certainly make me happy. 5:29 In our next story, we look at how fasting, exercise, and diet can raise 5:34 BDNF levels in our brain. There's 5:38 accumulating evidence that brain-derived neurotrophic factor may be playing a 5:41 role in human depression. BDNF controls the growth of new nerve cells, so low 5:47 levels may explain the atrophy of specific brain areas you see among 5:52 depressed patients. That may be one of the reasons exercise is so good for our 5:56 brains. Start an hour day exercise regimen, within 3 months you can get a
Fruits and Veggies Against Depression 6:00 quadrupling of BDNF release from your brain. 6:05 This makes sense. I mean, anytime we were desperate to catch prey or 6:10 desperate not to become prey ourselves, we needed to be cognitively sharp. And 6:14 so when we're fasting or exercising or in a negative calorie balance, our brain 6:19 starts churning out BDNF to make sure we're firing on all cylinders. So, of 6:25 course, Big Pharma is eager to get drugs to mimic this effect, but is there any 6:29 way to boost BDNF naturally? Yes, I just said it, fasting and 6:34 exercise. Okay, okay, but is there anything we can add to our diet to boost 6:39 BDNF? Well, higher intakes of dietary flavonoids appear to be protectively 6:44 associated with symptoms of depression. The Harvard Nurses' Study followed tens 6:48 of thousands of women for years and found that those who were eating the 6:50 most appeared to reduce the risk of coming down with depression. Flavonoids 6:55 occur naturally in plants, so there's a substantial amount in a variety of 7:00 healthy foods, but but wait, how do we know the benefits are from the 7:03 flavonoids and not just from eating healthier in general? You don't know 7:09 until you put it to the test. See, some fruits and 7:13 vegetables have more than others. Apples have more than apricots, plums more than 7:17 peaches, red cabbage more than white, kale more than cucumbers. So, if you 7:22 randomize people into one of three groups, 7:25 more high flavonoid fruits and vegetables, more low flavonoid fruits 7:29 and vegetables, or no extra fruits and vegetables at all, after 18 weeks only 7:34 the high flavonoid group got a significant boost in BDNF levels, which 7:38 corresponded to an improvement in cognitive performance. The BDNF boost 7:43 may help explain why each additional daily serving of fruits and vegetables 7:47 is associated with a 3% decrease in the risk of depression. 7:53 A teaspoon a day of the spice turmeric may boost BDNF levels more than 50% 7:58 within a month, consistent with the other randomized controlled trials that
Exercise, Fasting, and BDNF 8:02 have so far been done. Nuts may help, too. In the Predimed study, where people 8:06 were randomized to be sent weekly batches of nuts or extra virgin olive 8:10 oil, the nut group lowered their risk of having low BDNF levels by 78%. 8:16 And brain-derived neurotrophic factor is not just implicated in depression, but 8:21 schizophrenia as well. Have those with schizophrenia undergo a 12-week exercise 8:26 program, and they get a significant boost in BDNF levels, leading the 8:31 researchers to suggest that exercise-induced modulation of BDNF may 8:35 play an important role in developing non-pharmacological 8:38 treatment for chronic schizophrenia patients. 8:41 Okay, but what actually happened to their schizophrenia symptoms? Let's find 8:47 out. 30 individuals with schizophrenia randomized to ramp up to 40 minutes of 8:52 aerobic exercise three times a week or not, and there did appear to be an 8:56 improvement in psychiatric symptoms such as hallucinations, as well as increasing 9:01 their quality of life. In fact, you can actually visualize what happened in 9:05 their brains. Loss of brain volume in a certain region appears to be a feature 9:09 of schizophrenia, but 30 minutes of exercise three times a week and you can 9:13 get up to a 20% increase in size of that region within 3 months. Calorie 9:18 restriction may also increase BDNF levels in schizophrenics, but they 9:23 didn't just have them eat less, but eat healthier, less saturated fat and sugar, 9:28 and more fruits and veggies. It's like the Soviet fasting trials for 9:31 schizophrenia. They reported these truly unbelievable results, supposedly 9:36 restoring people to function. Fasting described as an unparalleled achievement 9:41 in the treatment of schizophrenia. Okay, but part of the problem is that the 9:45 diagnostic system the Soviets used is completely different, making any results 9:49 hard to interpret, but they do have a subgroup that does seem to correspond to 9:53 the Western definition, and they still report between 40 and 60% improvement 9:59 rates from fasting. But that's not all they did. After being 10:03 fasted for up to a month, they were put on a meat and egg-free diet. So, when 10:07 they report these, you know, remarkable effects even years later, that's for 10:12 those who stuck with the diet. Uh those who broke the diet evidently relapsed, 10:17 and the closer the diet was followed, the better the effect. They note that 10:21 not all patients were able to remain vegetarian, but they tried to keep meat 10:25 to a minimum. And look, we know from randomized controlled trials that just 10:30 removing meat and eggs can improve mental states with even just 2 weeks. 10:34 And so, you know, it's hard to know what role the fasting itself played in the 10:38 reported improvement. A single high-fat meal can drop BDNF 10:43 levels within hours. And you can prove it's the fat itself by seeing the same 10:48 thing injecting fat straight into their veins. 10:52 And perhaps that helps explain why increased consumption of saturated fats 10:55 and a high-fat diet may contribute to brain dysfunction. Neurodegenerative
Flavonoids, Turmeric, and Nuts 11:00 diseases, long-term memory loss, cognitive impairment. Maybe that helps 11:04 explain why the standard American diet has been linked to higher risk of 11:07 depression. Dietary factors modulating the levels of brain-derived neurotrophic 11:12 factor. Finally today, we've known our mental 11:16 state can affect our gut, but might our gut bacteria be affecting our mental 11:22 state? Before Thorazine was invented in 1950, 11:28 mental illness was often treated surgically. 11:33 In fact, in 1949, the inventor of the lobotomy 11:36 was awarded the Nobel Prize. But before tens of thousands were 11:42 lobotomized, colectomy was all the rage. There was 11:47 this theory that bad bacteria in the gut, intestinal putrefaction, was the 11:52 cause of mental illness. So, the cure was to just surgically remove the colon. 11:59 Yes, the surgery killed about one in three, but when they didn't die, 12:03 surgeons bragged that, for example, when he resected the colons of school 12:08 children as a preventative measure, there was a cessation of abnormal sex 12:12 practices such as masturbation, which was viewed at the time as a precursor 12:17 for mental illness later in life. There were others, though, that took 12:21 less drastic approaches, suggesting one could 12:25 instead treat this intestinal putrefaction by changing the intestinal 12:29 flora. So, over a century ago, there were reports of successfully treating 12:33 psychiatric illnesses like depression with a dietary regimen that included 12:38 probiotics. Doctors perceived a connection between 12:41 depression and feces deficient in quantity and 12:45 moisture and very offensive in odor. So, they gave people probiotics, and not 12:50 only did people feel better psychologically, but their feces 12:54 increased in quantity, became softer, more regular consistency, and the 12:58 offensive smell diminishes. Concurrent with the probiotics, however,
Exercise and Diet for Schizophrenia 13:03 all patients were started on a vegetarian diet. So, it may not have 13:08 been the probiotics at all. This field of inquiry 13:13 remained dormant for about 100 years, but a new discipline has recently 13:18 emerged known as enteric, meaning intestinal, neuroscience. Our enteric 13:23 nervous system, the collection of nerves in our gut, 13:26 has been referred to as our second brain, given its size, complexity, and 13:31 similarity. We've got so many nerves in our gut, as many as in our spinal cord. 13:37 And it kind of makes sense or the size and complexity of our gut brain is not 13:41 surprising when considering the challenges posed by 13:44 the interface with our largest body surface. 13:48 We have 100 times more contact with the outside world through our gut than 13:52 through our skin. And we also have to deal with our 100 13:55 trillion little friends down there. Takes a lot of processing power. 14:00 Now, anyone who's gotten butterflies in their stomach 14:04 knows that our mental state can affect our gut. 14:07 In fact, everyday stressors can affect the integrity of our gut flora. 14:12 So, our mental state can affect our gut, but can our gut affect our mental state? 14:19 We didn't know until recently. For example, many suffering from chronic 14:24 fatigue syndrome complain of gut dysfunction. So, researchers tried 14:27 giving people probiotics to see if their mental and emotional state could be 14:31 improved, and indeed it appeared to help. What about healthy people, though? 14:38 This is the study that really rocked the scientific establishment. 14:43 An assessment of the psychotropic properties of probiotics. 14:48 One month of probiotics was found to significantly decrease symptoms of 14:52 anxiety, depression, anger, and hostility. 14:56 How is that possible? Well, a variety of mechanisms has been proposed for how
Gut Bacteria and Mental Health 15:01 intestinal bacteria may be communicating with our brain. 15:05 Until that study was published, though, the idea that probiotic bacteria 15:09 administered to the intestine could influence our brain seemed almost 15:13 surreal, like science fiction. Science, yes, but fiction, no. Likely, 15:19 organisms already inside us carry out some degree of influence on our mental 15:24 well-being. So, might people suffering from certain 15:27 forms of mental health problems benefit from a fecal transplant from someone 15:31 with a more kind of happy-go-lucky bacteria? 15:35 We don't know, but this ability of probiotics to affect 15:38 brain processes is perhaps one of the most exciting 15:42 recent developments in probiotic research. 15:46 Visit nutritionfacts.org/audio to see all the podcast episodes with 15:50 descriptions that include links to the associated videos. 15:54 Sources cited and other details are available on each video's page. 15:58 Information about my books, How Not to Die, [music] How Not to Diet, and How 16:01 Not to Age, is at nutritionfacts.org/books. 16:04 All proceeds, which I get, are donated directly to charity. [music] 16:09 And I've got a new book in the publication pipeline, the manuscript for 16:13 How Not to Hurt, on diet and lifestyle approaches to pain management. It's been 16:18 handed in and will be published December 15th. 16:22 I'm going to be doing a series of webinars to feature some of the new 16:25 research that I discovered. Sign up for our free newsletter at 16:28 nutritionfacts.org/subscribe to stay updated on when those will be. 16:35 Nutritionfacts.org is a science-based nonprofit, and everything on the website 16:39 is free. There are no ads, no corporate sponsorships, no kickbacks. We're 16:43 strictly noncommercial, not selling anything, just put it up as a public 16:46 service, as a labor of love, as a tribute to my grandmother, 16:50 whose own life was saved with evidence-based nutrition. We just have 16:54 like a uh a Wikipedia-type nonprofit model where everything's free, and we 16:58 just hope maybe, you know, one in a thousand people will find it so viable 17:02 that they'll kick in a few bucks so we can continue to churn out new content to 17:06 help you and your family be healthier. Thanks for listening.
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