WEBVTT 00:01.241 --> 00:03.824 (bright music) 00:10.564 --> 00:13.981 (energetic upbeat music) 00:32.506 --> 00:34.260 (audience applauding) 00:34.260 --> 00:36.450 So first I wanted to thank everyone for being here. 00:36.450 --> 00:37.980 This is a really exciting opportunity 00:37.980 --> 00:39.210 to get to talk about something 00:39.210 --> 00:41.190 that I am very passionate about, 00:41.190 --> 00:43.470 which is the gut microbiota. 00:43.470 --> 00:45.937 And when Wayne invited me to come speak here, I thought, 00:45.937 --> 00:47.670 "Hmm, what can I talk about 00:47.670 --> 00:50.460 that's going to be new cutting-edge science 00:50.460 --> 00:52.380 that I will get to share with all of you?" 00:52.380 --> 00:54.270 And not only is the microbiota 00:54.270 --> 00:57.780 a aspect of cutting-edge science, it's also invisible, 00:57.780 --> 00:59.310 so it's perfect. 00:59.310 --> 01:01.890 And before we can really get into talking about 01:01.890 --> 01:05.580 the gut microbiota and the gut-brain axis, 01:05.580 --> 01:08.460 we have to understand what the gut-brain axis is. 01:08.460 --> 01:11.670 So I know I'm here to talk about brain health, 01:11.670 --> 01:14.130 but I'm actually gonna talk about your second brain, 01:14.130 --> 01:16.890 and this is the brain that resides in your gut. 01:16.890 --> 01:19.350 This is called your enteric nervous system. 01:19.350 --> 01:24.350 With 500 million neurons, the enteric nervous system 01:24.600 --> 01:27.360 is able to autonomously regulate itself. 01:27.360 --> 01:30.510 It signals to the central nervous system 01:30.510 --> 01:33.840 via afferent nerve fibers in the vagus nerve, 01:33.840 --> 01:37.350 and is able to autonomously regulate its own blood flow, 01:37.350 --> 01:39.660 mucosal secretions. 01:39.660 --> 01:42.360 And maybe one of the best ways 01:42.360 --> 01:44.760 of describing the communication that can go on 01:44.760 --> 01:48.900 between the digestive system and the central nervous system 01:48.900 --> 01:51.750 is by highlighting irritable bowel syndrome. 01:51.750 --> 01:54.120 And people who suffer from irritable bowel syndrome 01:54.120 --> 01:58.950 develop hypersensitivity to normal gas, normal bloating, 01:58.950 --> 02:00.240 but they're hypersensitive to it. 02:00.240 --> 02:02.760 And these signals of hypersensitivity 02:02.760 --> 02:04.980 are then relayed to their central nervous system 02:04.980 --> 02:07.320 and can impact their behavior as well as the way 02:07.320 --> 02:09.780 that they feel and function in daily life. 02:09.780 --> 02:11.220 People with irritable bowel syndrome 02:11.220 --> 02:13.260 are much more likely to develop depression. 02:13.260 --> 02:16.080 They have increased sensation of pain. 02:16.080 --> 02:19.260 It's just one of the ways that the enteric nervous system 02:19.260 --> 02:21.543 interacts with the central nervous system. 02:22.560 --> 02:25.140 But really understanding the enteric nervous system 02:25.140 --> 02:27.120 is only half of the story, 02:27.120 --> 02:31.260 and thanks to advances in research in the last decade. 02:31.260 --> 02:32.910 And this has to do with the ability 02:32.910 --> 02:36.930 to rapidly sequence genomes of our gut microbiota, 02:36.930 --> 02:39.720 and these are the bacteria that live in our gut. 02:39.720 --> 02:42.750 You have trillions of bugs that are housed in your gut, 02:42.750 --> 02:46.230 and thanks to the advances in technology in the last decade, 02:46.230 --> 02:48.840 we have seen an explosion, a literal explosion, 02:48.840 --> 02:51.420 of research involving the gut microbiota. 02:51.420 --> 02:55.650 And this was published in "Nature Biotechnology" in 2013. 02:55.650 --> 02:59.910 And in 2002, we had about 265 peer-reviewed papers 02:59.910 --> 03:02.700 published about the gut microbiota. 03:02.700 --> 03:06.810 By 2012, 2,683 papers. 03:06.810 --> 03:09.000 In 10 years, a tenfold increase 03:09.000 --> 03:10.620 in the number of papers published 03:10.620 --> 03:13.173 in peer-reviewed journals about the gut microbiota. 03:14.340 --> 03:16.620 I wouldn't be surprised if in 2015, 03:16.620 --> 03:19.200 we're approaching 5,000 papers published 03:19.200 --> 03:21.030 about the gut microbiota 03:21.030 --> 03:23.910 and how it influences different aspects of health. 03:23.910 --> 03:27.600 So what are we starting to learn about this gut microbiota, 03:27.600 --> 03:30.180 about these bacteria that live on our skin 03:30.180 --> 03:33.180 and that bacteria that reside in our gastrointestinal tract? 03:34.320 --> 03:39.300 Well, at a cellular level, you, me, all of us, 03:39.300 --> 03:42.570 we are more bacterial than we are human. 03:42.570 --> 03:43.830 Think about that for a second. 03:43.830 --> 03:46.020 Have you ever considered that? 03:46.020 --> 03:48.930 You are only 10% human at a cellular level. 03:48.930 --> 03:51.450 We are outnumbered 10 to 1 03:51.450 --> 03:54.480 by the number of bacteria that live in our digestive tract. 03:54.480 --> 03:56.013 It's kind of a scary thought. 03:57.330 --> 03:58.740 Not only are you outnumbered 03:58.740 --> 04:01.110 by the bacteria in your digestive tract, 04:01.110 --> 04:04.380 but they are able to influence numerous aspects of health. 04:04.380 --> 04:06.330 And the stomach houses some of them, 04:06.330 --> 04:07.560 the small intestine, more, 04:07.560 --> 04:09.930 but the vast majority of these bacteria, 04:09.930 --> 04:13.650 a hundred trillion bacteria live in your large intestine, 04:13.650 --> 04:14.523 in your colon. 04:15.630 --> 04:18.870 Not only are we outnumbered, but metagenomic studies 04:18.870 --> 04:20.970 looking at the total genomic material, 04:20.970 --> 04:24.090 total genetic material, of these bacteria 04:24.090 --> 04:26.250 have really started to shed some light 04:26.250 --> 04:30.030 on the genetic potential of our bacteria. 04:30.030 --> 04:32.370 We are actually outnumbered 100 to 1 04:32.370 --> 04:34.500 when we look at the total genetic material 04:34.500 --> 04:36.060 of the gut microbiota 04:36.060 --> 04:39.720 compared to the genetic material in the human genome. 04:39.720 --> 04:43.140 And these genes can be turned on or can be turned off 04:43.140 --> 04:46.500 depending on what you're eating, on various inputs. 04:46.500 --> 04:49.560 Antibiotics can turn on and turn off these genes. 04:49.560 --> 04:52.500 Pesticides, heavy metals, prebiotics. 04:52.500 --> 04:55.590 So if you're consuming fermentable starches, 04:55.590 --> 04:58.320 these genes can be turned on, can be turned off. 04:58.320 --> 05:01.650 And the availability of genes 05:01.650 --> 05:03.810 is totally misunderstood right now. 05:03.810 --> 05:05.040 It's totally underestimated 05:05.040 --> 05:07.680 what the genetic potential of all these genes are 05:07.680 --> 05:10.590 and how these genes could be actually influencing our health 05:10.590 --> 05:11.423 and whether or not 05:11.423 --> 05:13.420 we're able to turn them on or turn them off. 05:14.460 --> 05:18.000 And this idea that we are vastly outnumbered 05:18.000 --> 05:21.030 by the number of bacteria on our bodies, 05:21.030 --> 05:24.510 the number of bacteria living in our gastrointestinal tract, 05:24.510 --> 05:27.600 and the genetic material that these bacteria possess 05:27.600 --> 05:32.600 have kind of changed the idea of what the human organism is. 05:33.780 --> 05:36.750 Humans are now maybe thought of as a meta organism 05:36.750 --> 05:38.310 or a super organism. 05:38.310 --> 05:41.850 And this is an organism that is not just taking into account 05:41.850 --> 05:43.800 the way that human cells are working, 05:43.800 --> 05:45.030 but also taking into account 05:45.030 --> 05:48.090 the symbiotic relationship we have to have 05:48.090 --> 05:50.880 with our bacteria that are residing on us. 05:50.880 --> 05:54.300 And I have good news for you guys. You never eat alone. 05:54.300 --> 05:56.220 You'll never be eating alone again, right? 05:56.220 --> 05:57.690 You have commensal bacteria, 05:57.690 --> 06:00.990 which is what the gut microbiota is often referred to as, 06:00.990 --> 06:02.880 that are gonna be eating everything that you're eating. 06:02.880 --> 06:05.250 And that's something to think about before you go to lunch. 06:05.250 --> 06:07.230 Everything you're going to eat is gonna be seen 06:07.230 --> 06:10.500 by those gut bugs as it makes its way down there. 06:10.500 --> 06:13.560 And commensal actually comes from the Latin com mensa, 06:13.560 --> 06:17.010 which is table, and sal, together. 06:17.010 --> 06:18.270 And this is to eat together. 06:18.270 --> 06:20.340 So this is your opportunity to eat together, 06:20.340 --> 06:23.820 and you just are always having this company with you 06:23.820 --> 06:26.190 while you're eating food. 06:26.190 --> 06:31.190 And so we are programmed from birth 06:31.560 --> 06:34.200 to be colonized by bacteria. 06:34.200 --> 06:35.790 The fetus is sterile, 06:35.790 --> 06:39.660 largely sterile as far as we can tell, before birth. 06:39.660 --> 06:41.340 Before the mother gives birth, 06:41.340 --> 06:44.310 the bacteria in her vaginal canal begin to change 06:44.310 --> 06:47.400 in for preparation for colonizing the baby 06:47.400 --> 06:49.173 with specific microbes. 06:50.160 --> 06:53.670 Once the baby's born, those microbes are inhaled by it. 06:53.670 --> 06:56.460 They get covered in those microbes. 06:56.460 --> 06:59.370 Breast milk contains galactooligosaccharides, 06:59.370 --> 07:02.730 a specific prebiotic that can be used 07:02.730 --> 07:05.880 in order to promote the growth of certain microbes 07:05.880 --> 07:07.443 in the baby's digestive tract. 07:08.430 --> 07:12.150 My point is, we have evolved, 07:12.150 --> 07:14.910 we have this evolutionary need, this evolutionary niche 07:14.910 --> 07:17.880 for these bacteria to grow on us, to grow in us, 07:17.880 --> 07:20.100 and I think we're largely underestimating 07:20.100 --> 07:21.720 the role that these bacteria do. 07:21.720 --> 07:25.560 And we allow them to ride around in our digestive tract. 07:25.560 --> 07:28.380 We provide them with food sources. 07:28.380 --> 07:31.560 You know, there's between three and five pounds of bacteria 07:31.560 --> 07:34.200 residing in everyone's gut right now. 07:34.200 --> 07:35.033 Try not to grimace. 07:35.033 --> 07:37.350 I know that's kind of gross, but it's interesting to think 07:37.350 --> 07:40.053 that that's about the same weight as the human brain. 07:41.820 --> 07:43.590 But, what do, yeah, right, thanks. 07:43.590 --> 07:45.240 But what do they do for us in return? 07:45.240 --> 07:47.163 What are these bacteria doing for us? 07:48.330 --> 07:50.340 If I said this as a symbiotic relationship, 07:50.340 --> 07:52.680 we've largely viewed this as a parasitic relationship. 07:52.680 --> 07:53.940 We think of bacteria as bad. 07:53.940 --> 07:55.173 We don't want bacteria, 07:56.130 --> 07:58.470 but what are they doing for us in return? 07:58.470 --> 08:00.960 And this is where the research gets really exciting 08:00.960 --> 08:03.930 in starting to understand what these bacteria 08:03.930 --> 08:07.293 that are residing in and on us are doing for us. 08:08.220 --> 08:10.560 And thanks to advances in all these technologies 08:10.560 --> 08:11.790 that I've been talking about, 08:11.790 --> 08:14.280 we're much better able to understand 08:14.280 --> 08:18.750 the symbiotic relationship we have with these gut bacteria. 08:18.750 --> 08:20.670 So we know that the gut microbiota 08:20.670 --> 08:24.030 actually synthesize vitamins in infants 08:24.030 --> 08:25.290 in the first couple years of life. 08:25.290 --> 08:26.670 Almost all their B vitamins 08:26.670 --> 08:30.240 are obtained from their gut bacteria, as is vitamin K. 08:30.240 --> 08:31.500 They educate our immune system. 08:31.500 --> 08:34.440 So babies are born without almost any, 08:34.440 --> 08:35.820 their immune system is totally naive. 08:35.820 --> 08:38.730 It hasn't seen any pathogens, any microbes before, 08:38.730 --> 08:40.380 so they help educate the immune system. 08:40.380 --> 08:42.960 There's this huge interplay between your immune system 08:42.960 --> 08:45.660 and your gut bacteria as you're developing. 08:45.660 --> 08:47.550 They nourish epithelial cells. 08:47.550 --> 08:49.260 They produce short-chain fatty acids 08:49.260 --> 08:51.720 when they digest prebiotic starches 08:51.720 --> 08:53.490 that are found in fruits and vegetables. 08:53.490 --> 08:55.620 And these short-chain fatty acids 08:55.620 --> 08:57.570 actually serve as an energy source 08:57.570 --> 08:59.940 for the gut epithelial cells. 08:59.940 --> 09:02.040 And importantly, 09:02.040 --> 09:04.800 they interact with our central nervous system. 09:04.800 --> 09:06.810 And I'm gonna introduce this concept 09:06.810 --> 09:10.650 of what I like to call microbial mind control. 09:10.650 --> 09:13.290 And that might sound kind of strange to you, 09:13.290 --> 09:15.030 maybe sound kind of foreign, 09:15.030 --> 09:17.100 but the idea of microbial mind control 09:17.100 --> 09:19.140 shouldn't be that foreign to people. 09:19.140 --> 09:21.480 We all are familiar with rabies. 09:21.480 --> 09:24.900 Rabies is a viral infection where you're actually 09:24.900 --> 09:27.030 more predisposed to aggressive behavior 09:27.030 --> 09:30.030 because of this microbial mind control. 09:30.030 --> 09:31.560 You also develop hydrophobia. 09:31.560 --> 09:33.760 You're scared of water when you have rabies. 09:34.620 --> 09:38.490 Other organisms such as Toxoplasma gondii, 09:38.490 --> 09:43.490 which is a common bacteria found in cat poop, cat feces, 09:44.340 --> 09:45.900 actually can infect rodents. 09:45.900 --> 09:47.340 And when it infects rodents, 09:47.340 --> 09:49.950 rodents becomes sexually attracted to cats. 09:49.950 --> 09:51.270 This is microbial mind control. 09:51.270 --> 09:53.910 Sexually attracted to cats so that the cats can eat them 09:53.910 --> 09:56.310 and this organism can renew its lifecycle. 09:56.310 --> 09:59.220 Now, these are more of a parasitic type of relationship, 09:59.220 --> 10:02.340 but it just highlights the ability of microbes 10:02.340 --> 10:04.860 to actually manipulate behaviors. 10:04.860 --> 10:07.680 And so using germ-free mice, and these are mice 10:07.680 --> 10:10.770 that are kept in sterile isolator bubbles, 10:10.770 --> 10:11.910 totally plastic bubbles. 10:11.910 --> 10:14.670 It's like "Bubble Boy," but for a mouse. 10:14.670 --> 10:16.140 We're able to actually study 10:16.140 --> 10:21.120 what the presence or complete absence of this gut microbiota 10:21.120 --> 10:22.620 has on health. 10:22.620 --> 10:25.050 So what's been observed in germ-free mice 10:25.050 --> 10:27.630 is that they have all sorts of abnormal brain behavior, 10:27.630 --> 10:28.980 brain activity. 10:28.980 --> 10:30.450 They actually have decreased levels 10:30.450 --> 10:33.240 of one of the growth hormones in the brain 10:33.240 --> 10:34.500 that we were talking about earlier, 10:34.500 --> 10:36.810 brain-derived neurotrophic factor. 10:36.810 --> 10:39.840 They have increased levels of stress hormone, cortisol. 10:39.840 --> 10:41.880 They also have a lot more propensity 10:41.880 --> 10:45.540 to develop anxiety like behaviors. 10:45.540 --> 10:46.920 And what's really interesting 10:46.920 --> 10:49.800 is that you can actually ameliorate these behaviors, 10:49.800 --> 10:52.980 these anxiety like behaviors, by taking these germ-free mice 10:52.980 --> 10:56.640 and colonizing them with the microbiota 10:56.640 --> 10:58.590 from a conventionally-housed mouse. 10:58.590 --> 11:01.740 A mouse that's not kept in a sterile isolator bubble. 11:01.740 --> 11:04.950 Now, there's been some research looking at how a probiotic 11:04.950 --> 11:07.920 could colonize the germ-free mouse and manipulate behavior. 11:07.920 --> 11:10.710 And it was found that Bifidobacterium infantis, 11:10.710 --> 11:13.890 a common probiotic, is actually able to reduce 11:13.890 --> 11:15.600 these anxiety like behaviors. 11:15.600 --> 11:17.160 So the researchers who did this study 11:17.160 --> 11:18.817 were starting to wonder, 11:18.817 --> 11:21.000 "Well, is it just general sensing of microbes 11:21.000 --> 11:24.120 that's required in the gut or is it specific microbes 11:24.120 --> 11:26.670 having specific effects on behaviors?" 11:26.670 --> 11:28.920 And what they found is that if they mono colonize 11:28.920 --> 11:31.920 these germ-free mice with Bifidobacterium infantis, 11:31.920 --> 11:35.520 they had a reduction in anxiety like behaviors. 11:35.520 --> 11:39.180 If they mono colonize these germ-free mice with E. coli, 11:39.180 --> 11:40.290 they didn't see any reduction 11:40.290 --> 11:41.910 in those anxiety like behaviors. 11:41.910 --> 11:44.070 So now we're seeing that this is very specific 11:44.070 --> 11:46.200 to specific organisms. 11:46.200 --> 11:48.570 Not only that, but if they were to sever the vagus nerve, 11:48.570 --> 11:52.200 this line of communication between the gut and the brain, 11:52.200 --> 11:54.240 they lost all the positive effects 11:54.240 --> 11:56.673 of that probiotic supplementation. 11:59.040 --> 12:03.240 Now, a lot of this research has been done in animals. 12:03.240 --> 12:06.690 It's very difficult to study the microbiota in humans 12:06.690 --> 12:10.050 to develop causative relationships. 12:10.050 --> 12:11.700 However, there's some really interesting research 12:11.700 --> 12:13.620 that's being done in the last couple years 12:13.620 --> 12:15.180 looking at how probiotics 12:15.180 --> 12:17.220 can actually modulate brain activity. 12:17.220 --> 12:19.290 So this was a study where for 28 days 12:19.290 --> 12:21.150 they had their study participants 12:21.150 --> 12:23.490 consuming a fermented probiotic milk. 12:23.490 --> 12:25.530 So this is just a fermented milk product, 12:25.530 --> 12:26.673 probably like a kefir. 12:27.690 --> 12:30.150 And what they found was that they did a brain scan 12:30.150 --> 12:31.680 of these people after 28 days, 12:31.680 --> 12:35.220 and they saw increased brain activity in areas of the brain 12:35.220 --> 12:38.580 associated with emotion and cognitive function. 12:38.580 --> 12:39.960 So now we're seeing that probiotics 12:39.960 --> 12:42.483 are actually starting to work in humans. 12:43.470 --> 12:46.920 A similar study was looking at self-reported feelings 12:46.920 --> 12:49.080 after probiotic consumption, and they found 12:49.080 --> 12:52.140 that there was reduced self-reported feelings of sadness, 12:52.140 --> 12:55.560 reduced self-reported feelings of aggressive behaviors, 12:55.560 --> 12:58.620 kind of similar to some other things we've talked about. 12:58.620 --> 13:00.150 And these studies are ongoing right now. 13:00.150 --> 13:02.580 This is a 2013 paper, and, you know, 13:02.580 --> 13:04.020 these studies are brand new. 13:04.020 --> 13:04.920 And that's one of the things 13:04.920 --> 13:07.380 I think is really important to talk about with this field 13:07.380 --> 13:08.760 is that this field is in its infancy. 13:08.760 --> 13:11.160 Even though you saw that really fast increase 13:11.160 --> 13:12.810 in the number of papers that have been published, 13:12.810 --> 13:15.123 this field is still really far in its infancy. 13:16.320 --> 13:19.170 And in humans, we can't really look at the mechanisms 13:19.170 --> 13:20.010 of how these are working, 13:20.010 --> 13:22.320 but we can look at the mechanisms in animals 13:22.320 --> 13:25.350 and really start to understand how the gut microbiota 13:25.350 --> 13:28.323 is actually influencing brain health and brain behaviors. 13:29.400 --> 13:31.620 So what we're starting to find is that the gut microbiota 13:31.620 --> 13:33.840 is actually capable of influencing behavior 13:33.840 --> 13:36.270 in a variety of fashions. 13:36.270 --> 13:39.570 There's this direct communication via the vagus nerve. 13:39.570 --> 13:42.090 There's also the immunomodulation. 13:42.090 --> 13:43.590 As someone said earlier, 13:43.590 --> 13:46.860 70 to 80% of your total immune cells 13:46.860 --> 13:49.200 are located in your gastrointestinal tract. 13:49.200 --> 13:52.170 That represents a huge potential 13:52.170 --> 13:54.570 for your gut bacteria to interact with your immune system 13:54.570 --> 13:56.280 and perform immunomodulation. 13:56.280 --> 13:59.280 So it's well known that certain probiotic bacteria, 13:59.280 --> 14:02.670 as well as commensal bacteria, can induce the development 14:02.670 --> 14:06.720 of anti-inflammatory or pro-inflammatory immune cells. 14:06.720 --> 14:08.850 They also have all sorts of coats on. 14:08.850 --> 14:09.990 The bacteria have coats on them 14:09.990 --> 14:11.220 that interact with the immune system 14:11.220 --> 14:14.760 and can cause production of different cytokines 14:14.760 --> 14:16.833 as well as other inflammatory mediators. 14:17.880 --> 14:19.770 And then we also see that there's this idea 14:19.770 --> 14:23.370 of systemic communication between our gut bacteria 14:23.370 --> 14:26.160 and the central nervous system in our brain. 14:26.160 --> 14:28.500 And this is through production of neurotransmitters, 14:28.500 --> 14:30.483 production of bacterial metabolites. 14:31.350 --> 14:33.960 And some of the most important bacterial metabolites 14:33.960 --> 14:36.090 produced by our gut microbiota 14:36.090 --> 14:38.250 are these short-chain fatty acids. 14:38.250 --> 14:40.050 Short-chain fatty acids were well known 14:40.050 --> 14:42.240 for helping support gut health, 14:42.240 --> 14:43.800 but once they do make their way into serum, 14:43.800 --> 14:45.840 they actually can reach the blood-brain barrier 14:45.840 --> 14:47.220 where they cause the blood-brain barrier 14:47.220 --> 14:49.350 to increase injunction strength 14:49.350 --> 14:51.330 so it's actually decreasing the permeability 14:51.330 --> 14:52.590 of the blood-brain barrier. 14:52.590 --> 14:53.910 This helps keep out toxins 14:53.910 --> 14:56.193 and other potential harmful compounds. 14:58.200 --> 15:00.300 Not only that, but once these short-chain fatty acids 15:00.300 --> 15:01.590 make their way into the brain, 15:01.590 --> 15:04.410 they're actually able to alter levels of neurotransmitters 15:04.410 --> 15:06.300 directly in the brain. 15:06.300 --> 15:08.130 There's some really interesting research done 15:08.130 --> 15:10.170 by Jeff Gordon's lab, 15:10.170 --> 15:12.420 and this was kind of a groundbreaking study 15:12.420 --> 15:16.470 where he took the microbiota out of a obese mouse 15:16.470 --> 15:19.260 and transferred it into a lean germ-free mouse. 15:19.260 --> 15:21.180 That lean germ-free mouse 15:21.180 --> 15:23.280 had this huge increase in appetite 15:23.280 --> 15:25.440 because of neurotransmitters produced in the brain 15:25.440 --> 15:29.340 due to changes in its microbiota, and it became obese. 15:29.340 --> 15:31.320 These are just some of the ways that the gut microbiota 15:31.320 --> 15:33.510 is actually able to influence behavior. 15:33.510 --> 15:36.150 And we're starting to see that the gut microbiota 15:36.150 --> 15:37.440 influences mood. 15:37.440 --> 15:40.020 It's been associated with changing social behaviors, 15:40.020 --> 15:42.120 anxiety-like effects as we talked about earlier 15:42.120 --> 15:43.290 in germ-free mouse. 15:43.290 --> 15:45.240 Not only that, but the neurophysiology. 15:45.240 --> 15:46.800 It can stimulate the production 15:46.800 --> 15:48.540 of growth hormones in the brain 15:48.540 --> 15:50.910 that can help improve brain health or support brain health. 15:50.910 --> 15:52.960 And also it can influence sleep patterns. 15:54.330 --> 15:57.090 And there's a study looking at Lactobacillus brevis 15:57.090 --> 15:59.880 where they actually administered Lactobacillus brevis 15:59.880 --> 16:01.500 and they saw that the animals 16:01.500 --> 16:02.970 that were given Lactobacillus brevis 16:02.970 --> 16:04.260 actually slept through the night better, 16:04.260 --> 16:06.840 well, slept through the day because mice are nocturnal. 16:06.840 --> 16:08.850 But nonetheless, they were actually able to improve 16:08.850 --> 16:09.750 their sleep patterns, 16:09.750 --> 16:11.520 and the bacteria didn't even need to be alive. 16:11.520 --> 16:13.050 They did a heat-killed bacteria 16:13.050 --> 16:15.420 and they were still able to see this positive effect, 16:15.420 --> 16:16.410 thinking that it's either related 16:16.410 --> 16:18.360 to the coating of that bacteria 16:18.360 --> 16:20.310 and how it's interacting with the immune system 16:20.310 --> 16:23.670 or because it's simple administration of that bacteria 16:23.670 --> 16:25.740 is causing changes in the genome 16:25.740 --> 16:27.210 of the entire gut microbiota 16:27.210 --> 16:30.000 that's then reflected in a better sleep pattern. 16:30.000 --> 16:31.950 And I should note that those bacteria, 16:31.950 --> 16:33.420 the administration of that bacteria, 16:33.420 --> 16:35.550 also increased voluntary wheel running. 16:35.550 --> 16:37.560 So maybe we just need to eat more dead bacteria 16:37.560 --> 16:40.060 and we'll get rid of that obesity problem we have. 16:41.760 --> 16:44.640 Now, I talked about the production of neurotransmitters. 16:44.640 --> 16:47.190 The gut microbiota is starting to be accepted 16:47.190 --> 16:49.830 as a major source of production of neurotransmitters, 16:49.830 --> 16:51.600 and not only as a major source 16:51.600 --> 16:52.560 of production of neurotransmitters, 16:52.560 --> 16:55.140 but it also can manipulate and stimulate 16:55.140 --> 16:56.970 the production of neurotransmitters in the gut. 16:56.970 --> 16:59.250 A large amount of the body's serotonin and dopamine 16:59.250 --> 17:01.953 is actually produced within our enteric system. 17:03.570 --> 17:06.210 Not only that, but some of these rarer neurotransmitters 17:06.210 --> 17:08.550 such as tryptamine, this is a neurotransmitter 17:08.550 --> 17:10.560 that's not really considered very much 17:10.560 --> 17:11.670 when you're talking about brain health, 17:11.670 --> 17:14.613 but tryptamine is very commonly used as a drug, 17:15.480 --> 17:19.800 like psychiatric, hallucinogenic drugs. 17:19.800 --> 17:21.840 So, you know, the production of these neurotransmitters 17:21.840 --> 17:23.550 cannot be underappreciated. 17:23.550 --> 17:26.040 And again, we don't really fully understand 17:26.040 --> 17:27.510 what these neurotransmitters are doing 17:27.510 --> 17:30.300 when they're being produced by the gut microbiota. 17:30.300 --> 17:32.520 The serotonin and its precursor 5-HT 17:32.520 --> 17:33.840 that are produced in the gut 17:33.840 --> 17:35.760 probably aren't making their way into the brain 17:35.760 --> 17:37.260 and crossing the blood brain-barrier 17:37.260 --> 17:38.190 and actually influencing 17:38.190 --> 17:40.020 central nervous system function there, 17:40.020 --> 17:41.790 but they can be interacting through the vagus nerve 17:41.790 --> 17:43.860 and influencing function that way. 17:43.860 --> 17:45.900 And the gut microbiota is producing tryptophan, 17:45.900 --> 17:48.600 which is a precursor to serotonin, 17:48.600 --> 17:50.370 and that can cross into the blood-brain barrier 17:50.370 --> 17:52.803 and serve as more building blocks for serotonin. 17:54.960 --> 17:56.820 Now, someone also mentioned earlier 17:56.820 --> 18:00.160 that there is a very, very common association 18:01.148 --> 18:04.740 between mental illness, psychiatric neurological illness, 18:04.740 --> 18:06.420 and digestive problems. 18:06.420 --> 18:10.140 Well, unsurprisingly, alterations to the gut microbiota 18:10.140 --> 18:11.850 are also very common 18:11.850 --> 18:15.000 in neurological illness and psychiatric illness. 18:15.000 --> 18:17.340 Normally you have the small intestine 18:17.340 --> 18:20.340 being predominantly colonized by Lactobacillus, 18:20.340 --> 18:23.190 while the large intestine is predominantly colonized 18:23.190 --> 18:25.383 by Bifidobacterium and Clostridium. 18:26.400 --> 18:28.230 And changes to this makeup 18:28.230 --> 18:30.390 can have a large influence on the genes 18:30.390 --> 18:33.660 that are being expressed by this microbiota genome 18:33.660 --> 18:36.900 as well as the things that are being produced 18:36.900 --> 18:38.430 by this microbiota. 18:38.430 --> 18:42.000 There was a study where they induced autism in mice 18:42.000 --> 18:44.340 by causing immune reaction in the mother 18:44.340 --> 18:45.660 before she gave birth. 18:45.660 --> 18:49.470 And they were able to show that there was a metabolite 18:49.470 --> 18:53.370 produced by these bacteria, 4-ethylphenyl sulfate, 18:53.370 --> 18:57.120 that was increased in the autistic mice. 18:57.120 --> 18:59.550 And if they were able to take either the bacteria 18:59.550 --> 19:02.520 that produced it or administer it to healthy mice, 19:02.520 --> 19:05.553 they could induce autism-like symptoms in healthy mice. 19:08.130 --> 19:11.550 Speaking of of autism, this is a very common disorder 19:11.550 --> 19:14.820 where we see changes to the gut microbiota. 19:14.820 --> 19:17.550 There's a decrease in the number of Bifidobacteria 19:17.550 --> 19:19.980 in autistic children, this is pretty common, 19:19.980 --> 19:23.670 as well as an increase in the number of Lactobacillus. 19:23.670 --> 19:27.630 And although this is kind of a maybe confusing paragraph 19:27.630 --> 19:28.530 for those of you who aren't familiar 19:28.530 --> 19:30.600 with the different families of bacteria, 19:30.600 --> 19:34.230 all it's really meant to represent is that small changes 19:34.230 --> 19:36.810 in the overall makeup of the gut bacteria 19:36.810 --> 19:40.830 can have significant impacts on our overall health. 19:40.830 --> 19:43.440 And I wanna stress that this is all very correlative. 19:43.440 --> 19:45.240 These aren't causative studies really. 19:45.240 --> 19:46.560 This is looking at correlation. 19:46.560 --> 19:48.330 Changes to the gut microbiota 19:48.330 --> 19:53.330 and also changes to overall different health outcomes. 19:53.490 --> 19:57.090 And autistic children often display dietary aversions. 19:57.090 --> 19:59.790 There's foods that they will or won't eat. 19:59.790 --> 20:02.040 And the authors actually took this into account 20:02.040 --> 20:02.970 when they were doing this study 20:02.970 --> 20:05.490 to see if different changes in the gut bacteria 20:05.490 --> 20:07.950 was just simply associated to dietary aversions. 20:07.950 --> 20:09.690 And after controlling for all these variables, 20:09.690 --> 20:12.390 they still saw these changes in the gut microbiota, 20:12.390 --> 20:14.190 indicating that there's something else going on 20:14.190 --> 20:16.443 other than just dietary aversions. 20:18.420 --> 20:20.880 And so, you know, I'd just like to conclude 20:20.880 --> 20:22.530 by reminding everyone 20:22.530 --> 20:25.597 of the 2000-year-old Hippocratic statement, 20:25.597 --> 20:27.357 "All diseases begin in the gut." 20:28.260 --> 20:30.060 And I think this is maybe more true than ever 20:30.060 --> 20:32.100 as we're starting to understand 20:32.100 --> 20:35.280 what the role of the gut microbiota is. 20:35.280 --> 20:37.380 And right now we are all present, 20:37.380 --> 20:40.800 we're all taking part in the microbiome revolution. 20:40.800 --> 20:43.290 This is a very fast growing field, 20:43.290 --> 20:44.880 and we don't really understand 20:44.880 --> 20:47.370 what our increased exposure to antibiotics, 20:47.370 --> 20:49.590 our increased exposure to pesticides, 20:49.590 --> 20:53.640 our increasingly hygienic world is doing to us 20:53.640 --> 20:55.560 and is doing to our gut microbiota. 20:55.560 --> 20:56.730 There are a lot of researchers 20:56.730 --> 21:00.000 that are linking this overall overly hygienic lifestyle 21:00.000 --> 21:02.520 to changes in health outcomes. 21:02.520 --> 21:03.870 Cesarean section. 21:03.870 --> 21:06.990 When babies are born, and born via cesarean section, 21:06.990 --> 21:09.690 they're inoculated with a much different type of bacteria, 21:09.690 --> 21:13.800 a skin bacteria, instead of vaginal and fecal bacteria. 21:13.800 --> 21:16.050 And cesarean section is largely associated 21:16.050 --> 21:19.050 with increased risk of allergy, asthma, and other diseases, 21:19.050 --> 21:20.850 but also increased inflammation. 21:20.850 --> 21:22.170 And everyone knows that inflammation 21:22.170 --> 21:23.700 plays a major role in the development 21:23.700 --> 21:26.300 of a lot of different neurological diseases as well. 21:27.660 --> 21:29.820 So I just wanna remind everyone before lunch 21:29.820 --> 21:32.010 that you're not gonna eat alone. 21:32.010 --> 21:33.570 Take into account, you know, 21:33.570 --> 21:35.100 I actually have to think about this now. 21:35.100 --> 21:36.217 Every time I eat anything I'm like, 21:36.217 --> 21:38.820 "Huh, I wonder what my gut bacteria think of this?" 21:38.820 --> 21:41.160 And it's really, it's an amazing field, 21:41.160 --> 21:43.320 and I think you should be excited to stay tuned 21:43.320 --> 21:45.960 and watch what's gonna be happening in this field. 21:45.960 --> 21:46.921 And so thank you. 21:46.921 --> 21:50.338 (energetic upbeat music) 22:01.874 --> 22:04.457 (bright music)