 Good afternoon everybody, thank you very much for inviting me to talk to talk about vegetables. We think of vegetables as innocent, perhaps even virtuous, but they do have a dark side and it's important to explore this other side of vegetables because some people do have trouble with vegetables, some people do eat a paleo diet and still have symptoms such as pain or IBS symptoms for example which may not be completely resolved simply by changing to a paleo diet. So the first thing is a definition, what is a vegetable? So a vegetable is any part of the plant which is not the fruit or the seeds or the flowers and I would argue that the plant wants you to eat its fruit because it wants its seeds to be dispersed by you but it does not want you to eat its body and the vegetables are the body, the bodies of the plants and so whenever I'm thinking about any kind of food the first question I always want to ask is do we really need it for anything? We know from world history that there have been cultures around the world which have survived on very low plant diets and some people have even eaten almost no vegetables or fruits for most of the year and so it just begs the question of whether or not vegetables are really necessary because in Eskimos in particular we have historical information that tells us that Eskimos not only thrived and reproduced and were able to exercise without any carbohydrates or plants or fruits or vegetables they actually seem to have very low rates of cancer and so this is interesting because one of the things we're told about vegetables is that they're supposed to help us in our fight against cancer. So just as an experiment I wanted to get a feel for what kinds of evidence is out there supporting vegetables and health and so what I did was I went on PubMed and which is a search engine for those of you don't know looking for scientific articles and there over 80,000 studies about vegetables so I obviously couldn't go through all of those narrowed them down to randomize controlled studies having to do with vegetables and health and I used the word health because if anything that might induce a positive bias looking for evidence to support vegetables and so unfortunately most of these studies I had to eliminate from the consideration because most of them were irrelevant to the question. The vast majority of studies about vegetables were about how to get people to eat more of them not about whether or not they were actually healthy. So and of the studies that remained 18 of them were negative the investigators were looking for health benefits from vegetables and didn't find what they were hoping to see and as you might notice here another problem with vegetable studies is that the vast majority of vegetable studies are not studies of vegetables they're studies of fruits and vegetables and fruits and vegetables are very different from a plant point of view and from our point of view they're completely different creatures so hard to say. So in the positive studies I found 10 positive studies but unfortunately none of them controlled for refined carbohydrates it's very hard to say whether or not the health benefits that the investigators claimed were due to the vegetables were due to the vegetables or whether they were due to the fact that the people who were eating more fruits and vegetables were eating less refined carbohydrates and 10 other positive studies unfortunately manipulated more than one variable so they didn't just add more vegetables to people's diets they also happen to reduce sodium or do saturated fat or add exercise etc. So it's just hard to tell which part of the diet was or the intervention was responsible for the health benefit. I'm not saying that the vegetables couldn't have been responsible because they could have been we just can't tell because of the way the studies were designed. So the question is are vegetables actually good for us or not or would we just believe or want to believe that they're good for us. And so here's some of the arguments that we hear frequently about vegetables and why they may be good for us and they come down to several ingredients in the vegetables themselves and the argument that vegetarians and vegans in many studies do appear to be healthier in some respects. And so the micronutrient argument is an interesting one because when you look at it very objectively much as Dr. Lalonde did beautifully yesterday you find that animal foods are much more nutritious than plant foods. Not only did they contain more of the things we need they contain them in a more bioavailable form and they're actually I'm sure many people here know certain micronutrients that are not available at all in plant foods. So the next argument is fiber and fiber again I agree with Dr. Lalonde that fiber is not a nutrient we don't absorb it we don't metabolize it it is not it doesn't nourish us in any way. What it seems to do is interfere with the absorption of other things that are probably not good for us and that may be useful if you're eating things that aren't good for you. So it does seem to reduce appetite and probably because because it adds bulk it reduces cholesterol a little bit we will not go into the whether or not that's a good thing and it reduces glycemic index of sweet and starchy foods by about 10 to 20 percent. We all know that there are more effective ways of doing that than eating fiber. So but here but all of these when you look at the best available evidence right up to the minute in terms of heart disease, cancer, divertriculitis, polyps and IBS there's just no evidence to support a role for fiber and in many cases there's strong evidence against a role for fiber in any of these conditions. We don't know whether it's effective for weight loss or constipation that there just isn't enough evidence available yet for us to be able to figure that out. So so maybe fiber might not be as good for us as we thought but is it is it bad for us and you know I think it depends on the person because the problem with fiber is that we can't digest it but bacteria love fiber. They love dining upon fiber and they will digest the fiber for you and in the process they will ferment the carbohydrates and the fiber and creating gases and this will not only make you unpopular at parties but it can also cause significant discomfort for some people. So some people do better on a low fiber diet. So what about the argument that vegetarians and vegans are healthier than people who eat meat? It's very complicated because of the way the studies have been done but there are certain things that do seem to be true. Vegetarians do have consistently no matter how the study was done lower risk of heart disease significantly lower risk of heart disease and they do tend to weigh less as do vegans and they do have lower risk of certain cancers and higher risk of others but primarily lower risk of certain cancers but they die just as much as everybody else does. So but here's the problem with this data is that vegetarians and vegans they take better care of themselves in general and so all of the studies make this very clear. They smoke less, they drink less, they exercise more. We don't know if they eat fewer refined carbohydrates or not because it's usually not mentioned in the studies. So it's really impossible to figure out because vegetarian diets vary so much from one vegetarian to another much like any omnivorous diet does. It's really hard to know which aspect of the diet is protective. I'm sure we all know people who eat a vegetarian diet who eat in a very health conscious way and people who eat a vegetarian diet who eat a lot of junk food and they're just not the same diet. So now we're going to want to sort of the meat of the talk if you will which is the discussion of antioxidants and plant chemical defense compounds. This is really where vegetables are interesting to me. So part of the problem with studying food is that we tend to, well researchers anyway, tend to break the food into little parts and then look at it too closely and become completely disoriented about reality. So let's try to undo that. So just some examples of antioxidants. Antioxidants can be various types of compounds, a number of vitamins are antioxidants, a number of plant compounds here below are antioxidants just to sort of give you some idea of some of the things we're talking about. When JAMA did an excellent review of intervention studies, clinical intervention studies with vitamins A, E, and E, they found that overall if you supplement people's diets with these vitamins you actually increase their risk of death. The vitamin C intervention in selenium, the jury is still out. But notice it doesn't say that they're beneficial. So it's very interesting that people who study plants are very well aware of this, that the phytochemicals that we are told are so good for us, these special antioxidant chemicals, they're actually treated by the body as unwanted guests and we eliminate them very quickly. So rather than go into a discussion about what an antioxidant is and what it does, I think it's just in the interest of time better to say that it probably doesn't matter because even the USDA took down its own internet index list of compounds. It used to have a list on its site telling you what the antioxidant capacity was of various food compounds and it turns out that it actually is completely irrelevant or at least we don't have any evidence telling us that it's important. So how do plants protect themselves? Here are our friends, the crucifers, which we're told are extremely healthy for us and there are lots of them in the vegetable aisle. Crucifers, broccoli in particular is very high in one particular compound called sulfo-refane, which has been shown, it's been studied very extensively, we know a lot about it. It does help cancer cells to commit suicide, that's what apoptosis means. It inhibits angiogenesis, which is new blood vessel formation, which is how tumors grow and induces phase two enzymes. These are enzymes within our cells, which are responsible for detoxifying carcinogens. So it sort of up regulates those enzymes, sort of stimulates them and turns them on. So that can be good if you are eating carcinogens, then you might want to turn these enzymes on a little louder. These compounds also can reduce H. pylori colonization of the stomach that's a bacteria responsible for ulcers. But what is this stuff and why does broccoli make it? So in the broccoli plant sitting in the field, mining its own business, it has within its cells two compounds, one called glucosinolate, another called myrosinase, and they're harmless in and of themselves just sort of sitting there in the plant. But if the broccoli is cut or chewed, then these two compounds mix together and form this sulphurafane, which is an isothiocyanate. There are lots of them in the crucifer family, but we're going to look only at sulphurafane. And what is its job? The broccoli now needs to defend itself from the little creatures that are trying to eat it. It basically is molecules designed to kill small living creatures. So what might this mean for us? How does it do it? So the way that these chemicals kill or try to kill these small creatures that are trying to eat it is that the primary ways it poisons their mitochondria. The mitochondria are very important. They're the energy powerhouse of all of our cells. And it also causes all kinds of other problems as well as you look below you can see. And in in scientific studies, it's been shown that it can kill healthy cells as well as cancer cells, and it can actually cause cancer itself. So what does this mean for you when you're at home eating broccoli? What this means that well, here's some things you might need to know. One is that the glucosinolate, which is the one of the innocent parent compounds, if you cook or freeze broccoli, you'll reduce the glucosinolate concentration by about 50%. And the enzyme will be morosinase, the enzyme which works on the glucosinolate will be completely destroyed. But the bacteria in your gastrointestinal tract have myrosinase activity, so they can act on the remaining glucosinolate and turn it into sulforaphane. And you'll absorb about 75% of that. And then that's rapidly conjugated to our, to our intracellular antioxidant glutathione. That's our own intracellular, inside of every one of our cells, we have glutathione ready to detoxify things. Glutathione gets rid of sulforaphane as fast as it possibly can. So within three hours, it's all gone. So what happened, what when you really think about these compounds, which are supposed to be healthy, what we really start to see when we look at various types of vegetable compounds is a mixed message that these chemicals can be very useful if we're trying to kill things like cancer cells, but they also may be damaging healthy cells. And so it's, you know, it really depends on the person, on how much they absorb, what their enzyme, how fast they detoxify things, and how sensitive they are to various chemicals. And how much of these things they're eating, because the dose is very important. So one more vegetable example, and then, then we'll, we'll tie things up. The nightshades, these three particular nightshades contain within their, within the, you know, within these vegetables, you'll find glycoalkaloids. And glycoalkaloids are, they have also been found to have some potential benefits in research studies. So they can also, in animals, induce cancer cells to commit suicide. They can kill off bacteria and viruses, and they may have some anti-inflammatory properties. But what does the glycoalkaloid do for the potato, for example? We're going to look at the potato glycoalkaloids, in particular because, not only because of the best study, but they're the most potent. The glycoalkaloids and other, in the other nightshades are either weak or very low concentrations. So these are designed as pesticides. They're cholinesterase inhibitors, which is a neurotoxin. Nerve gas works exactly the same way. And they burst membranes open because they bind so strongly to cholesterol that it destabilizes the membrane of living cells. So that's how they try to kill invaders, how the potato tries to protect itself. And so in animal studies there's lots of data about animals becoming sick and gravely ill when they are exposed to high doses of glycoalkaloids, or feed that is very high in glycoalkaloids. However, in human studies we don't see a lot of problems. In fact, there was a very nicely done dose escalation study that showed you have to eat enough glycoalkaloid to the equivalent of 27 potatoes worth of glycoalkaloid to even feel sick to your stomach. So that's reassuring. But it is a known toxin and the federal government limits how much solanine, which is the name of the glycoalkaloid in potato, the federal government limits how much solanine can be in potatoes that go to market. And as they're traveling, as they're being transported and stored and so forth, the glycoalkaloid, the solanine content can rise. Solanine is completely indestructible with cooking. You can't cook it away. You can't fry it away. And in fact, if you fry potatoes over and over in the same oil they'll actually concentrate the solanine. You can't digest them away. They're really hardy. But the good news is they're very poorly absorbed by most people. So if you don't eat them too often you're probably okay. But they do have a very long half-life. If you eat them very frequently they can build up over time. But the good news is because almost all of the solanine is in the peel of the potato. If you peel the potato you've removed almost all the solanine. But of course then you've removed the part that everybody tells us is the best for us. So again we have with glycoalkaloids mixed messages. They are potentially toxic. But they're also potentially beneficial. Depends on the dose. It depends on the circumstances. It depends on the person. And they're just not good at differentiating between cancer cells and other types of cells. We have to be careful. And just to give you a little taste of a few other vegetables because in the interest of time we can't go through every group. There'll be a lot of information about vegetables and all kinds of foods on my website in several weeks. But for now just suffice it to say that the same pattern emerges when you look at onions and garlic. And also when you look at the capsaicinoids of peppers. These are all double-edged swords. And so the question is what do we do with all of this information. It's important to realize again circumstances. The dose makes the poison. If you're not eating too much of these things or if you're not sensitive you have a healthy gastrointestinal system. A healthy immune system. You're probably going to be okay with whole vegetables. Not concentrates or extracts or isolated compounds from vegetables but whole vegetables. We've been eating vegetables for millions of years. So most of us have adapted to be able to deal with. And you can see just by the way the body deals with the selphorophane from broccoli. How quickly it eliminates it. We you know we are very well protected against these compounds in most cases. But there are some people who don't do well with certain vegetables and this may be because there's some compromise in our natural barriers along the way. As we get older become exposed to certain environmental toxins or who knows why. So for some people this may be a delicious lunch. And for other people it may be a nightmare waiting to happen. And so and for some people they may need to lean more especially if you're very sensitive. A lot of food sensitivities. You may need to lean more in the direction of animal foods rather than plant foods. It depends on who you are. Because animal foods if this is your lunch. You do not need to deal with chemicals. You need to deal with fangs and claws and growling. And being chased and perhaps even being eaten. So if you but the problem is. So you know really my point really is not to malign vegetables it's just to open our minds about vegetables and think about them more you know sort of more objectively. And for each person to do their own individual experiments with vegetables because you know for example if you look on the internet and you type in nightshades you're going to get all kinds of stories of people who have pain with nightshades for example. But if you look in the literature the scientific literature you won't find anything. So it's just and you shouldn't wait for people to do those studies. You can do them on your own very easily. Just by knowing a little bit about the different compounds and various vegetables that you eat. So it's really important because for some people these vegetables are really very easy to tolerate and make up a perfectly healthy diet. I'm a in general a huge fan of the Paleo diet. But there are some people who do need to modify it based on based on their own individual sensitivities. And you know so in closing I just wanted to say that it may be that vegetables appear so healthy in all of the epidemiological studies because of what they are not and not because of what they are. It could be simply that vegetables are better for us because it helps us eat less of less of less doughnut your fewer doughnuts. Who knows exactly why. But you know it's really important I think just to keep an open mind about these things and be happy to answer any questions. All right so there's time for some questions but the author's event will be in this room in about 10 minutes. So anybody who is sitting at a table right now can you please not sit at the table and clear any of your things off of that table. So question time. Hi I was wondering you started to talk a little bit about fiber and gut bacteria needing to eat it. But I know that the gut is very essential to having a good immune system and it's important that we are able to feed the gut microbes. So how do you propose. I mean so I would think that would be a benefit for benefit to vegetables is to be able to feed the gut bacteria that helps our immune system. It does make sense in theory although we just have a lot of examples of peoples around the world who have been able to somehow thrive without plant matter in their diet. And so I don't know if I don't know how to answer the question except to say that there are good examples you know in the world that that argue otherwise. I'm not sure what the answer is to be honest. But I can't imagine given those examples that fiber is necessary although fiber might be helpful under certain circumstances depending on what else you're eating. It might not be the fiber but it could be other things. Right again I don't know I don't know the answer to be completely honest with you. I just know that there are people who have lived a long life without any fiber. So it's just interesting to think about. Hi my name is David. I have a quick question also about the fiber and you said that you know we can extract energy but isn't the truth that from soluble fiber we can already got bacteria can produce short chain fatty acids and those can have beneficial effects for metabolism and on inflammation. Yes although there are other ways to get short chain fatty acids and so you know it I don't want to pretend that I am a gut microbial expert because I'm not and I haven't looked at the literature about about gut microbes so I can't answer these types of questions in the amount of detail that I would want to be able to. Yeah I was what I've been reading about specifically was butyric acid and the ways you can get that are from you know gut bacteria production but also from dairy products so if we're looking at a more ancestral approach I think plant fiber might be a better source and that's something I want to get your opinion on is I understand that the polyphenols and like those things they might not be directly helpful but what do you think about some people who say they could be helpful through hormesis and like building up a tolerance to them. Oh right so so the polyphenols which are most of the polyphenols that have been studying the literature are are studying the fruits and so the nice thing about polyphenols is that the vast majority of them anyway are much more benign compounds because they're they're mostly pigments and pigments are not they're not designed by the plant to be toxic the plant wants you to eat its fruit and so it's a completely different category from vegetables to think about a lot of the the pigmented polyphenols. You're welcome. Hi you mentioned that the plant wants its fruit to be but not its structure and that seems to make a lot of sense to me I was expecting maybe to go into a little bit more detail on that. Most of the vegetables that have fruits I guess are the nightshades right the tomatoes and peppers so what's better to eat what's worse to eat. Oh that's such a good question I'm glad you mentioned that because I forgot to mention the nightshades are an interesting exception because many of them as you notice they are fruits they do have seeds and so for example the red peppers if we had had more time red peppers are you know spicy peppers for example we're not really supposed to eat those but certain birds enjoy them very much and it turns out that birds are much better dispersing the seeds than we are and so the plant has gone out of its way to attract the birds but to repel us and so it's a very interesting question because there's some fruits that are poisonous many berries many types of berries and so what the poison is so I don't know it's a really good question why some fruits it may be just be that the plan is trying to attract certain types of predators to disperse its seeds so what would be some of the human symbiotic you know predators or you know cooperative agents for plants you know I mean tomatoes is that there's not too many plants I can really think of that you know you're just eating the fruit except for fruits well I think it depends on me again I'm not saying that eating plants is bad yeah I'm just saying that if we're aware of what's in them it can help certain people with certain symptoms but if you don't it's a crapshoot because you have no idea what the effect is on some of those slide that seemed to say my heritage might help we don't know at this point well I think my point is that I don't see any strong evidence that says that it helps a healthy person as far as I can tell and it may just be just because the science hasn't proved to us that vegetables are healthy doesn't mean they're not healthy it just means the science isn't there yet and so I was just opening up the possibility that perhaps these compounds are really only irritants that we've had to evolve to deal with because we happen to eat them and maybe not that they're actually good for us do you know what I mean yeah okay one last question you mentioned potatoes peeling the skin if you peel them after you cook them are you still getting rid of all of the anti-nutrients or is it best to peel them before in other words if you bake a sweet potato are you baking that stuff into the potato well a sweet potato is not a potato well sweet potato white potato are different so night white potato is a nightshade but a sweet potato is not and so and I haven't seen any studies where they you know it I don't know about boiling the potato whether some of the solanine gets into the water of the of the you know the boiled water I don't know so the white potato has a solanine but the sweet potato has the oxalates and other things in it also right right every vegetable has its little as a way of protecting itself hi we're talking about how phytonutrients are eliminated from the body quickly and one way of thinking that about theater phytonutrients might be that you eat a vast array of phytonutrients and the body picks and chooses what it wants and eliminates the things it's not using so when those studies that identified the elimination of the phytonutrients did they actually look at the proportion of which phytonutrients were eliminated compared to what was taken in so that you might see if there was a discrepancy and indicating selective absorption of phytonutrients hmm do you mean between different that comparing different vegetable phytonutrients or looking at one specific phytonutrient well no I mean there's a there isn't any one phytonutrient I mean you there usually a lot of phytonutrients right phytonutrient just means plant chemical right phytonutrients plant so on one day you might your biochemistry might need the assistance of a c and e and in other days it might need b and d and so you might selectively retain the ones you need for whatever biochemical metabolic challenge you're facing that day and so if you just say that some of them are eliminated does that prove that they're all eliminated and oh no no the studies do not do not even ask that question right exactly the studies have a lot of limitations absolutely and that's not a question that I would that I so I mean it just can't say that just because they're eliminated that they're all eliminated you didn't use any of them no but so far the the ones that have been studied very extensively from very familiar the very familiar plant chemicals that have been studied extensively I come across the same pattern over and over again the sort of same phrases come up time and time again the mixed messages the double-edged sword the depends on the condition depends on the dose can't discriminate I come up you know across a wide variety of plant compounds so it's just interesting to think about yeah thank you thank you