Full Transcript Introduction to Nutrition Science 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. 0:23 Ideally, we should try to center our diets around healthy, unprocessed plant 0:27 foods. But in today's world, most of what fills our grocery carts isn't just 0:31 processed, but ultra-processed, which is good for shelf life, 0:36 but not necessarily our life. Let's take a closer [music] look. 0:40 Modern nutrition science began about a century ago in the context [music] of 0:45 nutrient deficiency diseases. Editorials in the Journal of the 0:49 American Medical Association had titles like sugar as food, heralding sugar as 0:54 one of the cheapest sources of calories. For 6 cents, you could buy 3,000 0:59 calories. But the nutrient deficiency era gave way to the dietary excess era. 1:05 No longer were we dying of nutrient deficiency diseases like scurvy as much 1:10 as we were dying from nutrient excess diseases like obesity and heart disease. 1:15 So, nutrition scientists became more about avoiding too many calories, too 1:19 much sugar, too much sodium, while still focused on nutrients. This allowed food 1:24 companies to get away with whipping out fiber-fortified Fruit Loops. But food, 1:30 not nutrients, is the fundamental unit of nutrition. And to its credit, the
From Nutrients to Food-Based Guidelines 1:35 field of nutrition started moving towards a more holistic view. 1:39 First-generation dietary guidelines emphasized individual nutrients, then 1:44 moved to second-generation food-based dietary guidelines, which largely 1:49 converged on encouraging diets rich in vegetables, fruits, legumes, beans, 1:53 split peas, chickpeas, lentils, whole grains, and nuts. 1:57 But an area of emerging importance is the degree of food processing. National 2:03 nutrition guidelines first told us to cut down on saturated fat, alcohol, 2:07 cholesterol, salt, and sugar. Then they started actually naming names, 2:11 suggesting citizens might want to cut down on cake, for example. So, from 2:15 nutrients to foods, and more recently, countries recommending limiting 2:20 processed foods. This was the bombshell that really 2:24 started the momentum. A commentary in the journal Public Health Nutrition in 2:28 2009 by Carlos Monteiro, 2:31 a nutrition professor at the University of São Paulo, 2:35 maybe the issue with nutrition and health is not so much the food nor the 2:41 nutrients as much as the level of processing. 2:46 For example, food-based dietary guidelines might tell us to eat more 2:50 vegetable soup. Great. But there's vegetable soup, then there are the 2:55 vegetable soup. I mean, we're talking about, you know, cleaning out your 2:59 fridge vegetable soup, a health-haloed organic quinoa and kale soup with a 3:06 heart-stopping 1,200 mg of sodium per can. 3:10 Uh how about a vegetable soup that has more salt than it has vegetables? Or a 3:16 vegetable-flavored soup that contains more artificial 3:20 flavors and MSG than it has vegetables. Um just like there's breakfast cereal, 3:26 and then there is breakfast cereal. Professor Monteiro and colleagues 3:31 proposed the NOVA food classification system. NOVA is not an acronym. It means 3:36 new in Portuguese, as in a new way to classify foods based
The NOVA Classification and Ultra-Processed Foods 3:41 on the level of processing. NOVA classifies all foods and food products 3:45 into four groups. Group 1 foods are unprocessed or minimally processed like 3:50 fresh, dried, frozen, or cooked plants or animal parts with nothing bad added 3:54 like salt or sugar. Group 2 foods are the salt, sugar, and 3:59 fats used in cooking. And group 3 includes traditionally processed foods 4:03 like when you add group 2 ingredients to group 1 foods. 4:08 But what really put NOVA on the map is group 4, its concept of ultra-processed 4:14 foods. These are industrial formulations of 4:17 several ingredients, which, besides salt, sugar, oils, and fats, include 4:21 food substances not used in culinary preparations like added flavors, colors, 4:26 artificial sweeteners, emulsifiers, other additives used to imitate real 4:30 foods. Like a frosted grape Pop-Tart that has more grapes on the front of the 4:35 box than inside it, with less grapes than salt, but may artificially taste 4:42 like grapes and look like grapes because of 1 2 3 4 5 different food dyes. 4:49 Simply put, ultra-processed foods are foods that can't be made in home 4:53 kitchens because they have been chemically or physically transformed 4:57 using industrial processes. And they typically contain little or no whole 5:01 foods, are ready consumer or heat up, and are fatty, salty, or sugary, and 5:06 depleted in dietary fiber and other nutrients. Like all the sweet, fatty, or 5:11 salty snacks like potato chips, ice cream, soda, candy, french fries, 5:14 burgers, hot dogs, chicken nuggets, fish sticks. Basically, almost everything in 5:18 a box or a bag. Why not just call them packaged foods? Well, they were thinking 5:24 about it, but we're afraid consumers might look at a bag of apples or 5:27 something and get confused. Before the NOVA classification system 5:32 was introduced, the issue of food processing was largely ignored or 5:36 minimized in education and outreach as well as in public health policy. But 5:41 NOVA exploded onto the stage, resulting in a supernova in the world of 5:46 nutrition. But what exactly is so revolutionary 5:52 about this concept of ultra-processed foods? I mean, wasn't fatty, salty, 5:56 sugary junk always a bad idea? What's so new about NOVA? 6:01 Monteiro suggests that there are harmful effects of ultra-processed foods that 6:06 are independent of the nutrient profile. Is that true? 6:11 That's exactly what I'll cover next. 6:16 At present, the United States has the lowest life expectancy of the top dozen 6:20 richest countries in the world. We also have the greatest share of our diet 6:24 composed of ultra-processed foods. In fact, most of what goes into our mouth 6:28 isn't considered real food. Could there be a connection? 6:33 Ultra-processed foods are said to be troublesome for a wide variety of 6:36 reasons like all the packaging, etc. But I'm just going to discuss the health 6:41 aspects. Based on studies encompassing nearly 10 6:45 million participants, greater exposure to ultra-processed food was associated 6:49 with a higher risk of a variety of adverse health outcomes, including
Health Risks Linked to Ultra-Processed Foods 6:54 all-cause mortality, meaning living a significantly shorter life. 7:00 As a reminder, ultra-processed foods are industrial formulations of processed 7:05 food substances that contain little or no whole foods and typically include 7:09 flavorings, colorings, emulsifiers, and other cosmetic additives. Think Twinkie. 7:15 So nutritionally vacuous that you could go blind from nutrient deficiencies if 7:21 that's all you ate. Some of the health outcomes make sense, like higher 7:26 ultra-processed food consumption being associated with more dental cavities in 7:29 kids. That made sense as a lot of them are 7:32 packed with sugar. Higher ultra-processed food consumption is also 7:37 associated with an increased risk of high blood pressure. That makes sense as 7:41 a lot of them are packed with salt. And with high blood pressure, as you 7:44 could see how there could be a higher rate of cardiovascular events like heart 7:48 attacks and strokes. And since cardiovascular diseases are our leading 7:52 killers, you could see how that could lead to increased overall mortality. 7:56 Obesity is also a no-brainer. A lot of ultra-processed products are packed with 8:00 calories, and furthermore, intentionally engineered with hyperpalatable 8:04 combinations of fat, sugar, salt, and flavors, so you can't just eat one, 8:09 promoting weight gain through so-called hedonic eating, meaning eating for 8:13 pleasure even if you aren't really hungry. 8:16 I can I can see all that, but why would there also be a higher overall cancer 8:22 risk associated with ultra-processed food consumption? Or a higher risk of 8:26 dementia? Or a higher risk of inflammatory bowel disease? 8:30 Or a higher risk of irritable bowel syndrome? And a higher risk of 8:34 developing chronic kidney disease, too. Overall, direct associations have been 8:39 found between exposure to ultra-processed foods in 70% of the 8:43 health issues that were investigated. A higher risk of dying from all causes 8:47 put together, higher risk of getting cancer, not sleeping well, suffering 8:51 from anxiety, depression, other common mental disorders, wheezing, 8:54 cardiovascular disease, Crohn's disease, abdominal obesity, obesity in general, 8:58 fatty liver disease, type 2 diabetes. So, increased risk of a variety of 9:03 chronic diseases and mental health disorders. And apparently, not a single 9:07 study reporting an association between ultra-processed food intake and 9:11 beneficial health outcomes. There was never a 9:14 "Take two Twinkies and call me in the morning." 9:18 Given the large body of evidence implicating ultra-processed foods in 9:21 human diseases and their ever-increasing consumption around the world, there's a 9:25 pressing need to recognize their contribution to the global burden of 9:30 disease. All right, but but wait. These are 9:34 associations. Just because A is correlated with B 9:38 doesn't mean that A causes B. Maybe B causes A. For example, snapshot-in-time 9:44 studies show that intake of higher ultra-processed foods is associated with 9:48 increased odds of depression or anxiety symptoms. 9:51 But individuals might turn to ultra-processed foods in an attempt to 9:54 mitigate stress-related anxiety. They don't call it comfort food for 10:00 nothing. Now, there are longitudinal studies show 10:04 that greater intake of ultra-processed foods preceded depression, but maybe the 10:08 food was just used to fend off bad feelings for years before any official 10:11 diagnosis. Uh but reverse causation, B causing A,
Are the Effects Independent of Diet Quality? 10:16 seems less plausible when it comes to non-mental health outcomes. For example, 10:22 it's harder to paint a picture of how a heart attack would cause people to then 10:26 go on to eat more junk food instead of vice versa. 10:30 The other big issue when trying to establish cause and effect from 10:33 observational correlational data is confounding. 10:37 Maybe the reason A is associated with B is that some third confounding factor C 10:43 is linked to both. For example, if people who eat more junk tend to smoke 10:48 more, no wonder junk eaters would be dying 10:51 more, but it would have more to do with the cigarette they put in their mouth 10:54 rather than food. And indeed, people consuming unhealthy diets are also 10:59 likely to smoke, drink, and not exercise, but we have ways to control 11:04 for these factors. Indeed, the majority of studies were adjusted for these 11:08 confounders. The most obvious confounding factor 11:11 though is that highly processed foods just tend to be more likely to be junky 11:16 crap. The reason cakes, crullers, candy, and cola are bad for us has less to do 11:22 with how much they're processed and more to do with the fact that they are cakes, 11:26 crullers, candy, and cola, packed with sugar and calories with very few 11:30 nutrients. Diets high in ultra-processed foods are 11:33 diets high in added sugar, saturated fat, sodium, calories, displacing more 11:38 nutritious foods such as fruits and vegetables, legumes, nuts, and seeds. 11:41 So, maybe ultra-processed foods are just markers of poor diet quality. And 11:45 indeed, the more ultra-processed foods we believe the more refined carbs are 11:49 eating, the more sugar, saturated fat, sodium, energy, cholesterol, and the 11:52 less fiber in their diet. So, where's the mystery? People who eat 11:58 more bad foods get more diseases. We already knew that. 12:02 What does processing per se have to do with it? 12:06 Because ultra-processed category foods are more likely to be crappy foods. I 12:10 mean, we could use it as kind of a heuristic that they probably won't be 12:14 good for us. For example, if you made up some rule that you're 12:19 going to avoid breakfast cereals with cartoon characters on them, you'd 12:23 probably end up healthier. Not because the graven image of Tony the Tiger 12:27 magically hastens you to the grave, but rather because they're proxies for high 12:32 sugar content. But for the developers of the 12:36 ultra-processed concept, ultra-processed was no proxy. They claim 12:43 that the harmful effects of ultra-processed foods are not fully 12:46 captured by their nutrient profile and even go as far to say we should avoid 12:51 ultra-processed foods irrespective of their nutrient profiles. 12:56 Whether ultra-processed diets are detrimental to health simply because 12:59 they are of poor nutritional quality or whether the nature and extent of 13:03 processing itself has health consequences has been this ongoing 13:07 debate. How might we settle it? Well, if it were the case that the association 13:13 between ultra-processed foods and poor health was solely because of the excess 13:16 saturated fat, sugar, salt, or just from a less helpful dietary pattern in 13:22 general, then if we were to adjust for dietary 13:25 quality, the association between ultra-processed foods and disease should 13:29 disappear, right? In other words, if it was all about the nutrients, then people 13:33 eating crappy diets high in saturated fat, salt, and sugar should have high 13:36 disease rates regardless of whether they eat more ultra-processed foods or less 13:40 of them, and people who eat really healthy diets should have low rates of 13:43 disease regardless of how many ultra-processed foods they consume. 13:47 But that's not the case. The majority of the associations 13:53 between ultra-processed foods and obesity and health problems remain 13:57 significant and unchanged in magnitude after adjustment for diet quality or 14:02 pattern. Meaning, even if you balance out dietary quality, those eating more 14:07 ultra-processed tend to do worse. This suggests that at least some of the 14:12 adverse consequences of ultra-processed foods are independent of dietary
Closing Remarks and Resources 14:16 quality. So, it's not as though the ultra-processed food companies can just 14:21 reformulate their products to be lower in salt or sugar and be done with it. 14:25 There appears to be something about this class of foods 14:28 beyond the standard nutrient profile that contributes to their deleterious 14:32 effects, and that's just what I'll be discussing in this extended series on 14:38 ultra-processed foods. Visit nutritionfacts.org/audio 14:44 to see all the podcast episodes with descriptions that include links to the 14:47 associated videos. Sources cited and other details are 14:51 available on each video's page. Information about my books how not to 14:55 die, how not to die, and how not to age is at nutritionfacts.org/books. 15:00 All proceeds which I get are donated directly to charity. And I've got a new 15:06 book in the publication pipeline, the manuscript for how not to hurt 15:10 on diet and lifestyle approaches to pain management. It's been handed in and will 15:15 be published December 15th. >> [music] 15:18 >> I'm going to be doing a series of webinars to feature some of the new 15:20 research that I discovered. Sign up for our free newsletter at 15:24 nutritionfacts.org/subscribe to stay updated on when those will be. 15:31 Nutritionfacts.org is a science-based nonprofit, and everything on the website 15:34 is free. There are no ads, no corporate sponsorships, no kickbacks. We're 15:38 strictly non-commercial, not selling anything, just put up as a public 15:41 service as a labor of love as a tribute to my grandmother 15:46 whose own life was saved with evidence-based nutrition. We just have 15:49 like a >> [music] 15:50 >> a Wikipedia-type nonprofit model where everything's free, and we just hope 15:54 maybe, yeah, one in a thousand people will find it so valuable that they'll 15:58 kick in a few bucks so we can continue to churn out new content 16:01 >> [music] >> to help you and your family be 16:04 healthier. Thanks for listening.
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