The Things We Eat...
Do you really know which kinds of food are good for you, and which are bad?
Filed under Fads, General Science, Health
| Skeptoid #216 July 27, 2010 Podcast transcript | Listen | Subscribe |
|
By Brian Dunning, Skeptoid Podcast
Episode 216, July 27, 2010
http://skeptoid.com/episodes/4216
Today we're going to take a collective look at all the conflicting warnings and exhortations we hear about what we should and shouldn't eat. It seems everyone has some pet theory that you shouldn't drink milk, or you have to eat organic, or you shouldn't eat "processed" foods, or you must only eat raw. There are always explanations for why this is: We didn't "evolve" to eat this or that; it isn't "natural" to eat something; our digestive systems weren't meant to handle a certain thing. I know what you're thinking: How is it possible to cover all those possible claims in a single Skeptoid episode? We're going to do it by stepping back from all of the specific claims and specific foods, way back. We're going to look at food as a whole, and study what it's made of, what those bits are, see what we need and what we don't. And then, with this as a foundation, we'll have the tools to effectively examine any given eating philosophy.
Originally, this episode was going to be about the specific claim that we shouldn't drink milk, based on the idea that humans are the only species that drinks another species' milk, and it's therefore unnatural. I've also been given the suggestion — several times — that we should never give pet food to pets, because its ingredients are not the ones they evolved to eat. I quickly realized that all of these notions are basically the same, and all depend on a fundamental misunderstanding of the nature of food. Dog food, beer, cheese, and cake frosting are all compounds that no species evolved to eat. Then how is it that we're able to eat them? In essence, it's because all food — in whatever strange form we want to present it — consists of the same basic building blocks, all of which we did evolve to eat, and all of which are found in nature.
Before we look at these building blocks, I need to state that it's impossible to be 100% comprehensive within the limitations of a Skeptoid episode. There are innumerable subtleties and exceptions and footnotes that I'm not going to go into. Most of these exceptions come from the fact that humans developed in a broad range of environments, and as a result, some groups are more or less adapted to certain compounds, lactose tolerance being an obvious example. People with phenylketonuria can't metabolize the amino acid phenylalanine. Some populations have difficulty synthesizing enough Vitamin D in their skin. These are just examples; there are plenty of others, and I'm not pretending to cover every nuance here. If you want to delve further, see the Further Reading suggestions in the online transcript for this episode. Today's discussion is at a level that applies generally to all humans, and to some degree to most other vertebrates as well.
Food breaks down into six basic compounds. All food consists of combinations of these six, and every one of them is found in nature:
1. Amino Acids
These are the building blocks of proteins. Proteins are essential for our bodies. We need to eat protein, which is then broken down by our digestive system into its constituent amino acids, and then our body reassembles them into whatever proteins it needs. Some amino acids are called essential, and this refers to those that our body cannot synthesize and that we must eat. There are eight essential amino acids, plus about fourteen others that are conditionally essential: needed by infants, growing children, and other certain populations. With few exceptions, the body makes use of all amino acids; there's no such thing as an amino acid that we can't or shouldn't consume. Proteins in food like enzymes and hormones are usually not used by the body as enzymes and hormones; they too are broken down into amino acids which are then gainfully employed as building blocks.
2. Fatty Acids
Like amino acids, fatty acids come in essential and conditionally essential varieties. Omega-3 and omega-6 are the two essential fatty acids that we must get from food because we can't synthesize them, and that have a wide range of important functions throughout our bodies; three others are usually considered conditionally essential for some populations.
All the rest of the fatty acids are ones that we don't need to eat. Our body does usefully employ most of them, but it can synthesize what it needs, so you generally want to minimize your food intake of them. These include saturated fats (where all available chemical bonds are "saturated" with a hydrogen atom) and the non-essential unsaturated fats, which include monounsaturated, polyunsaturated, and trans fats.
3. Carbohydrates
These are your sugars and starches, which all break down into monosaccharides: the single sugars glucose, fructose, galactose, xylose, and ribose. Two of those together may come from a disaccharide like table sugar; a longer polysaccharide chain may come from the carbs in a granola bar. Whatever we eat gets broken down into those monosaccharides (though some populations may have enzymatic deficiencies that hamper the digestion of some combinations, like lactose). Those monosaccharides fuel our metabolism, and are the principal building blocks of the synthesis of other needed compounds. Any extra monosaccharides are put together into space-saving polysaccharides for storage.
4. Vitamins
Exactly what is a vitamin? There's a simple and clear definition. We've just discussed the three basic types of nutrients; a vitamin is any other organic compound that our body needs, that we are unable to synthesize enough of, and that we must get from food. Vitamins were discovered throughout the first half of the 1900's, and each time we learned about a new one, it was given a successive identifying letter: Vitamin A, B, C, and so on. After we learned about Vitamin B we found it was actually eight different vitamins, and so we have Vitamin B1, B2, B3, and the rest. Many animals synthesize these vitamins from proteins and fats, so they don't need to eat such a diversity of different foods to get them, the way we do.
There are two basic kinds of vitamins: water soluble (vitamins B and C) and fat soluble (all the others). If you consume more water soluble vitamins than you need, the excess will be quickly and harmlessly discharged in your urine. Overdosing on fat soluble vitamins provides a bit more of a challenge to your body though, and can lead to hypervitaminosis, which can be dangerous in extreme cases.
With a few notable exceptions, anybody who lives and eats in a modern industrialized country gets more than enough of all the vitamins their body needs, and there's no need to spend money on vitamin supplements. If you eat three meals a day, the buckets in which your body has room to store vitamins are brim full, and vitamin supplementation would be like pouring more onto an already overflowing bucket. Save your money.
5. Minerals
These are defined as the inorganic chemical elements that our body needs. There are sixteen essential elements (chemically, they're not really all minerals) including iron, calcium, zinc, sodium, and potassium. There are some half-dozen others considered conditionally essential, but if you stick with the sixteen you're probably all right. Minerals obviously have to be consumed; our bodies are not atomic reactors and so we can't synthesize chemical elements.
With a very few exceptions, anyone who eats regular meals in an industrialized country gets more than enough of all the minerals they need. Perhaps the two most common exceptions are pregnant women who can benefit from iron supplementation, and people who avoid dairy products and could often benefit from calcium supplementation.
6. Water
Kind of an obvious one. It's the only thing anyone needs to drink — there's no substitute — and most of us get all we need from what's contained in our food and other drinks.
And so, there we have the six fundamental compounds that make up all food. The basic argument against all of the various "You shouldn't eat this or that" claims is that those foods all break down into the same building blocks, building blocks which you would also get from other food. The opposing argument in favor of those claims is that some of these building blocks are good (like essential amino acids) and some are bad (like trans-fat), and we should strive to eat foods that deliver the most good nutrients with the least amount of harmful contents. Kind of a no-brainer, obviously, but it's rarely the argument that's actually made. Instead, the arguments I usually hear call out a particular food based on some ideology rather than its actual contents. Not that there's anything wrong with ideologies, but they should not be misrepresented as food science.
Other than a glass of pure water, there is hardly a food source on the planet that delivers anything less than a radically complex assortment of proteins, lipids, and starches, laced with vitamins and minerals. It's the proportions that differ. Looking at it from this perspective, there's little fundamental difference between milk and orange juice. The orange juice contains more sugar and vitamins but less fat and protein, while the milk contains a more even spectrum of nutrients. An argument like "Cow's milk is bad because early humans didn't evolve to drink it" becomes completely goofy when you consider only this one irrelevant characteristic. The same goes for arguments against manufactured pet food. There is no reason at all why pet food should look like, or come from the same source as, the animal's natural food; so long as it delivers the nutrients the animal needs.
Cooking introduces chemical changes that are, for the most part, the same as the first step in digestion. Some compounds cannot be digested unless they're cooked first to break certain chemical bonds. Most claims that cooking destroys nutrients are wrong; cooking merely starts the ball rolling on what your digestive system was going to do to the food anyway.
One nice thing about being a technological society is that we have the capability to understand food science, and to design nutritious foods that are more attractive and tasty than our ancestors were able to find on the savannah. The bottom line is that if you wish to evaluate any given food's nutritional value, you must look at what it actually delivers. Simply considering where it came from, or who designed it, is not a useful assessment of its actual substance.
© 2010 Skeptoid Media, Inc.
References & Further Reading
ADA. "Position of the American Dietetic Association: Nutrient Supplementation." Journal of the American Dietetic Association. 1 Dec. 2009, Volume 109, Issue 12: 2073-2085.
Chiras, D. Human Biology. Sudbury: Jones & Bartlett Publishers, 2005. 81-92.
Holick, M. "Vitamin D Deficiency." New England Journal of Medicine. 19 Jul. 2007, Volume 357, Number 3: 266-281.
Kennedo, G. "Dietary Reference Intakes Tables and Application." Institute of Medicine. National Academies of Sciences, 14 Jan. 2010. Web. 25 Jul. 2010. <http://www.iom.edu/Activities/Nutrition/SummaryDRIs/DRI-Tables.aspx>
Simopoulos, A., Cleland, L. Omega-6/omega-3 essential fatty acid ratio: the scientific evidence. Basel: S. Karger AG, 2003.
USDA. "USDA Nutrition Evidence Library, 2010." Nutrition Evidence Library. USDA Center for Nutrition Policy and Promotion, 15 Jun. 2010. Web. 26 Jul. 2010. <http://www.nutritionevidencelibrary.com/default.cfm?>
USDA. "Questions To Ask Before Taking Vitamin and Mineral Supplements." Nutrition.gov. USDA National Agricultural Library, 11 Jun. 2009. Web. 7 Jul. 2010. <http://www.nutrition.gov/nal_display/index.php?info_center=11&tax_level=2&topic_id=1939>
Reference this article:
Dunning, B.
"The Things We Eat..." Skeptoid Podcast. Skeptoid Media, Inc.,
27 Jul 2010. Web.
22 May 2013. <http://skeptoid.com/episodes/4216>
Discuss!
10 most recent comments | Show all 112 comments
Tom again is bang on the money. I would go even further; under the FANZS there are a number of positions that can only be issued by populist causes.
This is incredible as standards are supposed to only based under measurable scientific issues and measurements.
I can understand that export standards for organic apply as organic folk expect to have organic produce (even if it isnt measurably different, the practice still holds some sway under AQIS inspection).
What I do not understand is that FANZS issues a standard under populism when food preparers are blatantly igorant of the chemistry and biology of their source materials.
Had this been a relevant statement under a standards body ( such as standards australia) the source material trans fat levels would have to be legally stated (as with GMO).
Personally, I think standards Australia sould haul FANZS and its disseminating organ in.
Its starting to lose scientific relevance and starting to appear to be a fasionable organ for trendy classes that would call them selves cooks.
Trans fat levels of a food, if enforced, should be monitored at import as well as local issue.
How many "natural" food groups that have trans fats in their matrix is hardly discussed.
Henk v., Oz
August 14, 2011 4:10am
addition
Please read, percent transfats of known types and toxic or deleterious effect to the average human.
If you are one of these freaks who runs a daily marathon, transfats may not worry you at all.
Orange juice might!
Homers such as moi just prepare most of our own food. Unlike the mythology of the homer, we know whats in the fridge and whats bad for us.
Thats what makes life so interesting.
and we are too fat for adultery~
Please guys, its not just fun to cook, its a health issue as well.
For the mums and dads? kids who cook and repair cars and lawn mowers have a slightly higher chance of being underpaid and maligned by the media than those who dont.
Such kids end up becoming scientists. The rest are the ones who only selectively listen and pay lip service to scientists.
Its worth being a scientist to wonder how the others walk and chew gum..and then do a study on just that!
Henk v, sin city NSW, Oz
August 18, 2011 3:55am
I agree with your general argument, Brian, but have to nitpick on a few specific points.
"With a few notable exceptions, anybody who lives and eats in a modern industrialized country gets more than enough of all the vitamins/minerals their body needs." This is not true, not even close to being true. Most people get enough of these micronutrients to appear to be in good health, but they do not get enough to be well-protected from disease and degeneration. If your statement was true, the American health crisis would not exist. RDA values are at best "adequate," never "optimal."
"Overdosing on fat soluble vitamins... can lead to hypervitaminosis." For A and D3, this is only true at reasonable doses for the synthetic forms of the vitamins. The naturally occurring forms do not cause these problems until doses at least ten times higher. Also, very little of excess vitamin C is removed in the urine - most of it either gets used or stays in the intestines.
Tom, trans fats are not formed in normal cooking. We mostly find them in partially hydrogenated oils. It is possible, however, for fats to peroxidize during cooking. There are plenty of additives that have NOT been overwhelmingly proven safe: artificial sweeteners, soy products in general and carrageenan, to name a few. You also do not consider the very real problem of chronic toxicity, or other damage that is not categorized as toxicity.
Jonathan S., Toronto
October 01, 2011 1:32pm
Sorry Jonathan, I forgot we were all dying at 17 on average.
Cut it with the atkinesque quackspeak. you arent the first to have a zeal about diet and be stuck in a mid 1930's salemans book. The fact that you are so young makes me happy, you'll lose this in 6 months after having to pay for your own food.
You do plan on funding expenses when at uni? You know, work? like we did in the old days?
Mud, (Oz) Sin City NSW,
October 06, 2011 10:39pm
Could you clarify the purpose of the 'dying at 17 on average' comment? Also... I haven't read the 1930's salesman's book that you referred to. I don't get my information from popular books, I know there's usually a lot of bias in such sources.
I do plan on paying for my own education, yes. And working during the academic year is hardly the only way to get by.
Jonathan S., Toronto
October 07, 2011 2:49pm
Write back when you have gotten a few past your lecturers and demonstrators..
I have noted that you do use a lot of language from the woo sites and even cut and paste some of their paragraphs and references.
Your alarmism on transfats, aspartame/methanol/formic acid, carbs and ancient data is all too apparent when these are googled to be found in self interest and hoax sites. A quick review of current literature should have set you straight (and no, I am not going to google for you. You arent supposed to be Steve).
Hit the direct literature and try to get it as recent as possible remembering that EB is not SB and a seminal study describing and indicating mechanism and arguing it is much better than an old book or some literature that quotes view on a subject by someone who publishes of something entirely different (a notable antivaccer is an astounding biochemist who has a myriad of view articles unrelated to her field and you have spotted another TWO).
If you say..."I do all that!"
I would respond "well please write about it!"
Good luck in your college endeavours, study 120% of the material given to you (I only have come across 2 students (in 35 years) who can consistently wing it and derive in the exam hall)aim for doing honours.
Next post, make it non-web and current if you want to relate a study. Look at EB very closely. Read Cam of thunderbay's posts on EB stats. You'll be surprised at the level of garbage that consitutes studies in lesser journals.
Muddie, Sydney Australia
October 14, 2011 5:49am
I do not cut and paste sentences from anywhere except as direct quotes. And that's hardly different from using the terminology of a scientific field.
You do not do science a favor by ignoring the bias that runs through a large part of modern research. I was quite surprised to find that teams of independent meta-analysts found critical flaws in over a third of the best peer-reviewed studies in medical science. Of course, the majority is not the only group affected by bias. Irrational zealotry is rife in the dissenters. But conflict of interest is equally common in more well-accepted research. It only shows that both sides need to be equally considered.
You also do little for the discussion when you refuse to directly address points that have been raised. I don't care if you say I haven't studied enough, I know that already. But it doesn't explain to me whether, for example, ethanol is or isn't relevant to the issue of potential poisoning from aspartame.
I've freely posted the information I have about these topics. It can't be difficult for you to do the same... unless you don't have any rebuttal besides "go look it up"
Are you referring to Weston Price with your "ancient data" comment? I hope you realize that not all information can become outdated, and that you don't need to have a degree in, for example, biochemistry, to know anything useful about biochemistry.
I don't know what your acronyms EB and SB stand for. There's another case of not making a constructive post.
Jonathan S., Toronto
October 14, 2011 3:58pm
I think you lost him and the condition (a) awarded to you has oak leaves and clusters.
Pho, Gerringong (the not so Brave) Australia
October 14, 2011 8:19pm
Hi,
I saw an experiment using an iodine solution and a vitamin c supplement:
In that experiment, the (brownish) iodine solution was mixed with a glass of plain water. Then the water turns brownish. And then, a vitamin c supplement was drop into the glass of water. As the vitamin c supplement dissolves, the brownish iodine-plain water mixture turns back into colorless. The purpose is to show that vitamin C is an anti-oxidant.
Now my question is:
-Is there any experiments like the one above that can help me test/compare the quality of protein shakes I wanted to buy?
TQ.
Raymond, Ipoh
February 13, 2013 12:07am
Make a comment about this episode of Skeptoid (please try to keep it brief & to the point). Anyone can post:
You can also discuss this episode in the Skeptoid Forum, hosted by the James Randi Educational Foundation, or join the Skeptalk email discussion list.
What's the most important thing about Skeptoid?
![[Valid RSS]](/images/valid-rss-rogers.png "Validate my RSS feed"){kind=small}
Trans fats are not additives. If you eat fatty fried chicken today you will get just as high a dose if you use your deep fry pan at home to your secret recipe as you would have done a century ago, or if you bought your chicken from KFC. (Although to be technically correct, if additives are a problem, they are a problem with the food, but I understood what you meant).
A lot of people use additives or e-numbers as a quick and easy reason why foods are unhealthy, and to be honest brian could get a months worth of epsisodes out of e-number myths alone. There are some people who will have anintolerence or allergy to some additives, but they are pretty rare. For most people they tend not to be an issue.
Far from being the "chemical soup" critics describe additives as, not many (in the big scheme) are all that new or unnatural. They are numbered to be standardised and as short hand. Exxxx is easier to fit on a packet than "red colour from this" or "preservative to prevent mayo from breaking up".
The amounts in your food tends to be miniscule. They take up a lot of space on the ingredient list, but are used in small doses. Unless you have an unfortunate allergy or intollerence, your body will treat them exactly as it would anything else. They have been proven overwhelmingly safe by a whole kaboodle of literature. To consume levels that are dangerous you will have to munch so much food that natural fats, sugars, etc will have already done way more harm.
Tom H, Kent, UK
May 05, 2011 9:48pm