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Pseudoscience of food


This semester I’m teaching a Senior Seminar course on the psychology of eating behavior.  This course is one of my favorites to teach, because it deals with an applied topic – particularly in the age of the obesity epidemic – and is one that intersects with my focus as a researcher.  My research deals mainly with animal models of the gustatory system, the physiology of hydromineral balance, and the controls of ingestive behavior.

My other motivation for teaching the course, though, is that there is possibly no facet of human existence that is as vulnerable to exploitation by unscrupulous hucksters peddling pseudoscience (usually to sell something).  I can’t easily decide what percentage of these hucksters are cynically preying on the public’s scientific illiteracy to move their merchandise, and which ones actually believe what they are saying is true.  Either way, my hope is to arm my students with at least some defenses, by giving them a better understanding of human physiology, and also some of the logical tools to separate science and pseudoscience.

The latest bit of hilarity to cross my computer screen was a post on a website called Truth Seeker Daily.  (The link to the article is provided through, a site that routes hyperlinks in such a way as to not raise the “hit” count of sites that don’t deserve the publicity.  So feel free to click.)

The article is titled What Happens To Our Body After Drinking Coca-Cola?

As is common with sites like Truth Seeker, there’s no clear indication who wrote the article or whether the article is original to their site.  These pseudoscience sites seem to use the strategy of liberally cross-posting one another’s articles, sometimes with minor modifications, perhaps to make it seem as though their crank idea is shared by hundreds of other websites.  They’ve taken to heart the truism that people tend to average all that they hear, so if you can get your message to show up a lot and in multiple places, it doesn’t matter how plausible the idea is in the first place.  To whit, a search on the title of this article shows that an article with the same title appears on just about every pseudoscience site in the Quackery Hall of Shame (Mercola, Healthyfoodhouse, etc.).

The article starts off with a fictitious timeline of what happens after consuming Coca-Cola:

After 10 minutes

Ten tea spoons of sugar contained in a glass of Cola, cause devastating “strike” on the organism and the only cause, by reason of not vomiting, is the phosphoric acid which inhibits the action of sugar.

I can’t even parse this sentence.  The only cause of what?  What’s causing what?  Where’s the phosphoric acid coming from?  What action of sugar is it supposed to be inhibiting?  I honestly don’t know – not because I’m ignorant about digestive physiology but rather the opposite – I know a lot about it, and none of this makes sense.

Yes, there’s sugar in a glass of Coca-Cola.  A can of Coke contains 39 g, which is about 150 calories, in line with other sodas, and about 50% more than what you might find in orange juice or a flavored iced tea.

Yes, there’s phosphoric acid and citric acid in Coca-Cola (and lots of other stuff we eat and drink, like orange juice).  There’s also hydrochloric acid in your stomach.  However, the concentration of these acids in soda are simply not strong enough to cause acute tissue damage, and the notion that drinking some Coca-Cola is going to acidify your blood or internal organs is silly on the face of it.  Our bodies naturally use strong acids as part of the digestive process, and these acids in our gastrointestinal tract don’t alter the chemistry of our blood.  Why should adding a little extra from our food and drink be any different?

After 20 minutes

A leap of insulin levels in bloodstream occurs. The liver converts all the sugar into fat.

The absorption of sugar does cause the production of insulin.  This is a normal response to eating or drinking any food that contains sugar or starches.  It is true that over the long term (i.e., decades of life), problems can result from diets that consistently provoke elevated insulin levels, but this is not the case with the casual Coca-Cola drinker.  (In any event, it wouldn’t be specific to Coca-Cola or even soda.)

What about “The liver converts all the sugar into fat”?  Insulin has several functions, and one is to increase the formation of triglyceride fats from glucose (a simple sugar).  However, insulin also causes glucose to be converted into glycogen, a carbohydrate molecule that serves as an easy-access energy supply for the body.  Because glycogen, stored in the liver, muscles, and astrocytes of the nervous system, is easier to convert back into glucose than are fats, the body stores several hundred calories worth of ingested sugar as glycogen, rather than fat.  Insulin also activates glucose transport in cells all over the body, permitting the sugar absorbed from food (or Coca-Cola) to be metabolized in cells.

In short, especially when we are hungry, most of the sugar we’d get in a can of Coca-Cola is 1) burned for energy or 2) stored as glycogen and burned later for energy.  Left over glucose is either excreted in the urine or stored as fat, but this is hardly “all the sugar”.  More of the sugar will be stored as fat if you happen to you drink the Coca-Cola when you aren’t hungry and if you are otherwise well-fed.  But then, taking in extra calories of anything in this situation will cause you to put on more fat.

After 40 minutes

Ingestion of caffeine is finally completed. The eye pupils are expanding. Blood pressure rises, because the liver disposes more sugar into bloodstream. The adenosine receptors get blocked, thereby preventing drowsiness.

Coca-Cola apparently contains a third demonic molecule (other than sugar and phosphoric acid): caffeine.  Most people would probably be happy about this, but our article writer attempts to make this as sinister-sounding as possible:

“Ingestion of caffeine is finally completed.”  Presumably our article writer meant to say “absorption” of caffeine, since “ingestion” implies we’ve been nursing the same can of Coke for almost an hour.

“The eye pupils are expanding.  Blood pressure rises…”  The eye pupils?  Presumably our article writer meant to say the pupils are “dilating”.  Dilating pupils and elevated blood pressure are indicative of activation of the sympathetic nervous system (our “fight or flight system”).  Here our article writer has something right.  You actually would expect to activate your sympathetic nervous system after drinking a Coca-Cola – that is, if you were drinking a Coca-Cola while being attacked by a tiger!

A sense of perspective is helpful here.  There’s about 35 mg of caffeine in a can of Coke, compared with about 150 mg in an 8 oz. cup of coffee.  In fact, if a can of Coke has just a little bit more caffeine than a tall decaffeinated coffee at Starbucks!

Plus, if you were having your Coca-Cola with a bit of lunch, it’s likely your parasympathetic nervous system would be activated, counteracting any sympathetic effects of the caffeine in the Coke.  This antagonistic system – the “rest and digest” system – is required for efficient digestion.

“The adenosine receptors get blocked…”  True, caffeine is an antagonist of adenosine receptors.  Is it scary to have your adenosine receptors blocked?  Adenosine is a neurotransmitter whose levels rise the longer we have been awake.  So adenosine contributes to drowsiness and sleep.  Blocking them is a bad idea if you want to get to sleep, and a great idea if you want to stay awake.  Bottom line – don’t drink a Coke before bed.  On the other hand, there’s not a huge amount of caffeine in a can of Coke, so there’s not going to be a huge effect on your ability to sleep either.

After 45 minutes

Body raises production of dopamine hormone, which stimulates the brain pleasure center. Heroin has the same principle of operation.

Right, that’s why Coca-Cola is as addictive as heroin?

First of all, there’s more misuse of terminology here.  Dopamine is released as a hormone by the adrenal glands, but mention of the “brain pleasure center” suggests the article writer is focusing on dopamine’s role as a neurotransmitter, rather than a hormone.

Does Coca-Cola cause dopamine release in the brain’s pleasure center?  Well, since Coca-Cola is a pleasant drink, probably so.  What else causes dopamine release in the brain pleasure center?  Orange juice.  A slice of pie.  A ham sandwich, especially when we’re hungry.  Bumping into a friend on the street.  Riding a roller coaster (in some people).  Successfully playing a video game.  Getting a kind word from a stranger, or a pat on the back from a parent.  A tall glass of water on a hot day.

And heroin.

After 1 hour

Phosphoric acid binds calcium, magnesium and zinc in the gastrointestinal tract, which supercharges metabolism. Releasing of calcium through urine also rises.

Wait, what’s calcium, magnesium, and zinc doing in the gastrointestinal tract?  We must be eating lunch with our Coke.  Okay, didn’t know that.  I’ll roll with it.

It’s true that there are interactions between the components of the food that we eat which can make absorption of some components more or less efficient, depending on what else we are eating at the same time.  This simple fact provides pseudoscientists with plenty of room to operate, and it seems like many dietary advices from disreputable sources fall into the category the right or wrong mixes of foods.  For example, it’s interesting this article writer is worried that calcium and zinc absorption are interfered with, since it’s so easy to find the advice that calcium interferes with zinc.  So what are they doing in the GI tract at the same time, anyway?

We evolved to consume complex foods.  Almost anything we eat is a hodgepodge of minerals, acids, macronutrients, and undigestible fibers.  The differences in absorption efficiency are usually not anything to be concerned about, unless something you are eating is interfering with the absorption of some prescription medicine whose dose has to be exact.  (For example, a study of calcium absorption demonstrated that zinc and calcium do interfere with one another, but only when someone is taking extremely high zinc doses simultaneously with lower-than-normal calcium.)

The statement that “releasing of calcium through the urine also rises” is difficult to square with the statement that phosphoric acid is interfering with calcium absorption.  If less calcium got in, less can go out.  If too much got in, then extra should go out.  Sounds to me like the kidney is doing its job.

After more than 1 hour

Diuretic effect of the drink enters in “the game”. The calcium, magnesium and zinc are removed out of the organism, which are a part of our bones, as well as sodium. At this time we have already become irritable or subdued. The whole quantity of water, contained in a coca cola, is removed by the urine.

Now I’m really getting irritated.  Caffeine’s diuretic effects have probably been overstated.  A recent peer-reviewed review article concluded that if you ingest about 8 times the amount of caffeine in a can of Coca-Cola, and if you’ve not had caffeine in awhile, then you’ll have a short-term increase in urine output.  If you drink less, or if you are a regular caffeine drinker and have built up a tolerance, your urinary output will not be in excess of normal.

Why is the notion that drinking caffeinated drinks causing diuresis so widely believed?  That’s no mystery.  If you drink a couple of cups of coffee or a couple of glasses of soda – two of the most routinely consumed beverages in America – then of course you will have to pee.  Not because of the caffeine – because of the water.  We take in about 80 oz. of fluid daily, and we lose about 80 oz. of fluid daily.  However, if we drink beverages in addition to what we need – like coffee to wake up, or Coke for a sugary treat – we’ll have to pee the extra out.  No mystery.

In fact, when we pee, we also get rid of sodium, potassium, calcium, magnesium, sugar, and protein metabolites that we have accumulated beyond our body’s needs.  Again, that’s your kidneys doing what they are designed to do.  When you have water to get rid of, you have the chance to get rid of the extra minerals.  In fact, if you were to have a problem getting rid of the extra minerals, your blood pressure would rise, and you might be in actual (as opposed to made up) trouble.

The rest of the article goes off on the usual suspects: artificial colors, preservatives, and artificial sweeteners.  Suffice it to say that the rest of the article uses the exact same playbook – take a kernel of a connection to real physiology, throw in some discredited research, fail to mention the most recent research, and mix in as many scare words as possible.  Probably in the future I’ll return to those topics (especially artificial sweeteners, since they are such a popular target of the pseudoscientists).

For now, though, I’m tired and, from reading this stupidity, a little depressed.  Maybe I can find something around here that blocks adenosine receptors and has the same principle of operation as heroin to make me feel better…

After 10 minutes

Ten tea spoons of sugar contained in a glass of Cola, cause devastating “strike” on the organism and the only cause, by reason of not vomiting, is the phosphoric acid which inhibits the action of sugar.

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1 Comment

  1. Mikels Skele says:

    It’s the smarter-than-thou movement, not to be confused with the bowel movement, though similar in some ways.

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