Thursday, April 26, 2007

Nuking food...

I just read this objection to sterilizing food using radiations:

Bacteria are living cells. How can they be lethally affected - killed - and the cells of the food on which the bacteria may be living remain unaffected? Logically, we must assume all living cells are affected by high energy radiation. But what are those affects? And are any of the affects dangerous to human health?
I hope that slab of meat is already dead when they pass it through the machine...

Thursday, March 8, 2007

Pills of... misunderstanding

Sometimes it is quite frustrating to meet a new wonderful person, and find out that we do not speak the same language. It is really a shame! Just think about all the important facts we are not able to share because of a language gap!
This is the way that sometimes scientists feel when what they say is misunderstood: frustrated. It is nobody's fault but the tradition of using words to mean something different according to the context. To illustrate this point, I will give a short list of terms which are commonly used by scientists in a completely different meaning than the ordinary language:

Organic: we've seen this before. For a chemist, organic simply means that something contains the chemical elements carbon and hydrogen, with some oxygen, a little sulphur, some phosphate and of course nitrogen. Methane gas is best known for its use for heating and for cooking. It is hard to think of the methane gas as organic, but strictly speaking, methane is the prototype of the family of alkanes. But nowadays it is possible to buy organic produce, and eggs, and even organic meat! For the vast majority of people, "organically grown" means that something has been produced without the help of man-made fertilizers and pesticides, using manure as fertilizer. For a chemist, regular meat and produce are just as organic as "organic" ones, since they contain all the above mentioned elements. I wouldn't like to eat feldspar*, no thanks!

Chemicals: this is one of my favourite misunderstandings. In chemistry, we define a chemical compound whenever we have an homogeneous substance of which we can define the exact chemical characteristics, such as melting point, composition, if we're lucky the structure. In the collective mind, a chemical usually sits in a purified form on a shelf in a laboratory. So it is hard to see why vanillin, extracted from the cured vanilla pod, is considered a chemical compound** by a chemist. According to definition, though, vanillin's chemical characteristics are well defined, including its structure. Vanillin can also be easily synthesized in a lab (and it is absolutely identical to the one synthesized by the plant). Another very common chemical is glycine, the simplest aminoacid, synthesized by virtually all plants and animals and present in almost all the proteins. Its chemical properties are very well defined, but normally people do not think of stuff made by plants and animals as being chemical, because when people hear about chemicals they immediately think of man-made substances, usually toxic. Not so, not so...

Nuclear: for people who studied Latin at school, this is trivial. Nucleus comes from a Latin word meaning "core", therefore the nucleus (adj: nuclear) is basically the core of something, whether it is a cell or an atom. So scientists were quite confused when people were scared of taking a nuclear magnetic resonance (NMR); in the end, they changed the name to the friendlier definition of "magnetic resonance imaging" (MRI). This technique has nothing to do with radiation, but with the magnetic properties of the atomic nucleus. Radioactivity is nuclear, in a sense, because it is generated in the nucleus. The bad reputation probably comes from the "nuclear bomb", which uses the power harnessed in the atomic nuclei to wreck havoc. So when a journalist asked a geneticist to change "nuclear" with "of the nucleus", we all were a bit annoyed.

Aromatic: this is really funny! For many people, aromatic means that something has a very good smell... Aromatic herbs, aromatic gardens... But in chemistry, there is a whole category of compounds which are called aromatic and frankly, they stink! Have you ever tried to solve a moth invasion using naphthalene? I have (I had an invasion of carpet beetles) and my house stank for days and days... Aromatic compounds have very special characteristics and their chemistry takes many chapters in an organic chemistry textbook; the best way to describe them is by imagining very flat molecules (they are planar) with a very strong stability***.

* no carbon in feldspar; it is a rock that contains mostly silicon and aluminium. Yummy!
** it is an aromatic compound, but this one actually smells good!
*** for the most curious people, wikipedia has a very good article on aromaticity.

Tuesday, February 27, 2007

Pills of... vitamins: fact #2

Here we are for the second episode of this very energetic saga (pardon me my bad pun). In the previous episode, we have seen our heroine prevailing over shaggy traffickers of natural vitamins.
In this post, I will also tell why, in part, but only in a minuscule part, I think the supporters of natural vitamins are right - and where again they're missing the target.

From a chemical point of view, it does not matter where a substance comes from - as long as two substances have the same chemical structure, they will have exactly the same properties. If I take carbon from the moon, it will have the same chemical properties of carbon on earth (maybe not the physical properties*). If I take methane from mars, it will behave exactly like the methane on earth. If I take vitamin c from a pill, it will be absolutely identical to the one synthesized by plants and animals**.
I concede there are some exceptions, of course. Vitamin E is a case in point: in commercial products there are two forms***, of which only one is active (they cannot be synthesized separately - animal and plants are smarter than humans and they can make only the active form); but why people mistrust scientists so much? Why don't people believe that only the active ingredient is counted? (Indeed, the labels talk about vitamin E equivalents)****.
But why the vitamins coming from food might offer some advantages to us?
Personally, I came to the conclusion that gorging myself on vitamins once a day might be not the best way to get my daily supply. You see, besides a couple of vitamins (A and D), the human body has no storage facilities for vitamins. If I eat 600 milligrams of vitamin c in the morning, but I only need 5 milligrams during that particular time, then the excess will be happily excreted with the waste material (in the form of pee). That's good, because a scientific paper some time ago showed that high concentration of vitamin c, especially in presence of iron (hey! my supplement contains 27 milligrams of iron!) could work as pro-oxidant - which means that it could actually make things worse, not better! But going back to the main issue, it means that 555 milligrams are literally wasted! Later in the day, I may need more vitamin c, but of course it is not available anywhere in my body, because it has been already disposed of! Dahh!
To counteract this problem, now it is possible to purchase slow-release vitamin c (I don't know whether other vitamins are available in slow-release form). My point is: why don't I simply eat more oranges? Say one orange every two hours? Fruit is tastier than pills, probably just as expensive (when buying it in the season), and it contains precious minerals and fiber... Besides, there are so many reports that other compounds in fruit and vegetables might be not just beneficial for our health, but actually necessary!
Of course, it is wise to take a pill whenever we feel we won't meet our daily requirements, say if we are travelling, or we have a cold...
Still, this argument does not justify the people who discredit food supplements, only to suggest exotic alternatives... Especially very expensive alternatives...

* a gross approximation is that chemistry deals with the "outside" of atoms and molecules - so the way they react with each other; physics deals with the "inside" of the atoms - so we don't include the properties of isotopes in our discussion: it is already complicated enough! (And not really relevant).
** also because a new commercial production line for vitamin c isolates the vitamin produced by friendly bugs - so even the vitamin c found in pills is technically coming from a biochemical source. I am not sure it reached the whole planet yet, though.
*** dl-alpha tocopherol is a mixture of d-alpha tocopherol and l-alpha tocopherol. They cannot be easily separated by conventional means, and anyway, the inactive form is harmless. It's simpler to leave it there.
**** not all scientists are after the money (actually, given the little salaries they receive, they're definitely not after the money)...

Monday, February 19, 2007

Pills of... vitamins: fact #1

So OK, we all have done it... In the middle of the night, when the house is quiet, we tiptoed to the drug cabinet and popped in our mouth one or two of those magic pills... Nothing feels really wrong, we just feel we need an extra boost to keep up with our busy schedules... But wait! There is nothing illegal here: those pills were... vitamin pills! Yes!

But what are vitamins?

Vitamins are organic molecules. In chemistry, organic has a different meaning than in our everyday life: it means that something contains carbon*, with a touch of the elements hydrogen, nitrogen and oxygen. This is opposed to inorganic - iron is one inorganic element we need for our well-being.
There are many vitamins around, but they all share the fact that we need them in minuscule amounts, in the order of few micrograms or milligrams per day. That's smaller than a grain of peppercorn. By comparison, a healthy man needs about 50 grams of proteins every day. That's at least 50000 times more than vitamins! I will tell you more about the so called RDI (recommended daily intake) in one of my future posts.

The fact that vitamins are organic molecules has a very important consequence: they are all made by living organisms - you can't find them on the moon. Nope, not even one. So why do people talk so much about natural vitamins? And why there are no unnatural vitamins?

I bet you are confused right now. I would be too. The web does not help either... Read here what I found browsing the net, on a information page (let's call it - not its real name**) of a company which sells "natural" products:

"vitamin C; ascorbate (food); dehydroascorbate"

is the primary vitamin found in food (according to them, good for us), while:

"ascorbic acid; most mineral ascorbates (i.e. sodium ascorbate)"

is the vitamin analogue in chemical form (according to them, bad for us). Once I stop laughing, I will explain in detail why this classification bothers my conscience.
OK, I regained control of myself. Granted, some people haven't got past chapter one of their chemistry book, and here we clearly have a case.
There are two obvious mistakes here, which I highlighted in bold font (to be honest, there are more just in that statement, but I don't want to write a chemistry book, not yet ;-) ).
I will give you a more familiar example. I do not like vinegar, but many people do. So, the chemical that gives tartness to vinegar is called acetic acid. By the way, there's plenty of it in the salt & vinegar potato chips (I find them too strong for my taste). Acetic acid, being an acid, dissociates in water*** to give two ions: one of them is called acetate (CH3COO-), the other is H+ (AKA hydron, whose increase in concentration makes the pH more acidic). The names ending in ~ate are used in chemistry to identify ions (with a negative charge).
So what happens if I dissolve ascorbic acid in water? Yes! That's it: I have ascorbate and an ion H+. Good, so we now know that ascorbate is just the name of the anionic form of ascorbic acid. So why the site list them separately? Clearly, it is a mistake! Too bad...

So now we can proceed to solving the second mystery. Where does the sodium in "sodium ascorbate" come from?
This is not more complex to explain, but here we need the help of another friend, the cooking salt (AKA sodium chloride or NaCl). If I dissolve sodium chloride in water it will dissociate in two ions: Na+ and Cl-. This is a characteristic of salts.
So, if I dissolve sodium ascorbate in water, I will have an ion sodium and an ion ascorbate. So again, sodium ascorbate in solution gives the ascorbate ion. What happens to the ion sodium in our bodies? If you have healthy kidneys, it will be eliminated with the urine, as happens every day of our life. The second irritating mystery has been solved.

This classification based on the names of the substances is misleading and therefore should be avoided. Even if I dissolve potassium ascorbate (or any other salt of ascorbate) in water I will have an ascorbate ion, and that is the "active" part of vitamin C.
There is no way a chemist can conceive an explanation for giving different properties to the ascorbate that comes from food and the one that comes from other sources, because they have the same identical structure!

The site contains many more mistakes and it is misleading in other points. It states that the vitamin B2 in commercial pills (but not the ones they sell!) is synthetically produced with 2N acetic acid.
The person who wrote this information is not aware that most companies have switched to a fermentation method (using bacteria as mini-manufacturers) for the commercial production of vitamin B2, which is more cost-effective than chemically synthesizing something from scratch.
To a chemist, "
synthetically produced with 2N acetic acid" only means that a moderately concentrated solution of acetic acid (again, the one in vinegar) was used, but on which substance? And???Fermentation is the process by which some friendly microorganisms take sugar and use it to grow and prosper, and make other useful stuff (for us) in the process. Think about yogurt or bread. In this case, the microorganisms are encouraged to make vitamin B2. This is isolated from the other molecules, concentrated and put into pills.

These examples were enough for me to strongly doubt the validity of all the other information in the web site. I am seriously concerned about the message these persons are sending: don't buy pills from the drug store! Buy them from us! We don't tell you how we make them, but just trust us... They are natural!
Nomenclature of acids and salts is usually in the first chapter of the book. I hate when people use these tricks to induce people to buy their "natural" products.

There is more to say on this topic, but it is not the case to overwhelm you now. I'll wait until next time!

* For those among you who want to know more about this topic, the chemistry of carbon compounds is described in organic chemistry. 

** I apologize for not providing the real links, but to me the problem does not consist in a single page; there are many and this excerpt is just an example.
*** not all molecules are dissociated, but it is a characteristic of this acid.

Sunday, February 18, 2007

Welcome: this blog explained

So... there we go. I finally joined the blogosphere... Wasn't hard, was it?

Let me say a few words about this blog.
Sometimes I use google to search for an answer to a bizarre question that just crossed my mind. Why is urine yellow? What is the chemical compound in fava beans that can kill some people with an enzyme deficiency? How does ringworm look?
Sometimes I find very good answers, generally in university or hospital web sites - too often I run into forums and sites where either the people have absolutely no idea of what they are talking about, or they are pushing forward their not-so-hidden agenda. I can tell, I have a lot of common sense...

Given that I spent more or less 8 years in a biochemistry lab, and some of these years were in a lab associated with a medical school, let's see if the taxpayers' money can be returned to them with some interests.

I pledge to do my best to explain science to people, especially medicine and biology, so that they can make their own decisions with at least some honest background knowledge. I am on nobody's payroll but the scientific truth. May the force be with me!