Blubber

Fat is a much-maligned substance in the twenty-first century world we find ourselves in; exhortations for it to be burnt or exhumed from one’s diet abound from all sides, and indeed entire industries are now founded on dealing with the unwanted stuff in one form or another. However, fat is not, in fact, some demonic hate figure designed specifically to kill all that is good and beautiful about our world, and since it is at least relatively interesting I thought it might be worth investigating a few bits and pieces surrounding it over the course of a post.

All fats are based upon a molecule called glycerol, or propan-1,2,3-triol to give it its technical IUPAC name. Glycerol is a very interesting substance used for a wide range of purposes both in the body and commercially; it can be broken down to form sugar, can be used as a laxative, is an effective antifreeze, a useful solvent, a sweetener, is a key ingredient in the production of dynamite and, of course, can be used to store energy in fatty form. Glycerol is, technically speaking, an alcohol, but unlike most everyday alcohols (such as the ethanol upon which many of our favourite drinks are based) each glycerol molecule contains not one but three alcohol functional groups. In a fat, these alcohol groups act like sticking points, allowing three different long-chain carboxylic acid molecules known as ‘fatty acids’ to attach to each glycerol molecule. For this reason, fats are also known as ‘triglycerides’, and precisely which fat is formed from this structure depends on the structure of these fatty acids.

Fatty acids consisting of shorter chains of carbon atoms have less atoms with which to interact with their surroundings,  and thus the intermolecular forces between the fatty acid chains and other molecules are weaker for shorter-chain acids. This has a number of effects on the properties of the final product, but one of the most obvious concerns its melting point; shorter-chain fatty acids generally result in a product that is liquid at room temperature, and such products are designated as ‘oils’ rather than fats. Thus, not all triglycerides are, technically speaking, fats, and even triglycerides are part of a larger chemical family of fat-like substances known as ‘lipids’ (organic chemistry can be confusing). As a general rule, plants tend to produce oils and animals produce fats (presumably for reasons of storage), which is why you get stuff like duck fat and olive oil rather than the reverse.

The structure of the fatty acids is also important in an important dietary consideration surrounding fats; whether they are saturated or unsaturated. In chemistry, carbon atoms are bonded to one another by covalent bonds, consisting of a shared pair of electrons (each atom providing one electron of the pair) that keeps the two atoms bonded together. Most of the time, only one pair of electrons forms the bond (known as a single bond), but sometimes the relevant carbon atoms have a surfeit of electrons and will create another shared pair, forming a double covalent bond. The nature of double bonds means that the carbon atoms involved can accept more hydrogen atoms (or other electrophiles such as bromine; bromine water is a good test for double bonds) whereas a molecule made up entirely of singly-bonded atoms couldn’t accept any more and would be said to be saturated with hydrogen. Thus, molecules (including fats and fatty acids) with only single bonds are described as saturated, whilst those with double bonds are known as unsaturated*. A mixture of the food industry and chemical fraternity has developed a whole host of more specific descriptive terms that give you more detail as to the chemical structure of your fats (stuff like monounsaturated and such), and has also subdivided unsaturated fats into two more categories, cis- and trans-fats (the names refer to the molecules’ arrangement in space about the double bond, not their gender orientation).

With all these different labels, it’s no wonder people have so much trouble remembering, much less identifying, which fats they are ‘supposed to avoid’. Saturated and trans-unsaturated fats (which occur rarely in nature due to enzyme structure and are usually manufactured artificially) are apparently bad, mono-unsaturated (cis-) fats are good, and poly-unsaturated (cis-) fats good in moderation.

The extent to which these fats are ‘good’ and ‘healthy’ does not refer to the effect they will have on your waistline; all fats you eat are first broken down by your digestive process, and the resulting calories produced are then either used to power your body or turned into other sorts of fat that take up belly space. This process is the same for all types of energy-containing food and I shall come onto a few details about it in a paragraph or two. No, the relative health risk of these different fat types refers instead to the production of another type of lipid; cholesterol, which has such a complex, confusing structure and synthesis that I’m not even going to try to describe it. Cholesterol is a substance produced intentionally by the body and is very useful; it is used in the production of all sorts of hormones and vitamins, is a key ingredient of bile and is used in helping cells rebuild themselves. It is transported through the body by two different substances known as LDL (low-density lipoprotein) and HDL (take a wild guess) that carry it via the bloodstream; and this is where problems arise. The precise mechanism behind it is not known, but an increased consumption of trans-fats and other ‘bad’ triglycerides leads to an increase in the amount of cholesterol and LDL in the bloodstream. If this stuff is allowed to build up, cholesterol can start to ‘stick’ to the sides of one’s blood vessels, slowly reducing the effective size of the blood vessel until it is almost completely shut. This greatly reduces the flow of blood through these vessels, and this can have particularly dramatic consequences if the large, important blood vessels close to or supplying the heart are affected, leading to coronary heart disease and a greatly increased risk of heart attacks. HDL, for some reason, doesn’t apparently contribute to this affect, leading HDL to be (misleadingly, since it’s not actually cholesterol) dubbed ‘good cholesterol’ and LDL as ‘bad cholesterol’.

Clearly, then, having too much of these ‘bad fats’ can have some pretty serious consequences, but public realisation of this has lead all fat to be considered as a disgusting thing to be shunned. Frankly, this is just plain old not true, and it is far easier to live a healthy life with a bit of meat** on the bones than to go down the super-skinny angle. Fat is a vital body tissue, required for insulation, vitamin transport, to store energy, to prevent the disease and provides many essential nutrients; omega-3, the ‘essential oil’ (meaning it is not produced by the body) found in fish that is thought  to play a role in brain development and other bodily functions, is nothing more than an unusual fatty acid.

If you want further evidence as to the importance fat plays in one’s body, I refer you to a condition known as lipodystrophy, in which one’s body cannot produce or store fat properly. In some cases this is localised and relatively harmless, but in incredibly rare cases it manifests itself as a hereditary condition that causes abnormal bone and muscle growth, facial disfigurement and requires an incredibly strict diet (in direct contravention of the massive appetite the condition gives you) in order to control one’s levels of cholesterol and carbohydrate intake. In many cases, sufferers of this horrible condition will not live past twenty, if they even get that far.

*Vegetable oils tend to be more frequently unsaturated than fats, as this is another factor that reduces their melting point and makes them liquid. A key process involved in producing margarine involves taking these vegetable oils and adding hydrogen to these double bonds, a process known as hydrogenation, in order to raise their melting point and make the margarine solid and spreadable. Chemistry!

**Although, as anyone who likes their bacon skinny will tell you, fat is most certainly not meat. In fact, it’s not even alive.

Drunken Science

In my last post, I talked about the societal impact of alcohol and its place in our everyday culture; today, however, my inner nerd has taken it upon himself to get stuck into the real meat of the question of alcohol, the chemistry and biology of it all, and how all the science fits together.

To a scientist, the word ‘alcohol’ does not refer to a specific substance at all, but rather to a family of chemical compounds containing an oxygen and hydrogen atom bonded to one another (known as an OH group) on the end of a chain of carbon atoms. Different members of the family (or ‘homologous series’, to give it its proper name) have different numbers of carbon atoms and have slightly different physical properties (such as melting point), and they also react chemically to form slightly different compounds. The stuff we drink is that with two carbon atoms in its chain, and is technically known as ethanol.

There are a few things about ethanol that make it special stuff to us humans, and all of them refer to chemical reactions and biological interactions. The first is the formation of it; there are many different types of sugar found in nature (fructose & sucrose are two common examples; the ‘-ose’ ending is what denotes them as sugars), but one of the most common is glucose, with six carbon atoms. This is the substance our body converts starch and other sugars into in order to use for energy or store as glycogen. As such, many biological systems are so primed to convert other sugars into glucose, and it just so happens that when glucose breaks down in the presence of the right enzymes, it forms carbon dioxide and an alcohol; ethanol, to be precise, in a process known as either glycolosis (to a scientist) or fermentation (to everyone else).

Yeast performs this process in order to respire (ie produce energy) anaerobically (in the absence of oxygen), so leading to the two most common cases where this reaction occurs. The first we know as brewing, in which an anaerobic atmosphere is deliberately produced to make alcohol; the other occurs when baking bread. The yeast we put in the bread causes the sugar (ie glucose) in it to produce carbon dioxide, which is what causes the bread to rise since it has been filled with gas, whilst the ethanol tends to boil off in the heat of the baking process. For industrial purposes, ethanol is made by hydrating (reacting with water) an oil by-product called ethene, but the product isn’t generally something you’d want to drink.

But anyway, back to the booze itself, and this time what happens upon its entry into the body. Exactly why alcohol acts as a depressant and intoxicant (if that’s a proper word) is down to a very complex interaction with various parts and receptors of the brain that I am not nearly intelligent enough to understand, let alone explain. However, what I can explain is what happens when the body gets round to breaking the alcohol down and getting rid of the stuff. This takes place in the liver, an amazing organ that performs hundreds of jobs within the body and contains a vast repetoir of enzymes. One of these is known as alcohol dehydrogenase, which has the task of oxidising the alcohol (not a simple task, and one impossible without enzymes) into something the body can get rid of. However, most ethanol we drink is what is known as a primary alcohol (meaning the OH group is on the end of the carbon chain), and this causes it to oxidise in two stages, only the first of which can be done using alcohol dehydrogenase. This process converts the alcohol into an aldehyde (with an oxygen chemically double-bonded to the carbon where the OH group was), which in the case of ethanol is called acetaldehyde (or ethanal). This molecule cannot be broken down straight away, and instead gets itself lodged in the body’s tissues in such a way (thanks to its shape) to produce mild toxins, activate our immune system and make us feel generally lousy. This is also known as having a hangover, and only ends when the body is able to complete the second stage of the oxidation process and convert the acetaldehyde into acetic acid, which the body can get rid of relatively easily. Acetic acid is commonly known as the active ingredient in vinegar, which is why alcoholics smell so bad and are often said to be ‘pickled’.

This process occurs in the same way when other alcohols enter the body, but ethanol is unique in how harmless (relatively speaking) its aldehyde is. Methanol, for example, can also be oxidised by alcohol dehydrogenase, but the aldehyde it produces (officially called methanal) is commonly known as formaldehyde; a highly toxic substance used in preservation work and as a disinfectant that will quickly poison the body. It is for this reason that methanol is present in the fuel commonly known as ‘meths’- ethanol actually produces more energy per gram and makes up 90% of the fuel by volume, but since it is cheaper than most alcoholic drinks the toxic methanol is put in to prevent it being drunk by severely desperate alcoholics. Not that it stops many of them; methanol poisoning is a leading cause of death among many homeless people.

Homeless people were also responsible for a major discovery in the field of alcohol research, concerning the causes of alcoholism. For many years it was thought that alcoholics were purely addicts mentally rather than biologically, and had just ‘let it get to them’, but some years ago a young student (I believe she was Canadian, but certainty of that fact and her name both escape me) was looking for some fresh cadavers for her PhD research. She went to the police and asked if she could use the bodies of the various dead homeless people who they found on their morning beats, and when she started dissecting them she noticed signs of a compound in them that was known to be linked to heroin addiction. She mentioned to a friend that all these people appeared to be on heroin, but her friend said that these people barely had enough to buy drink, let alone something as expensive as heroin. This young doctor-to-be realised she might be onto something here, and changed the focus of her research onto studying how alcohol was broken down by different bodies, and discovered something quite astonishing. Inside serious alcoholics, ethanol was being broken down into this substance previously only linked to heroin addiction, leading her to believe that for some unlucky people, the behaviour of their bodies made alcohol as addictive to them as heroin was to others. Whilst this research has by no means settled the issue, it did demonstrate two important facts; firstly, that whilst alcoholism certainly has some links to mental issues, it is also fundamentally biological and genetic by nature and cannot be solely put down as the fault of the victim’s brain. Secondly, it ‘sciencified’ (my apologies to grammar nazis everywhere for making that word up) a fact already known by many reformed drinkers; that when a former alcoholic stops drinking, they can never go back. Not even one drink. There can be no ‘just having one’, or drinking socially with friends, because if one more drink hits their body, deprived for so long, there’s a very good chance it could kill them.

Still, that’s not a reason to get totally down about alcohol, for two very good reasons. The first of these comes from some (admittely rather spurious) research suggesting that ‘addictive personalities’, including alcoholics, are far more likely to do well in life, have good jobs and overall succeed; alcoholics are, by nature, present at the top as well as the bottom of our society. The other concerns the one bit of science I haven’t tried to explain here- your body is remarkably good at dealing with alcohol, and we all know it can make us feel better, so if only for your mental health a little drink now and then isn’t an all bad thing after all. And anyway, it makes for some killer YouTube videos…