Sugar, Sugar

How do you get high cholesterol?

The quick answer to this is: Nobody really knows.  We know that the liver makes it and that you can absorb some from your diet.  This chap has a fairly extensive discussion which gets down into the science that your average NHS site doesn't.  He also makes some fairly interesting observations that I'll tackle later**.  In short, you need cholesterol to keep your cells healthy, to help repair damage and to stop water from leaking out of your skin.

The problem is when you are making too much of the cholesterol transporter that takes the cholesterol to where it is needed, from where it is made (in the liver).  Just like an old car going slowly over a cobbled street, this 'transport out' system can grind to a halt over the parts of arteries that have been damaged by various things, dumping its load of cholesterol right there, on the damage.  This 'carrier' of the cholesterol out from the liver often seems to be confused with the cholesterol itself, and is referred to as LDL cholesterol. 

If you were a GCSE student, at this point I'd tell you that the L in LDL stands for Loathsome. 

We don't like this carrier, or the cholesterol carried by it.  It is a vintage car running on unleaded petrol***. It leaves lazy, lie-about cholesterol all over the place, fighting with itself while wondering when the next cheque from the trust fund is going to arrive.

The liver also produces the HDL - High Density Lipoprotein, or, for you GCSE students out there, the Happy cholesterol.  We like this carrier because it contains helpful, hard-working cholesterol - socialist cholesterol, if you will;  the sort of cholesterol that will clean up after all night parties held by the Bullingdon club, because that's just the sort of thing that this cholesterol does. This is the road bicycle of cholesterol carriers; the low-polluting high-density kudos-rich carrier of cholesterol.

Just as society needs to value the people who do the mundane jobs; the jobs that keep the system running, we need to value HDL.  HDL should probably be paid more.  What's important is less that the overall amount of cholesterol that you have is low but rather that  the ratio of HDL to LDL is big enough.  If you get too many trust-fund babies and not enough people doing stuff, then society will collapse.  If your LDL gets too high in relation to your HDL then you are at a higher risk of having a heart attack and your body will collapse.

We don't really know what causes the liver to produce more of one type of cholesterol or another.  We don't really know why cholesterol levels can get higher, or why the ratio of HDL to LDL can change.  What we do know is that we have observed some correlations:



Things that cause your cholesterol levels to get higher, or the ratios to get worse.

Funnily enough, its not the eating of cholesterol rich foods that's the problem.  While some foods, such as eggs, prawns and offal (if the livers of various animals make cholesterol, then the livers of various animals are going to have cholesterol in them) contain significant amounts of cholesterol, the ingestion of these foods has an insignificant effect (probably - it's always a 'probably') on the levels of cholesterol in your blood, and may even raise the HDL to LDL ratio (cite various articles, which I can't be bothered to look for right now, because you aren't my mother), which would be a good thing according to current theories.  So you probably don't need to worry too much about eating these foods - although moderation would be good; don't eat them every day.

Saturated fats seemed to be fingered as the culprit in most places: Here, here and here, for example. Again, I can't find any detail on how this works, but there does seem to be a correlation.  Some links suggest that saturated fats raise LDL levels, but other links suggest that saturated fats may actually be responsible for raised HDL levels (remember: HDL = Happy fat).  And here, we have the start of a conundrum which I shall deal with in the section after next.

Trans fats - vegetable oils that have been hydrogenated so that all the double bonds are broken down and hydrogen added to their available ends - appear to be the big daddy of cholesterol badness.  Trans fats are - or were - commonly used in industrial food production because they make food production cheaper and easier.  Many states in America have now legislated that all foods containing trans fats be labelled as containing trans fats.

While we don't have compulsory food labelling in the UK (why not?), the Food Standards Agency claims that voluntary control of trans fats has reduced their presence in the British diet (by how much the use of trans fats has been reduced is not clear, as food isn't clearly labelled when it contains trans fats, although 'hydrogenated vegetable oils' is one clue that they're present).  British Doctors are asking for legislation banning trans fats altogether.

Alcohol - too much alcohol can raise your triglycerides. Triglycerides are related to cholesterol levels in a way I have yet to comprehend, but the correlation seems pretty consistent and agreed upon over all the discussions that touch upon it. I have been looking for evidence of the Presybterian / Methodist-culture assumption that anything-you-enjoy-must-be-bad-for-you biasing opinions, but it isn't really there. That's too much alcohol, by the way, a definition which seems pretty open to debate - maybe that's where the tinpot tabernaclists have their influence, in that they define a level which is lower than it should be (given the corresponding evidence that just enough alcohol is actually pretty good for your cholesterol levels - both amount and HDL / LDL ratios).

And lastly, but probably not least, fructose - or fruit sugar - appears to have a huge deletory effect on cholesterol levels.  This is the one that suprises most people, but the evidence is sprinkled throughout the links I've given so far, especially the first one, by Mark Johnson. Or you can look at this.  Or you can look at a list of URLs dealing with this issue, and pick your own cite. 

While fructose is, obviously, present in fruit, it's also a derived commercially as a by-product of the extraction of ordinary sugar (sucrose) from sugar cane; it is 'sweeter' than sucrose and is omnipresent in our diet as the corn syrup used industrially to sweeten foods, or brown them. 

Fructose is hypothesised to be responsible for metabolic syndrome. 

All the evidence indicates that it's evil, and it's everywhere. It's probably OK to eat fructose in small amounts - such as the levels available from one or two helpings of daily fruit - but if you are eating commercially produced food, it seems, you are eating fructose and all that that implies.

Fructose and too much alcohol seem to work in similar ways.

So, those are the big baddies for now -  interestingly, the two food groups which seem to be most responsible for raised cholesterol levels are the two foods that have been added to our diet recently as a result of industrial innovation to make the large scale production of food even cheaper.


Food which actually may lower your cholesterol or cause the ratios to get better.

This would mainly be oats.  The key thing about oats is that they contain soluble fibre and "Soluble fibre binds to bile acids in the small intestine, making them less likely to enter the body; this in turn lowers cholesterol levels in the blood"

Everything you need to know about soluble fibre can be found in this Wikipedia article.

To be fair, anything that contains soluble fibre is fair game - and that means most vegetables.

Soy Protein - here's the Wikipedia link.   Note that other sources say that the correlation hasn't been established.  Google for yourself.

Red wine - here's a New Yorker Science Article (I decided that the Daily Mail was a link too far).  A more scholarly assessment is here.  Please note that neither article links to a definitive assessment of what actually is a moderate level of imbibing.  That's because I don't think one's been done. 

Garlic.  This has been established according to the scholarly article linked. 

Monounsaturated fats.  Here's the link to the Wikipedia article and in that article, you'll see lists of which oils are monounsaturated.  Olive oil is top of the list - but there are some suprising inclusions.  The article notes that tallow (beef fat) is 50% monounsaturated. That's the fat you get in steaks that in other articles is slated.

Please note that the wiki article is very careful to say that the ingestion of monounsaturated fats lowers LDL cholesterol and may raise HDL cholesterol.  May.  I'll deal with this next section.

Unsaturated fats. If monounsaturated fats lower your cholesterol level, then polyunsaturated fats lower it still further, right?  Hmm.

There are all sorts of odd things, that, Daily-Mail stylee, are now found to lower cholesterol and / or lower LDL and / or raise HDL.  For examples, orange peel, or tumeric, ginger, cinammon and rosemary.  This is a fertile field for quackery, and while none of these 'correlations' are likely to be incorrect to the extent that they damage someone adjusting their diet on the basis of the 'correlation' being represented as fact - in other words, 'it can't hurt' - I can find very little evidence to back most of this stuff up.  Mind you, I haven't spent a long time looking.
.

Food about which there is some reliable controversy

Coconut oil and milk. This refers to the milk and oil that is made from the coconut 'meat' found inside the coconut, rather than the very delicious water that drains out of a recently cracked green coconut. 

Coconut oil / milk is high in saturated fat, according to a few of the links already provided (1 2 3) In fact, as that second link shows, there are different types of saturated fat, and the profile of coconut oil is distinctly different to, say, the profile of lard.

There has been one bit of research, where people eating a diet high in coconut oil and various derivatives had their cholesterol measured and it was low; they then moved to New Zealand and Australia and reduced their intake of coconut derivatives.  Their cholesterol immediately went up.

There's an awful lot of anecdata relating to coconut oil and meat out there****, which indicates that coconut oil may not be the Big Bad that, say, the NHS makes it out to be.  There's a mechanism to explain the difference between this saturated fat and the saturated fats which seem to correlate to high cholesterol and high LDL levels, that is the different balance of triglycerides (i.e. the preponderance of shorter chain triglycerides) in coconut oil. 

I'm fairly convinced that coconut oil isn't the big bad that conventional government advice would have it be. 

Saturated fats.  While an excess of them probably is reliably correlated to high cholesterol levels, there are indications that saturated fats may actually raise HDL levels.  That link, mind, presents the thoughts of someone convinced by the Atkins diet, but I've read such murmurings elsewhere.  This probably deserves its own post at some time.


How much fat should you eat?

The important thing is that one realises that a fat-free diet is really not very healthy at all.  All the indications are that the fat that you do eat should be largely monounsaturated or polyunsaturated, although there are indications that a small proportion of saturated fat in that won't hurt.

In order to lower cholesterol, it's essential that one avoids trans fats and fructose, in the form of corn syrup.  To my mind, the easiest way to do this is to avoid commercially made foods, especially sweet foods.  I've already started making sure that I eat a bowl of porridge a day; I'm (sadly) going to be giving up the golden syrup that I love to dribble all over it (Golden syrup is essentially corn syrup). 

So.  The NHS recommends no more than 20g of saturated fat per day for a woman, and that seems reasonable enough.  What I think is important, though, is that that amount isn't reduced too much in a fit of healthy eating.  Looking around various sites, it's probably important that that amount doesn't go beneath around 12 g a day for reasons of maintaining the HDL levels.

About 30% of the calories in your diet should come from fat in total. Saturated fat should be limited to 7 of that 30%.  This means that the rest of the 'fat' 30% - around 65 g, or two and a bit ounces - should come from monounsaturated or polyunsaturated fat.  This is not an abstemious amount. 

Conclusion

When trying to lower my cholesterol total while maintaining the favourable HDL: LDL profile, I should be doing the following:

1.  Avoiding all trans-fats and corn syrups.  This means being neurotic about avoiding commercially derived biscuits and cakes. Absolutely avoid commercially sweetened products that may contain fructose.

2.  Not worrying too much about the amount of oil in my cooking so long as it is monounsaturated (olive)  or polyunsaturated (corn) oil. Not to use ridiculous amounts, though, but most certainly, not to cut fat and oil out of the diet altogether.  Oily fish such as tuna and salmon raise the amount of 'good oil'.

3.  Include a small amount of saturated fats in the diet - this could be coconut oil or (from further reading) lean red meat such as beef, in moderation.

4. Eat oats and tofu, drink red wine (in moderation), and put plenty of garlic into everything.

I'll look at specific issues when I write about recipes.

edited to add: The ocado website lists the ingredients in many foods. Here, for example, are the ingredients in Tunnocks Caramel Wafers.  You'll see something listed there called 'invert sugar'.  The wiki link for invert sugar describes it thus: "Inverted or invert^[1] sugar syrup is a mixture of glucose and fructose; it is obtained by splitting sucrose into these two components"

While corn syrup may not be prevalent in this country, it seems that invert sugar is.  You can use the Ocado website to investigate anything that you're worried about.

I investigated Tunnocks fairly randomly - they seemed to me to have the sort of sweetness that is disproportionate to their size, and I suggest that this is possibly a sign that a fructose-containing syrup, if not specifically corn syrup, is one of the ingredients.


**The problem with all of this survey of the literature that I've done is that I am having to disinter the knowleadgable from the fantastic, and the Daily Mail from the rational.  What Mark Johnson says chimes with what I've read elsewhere, and he gives a nice list of references

***I'm just about to stretch a metaphor.  Please do excuse me.  Also remember that we actually do need some LDL because otherwise the cholesterol that we need wouldn't get where it is needed, just like we do need some sort of incentive in society.

****Much of it, admittedly, from organisations trying to sell coconut products.