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There's a few misunderstandings around the subject of cholesterol, in particular which numbers are important.
Cholesterol is made up of 3 main parts - LDL, HDL and Triglicerides (Trigs). HDL is considered to be "good" and the other two "bad".
Early research into cholesterol and heart attacks came to this conclusion:
"high cholesterol means greater risk of heart attack"
Then they did some more research and narrowed it down to:
"high LDL cholesterol means greater risk of heart attack"
Then they did some more research and came up with:
"High levels of small particle LDL cholesterol means greater risk of heart attack".
Most people are not up to date with this and seem to be stuck on the first one, possibly the second. So treatment for cholesterol tends to be based on what your total cholesterol test result is - despite the fact that we now know it revolves around LDL. Even if a GP looks at the LDL test result, they will tend to prescribe a statin, which reduces the LDL - but this does not necessarily improve the particle size.
So the treatment does not necessarily address the right problem.
The real danger is the particle size of the LDL and because of the way that HDL, LDL and trigs are made, we can get an idea of the LDL particle size by looking at the relationship between trigs and HDL. If you take your trigs result and divide it by your HDL result, a low number (below 1.3 at least) is good. So high trigs are bad, high HDL is good.
So for example, if your total cholesterol is 5.2, this will be considered to be too high and you will probably be prescribed statins. However, your detailed test results might reveal that your LDL is 1.9, Trigs 0.8 , and HDL is 3.5. This is a pretty good profile and theres no reason to reduce your cholesterol at all. Most of the cholesterol in this example is HDL - the good stuff. The trigs are low which means that the LDL particle size is good.
But if you don't know what the cholesterol breakdown is, the total cholesterol of 5.2 can look quite bad. On the other hand, your breakdown might be HDL 0.5, Trigs 1.5 and LDL 3.2 which is not good at all and you would need to take some action to sort out your cholesterol.
So from all that we know:
- HDL should be as high as possible
- trigs should be as low as possible
- LDL should not be ridiculous, but if the other two are ok then there may not be a problem.
- Total cholesterol doesn't actually tell you that much (unless its ridiculously high)
The most common treatment for high cholesterol is statin drugs. Statins work to reduce the LDL specifically, but this appears to be a reduction in the overall level of LDL and may have no effect on particle size. So they can quite easily be aiming at the wrong target.
A better approach to improving your cholesterol profile can be to lower your trigs and raise your HDL.
Trigs are manufactured in the body from carbohydrates. Reducing the amount of carbohydrates in the diet tends to reduce the trigs. HDL can be raised by increasing the amount of "good fats" in your diet - such as fish oils, nut oils and so on. Often these two approaches lower the LDL at the same time. Plus of course, lowering carbohydrates generally improves blood glucose(BG) levels as well.
The other factor which can make quite a difference in terms of cholesterol levels is exercise and in particular regular exercise.
There is however a lot of talk about reducing fat in order to reduce cholesterol and this is where there's more of a problem. If you reduce your intake of the good fats, then your HDL will go down and your cholesterol profile will get worse. Plus, most of the evidence for reducing fats helping cholesterol levels has been performed on people on a high carb diet. It appears that if you eat less fats on a high carb diet, then your cholesterol goes down a little. On the other hand, people on a lot less carbs, but eating MORE fat have a much better improvement in cholesterol levels and profile.
In a study involving 48000 canadian women on a low fat diet, over a period of 8 years, there was shown to be no signifcant improvement in the rates of heart disease. However, all of the studies into low carb diets either show an improvement in overall cholesterol or an improvement in the cholesterol profile - or both. However, this is only in studies where "low carb" is a significant reduction. The standard intake of carbs is 230g per day. Some "low carb" studies have been on 210g of carbs per day. The studies which do show a significant difference are at levels of 150g/day or lower.
So eating less fat may make a small difference in reducing cholesterol, but eating less carbs appears to make far more of a difference.
There's another myth about cholesterol which is proving particularly hard to shift because "everyone knows" that eating eggs raise your cholesterol. Except that it doesn't. This is a misunderstanding based on the fact that eggs contain cholesterol. But that cholesterol has to pass through your digestive system and get processed like all other foods and by the time it gets through all that, its been converted to something else. Its no longer cholesterol. So the cholesterol in eggs does not lead to higher cholesterol in your bloodstream *
This myth was debunked about 10 years ago but people still believe it today. In an edition of BBC Radio 4's News Quiz last year, they mentioned a new survey that eating eggs does not raise cholesterol. Nobody on the programme gave any indication that they were aware this was old news. Its a myth that lives on, long after its been disproved.
Its not just eggs of course, but any food which contains cholesterol - something which is marked on many food packets in the USA, but not in europe. Eating cholesterol is unlikely to raise your blood cholesterol level.
Finally, theres one other thing to consider. Cholesterol is necessary. It performs or helps with a number of functions in the body including the body's repair systems. This may be why smokers have higher LDL levels in particular. The body will increase its production of cholesterol in order to help repair the damage caused by smoking. At diagnosis, many type 2 diabetics have high levels of triglicerides and this may be due to the damage caused by high BG, or perhaps a reaction to what is causing the insulin resistance.
This may in some way explain why elderly patients with very low levels of cholesterol (particularly women) have a higher mortality rate. The cholesterol level is too low for some of the body's essential systems.
So when looking at cholesterol its important to look at the whole picture. As with many things connected to diabetes, things are not as simple as they are first made out to be. The more you dig into it and the more you increase your understanding the better off you will be.
*There are a tiny proportion of people for whom the opposite is true and eggs will raise their cholesterol according to research. But this is the exception rather than the norm.
This is a series of blog entries about diabetes myths. Diabetes Myth #1 - Its all your own fault Diabetes Myths #2 - Its all about sugar
Diabetes Myth #3 - Calories Count Diabetes Myth #4 - Cures Diabetes Myth #5 - The Diabetic Diet Diabetes Myths #6 and #7 - "Diabetes is progressive" and "Pills or Insulin mean failure" Myth #8 - Glycemic Index is the answer. Now whats the question? Diabetes Myths #9 - Cholesterol Diabetes Myths #10 - HbA1c is an Average
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Nicky.