How your cholesterol is calculated

[Guest guest]

I am finding out more fascinating stuff in Zoe Harcombe's book, The Obesity

Epidemic.

On pages 124-5 she explains how your level of LDL ( " bad " ) cholesterol is

estimated.

Did you know that before a cholesterol test you ought to fast for 12 hours and

not drink any alcohol for 24? This is because food and alcohol affect levels of

triglycerides. The triglyceride level is used in the calculation of cholesterol

levels.

It is only possible to measure total cholesterol and HCL ( " good " ) cholesterol,

so levels of LDL ( " bad " ) cholesterol are estimated by means of the following

formula:

LDL = total cholesterol - HDL - triglycerides/5

The problem with this is that only 2 of the 4 things in this equation are known

(not enough).

Triglycerides are associated with an increase risk of heart disease. They

increase with levels of carbohydrate in the diet, so the " normal " (high carb)

diet raises triglycerides and a low carb diet reduces levels. If you have been

eating fewer carbs, your triglyceride levels will have fallen, which is good,

but it does affect the calculation of bad cholesterol.

LDL will rise if (a) total cholesterol rises and/or ( HDL falls and/or ©

triglycerides fall.

LDL will fall if (a) total cholesterol falls and/or ( HDL rises and/or ©

triglycerides rise.

Because of the way LDL is estimated by this formula, if LDL rises, HDL falls and

vice versa - by definition. The strange result of this is that a fall in

triglycerides, which would be welcomed by doctors, is accompanied by an

automatic increase in LDL (because of the formula above), which is not welcomed

by doctors.

As Zoe says, this just shows how unscientific the whole thing is!

(I hope I have explained this well enough. If not, please refer to the book.)

Miriam