Prompted by a recent posting here, I was browsing the British Dietetic Association website (bda.uk.com). As the regulars here will know, I don't hold dietitians in high regard, and what I read didn't help matters.
Of all the many scientifically-dubious statements on that website, the assertion in the title sent my blood pressure up by a few Torr. The exact quote is this:
"When you eat saturated fat it is converted into blood cholesterol by the liver. Saturated fat also slows down how quickly cholesterol is removed from your body."
Which you can find here under "Cholesterol":
The other papers are equally amusing (at least if you have a sick sense of humour), but I thought I'd focus on this one for the moment.
Let's start with the most glaringly obvious problem here: cholesterol is synthesized from acetyl coenzyme A, which is a sort of general-purpose Lego block that crops up in all sorts of metabolic processes. The pathway from acetyl-CoA to cholesterol is a long and winding road, but it has nothing whatsoever to do with saturated fats. To be clear: saturated fats are not converted to cholesterol, in the liver or anywhere else.
As for the second part of the sentence, it's hard to be sure what it even means. "Removed from your body?". Why would your body want to remove a critical substrate that it diverted energy and materials into synthesizing? What's the mechanism by which saturated fatty acids might purportedly slow down such "removal"?
Now it could be that they're referring to the balance between LDL-C and HDL-C, HDL-C being a scavenger lipoprotein that mops up unused cholesterol and returns it to the liver for recycling, and offsets the inflammatory effects of LDL-C. However, since saturated fats have little or nothing to do with LDL/HDL balance (except inasmuch as low-fat diets tend to promote a low level of HDL) this interpretation doesn't make much sense either.
It's worth reminding ourselves what a saturated fatty acid actually is (there's no such thing as a "saturated fat" - I'm using that term here simply because people are familiar with it). The difference between a saturated fatty acid and a monounsaturated fatty acid is a missing proton. A polyunsaturated fat is missing more than one. A proton is a very very small thing. Yes, that missing proton has some surprisingly noticeable chemical effects: the bond where the proton is missing becomes 'kinked', which makes it more susceptible to certain chemical reactions; it changes the nature of the electrostatic bonds between fat molecules, which changes their melting point. However, your body pays very little attention to this. Saturated fats, by and large, are treated the same as unsaturated ones: they are burned for energy.
But the BDA does not believe any of this.
When you eat saturated fat it is converted into blood cholesterol by the liver.
If you were to read statements like this on a private blog or a YouTube comment, you could laugh it off as the product of ignorance. It wouldn't matter one way or the other. But the BDA does matter. Their pronouncements are repeated in NHS advice, in the press, and in Government statements. So when the BDA says something inaccurate (otherwise known as "making stuff up"), it gets accepted as fact. The average man in the street does not have enough knowledge to do anything except take the statement at face value.
So I have a little advice for the BDA: get your act together, and fix some of that semi-literate rambling that you present as 'food facts' on your website. It does not matter if you, as individuals, believe privately in unicorns, aliens, or that when you eat saturated fat it is converted into blood cholesterol by the liver. However, when you spread your beliefs beyond the confines of your own ill-informed echo chamber, people suffer and die. No doubt it will take some time for you to sort yourselves out. In the meantime, please: primum non nocere.
Note for the pedants: I'm aware that 'nocere' is the infinitive, not the imperative. But that's the traditional phrasing, so I didn't fiddle with it.