Fat, cholesterol and heart disease?

A lot of people here are handing out advice based on saturated fat and cholesterol causing heart diseas. What I want to know from these people is how in fact saturated fat and/or cholesterol leads to heart disease.

Before you answer, consider these facts;

*Fats, or lipids, as well as cholesterol are carried around the bloodstream encased in Lipoproteins. The lipids and cholesterol are ONLY handed out to cells that ‘ask’ for them, by way of a specific receptor. No receptor, no exchange.

*The lining of the arteries, the endothelium, is a non stick surface, designed to allow blood to flow freely, with nothing sticking to it

*When something does damage the endothelium, lipids and cholesterol are amongst the last things to be deposited at the injury site
http://circ.ahajournals.org/cgi/content/abstract/6/4/481

*The composition of fatty acids in arterial plaques is 74% unsaturated, of which 41% are monounsaturated
Lancet, Volume 344, Issue 8931, 29 October 1994, Pages 1195-1196


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2 Responses to “Fat, cholesterol and heart disease?”

  1. janitor Says:

    Yes, it is true that, from the previous answer, fats have nothing to do with cholesterol build-up, especially if fat catabolism is in question. This is so because the net number of carbons entering the TCA cycle from fatty acids is the same as the number of carbons coming out–thus there is no formation of acetyl-CoA, one main component, aside from malic acid, that comprises fatty acid molecules. Carbohydrates, and their excess if I might add, are actually the ones having the terminal fate of either being stored as glycogen or, usually for people having predisposition to obesity and/or diabetes, converted as fat upon carbohydrate catabolism–this includes the fatty acids transported by the serum lipoproteins (like LDL and HDL) circulating in our bodies.

    I believe that is the least biochemistry you have to know regarding fat metabolism, although you may know a lot more than I do in this respect. Now, your question is how EXACTLY does "saturated fat" or "cholesterol" leads to cardiovascular disease, and the answer to this is, no surprise, IT DEPENDS. In reality, there is no one explanation as to how cardiovascular disease arise from the components you have mentioned; what we do know is that most CD do INVOLVE the components you said and actually participate in a large part more often than not.

    Regarding the "facts" you have mentioned, yes, they may be "facts", but if you consider patients admitted for cardiovascular diseases and even prior to their hospital admission, you will find that at least one of the facts you have mentioned are actually flawed primarily because of their metabolism and physiology–this is only one reason and one type of answer to your inquiry. While lipids, or fatty acids if you will, and cholesterol have a receptor mechanism for its transport, this process has an inherent "flaw" in that an EXCESS of transported lipids in serum lipoproteins actually bypass the receptor-mechanism you have described; this is analogous to filling a cup of water continuously, with the excess water flowing out. Because there is an excess lipoproteins, not all of it is transported to its designated site, and there are specific sites in the body where lipoproteins are transported.

    Since the vascular lining is "non-stick", so to speak, the transported lipoproteins are allowed to travel in the circulation freely UNTIL settling in a narrow artery–a big problem especially if there is an influx of serum lipoproteins carrying fatty acids. And while endothelial damage MAY NOT, as what you claim in the third "fact" you mentioned, be the typical place where lipoprotein deposition occurs, the fact that serum lipoproteins have a tendency to settle to the site of injury has to be taken into consideration. Coming from the AHA, they should know better than to exclude this POSSIBILITY, because in the world of medicine, not everything revolves around facts, but more on possibilities. This is exactly why some medical diagnosis are skewed because physians tend to facts rather than possibilities. And I believe this is where your "facts" fail, because it rules out all other possibilities.

    Again, whether saturated or unsaturated, the composition of fatty acids in plaques is only an estimate; the main idea is that a plaque built up. And if such is dislodged on a narrow arterial vessel, then you have the catalyst for a cardiovascular disease, whether it’s a myocardial infarction, stroke, pulmonary embolism, or deep vein thrombosis.

    Of course, this is only ONE of the many possibilities, because there are other reasons out there that actually goes around the facts you have mentioned. One of them is a genetic predisposition to cardiovascular disease, which could start with a metabolic abnormality in fat metabolism and eventually leading to the disease itself if left untreated. The advice/s people give here in Answers are perhaps more on the subtle side of things. I am not instigating other people’s "beliefs" because for all we know, they may have gotten those "facts" from professionals as well. And this is exactly why I do not necesarily approve of solely depending on facts alone, as it does not leave any room for possibilities (unless of course everything tends toward the facts, although in this case I can confidently say otherwise).

    I only learned the elementary biochemistry just last semester, and admit that my knowledge is still novice with regards to biochemistry. However, what I do know is that any influx or compromise on the mechanism you have listed actually trigger or maybe even catalize or pre-dispose a person to have a cardiovascular disease (not to mention vascular abnormalities). Again, I apologize if this does not pin-point you to the true answer itself because, in reality, there is none but a web of possibilities; or maybe someone out there really knows the answer.

    Hope this helps in some way.

  2. iluvtorofl Says:

    Eating fat has nothing to do with cholesterol levels. Eating sugar does. And I doubt that cholesterol, at least LDL, has anything to do with heart disease.