Saturated vs. unsaturated fats

  1. ShawnD

    ShawnD 986
    Science Advisor

    Which kind of fat is worse?

    My highschool biology teacher said saturated fats were worse because saturated fats are more rigid. For example, vegetable oil (unsatured) is a liquid at room temperature, but butter (saturated fat) is solid at room temperature.

    My university chemistry teacher said unsaturated fats are worse because they are more reactive and tend to bond to things to make thick substances (sort of like the alkenes in gasoline make thick gunk that forms in the carb of your car if you don't drive it for a while). He gave the following example. If you eat saturated fats that are 100 carbons big (just for example), that saturated fat will not bond to anything and will stay 100 carbons big. If you eat unsatured fats that are 100 carbons big, the fats may bond to other things to make substances that are much bigger; say 200 carbons big.


    I don't follow health issues too closely and both teachers lack credibility in their own way.
     
    Last edited: Feb 23, 2004
  2. jcsd
  3. Your highschool teacher is right. Saturated fats, because the are linear, can pack together more neatly, say along the walls of your arteries, and Van der Waals forces keep them together. Unsaturated fats have at least one kink in the chain and can't pack like saturated fats.

    I believe you can take unsaturate fats, which are liquid at rt, and saturate them into a solid at rt, with the same number of carbons.

    That's the main difference between vegetable oil and margarine, if I'm not mistaken.
     
  4. Monique

    Monique 4,700
    Staff Emeritus
    Science Advisor
    Gold Member

    Ok, just to explain the two terms: saturated means that all free bonds have reacted with hydrogen atoms, while unsaturated means that there are double bond in the molecule (not completely hydrogenated).

    The consenses in the medical world is that saturated fats are bad and unsaturated fats are better. Most current guidelines say it's okay to obtain as much as 30% of daily calories from fat as long as only a third of that fat is saturated. However, quite a few scientists and health practitioners would prefer to see total fat limited to around 10%.

    Saturated fats can be used only for energy; they are incapable of performing other essential functions for which fats are needed by your body. More importantly, saturated fats (particularly animal fats) raise your total blood cholesterol and have been linked to heart disease and various cancers.

    A possible reason why this occurs is that saturated fatty acids take up the space occupied by cholesterol in the fatty acid particles such as HDL and LDL. Cholesterol cannot be taken up and thus stays in the plasma.

    (the reason why saturated and not unsaturated fats can do that, is that saturated fats don't have double bonds and are thus flexible straight molecules. Unsaturated fats contain double bonds and are thus more rigid and have a crooked conformation. So saturated fats should nicely fit into a micel, while for unsaturated fats this should be more difficult? Just my thought..)

    Avoid processed foods that contain fats that have been "partially hydrogenated. The process of hydrogenation changes unsaturated fat to saturated fat. It also changes the shape and configuration of the fatty acids, producing what is known as trans fat, which is difficult for your body to utilize. Trans fats have been shown to increase "bad" LDL cholesterol and decrease "good" HDL cholesterol. In the U.S., margarine is the number one source of trans fats. To find out if a product contains partially hydrogenated (trans) fat, check the ingredients. Some collegues of mine eat real butter on their bread for this reason, instead of margerine.

    I've never heard the reactive argument for the unsaturated fatty acids before..

    Some info came from:
    http://www.womensmedia.com/health-fat.html
     
  5. He is absolutely incorrect and I have to disagree with the others.

    You have failed to distinquish between CIS unsaturated and trans unsaturated. The trans can form a lattice like structure that is much worse than that of saturated fats.

    Although, CIS fats are extremely good for you, due to the reasons mentioned above.

    Nautica
     
  6. I'm not 100% sure but I think saturated fats are basically worse for you naturally. But in some unsaturated fat products such as maragrine the transfats that are a bioproduct can make unsaturated fats worse. My Biology teacher says this is recent information and is being looked into though. I'm just in High School biology so pay attention to what the masterminds above me are saying more fluently. :wink:
     
  7. ShawnD

    ShawnD 986
    Science Advisor

    Maybe that's what my chem teacher meant, it sort of follows the description of what he said happens.

    What's better then, margarine or butter?
     
  8. While Margarine is vastly more popular I'm guessing due to the ill-affects of the transfats that are associated with margarine would make butter healthier for you.

    However don't risk things on my answer. :wink:
     
  9. ShawnD

    ShawnD 986
    Science Advisor

    Well actually it doesn't matter what you say, I'll always use butter because it tastes so much better. Try making macaroni and cheese with butter then try with margarine. There is just no comparisson.
     
  10. CIS unsaturated fats - olive oil, fish oils, flaxseed oils are essential fatty acids and are extremely good for you.

    Saturated fats - butter is bad for you.

    Trans unsaturated fats - margerin is extremely bad for you.

    Nautica
     
  11. adrenaline

    adrenaline 274
    Science Advisor

    The consensus is still out on the transfatty, although it doesn't look good. This is due to the fact that we do not have good food labelling of the content and amount of transfatty acids in these processed foods so clinical studies are inherently hampered by this.

    This is a good article in Circulation, a pretty respected journal for the cardiologists. I think the transfatty acids will prove to be the worst Lp(a) inducer of all the fatty acids. (Lp(a) is the most athrogenic "bad" cholesterol there is and high values are associated with almost a 70% chance of having a heart attack.)

    http://www.americanheart.org/presenter.jhtml?identifier=1728

    In other words, trans fatty acids from animal fat may be the bigger bad guy than the hydrogenated oils. It will be interesting.
     
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