RE: cholesterol in shrimps and other crustaceans

From: Mark Boulter (markb@sydneyfishmarket.com.au)
Date: Thu May 04 2006 - 20:18:14 PDT

  • Next message: Thanh Binh: "Re: cholesterol in shrimps and other crustaceans"

    Clive, etal;
     
     
    Rosemary Stanton, a very well respected Australian Nutritionist produced
    this piece a while back.
     
    Mark Boulter
    Sydney Fish Market
     
     
    PRAWNS & CHOLESTEROL <http://www.apfa.com.au/media/media.cfm>
    by Dr Rosemary Stanton PhD, APD

             
             
            
    30 August 2002

    Dr Rosemary Stanton PhD APD, is a qualified nutritionist.

    Prawns are an excellent source of protein and a great way to get iron,
    zinc and vitamin E. As a bonus, they have very little fat and virtually
    no saturated fat and are a good source of omega 3 fatty acids. But
    prawns do contain cholesterol. Let's take a closer look.

    Cholesterol is a waxy type of fat that is present in all animal tissues.
    Babies get it from their mother's milk. We could not exist without
    cholesterol because it is a structural component of all body cells and
    also an important building block for the body to make some hormones,
    vitamin D and the bile acids needed to digest fats. That's the good news
    about cholesterol.

    We also need to look at a more sinister side of cholesterol. Because the
    body must have some cholesterol, we have a way to make it in the liver.
    This is essential for those who do not eat animal foods, but sometimes
    the body's cholesterol-making mechanism goes into overdrive and produces
    too much. This excess cholesterol circulates in the blood attached to
    proteins called low density lipoproteins (or LDL). LDL cholesterol (or
    "bad" cholesterol) can clog arteries and impede blood flow to vital
    organs such as the heart.

    Cholesterol can also be carried in the bloodstream attached to high
    density lipoproteins (HDL). This is 'good' cholesterol which is taken
    back to the liver for the body to recycle for essential purposes.

    Some people inherit genes that encourage the body to make too much
    cholesterol, and if they eat too much saturated fat their 'bad' LDL
    cholesterol level increases. Most people in Western countries consume
    high levels of saturated fat and this is the major cause of excess
    cholesterol in the blood and cholesterol deposits in the arteries.

    Let's get back to prawns. Adults normally produce about 1 gram (1000mg)
    of cholesterol a day to satisfy the body's essential functions. If you
    eat foods containing cholesterol, the body should cut back on its own
    production. A breast-fed baby getting cholesterol from its mother's
    milk, for example, makes very little cholesterol because the milk
    contains enough.

    A serving of 100 grams of flesh from prawns grown in Australian waters
    will provide approximately 130mg cholesterol (range 120-160 mg/100g) or
    about one-eighth your normal cholesterol production. The cholesterol in
    Australian prawns is about two-thirds the level usually quoted from
    American shrimp.

    In theory, when you eat prawns, your body should reduce the amount of
    cholesterol it makes. However, if your diet is high in saturated fat and
    you have the 'wrong' genes, your cholesterol-production mechanism may
    not work effectively and the cholesterol from prawns (or fish or any
    other animal food) can add to what your body is making which may be
    several grams a day.

    To put this into perspective, even if your body does make too much
    cholesterol, the quantity of ready-made cholesterol you would get from
    prawns will be only a fraction of the total. It is much more important
    to reduce the saturated fat in your diet than to fuss about foods
    containing ready-made cholesterol.

    There are some problem combinations which provide high levels of
    saturated fat and cholesterol for example, fried bacon and eggs, or
    seafood battered or crumbed and then fried in saturated fat.

    Prawns themselves have virtually no saturated fat, so as long as you
    have them grilled, barbecued, steamed or cooked with a 'good'
    unsaturated fat like olive oil, they should not cause problems.

    Experimental evidence backs this. In spite of public confusion over
    prawns and cholesterol, there have been very few studies where people
    have been fed prawns and had their blood cholesterol levels measured.
    However, a study was conducted a few years ago in which researchers in
    the United States gave 18 volunteers 300g of shrimp every day for three
    weeks. Their total blood cholesterol levels rose slightly, but further
    examination showed there was a greater proportional increase in 'good'
    HDL cholesterol than in 'bad' LDL cholesterol. The subjects triglyceride
    levels (another type of undesirable fat) fell with the shrimp diet.

    The Japanese are the world's greatest consumers of prawns. They also
    have the highest life expectancy and it is possible the two things could
    be connected. At the very least, it is fair enough to say that the
    cholesterol in prawns and other seafood is unlikely to damage the
    arteries provided the seafood is not battered or crumbed and cooked in
    saturated fat.

    A note about omega 3 fatty acids:

    Like all seafood, prawns contain omega 3 fatty acids. These valuable
    fats lower triglyceride levels and have many other benefits for heart
    health. Prawns have less fat and therefore contain a lower level of
    omega 3s than some other seafood (like Atlantic salmon), but the omega 3
    content in prawns (average of 120 mg/100g) is well above the minimum
    60mg/100g required for an official label of "good source of omega 3
    fatty acids".

    Prawns are:
    *A good source of omega 3 fatty acids
    *An excellent source of protein
    *A great way to get iron, zinc and vitamin E
    *Low in saturated fats

    N u t r i t i o n I n f o r m a t i o n:
    (one serving of prawns, 100g flesh)
    energy 420kJ (100 cals)
    protein 24g
    fat 0.9g
    saturated fat 0.1g
    omega 3 fat 120mg
    carbohydrate 0
    sodium 485mg
    zinc 1.8mg
    iron 1.6mg
    Vitamin E 2.9mg

    Written and authorised by Dr Rosemary Stanton, August 2002.

    Published by the Australian Prawn Farmers Association
    P.O. Box 3128, South Brisbane, QLD 4101.
    Ph: 07 3255 1070 Fax: 07 3844 7307
    August, 2002

    ________________________________

    From: owner-seafood@ucdavis.edu [mailto:owner-seafood@ucdavis.edu] On
    Behalf Of Clive Askew
    Sent: Friday, 5 May 2006 12:50 AM
    To: Seafood research and extension information exchange
    Subject: cholesterol in shrimps and other crustaceans

    Dear list,
    The recent correspondence on cholesterol in albacore has reminded me of
    the difficulties I have had getting any recent data on cholesterol in
    shrimps, prawns and other crustacea. I have read that current thinking
    is that much of what was originally recorded as cholesterol is now found
    to be other sterols related to plant sterols, and hence likely to reduce
    rather than raise blood cholesterol. However I have been unable to find
    recent papers on this. Can anyone help please?
    Thanks.
    Clive Askew
    Shellfish Association of Great Britain
    Fishmongers' Hall
    London Bridge
    London


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