Wednesday, 22 September 2010

Good Fat, Bad Fat

I had high expectations of this episode of Case Notes, given its Taubes-esque title:
  • Dr Mark Porter investigates how the good and bad fats we eat can impact on our health, including trans fats that are found in many take away foods and are associated with heart disease. And he discovers that the health benefits of eating Omega fats depend on which you eat and when you eat them - too much Omega-6 for example, can hinder the benefits of Omega-3. Case Notes unpicks health messages about fat consumption that are confusing and contradictory.
There are a few nuggets tucked away in the program but sadly the moderately sat-fat phobic opening limited my expectation.   I say 'moderate' because the news that sat-fat is nothing to be scared of has obviously permeated Radio 4, but they are not ready to do away with the old mantra just yet, as Dr Alex Richardson illustrates,
  • Really for most of the post-war period we were told that all fats are bad. The real issue is not the quantity of fat in our diets, it's the quality - it's the type of fat that actually matters. Dietary fats are divided into two main types - saturated fats, these are the ones which you'll find in meat fat, butter, lard, mainly from animal sources but also some tropical fats like coconut and palm. But these fats - they're not unhealthy in themselves but they are unhealthy in excess. So cutting down on the amount of fats that you get from meat and butter and cream and cheese and so on is probably a good idea for most of us in the Western world. Then you've got the unsaturated fats. Now these you can actually tell the unsaturation by asking yourself the question: How liquid is this at room temperature? Saturated fats, like butter or lard or meat fat, are largely solid at room temperature, the unsaturates are liquid oils.
The program also gives a heads up on the ratio of O3 to O6 (the latter prevalent in soy and cereals).  There is some discussion of O6 and inflammation.  There is also a good deal of focus on cutting back on O6 (avoiding processed foods and grain oils).  Dr Alex Richards even mentions HG!
  • In the diet on which we evolved, the hunter gatherer type diet, the ratio of omega-6 to omega-3 fats in the human diet was some people say one to one, in equal parts but certainly no more than about four to one in favour of omega-6. What we have now, we have an omega-6 to 3 ratio which at the national level in the UK is at least 10 to one and for many people's diets 20 to one or a 100 to one in favour of omega-6. This is not good. If there is one statistic or one piece of information that everybody would benefit from knowing it is their own omega-6 to 3 ratio in their own body tissues. The reason this omega-6/3 ratio matters so much is that they compete for the same enzymes in the body. So certain enzymes will use either an omega-6 fat or an omega-3 fat, they're blind to which it is, and they will turn it into a substance that will influence your immune system, your blood flow, your hormones. If it's an omega-6 fat the derivatives - the substances we make from our fats - will tend to be pro-inflammatory and pro-thrombotic - they will block and restrict blood flow and make the blood stickier and more likely to clot. If they're omega-3 fats the very same enzyme will produce substances that are broadly anti-inflammatory and anti-thrombotic
Change is definitely in the air, but we will have to wait a bit longer to witness the change we want to see.

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