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good prospective study of the Mediterranean diet
Posted: 26 February 2013 12:51 PM   [ Ignore ]   [ # 16 ]
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George - 26 February 2013 11:10 AM
macgyver - 26 February 2013 10:22 AM

Even if we did, there will be genetic differences between you and your brother so who’s to say those genetic variations aren’t important?.

Sure they are important. But until we get to the day when we have the resources and knowledge to test everyone and make sense of the role genetics play here (looking at the map I am inclined to believe Spaniards are different enough from the English to take genetics into consideration—although that could be the racist in me speaking again), we should at least try to stay away from making sweeping assumptions like the one based on the Mediterranean diet study. We no longer tell all the kids they should drink milk, do we?

I don’t agree with that. Spain is not a walled city. There is tremendous genetic flow from between countries such that there are more similarities between individuals of Spain and other countries than there are differences, and more differences between individuals within a country than there is between populations of different countries.. If you are waiting for the day when someone can tell you that this or that particular recommendation is applicable to you but not your neighbor you will be waiting an awfully long time. I am well aware of all the efforts to make medicine more individualized but we are no where near having that kind of resolution in our data that would allow us to come up with recommendations such as the ones you are looking for.

In the mean time we can certainly make reasonable conclusions based on what we do know such that the population as a whole will live longer and better. In this particular case, any suggestion that this might be an effect limited to only to a Mediterranean population is naive. If you look at the particular diet in question it includes many features that have been extensively studied on their own. There is significant evidence that diets high in refined carbohydrates and sugar lead to increased rates of diabetes and heart disease. Similarly there is good evidence that diets high in red meat lead to increased rates of heart disease and certain cancers. Polyunsaturated fats are well known to have positive effects on lipid profiles when they are used instead of saturated fats or trans fats. Diets that include a higher intake of fish have also been linked to better cardiovascular outcomes. These studies have been done in different groups of people all around the world. The Mediterranean diet is simply a diet that incorporates many of the things we already know to be part of a healthy diet. I don’t think its unreasonable for the medical community to advise people that this is what the evidence currently implies.

We can wait longer until we have a more data but at what point is it then permissible to make recommendations? If you’re waiting for the perfect answer tailored specifically to your genetics you can sit back eat twinkies and believe that our knowledge is so imperfect that your chances of a good outcome are as good as anyone who follows current guidelines for a healthy diet but you are going to have a long wait.  Lets put it another way. If we were to create two groups of Americans assigned entirely at random to eat a Mediterranean diet or a diet akin to what the average American currently eats and then follow them for 20 years which group would you bet on having the better outcome if we put some real money on it? If you have even the slightest inclination to go with the Mediterranean diet group than I would suggest that its irresponsible for the medical community to not be recommending such a diet at this point. No one is putting a gun to anyone’s head and making them eat this way. They have simply published a study that gives further evidence to something we already had significant evidence for. Anyone who doesn’t want to listen is free to eat their twinkies.

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Posted: 26 February 2013 02:19 PM   [ Ignore ]   [ # 17 ]
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And I don’t agree with that. To say that there are more genetic differences within a population than between different groups of peoples is know as Lewontin’s Fallacy and simply not true. It is true only when we look at the frequency of specific loci, but overall two Spaniards are on average always genetically closer to each other than is a Spaniard to, say, an Eastern European.

Do the high carbohydrates and sugar diets lead to the same increased rates of diabetes and heart disease for all races? I doubt that. Different groups of people all around the world will get drunk when they drink alcohol, but most people in Japan will require a lot less alcohol in their bodies to get as intoxicated as a person from Europe.

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Posted: 26 February 2013 02:46 PM   [ Ignore ]   [ # 18 ]
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I am aware of Lewontin’s fallacy but you are misapplying it here. He argues that there are no significant differences between groups but that is not what I am saying. Even those who argue with Lewontin’s proposition agree that there is greater genetic diversity within groups than between them. They simply argue that group differences are great enough that you can actually identify groups based on their genetic makeup.

Lets say for example that we find a relationship between Olive oil consumption and Bad cholesterol (LDL) such that for every gram of Olive Oil one consumes in a day there is a 10% drop in LDL level among Spaniards. If you look at the populations whole you will get a range of responses such that some people see no drop at all and other see a 20% drop with a standard bell curve distribution. If you did the same study in Americans maybe you would find a 9% drop on average with a range of 0% to 18%. The difference between individuals in any group is going to be much larger than the difference between groups for most things especially if the trait you are looking at is governed by multiple genes as in the case we are discussing ( diet and cardiovascular disease).

As a result it may be reasonable to consider such things when making recommendations but it is unlikely that the small genetic diversity between groups would ever be large enough to wipe out a difference as large as the one seen in this study especially when a large number of individuals from a mobile 1st world population are included. I’m not saying its impossible just very unlikely. Again you have to keep in mind that this study merely confirms things we have already learned from many other studies done around the globe in various populations.

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Posted: 26 February 2013 03:45 PM   [ Ignore ]   [ # 19 ]
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I don’t think I ever said the effect in other populations would be wiped out. If the diet is as effective as the study suggests (if!, I still don’t think that one study is sufficient to jump to some definitive conclusions), other groups will need to be looked at before we can assume the result would be the same for everybody.

And you are still wrong about the genetic difference within/between group(s). If I die of a heart attack (which I most likely will) and my brother doesn’t, and my dog dies of a heart attack, (and assuming that genetics plays a role here), it doesn’t mean that I am genetically closer to my dog than I am to my brother. Sure, there is a bell curve related to heart diseases in dogs just like there is one in humans, but so what? No, two people within a population will always be genetically closer to each other than either of them will be to a person from different population. Lewontin was wrong on this (you should look it up, as I doubt you understand what he was after) and so are you.

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Posted: 26 February 2013 08:37 PM   [ Ignore ]   [ # 20 ]
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macgyver - 26 February 2013 12:51 PM

The Mediterranean diet is simply a diet that incorporates many of the things we already know to be part of a healthy diet. I don’t think its unreasonable for the medical community to advise people that this is what the evidence currently implies.

This is essentially what it comes down to.

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Posted: 26 February 2013 09:00 PM   [ Ignore ]   [ # 21 ]
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Re the map.  George, where did you find it? It’s a very interesting map and I wonder if there were any explanations for the patterns on the website you got it from.

Lois

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Posted: 26 February 2013 09:10 PM   [ Ignore ]   [ # 22 ]
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Lois - 26 February 2013 09:00 PM

Re the map.  George, where did you find it? It’s a very interesting map and I wonder if there were any explanations for the patterns on the website you got it from.

Lois

Here:
jaymans.wordpress.com

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