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Monday, October 7, 2013

Does the Mediterranean Diet Reduce Cardiovascular Risk?

By now, most of you have almost certainly read about the latest examine on the "Mediterranean diet program" (one), a diet regime that was developed by diet plan-heart researchers and is based loosely on the classic diet plan of Crete and specific other Mediterranean locations.  The popular press has been enthusiastically reporting this demo as extended-awaited proof that the Mediterranean diet plan reduces the chance of cardiovascular events-- by a full 30 p.c above a four.8-year period of time.  I wish I could share their enthusiasm for the review.

Let me start off by saying that I consider the Mediterranean diet program is a reasonably healthier diet program pattern, undoubtedly a main improvement over the common diet regime.  In this distinct examine, participants had been inspired to consume a lot more olive oil, nuts, fish, fruit, veggies, beans, white meat and wine and consume fewer baked items, spread fats, purple meats and soda.  The Mediterranean diet regime team was split into two, with one half acquiring added-virgin olive oil and the other half receiving nuts.  Here is how they ended up instructed and followed up:


For individuals in the two Mediterranean diet program teams, dietitians ran specific and group dietary-instruction periods at the baseline pay a visit to and quarterly thereafter. In every single session, a fourteen-item dietary screener was utilized to assess adherence to the Mediterranean diet regime (Table S1 in the Supplementary Appendix) so that customized advice could be supplied to the research participants in these teams.



The comparison group was a "lower-unwanted fat diet plan" group.  Diet designs scarcely transformed in this team in excess of time, with nutritional excess fat only lowering from 39 to 37% of energy more than the program of the trial.  The cause gets distinct when you go through the description of how they ended up instructed and followed up:

Individuals in the control group also obtained nutritional coaching at the baseline visit and concluded the fourteen-merchandise dietary screener used to assess baseline adherence to the Mediterranean diet plan. Thereafter, throughout the first three many years of the demo, they obtained a leaflet detailing the lowfat diet plan (Table S2 in the Supplementary Appendix) on a annually basis.



So essentially, they got instruction at baseline and a pamphlet in the mail when a yr, even though the Mediterranean diet program team obtained quarterly visits with a dietitian, diet program screening, and "individualized suggestions".  Anyone see a difficulty here?  The investigators did, halfway via the research:

However, the realization that the much more infrequent check out schedule and significantly less powerful assistance for the control team may be constraints of the demo prompted us to amend the protocol in October 2006 [3 several years following the starting of the trial -SG]. Thereafter, participants assigned to the management diet regime received personalised suggestions and have been invited to team classes with the identical frequency and depth as individuals in the Mediterranean-diet teams, with the use of a different nine-merchandise nutritional screener (Table S3 in the Supplementary Appendix).



Why did they have a reduced-body fat diet regime handle group to start with?  The position of a control team is to eradicate all variables from your comparison except the factor you happen to be intrigued in, in this scenario, diet regime.  In this research, they presumably selected a lower-body fat diet for the management group because numerous trials have demonstrated it to be ineffective at protecting against cardiovascular activities*.  If you want to see a therapy result, you need to use a fairly ineffective comparison group, or else there will be no big difference among teams.  Since people tend to turn out to be healthier when they undertake any type of health-oriented diet program adjust, and/or satisfy with dietitians and physicians regularly, the low-excess fat diet intervention must have managed for this possibly essential variable.

However, since the diet program of the manage group remained primarily unchanged, and it received a less intense intervention than the Mediterranean diet plan team, it was not a suitable manage, and you will find no way to know how significantly of the 30 per cent reduction in functions was because of to the Mediterranean diet plan itself, and how a lot was owing to increased diet vigilance and browsing frequently with dietitians.  Dr. Peter Attia just lately made the exact same point (

Title: Does the Mediterranean Diet Reduce Cardiovascular Risk?
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Posted by: Admin Updated at: 11:15 PM

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