March 31, 2010

health wednesday

How many times have I told my parents to stop getting their health advice from the 6 o'clock news? Too numerous to count. It's alway sensationalized, completely overstated, misleading at best, and sometimes just plain wrong. So as a public service to them (and anyone else interested in my ramblings), every Wednesday I'm going to post over something related to health that I find interesting. Current dogma says fat=bad. Except the data doesn't back that up too well. If you want a very detailed assessment that knocks so many holes in that theory that it sinks, try Gary Taubes' Good Calories, Bad Calories. It's not written by a doctor or scientist but it is exhaustive in its approach. But I digress...where was I? Oh, yeah. Fat=bad, especially saturated fat (animal fat). A recent publication looked at fat and diet. But the lead researcher says it better than I can, "For 60 years we've been recommending reduced saturated-fat consumption without a focus on what should replace it in the diet," lead investigator Dr Dariush Mozaffarian (Harvard University, Boston, MA) told heartwire. "In practice, what's happened, if you look at trends over the past decade, saturated fat has been replaced by carbohydrates, largely refined carbohydrates. There have been several recent meta-analyses of observational studies showing that if you reduce saturated fat and don't pay attention to the replacement, there is no association with lower heart-disease events." Mozaffarian pointed to a recent meta-analysis of prospective epidemiologic studies showing that there was no significant evidence that dietary saturated fat is associated with an increased risk of coronary heart disease or cardiovascular disease. So essentially, that study saw no effect of saturated fat on heart disease. American Heart Association, are you listening? Hello? Low fat diets don't hold up well in studies. Anyone? Really? Nobody? So these guys wondered, "well, what if instead of replacing saturated fat (animal fat) with carbohydrates, you replaced it with polyunsaturated fats (plant fat)?" So they looked at 8 different clinical trials in humans (not mice or rats), grouped them together by fat amount and type of consumption, and looked to see of who got the pleasure of visiting the hospital because of heart disease. It turns out that for every 5% increase in plant fat consumption, there was a 10% decrease in having a heart attack or just plain keeling over. Long story short, replacing saturated fat with refined carbohydrates (bread, pasta, etc) doesn't do squat to heart disease. Replacing it with plant fat (vegetable oils like soybean oil) improved your odds of bypassing the bypass, so to speak. And this study didn't even make use of the oils from olive oil, nuts, or fish which all have protective evidence by themselves. Perhaps disease would be reduced even more. Take home advice? Eat less grains overall, especially the refined ones. Replacing saturated fat with polyunsaturated fats - not carbs -reduces CHD risk (free subscription required) Mozaffarian D, Micha R, Wallace S. Effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a systematic review and meta-analysis of randomized controlled trials. PLoS Med 2010: DOI:10.1371/journal/pmed.1000252.


Steve Parker, M.D. said...

I'm glad to see covered this. Most cardiologists haven't been getting the message.


Isaac said...

I know they don't teach nutrition in med school (and I sincerely doubt they get it in residency) but this stuff ain't exactly rocket science And yet, we've had two oncologists tell my brother that there's no real bad foods. You just need to eat what you like. Seriously? The entire field of medicine really has come around on this mentality. Good to see docs like yourself changing course.

David Brown said...

Replacing saturated fats with polyunsaturated fats is not a good idea. The Harvard group would do well to stop demonizing saturated fats and extolling polyunsaturates. Suggest readers familiarize themselves with the problems associated with excessive omega-6 consumption.

Isaac said...

They do comment in the article that these were omega 6 and implied omega 3s could even do better yet. To me, the jury is still out on what the ideal (if that's even possible) fat combinations are. The Meditterranean Diet is probably the diet with the strongest clinical evidence behind reducing disease and it's definitely not low fat but it's not real heavy in saturated fat either. In the end, there's probably more than one way to skin a cat and you have to find what works with the individual.

I'm just happy to finally see them realize that carbs are in large part responsible.