I often get asked the question, “What is the best diet for heart health?” And my general answer is this:
There are many different dietary patterns that can optimize both your Home Security System and your Lipid Neighborhood…the Standard American Diet (the acronym is SAD for a reason) just isn’t one of them!
But anyway, the DISCO-CT trial has been hailed as evidence that the DASH diet (you can Google that, but it’s famous for being a salt-restricted regimen) can “reverse heart disease” in people with plaque in their coronary arteries. But before you permanently throw away the salt shaker, let’s take a look at the study.
So here is the basic rundown (and you’re welcome to check out the full article BELOW):
Ok, so let’s talk about it!
-This was a randomized trial with 45 people in the DASH diet arm and 44 people in the “usual care” arm. (Usual care is terrible…just remember that). Notably, the people in the DASH group were told to eat at least 5 meals per day and wait no longer than 3 hours between meals. Got plaque? Eat a snack…all day long! There was also more intensive lifestyle and exercise education along with accountability measures for those on the DASH diet, for what it’s worth, if anything.
-These people all had significant plaque in their coronary arteries as determined by CCTA (which is a CAC on steroids…it not only gives you the calcified plaque, but also degree of stenosis (narrowing) and high-risk plaque features, such as non-calcified “soft” plaque. They had a CCTA at the beginning of the study and repeated this after about 70 weeks, give or take.
-The groups were said to be “evenly matched” at baseline…this is important, since it wouldn’t be fair to compare a group of professional basketball players with a group of professional hot dog eaters, for instance. However, upon closer inspection:
-In the DASH arm, 51% of participants were exercising at baseline, and by the end of the study, this had increased to 78%. Conversely, in the control group, only 29.5% were exercising at baseline, which improved to 50% by the end of the study. Additionally, the control group included 22.7% of people who WEREN’T EVEN DOING ANY LEISURE PHYSICAL ACTIVITY. A group of sloths thrown into one group could potentially affect results in a study of jaguars, don’t you think?
-The baseline bloodwork of both groups was similar…except the control arm had average triglycerides of 109.1 vs only 72.2 in the DASH group! Although there are caveats, this suggests a more insulin-resistant group in the control arm at baseline. But, by the end of the study, those on the DASH diet had triglycerides INCREASE from 72.2 to 96.4…not a very encouraging trend. (And the control group got worse as well). However, 18% of the DASH group lost enough weight to drop the “obesity” classification (dropping BMI to <30), whereas only 1 patient was able to achieve this in the control arm. (Username “Skinny Fat” has requested to enter the chat…)
-Although the LDL cholesterol was virtually identical at baseline, the DASH group dropped from about 109 mg/dL to 91 by the end of the study, whereas the control group dropped from around 109 to 101. There were medication changes allowed during the study, and given that the DASH diet typically reduces LDL-C by about 5 mg/dL, it’s possible that most of this effect in both groups was due to intensification of lipid-lowering therapy. However, the statement in the publication that both groups were on “optimal medical therapy” is an insult to the word “optimal.”
Ok, so how about the all-important PLAQUE RESULTS???? We already know from the headlines that the DASH diet leads to reversal of coronary disease…or does it?
-Percent atheroma volume, or PAV, which is a measure of OVERALL PLAQUE BURDEN (you can read more about this in Chapter 8 of my book), INCREASED in both arms…and the increase wasn’t trivial. In fact, anything over 1% is considered a “rapid progressor” with accompanying high-risk of future cardiovascular events. And the DASH group had a PAV increase of 1.0%. Oops. And the “usual care” group increased by 1.1%. Conversely, reduction of PAV by 1% is associated with a 20% decrease in cardiovascular events, which is the most important metric at the end of the day.
-BUT, both groups did reduce the “soft” plaque (NCPV) by a smidge, and the DASH group reduced NCPV by 51.3 mm3 vs a reduction of 21.3 mm3 in the control arm. So the clear conclusion must be that, since this result reached statistical significance, we now have the answer for the best diet to reduce plaque!!!!!!!
Well, there are many factors that reduce plaque. Exercise and medications have both demonstrated reductions in plaque volume in prior studies, and statins, in particular, tend to shift plaque from “soft” to a more calcified phenotype. Trying to disentangle those effects from the dietary intervention would seem a difficult task. However, the fact remains that EVERYONE WAS A RAPID PROGRESSOR, so whether you were on a DASH diet or some other abomination, aggressive measures beyond what was employed in this study ought to be taken to prevent what appears to be an imminent coronary event.
So wherever you’re DASHing off to for your next meal, make sure that you are “Controlling your insulin, controlling your life.” And take whatever headlines you read with a grain of salt😊
