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Good diet trumps genetic risk of heart disease

October 20th, 2011

I posted last week about “epigenetics” — the idea that, while the genes you’re born with are unchangeable, environmental influences can dictate which of your genes are turned “on” or “off.” A few days later, I saw a mention of this PLoS Medicine study in Amby Burfoot’s Twitter feed. It’s not an epigenetic study, but it again reinforces the idea that the “destiny” imprinted in your genes is highly modifiable by how you live your life.

The study mines the data from two very large heart disease studies, analyzing 8,114 people in the INTERHEART study and 19,129 people in the FINRISK prospective trial. They looked at a particular set of DNA variations that increase your risk of heart attack by around 20%. Then they divided up the subjects based their diet, using a measure that essentially looked at either their raw vegetable consumption, or their fresh veg, fruit and berry consumption. Here’s what the key INTERHEART data looked like:

Breaking it down:

  • The squares on the right represent the “odds ratio,” where the farther you are to the right (i.e. greater than one), the more likely you are to have a heart attack.
  • The top three squares represent the people who ate the least vegetables, and the bottom three squares are those who ate the most vegetables.
  • Within each group of three, GG are the people with the “worst” gene variants for heart attack risk, AG are in the middle, and AA are the people with the least risk.

So if we look at the top group first, we see exactly what we’d expect: the people with the bad genes are about twice as likely to suffer a heart attack as the people with the good genes. But if you look at the middle group (i.e. eat more vegetables), the elevated risk from bad genes is down to about 30%. And in the group eating the most vegetables, there’s essentially no difference between the good and bad genes.

How does this work? The researchers don’t know — partly because no one’s even sure exactly how the bad gene variants cause higher risk. (There are some theories, e.g. that it affects the structure of your veins and arteries.) But the practical message is pretty clear: if you eat your veggies, you don’t have to worry about this particular aspect of your genetic “destiny.”

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  1. Tom
    October 22nd, 2011 at 02:28 | #1

    This is among one of the vast number of observational studies though. Sure at the end of the day with a lot of data we can determine a correlation or two, but there’s no causative link that can be established. Maybe people who eat vegetables are more health-conscious, maybe they exercise more, maybe they exercise less, maybe they have a special heart disease-counteractive gene that causes them to also eat vegetables, maybe they are less likely to be construction workers, maybe some of them are vegetable eating aliens who don’t get heart disease and bring down the average, etc., etc., etc.

  2. alex
    October 22nd, 2011 at 14:55 | #2

    @Tom: The point of the study isn’t to establish a causative link between vegetables and heart disease. It’s entirely possible that the vegetable-eaters are more health-conscious or exercise more or whatever — whatever the mechanism is, the result is that this subgroup of people is not at an elevated risk of heart disease DESPITE having a particular genetic variant that should predispose them to heart attacks. So the key take-away is that the environmental factors (whatever they are, but which are correlated with vegetable consumption) negate the genetic factor.

  3. Tom
    October 23rd, 2011 at 20:28 | #3

    Agreed. That’s what I was getting at. My point was that we can’t take the results of the study and use them to recommend vegetable consumption as a risk reducing action for heart disease.

  4. Febo
    October 24th, 2011 at 14:40 | #4

    … I’ve read somewhere else that the risk of coronary disease is heavily influenced via iron in the blood, and i we took in ours mind the fact that iron is primarily found in red meat… … …

  5. Febo
    October 24th, 2011 at 14:41 | #5

    @alex iron

  1. October 20th, 2011 at 17:06 | #1
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