If you are one of those people who move the veggies around their plate without taking a bite, sorry about this: Scientists don’t have conclusive proof about which specific vegetables are good for our health just yet. But they're getting closer.
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New research from the University of Western Australia looked at whether eating vegetables might be associated with a lower risk of heart disease and stroke.
The team recorded the diets of over 900 women above the age of 70, then measured the thickness of their carotid artery wall (the main artery in your neck). A thickened carotid artery has previously been linked to heart disease and stroke risk.
Women who reported eating three or more portions of vegetables a day had thinner artery walls, compared to women who ate fewer than two portions of vegetables a day. Thinner artery walls mean blood vessels are clearer, making them more able to move blood around.
But not all veggies appear to be equally effective. Cruciferous vegetables, a group that includes cabbage, cauliflower, broccoli and Brussels sprouts, seemed to have the biggest association with artery wall thinness.
Any potential effect is likely to be very small, though. The difference in artery wall thickness between women eating three portions of vegetables and those eating less than two portions was only 0.04 millimeters, equivalent to a 4.6 percent reduction.
If you were hoping fruit was linked to the same sorts of effects, it wasn’t, suggesting fruit might not be as important to this particular area of our health.
Previous research found that diets high in fruit and vegetables were associated with positive health effects, but this study is the first to look at the possible effects of specific groups of vegetables.
The research is far from conclusive. The study only shows an association between vegetable intake and artery wall thickness, not a cause-and-effect relationship. We don’t know for certain whether these associations actually have any meaningful impact on our health.
Scientists have shown that reducing the thickness of the carotid artery wall by 0.1 millimeters is associated with a 10 to 18 percent reduction in the risk of heart disease and stroke. They are hopeful that the smaller artery wall reductions seen in people eating lots of vegetables will have a similar effect, but researchers didn’t look at whether these particular women had more or less heart disease or stroke.
It is unclear exactly how vegetables might positively impact our health. The researchers speculate that the potassium and nitrates in vegetables may be responsible since the association was weakened when these factors were adjusted for.
But the mechanisms by which artery wall thickness is determined are even more puzzling. Researchers suggested that vegetables might reduce the risk of plaques forming in arteries or reduce the chances of patients developing high blood pressure. Either of these factors could cause the artery walls to thicken.
Until scientists serve up some more research next to the broccoli, we won’t have conclusive proof about which vegetables have the best impact on our health.