 There was a famous study from Harvard, published back in 1999, that found that women who used oil and vinegar salad dressing about every day went on to have fewer than half the fatal heart attacks compared to women who hardly ever used it, less than half the risk of the number one killer of women. They figured it was the omega-3s in the oil that explained the benefit, but I know what you're thinking. Those who use salad dressing every day probably also eat salad every day. And no, they were able to adjust for vegetable intake, so it didn't appear to be the salad. But why does the oil get the credit and not the vinegar? If only there was a way we could test that. Well, what about creamy salad dressing? They were also made from omega-3 rich oils like canola, in fact even more so than oil and vinegar dressing. So if the oil and not the vinegar, then creamy dressing would be protective, too. But it's not. No significant decrease in fatal heart attack rates or non-fatal heart attack rates for that matter. Now it could be the eggs or butterfat counteracting the benefits of the omega-3s, but maybe the vinegar is actually playing a role. But how? Well, if you're paying close attention in the vinegar weight loss video, the title of that paper was vinegar intake enhances flow-mediated vasodilation via up-regulation of endothelial, nitric oxide, synthase activity. In other words, vinegar enhances arterial function by allowing our arteries to better dilate naturally by boosting the activity, the enzyme in our body that synthesizes nitric oxide, the open sesame signal to our arteries that improves blood flow. If you remember, acetate is cleared out of your blood within a half an hour after consuming a salad with a tablespoon of vinegar in it. Apparently not enough time to boost the AMPK enzyme, but within just 10 minutes those kind of acetate levels can boost the activity of the nitric oxide synthesizing enzyme within human umbilical cord blood vessel cells in a petri dish. But what about in people? They measured the dilation of arteries in the arms of women after they had a tablespoon of rice vinegar, a tablespoon of brown rice vinegar, or a tablespoon of forbidden rice vinegar. In other words, vinegar made from black or purple rice. All the vinegars appeared to help, but it was the black rice one that most clearly pulled away from the pack. Black rice contains the same kind of anthocyanin pigments that make some fruits and vegetables blue and purple and may have independent benefits. For example, if you give someone a big blueberry smoothie containing the amount of anthocyanins in a cup and a half a while blueberries, you get a nice spike in arterial function that lasts a couple hours. Thus the maximum forearm blood flow in the forbidden rice vinegar intake group might be attributed to an additional or synergistic effect of anthocyanin with the acetate. But it could also just be the antioxidant power of anthocyanins, in which case balsamic vinegar, which is made from red wine, may have a similar effect, as it was shown to have remarkably higher free radical scavenging activity than rice vinegar. Enough to counter the artery constricting effects of a high fat meal? We've known for nearly 20 years that a single high fat meal, sausage and egg McMuffins with deep-fried hash browns, can cripple our artery function, cutting the ability of our arteries to dilate normally in half within hours of it going into our mouths compared to frosted flakes. Even with that massive unhealthy sugar load, no effect on the arteries, because there was no fat. And not just animal fat, we're talking about. About a quarter cup of safflower oil had a similar effect. In fact, the very first study to show how bad fat was for our arteries basically dripped highly refined soybean oil into people's veins. But extra virgin olive oil isn't refined. We know some whole food sources of plant fat, such as nuts, actually improve artery function, whereas oils, including olive oil, worsen function, but they didn't specify extra virgin here. I mean, you can see, smell, taste, the phytonutrients still left in extra virgin olive oil. Are they enough to maintain arterial function? No. A significant drop in artery function within three hours of eating whole grain bread dipped in extra virgin olive oil. And the more fat in their blood, the worse their arteries did. Ah, but what if you ate the same meal, but added balsamic vinegar on a salad? That seemed to protect the arteries from the effects of the fat. Now, balsamic vinegar is a product of red wine. Would you get the same benefits just drinking a glass of red wine? No. No improvement in arterial function after red wine. Huh. Why does balsamic vinegar work but red wine? Not. Maybe it's because the red wine lacks the benefits of the acetic acid in vinegar, or maybe it's because the vinegar lacks the negative effects of the alcohol. And a third option might be it was the salad ingredients that had nothing to do with the vinegar. To figure out this puzzle, all we'd have to do is test non-alcoholic wine. And non-alcoholic red wine worked. So maybe it was the grapes in balsamic vinegar, not the acetic acid. And indeed, if you eat a cup and a quarter of seeded and seedless red, green, and blue-black grapes with your sausage and egg McMuffin, you can blunt the crippling of your arteries. So plants and their products may provide protection against the direct impairment in endothelial function, unless those products are oil or alcohol.