A famous study from Harvard University published back in 1999 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. That’s less than half the risk of the number-one killer of women.
Researchers figured it was the omega-3s in the oil that explained the benefit. I know you’re thinking: Those who use salad dressing every day probably also… eat salad every day! So perhaps it was the salad that was so beneficial. But, no, they were able to adjust for vegetable intake so it didn’t appear to be the salad.
Why, though, does oil get the credit and not the vinegar? Well, what about creamy salad dressings? They’re also made from omega-3-rich oils like canola, in fact even more so than oil and vinegar dressing. So if it’s the oil and not the vinegar, then creamy dressings would be protective, too. But they’re not. They found no significant decrease in fatal heart attacks rates or in nonfatal heart attack rates, for that matter. Now, it could be the eggs or butterfat in these dressings counteracting the benefits of the omega-3s or perhaps the vinegar is actually playing a role. But how?
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Vinegar enhances arterial function by allowing our arteries to better dilate naturally by boosting the activity of the enzyme in our body that synthesizes nitric oxide, the open sesame signal to our arteries that improves blood flow. Acetate is cleared out of your blood within half an hour of consuming a salad with a tablespoon of vinegar in it. This apparently isn’t enough time to boost the AMPK enzyme, but within just ten 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? Researchers also measured the dilation of arteries in the arms of women after they had one tablespoon of rice vinegar, one tablespoon of brown rice vinegar, or one tablespoon of forbidden rice vinegar that’s made from black or purple rice. All the vinegars appeared to help, but it was the black rice one that mostly 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 one and a half cups of wild blueberries, you get a nice spike in arterial function that lasts a couple of hours.
Thus, the highest maximum forearm blood flow in the forbidden rice vinegar 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 by themselves. This could mean that balsamic vinegar, which is made from red wine, may have a similar effect, as it’s been shown to have remarkably higher free radical scavenging activity than rice vinegar. Could it be enough to counter the artery-constricting effects of a high-fat meal? We’ve known for nearly 20 years that eating a single high-fat meal like Sausage and Egg McMuffins with deep-fried hash browns is crippling to our arteries, halving their ability to dilate normally within hours of consumption. Even a bowl of Frosted Flakes, with its massive, unhealthy sugar load, it has no effect on the arteries because it lacks fat.
We aren’t just talking about animal fat. 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. Does this apply to extra-virgin olive oil, which isn’t refined? We know that some whole food sources of plant fat, such as nuts, actually improve artery function, whereas oils, including olive oil, worsen function. But you can see, smell, and taste the phytonutrients still left in extra virgin olive oil. So are they enough to maintain arterial function? No. Research showed 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 the subjects’ blood, the worse their arteries did.
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. Because balsamic vinegar is a product of red wine, you might ask whether you’d get the same benefits drinking a glass of red wine. No. They found no improvement in arterial function after red wine. So why does balsamic vinegar work, but not red wine? Maybe it’s because the red wine lacks the benefits of the acetic acid in vinegar or because the vinegar lacks the negative effects of the alcohol. A third option might be that it was the salad ingredients and had nothing to do with the vinegar.
To figure out this puzzle, non-alcoholic wine was tested. The result? Non-alcoholic red wine worked! So maybe it was the grapes in balsamic vinegar and not the acetic acid. Indeed, if you eat one and a quarter cups 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.
Michael Greger, M.D./Care2.com