 A single serving of blueberries can help mediate the arterial dysfunction induced by smoking a cigarette. They investigated the effect of a single serving of frozen blueberries on young smokers. Smoke a single cigarette, and the amount of your arteries to relax naturally drops 25% within two hours. But eat two cups of blueberries 100 minutes before, and that same cigarette causes less than half the damage, demonstrating that a single big serving of frozen blueberries could counteract the artery dysfunction induced by smoking. However, of course, it should be noted that blueberry consumption cannot be considered a means of preventing health consequences due to smoking. This can only be realized by stopping smoking, or even better, not smoking in the first place. Two cups of blueberries is a lot, though. Yeah, you could easily chug those down to smoothie, but what's like the minimum dose? We didn't know until a group of British researchers decided to put it to the test to enable them to do a double-blind study. They had to create a placebo-controlled fake blueberry drink, so they used a freeze-dried wild blueberry powder to give people the equivalent of three quarters of a cup of fresh blueberries, one and a half cups, one and three quarters, about three cups, or four cups. They concluded blueberry intake acutely improves artery function in an intake-dependent manner. Okay, so what's the optimal intake? After the placebo, nothing happens, but after eating one and three quarters cups worth of blueberries, a big spike in artery function improvement within just one hour of consumption. And that seems to be where the effect maxes out. Less than a cup is good, but between one and two cups seems better, with no benefit going beyond that in a single meal. When you cook them, like what if you put them in a blueberry pie or something? The same remarkable improvement in artery function baked into a bun, just spiking an hour later since solid food passes more slowly through your stomach. And then if you eat blueberries week after week, you get chronic benefits too, in terms of reduced artery stiffness and a boost in your natural killer cells, which are one of your body's natural first lines of defense against viral infections and cancer. But wait a second, how can blueberries have all these amazing effects if the anthocyanins, the blue pigments in blueberries, purported to be the active ingredients, hardly even make it into our system? Women were given more than a couple blueberries to eat, and they couldn't find hardly any in their bloodstream or flowing through urine. Here's what's called a chromatogram, with the spikes showing all the little anthocyanin peaks in blueberries. Here's your blood before eating blueberries, obviously no signs of the pigments. After one hour, you start to see them appear, and a few hours later they become a bit more distinct, but all in all, just a few billions of a gram per milliliter show up. So either anthocyanins are extremely potent and therefore active at low parts per billion blood concentrations, or somehow their bioavailability has been underestimated, so researchers decided to radioactively tag them and trace them throughout the body. What happens is that blueberry pigments are metabolized by our liver and our microbiome, the good bacteria in our gut, into these active metabolites that are then what's absorbed into our system. So it's kind of a team effort to benefit from berries, and that would solve this mystery as well. Have you ever noticed this second spike in benefit over here at six hours? How does that make sense? Well, some of the metabolites peak in the bloodstream within an hour, but others ramp up more slowly, especially if the berries have to make it all the way down to the colon. And it's not just spikes at one hour and six hours. If you track them out even further, some go up even more. So like a day later, you may still be experiencing berry benefits as our gut bacteria continues to churn out goodies that get absorbed back into our system, feeding us as we feed them. Eating blueberries can so feed our good bacteria that it's like taking a natural probiotic, a win-win, all around.