Blueberry Blocking Effects of Yogurt

  asks in his NuteitionFCRS.ORG BLOG, “What happened when researchers tried to tease out what’s in dairy that interferes with the health benefits of berries and tea?”

A trio of Harvard studies that followed more than 100,000 women for more than a decade found that those consuming the most anthocyanins—the brightly colored pigments found in blueberries, strawberries, and other berries—had an 8 percent reduction in risk of developing high blood pressure. Great, but how many berries? As you can see at 0:22 in my video Benefits of Blueberries for Blood Pressure May Be Blocked by Yogurt, those in the group consuming the most berries every day were only eating about 6 strawberries or just 11 blueberries, which is about a tenth of a cup. Maybe the biggest berry eaters just happened to have other healthy habits that were the real reason they did better? After all, you’re probably more likely to sprinkle blueberries on oatmeal than on bacon and eggs. Yes, but the researchers controlled for intakes of whole grains, fiber, and salt, as well as smoking and exercise habits and a number of other factors, yet the apparent berry benefit still remained. You don’t know for sure about the benefits of berries, though, until you put it to the test. 

The title of a randomized, double-blind, placebo-controlled clinical trial gives away the thrilling conclusion: “Daily Blueberry Consumption Improves Blood Pressure.” But how can you do a double-blind trial with a food? How can you convincingly create a fake blueberry? A blueberry placebo? In this study, the researchers used whole blueberries—about a cup’s worth—but powdered them. A look-alike placebo powder had the same amount of sugar and calories as the real blueberries but without the actual blueberries. As you can see at 1:26 in my video, those in the placebo control group had no real change over the eight-week study. They started out with a blood pressure of 138 over 79 and ended up with 139 over 80. Those in the real blueberry group, though, experienced a significant drop, going from 138 over 80 down to 131 over 75. Now, a systolic blood pressure level of 131 is still too high; you’d like to see it go down at least to 120 or even 110. So, blueberries alone may not cure you. However, the fact that you can get a clinically significant improvement in a killer disease just “by the addition of a single dietary component” to your diet is quite impressive.

Is more better? What about twice the dose? More like two cups of fresh blueberries a day. Researchers found the same kind of significant drop, as you can see at 2:09 in my video, but increasing the amount didn’t seem to make the blueberries work any better. So, one cup may be all we need. Even less than a cup may work too, but we don’t know because it’s never been tested. 

Overall, there have been five interventional studies to date on the effects of blueberry supplementation on blood pressure. Put all the studies together, and the results do not show any clinical efficacy. Wait, how could this be the case? I just discussed two studies that produced a gorgeous effect. Have I been cherry-picking studies—or rather, berry-picking them? If you read the papers closely, the blueberries in the two studies that detected a significant effect were prepared with water. The researchers simply mixed the blueberry powder with water. “However, the blueberries in the non-significant effect were prepared with yogurt and skim milk-based smoothie…”

To read the entire article, click here.

0 replies

Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply

Your email address will not be published.